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ALBERT R. MANN LIBRARY
AT
CORNELL UNIVERSITY

 

 

 

 

 
PL POCKET PARTS

DATE DUE

GAYLORD PRINTED INUSA

 
DEPARTMENT OF THE INTERIOR
UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, Director

PROFESSIONAL PAPER 82

THE

GEOLOGY OF LONG ISLAND

NEW YORK

BY

MYRON L. FULLER

 

WASHINGTON
GOVERNMENT PRINTING OFFICE
1914
WE

4G

>
lea
Introduction.
Location.

CONTENTS.

Geolovie Tela tions: acces cues ears eel apd tan noe on at taal ots abate dey iis oil aie ed ad shales te
Purpose of this investigation... . 2.00 < 6522s ssseselesdie cence as smbbeecleeende ceceeeesinegimcece boaue yeainee
Status of Pleistocene correlation............. 000000002 ee ee ee ee eee eee eee eee eee
Results of the work........ 22.0002 22 e eee e eee eee Peace LEpS a aoa SSO a aE
SCOPE Of this FEPOT tices anc weanieamirccde Meltoers weenie ies ac ovale g sistdinuaeeiuek's eos eis datapath Pe ee
Field work and acknowledgments............22.0 00000 c cee een eee ee eee eee eens

Development

of the geologic literature on Long Island..............20.0 00-0002 e cence eee eee eee ee dee eee

General trends acces b ess Yur daaeeeeecisecs se nekoek eck eee enis Samaemoneghueeess te Seems She ee eee
Literature from 1750 to 1837 (alluvial phase)............... 2-0-2222 eee ee ee eee eee eee eee eee
Literature from 1837 to 1842 (diluvial phase)......-..........-2.2.2--0- ee eee cece ee eee eee eee eee eee eeee
Literature from 1843 to 1878 (early paleontologic phase)..........-.---2----2-22ee- cece eee eee eee eee ee eee
Literature from 1878 to 1900 (early drift phase)................2.-. 2-202 02 eee eee eee eee eee eee eee eee
Literature from 1901 to 1908 (later drift phase).......-...2.-2..2 20.222 e cece eee e eee eee eee eee e sees
Literature of contemporary Pleistocene deposits in New Jersey.........---222- 220-02 e cece cece e eee eee eeee
The present report...... eA eal pial NR ad Pad aia ated Aa Nn So a a cata edI a hd Catt Df leap et RNY Re oe So

Physiography

Significance of topography......--...-22222. 20-22 c eee ee eee eee eee eee eee eee eee eee e eee eeeeeeees
General features.......2.....0...2. 20002002 ee eee cence e ee fain Sa eo BO AIIM ne 8. Ota ee ee TA fod Sek
Hornet thesland 232 teys coerce cancun < on oeann manasa ie ab ewes ene CREA em aiies Bema as
A SENCLESANVOIVE 2.x anced nce mernernaiene sire enw a5 See ARR RA RSE Sa 2 EGA EER RR EAR Ra TEER ES
SHaS GRIM CR: csi Seeeels Spe pees eS See each adn ee SER See Bee ee Se eee eee es
Northshore SCarpeen.cescensacaceccddules vec woos Seemes care dace meh MreaaenIa ae Ae aa eelcnneteneiale a Poe
Harbors:ofthe northi shore s.sjca-.ccematieve pce ug Antico seeee beg pce ama E eae as v dors casita tr
Shoredine-east of Port Jefferson... sce dsesocigeeeteeee wea: ss edadevewagedoee eseec is esdneckeweesess<
Peconic and Gard iners! ba ie\s.di. soasctscxe oceans Mee = Cee eee eK eo ES EEE eeeeA Bete
Outlnerot the: southiishorév. 2. 4 oenece ses sadeeseces nee ys vk Se oe eekeeun se cues feces ee ecedee see oe

Surface li

MEAME NS exeswie se Sees Bee aseocegieS Ses Devs SSeS ice ese MSS Bd SL Ses are epee gave Sood wie fayane Beabsebus caishass FEES

Tnflwence-of thesCretaCeous: oo vec ccc cis cca Suieaec cece sees £54 Seahbaueb nue: sosd Goose Meee teLe
Marinette me mnianteec.6.. so ceca ne o.o5c.00 aieheeickwdutwiebecse oR eo owemeeStaees Samhain aaeseees
Mannette: plat@dtveccs .crxinscecadiextiaes an ememneea eee scone Mnsemmies Se eee Peer ecee
Hills of MannettO:g1avels ia. csccscecaiecclesgecn occu s dese se clei Sadie es ge wad Eel taests eg el
Mamliasse (er lace slats Sesctatssstchates cesta tet rare chal SA ARAL Ee ca stall cre nr aad Shit PARI Maal nea EN ected i een
Higher plateaus. 2: ..s0«. soeeseeeees x 2 eese eadeeedeceee ty cesses per edekistaaw ests es areuresdeeeay ex
Lower-plateaw or terrace ewiesiedmese teteees ees veda ee ese esa nnese see eeesesu lee sas uietee dese sd
MORALNGS 20 2e eS Sates sein Aue ls Tan ot eh i, Ses i a al ha rect NS fe ree ah ads Ste NEES
Morainés ot istratiiied Ginits.s .cc2cc.c 1 aaendgdeaighes 2$4.24 sStdapesosaaeens cece ee eOeeEoeeeascs

Extent and general character.......---.. 22020020 cece ccc ne ee ee eee ee eee eee tenes
Moraimall Conesisd2ct.sscuec. cae s aetenerc eeAa Sas «Se cei eotiiels ake doa elses jo edeStete Sets
Paola tedscOnesy sccrsvsitil ss-uiote oop Baia e RE Neri lOik Se a ard Sra Moe La alates santere ¢ aclaldceiictinetyls Siero
Confluent comes ct caisaicle ds capate iid Bevaice sia hate's = watery pg SARE O Lilia aisle al amas Biesielele Sete
Morainal vidgesvee.sccevsscec2ecces sy exeneesiacke sees cr eeee seeders sess 2+3e0Rehcedeeeeeees
Simple nd g@sievccudwns cqeteh ss evammdeteree ty guistcaxexgucedee ss eeelevaseakcednegee sess
Dowblemdees: jess lak es detest hdawde ees ed bosibnie saniowet raise danseleceigssd Os
Compound tId p69 sc... cedse nsec ee ceeded ht onsen genes Si de Bice brcvonrvastiiticl ee Sakti
Depressed aioralies sc cast ccdt soe atee ee eid cman teetedeea eet cssemmaaeesee le ees

Ta] MOTAINES: <tc avis skews seer ya Shue eae ete cee Cena ooa S2acw ees eaakee eee s

General Teatures.iee ss ceceeaeee ye es ceain isthe sheen cae wee ANaeMRG eee Uiazataarwabieiens 2%
Moraines due:to‘ice-shoverand drags... .scserew seh eve y deenece eek eee xo2 eee ee eee

Pseudomoraines......-..--.-----0-00 20-2 ee eee teers mune bu abe Gees pee bee sk Gams eee eee 228
Iv CONTENTS,

Physiography—Continued.
Surface lineaments—Continued.

Outwash deposits adjacent to moraines..............----. 2020-22 e ee eee tet eee eee
SDP LOS EAMISS 0 oy eu. encene een ealose ara SoS a shanchned cena S Bs calcd DO RRS eA a ee a Hae eae es
Gon AST ta aie at csnste cratering a os lec tatet tees eg a tows ede Rs MEE ESD See ER EE
Outwash deposits distant from moraines..............---- 0-2-2222 eee eee eee teers
Confluent plate scc: vets ecehnce add ee ee succen (Aes aye ae dy eloucmemeeenas ane anneal ess
Compound Langone yccien Hades tse sid ek ousvael on eee ee sins meee ng is See anelealnsts
ECON AT YOULWASH: LEA UUTOS osc ccccis coe alge ae oon HEE PEM RES UES TS ae ESE
WOLTER ec sey foot Pe ett ek Sat Ps ye al ge SS STE AY fae Sec ne a Grd ae Rn cao arrays abel opens eT
Kettles of the till moraines: w..2 << 5.242 oo 4 tecmmnaacnan 2252S Si a4 Seedeemadadacesd +,ageeee ees =
Kettles of the stratified moraines..........2.. 20.20.2022 cee e eee eee eee cee eee eee eee
Kettles of the outwash deposits... .. 2.2222 cccenssencnnsny nese ssevemececeeees esse neeeaeaee set
Kéttles.from buried ié¢e bloéke.... 2... coc ccncniee dace sense ssa cneeaeecee saved teeeeeeeneeee
Kettles from projecting-ice masses. 1.22224: .4720deceeeeer ee eos sc ucigeeneer eee cae cee eeeee (3%
POTIQVE GOT acl snp state et ate ohare ha ant na ets we ose Daic A Nene nceSeed: tal Reh Rare nd Ne Spshcpenenta ice
LOS DNGss Olid C82 x ianeae hada eel oe Ve eaten ein bie cotemtae ld 2 Rha enews sie icia atchatabe toilets
MAG es a Sle ca ale PA ele ccrse net Nr cane tenet Aas atta eele Leave aN tM sl ae Cael ret Yeedeer

Terraced Kettles: o:2ccccnecnaccwn ote 2head Kemeedeaemat:

eG Ut GAINS 35: eouccccar ern ce meee ee Seen asada aaueeee

Double kettles and kettle chains....................---------
Keetilesvalleyas: seccasccaa: oa seatmacen eek e es Basen
Pitted or kettle plains. . 2 222020052200. sees goose eeacinceed
Kettles of doubtful origin............-..2.2----0-.02-2--2--5-
Kettles of the Manhasset surface.............2222222-22002ee eee ee
PERCU COKOTEOR sc nnsisictitete’s< w's:squiauis we be erneca el wena Se a wy at Anam

Pre-Mannetto valleys

Valleys associated with the moraines

Outflow chanel... 22. 2c ps sciecaomeceiu ged ses sa sauiddedas

Outer morainal fosse

Relation to kettles
Forms of channels
Post-Wisconsin valleys
Nature and extent of erosion

Amphitheaters
Notched cliffs

Details of landslides

Valleys in Mannetto gravel_........2.20.2.-.2---00 020202 c ener eee
Older valleys in the Manhasset formation.....--......-......-.-.--

Minor channel se. ccldis seca ea bo aishicsventetess antec saeeue

Tnnér: morainal foss@2.. 2s. o20.20 5 sees Oeisene eee eeesee te deuse
Outwashychanniel$icc ate: csv calnbeenereae acu sits ew eseuee

Forms of the valleys.......00..0-0-0c0c0c0eeeeeeeeeee sees ee.

Movements of clays.-..........2..222.00200c0eeeeee eee

seh Saniersvetnlig § Ris aca ca RRP eARRSH SiS Gus re gobs eo lee Hey Ble a Bea Siw elm we ee dele Sermepiese Yeycel ol GSS Scan ewes:
CONTENTS.

Physiograph y—Continued.

Submarine features. ccc scsteucanccsss sda wees d coy ve yes swuiidens be sess xendeens she a PA eee
Jsonip sland! Sourmd inset. secaew.cais ned oad patie aie oS Sn Samra nceeee Ga ok Recbaan ge Pe agaeeey Reka?
‘LiveereatsSourid: Valley. ciccc uc 2c aN ela Rae ae OE aS Sae oaRSOe od cend Sees LS

Hater channelscic:ccsccues seeps eagerstqncdok exons MED eeReR ELE Es C4 MeGREE SE Mane eCeKe esas

Corie isi OTs 222-5252 nal pena ecpetel te aaa ea Nest aa estan sca aes ais ch ise OR vee eh abe Sricsdcde tae aagsnES
Submarine channels of the Hudson............ 2.0.0.0... eee cece eee ee eee ee te beeen eee
General conditiongin... ...6355.5-4sseeses doe ose bdneee nce Sede ebeEde dee ey essseaeeebdage ssl lss
Channel of the continental shelf..........2..2.. 200.22 e eee eee eee eens

Hudson River rock channel........... 22.0.2 2020 e eee eee eee teeter eect eeeeneeeee

Bastory of the: channels iiiccacticciasccnmitcnesicsearamniend cee eaeeanw ei es see sane aeeeels cas ee
Agencies of formations s2cctds.sucise lsc 5 ohhdaae nel’ vacGuleuaeseubeees ses ceuee eee veded ¢

Cutting of the'700-foot:chantiel os s..cs02% 2s seevwasedexee ss sds aceeddages sey asedeesesseee es

The broad outerdepresslonise.. cs s..05: cna eaet stance sas ateaeiaekee 646.0 aaeaciguaise: $445

"TNE Outer GAany Oi. iach. g ova raragin cade 2 « cela sbamieuaaladieus mae oe SHORE Beane aneuledes e206
Obliteration of the earlier channels. .........-...22..--222-2 22 eee eee ee etc eee eee eens

Cutting of the present upper channel...............2.-00.00 22-220 e eee eee eee eee eee

Hilling: of therupper channel. ci. ciscce tergccteisto ea euie es coe oreelslavesedieis oyada eulacdwiaceley ys ¥
Stratigraphic geclogycnhs shaves acoen  pelciaseceeeeb cee nadeeeeeioene ves Fe tgeneeaebie sy ess ye ereeeeneee res
Method of mapping ses. c2..00es5i cesmeeseeuand ever te lesiGeedgey bie ted p peeeeeeh Gey beer saceamseene tees
Pré-CretaceOus r0CkKs civics sistas 5 bseatidinee aciels 2 aes seawdadwldd ev osaenmbeumlléds bie ud siacaneiegs ze
Cretaceousisystem -s..o0265652205 2204 WeeediaiwaNe 24 < 2Gutanse ceeds £54.50 SORMaSE ONS He ota neeoedene as
Character of the deposlts: <cscncvcongdcseeesetes 4a GbR ateiiaiis i. cee aetheededseescoteeasenesea eeeee
Distribution of Cretaceous deposits. ..........-- 22-22. 0200 2-2 eee ee eee eee
SUTAGECULCTO PS. 22.0005. oes ee cece bas eae eee ee eee Mo(ereisiooclas AR MNGM tla eae

Pls POU G asc sieeshatelnig sierclereeisle craic dele’ u'a!| ng u ap lpheteeeabmeectees assed deGeseys oes Guneeatwekewe

West side of Hempstead Harbor. ._.........2.....- Goes Ste ha Se SRA Sasa See e SS
G lei ICON Gr faites Aa et eo he aca cul acted Sad eee eee es wos CRO a a am 2
Peay CMTE ese cama ieee cr ate oS Ae AUREL S Ue een AR AU Aalae Ae heme CMe
Wat O GO Wil wencunciados eesdee nding AE oie tart asues Cred dh meres aaa eee eee eeee ceales
MANN GG cas ba 3.54 Sa atedipinth glee a Seu ostousAdedinse 2 Ses see emma ecisiles 1) 2ccuemnameee sees

Cold: S pringvHarh OP cacsccceeinwns eat eccmemeeser sees Gos acest s ar pe aedebkles eae
Isloyds Necks: ist atwcaisnee eae eel ae stenkehile fesau peuita tease ss be das amy ee ate
Great Neck, Huntington........-.. eed 4 Helamereebureee dices PeRUESegisk ee EE Ss cewRba Gece eds
Little Neck, Huntingtonsscccuy 2:23 ssavhereedeex ev se bsar.4esobeseeed spies cesseeaeuplog ssc
Eaton; NeC@kessiy ss sviaceteeiden ety aca Seueeceuiess sees opkameceeuigre rad aaaiuneele eae dou
Northeast: of Northiporte.5.4 cciccen es tee 2 ura eneenelies 1a ek add Neidebuleined acs,cuenbenemeaxaese
Disc Hal Soc ieteescmsnine oe ie cstleaas ot Saag ehamaenees 2 eceheabalena tes aca e warpatee mace
Wiyanidanelics aietsceu iii ss a5 dc sesh duidade Sete. eeitidh eat ated s Ah eee eee
Farmingdale and Bethpage......-..-... 222.0222 2.2 eee eee eee eee eee ene cee
Melwall@naocantsorcsecniee) 4: ei ates a enemies asa aaeenemcncat eS Pe ae Oeyieee lees sees
Cretaceous deposits penetrated by wells.............-....-.-2- 2222-222 e eee eee eee eee
Structure:of the Cretaceous bed sic soi. ci: 2osemaus ee wes ct eaaew he ev ey sed Sneek ee eeyetacd

Tertiary (7) SySteMis es cotancerst ehus py eseeeeceteeee yess se reseecseeeeae es pulbcu a ndscsuenehars geeaee
Distribution csccesex0s2eeecceie oxo e ste ae saee Renee SESS Some eme ales s+ oe ois eee Shee ees Sh ce
Hocene (2)series i... ac aewwseaues, was ancteleageake Estee: poainedyeeebe sire tex eeudemes eeue tex ses ean
Miocene (?) series-...<.20s+see0 0222+ +1eenbeeeeede pe ecleye tees ew ae rents see SN care ease Seas
PlOCeNEe! (7) BETCS snows sss sass keaaeeens eens esas eae E MUSE Ese Es eeeede Fea sonst Cais Spleen wee

Lafayette: (2) formation . 42 2 -t42 4 aeieee ete es 24 caadeoseanee os ose he ccd ade ieest Aesnae ae

Quatemary systOM. aiceccsiewe side $4 Sas se eaSeE HEE ee NOK oa RRR cae eee ks Salsislaa cantare Sete auelss

Pleistocene sees. ssasnshiciss o22 2s edema aeusienioees these atruWaRtedt2 4 eee ARC owe gee
VI CONTENTS.

Stratigraphic geoloey—Continued.
Quaternary system— Continued.
Pleistocene series—Continued.

Mannetto gravel— Continued. Page.
Structureck. atau gee ua 5 ce ees batts 8 Ste ee ata atl ee, a ui sl slctebciale edeurteaslelwialass 81
Distr butionco 33.22 s Fak sean ot assure eae ewe and co bi SAE SE ee RASE Eo Eas EES oe ee 81

Outcrops in the interior of the island...........-.------+- 2-2-2 2-2 eee eee eee eect 82
Melville: « g5ccuneces te meso ce sete Dao AeeOe EEE RE Redmnine toe tee ae ey Pees pec 82
South end of Mannetto Hills...............--22---++- i npuhadlabaieas sy CaERRREee eee 22 82
Half Hollow Hills..........2....02---22200- i GU Reradasien ieee es at caeeese 82
Dix Eile? apc octet ee shell sal he Ata td win tsnareeeee ee Munem s 82
‘Whieatley Hillss scien a a cue ante lun th eee eas Ditasader cms GekasaaeMeetee es 82
Knobs of the north-shore necks.............-.2.-.----2-202 2-22 eee eee ee erent Meee 82

Outeropsrom the coastic 2 vies a nec cndekigdehises See ad gs ocueebieedexerss¥- deceseeee ses 83
Broken: Grout). 055 so cacdcdsa cc andose doing so bo elen : ada deehe ee seace reese ees 83
baton N@CG cocconcucse it dacobceeewaaneeenaySbhedts J eenomueeeae ees oAaEweMe ee 83
Little and Great necks, Huntington ............-2-22.2.-2-2-2 2022-222 eee eee eee 83
MNOS Ch IN OCG 8 on scree atiaencisies crack 2 asd SRST AOS CRS Seon a Ae aS Sendo oes RRA EOS 83
Hempstead Harbot 2.222000 ovis re ostcredeaw si seeene ds 2 cacmenesets So de4e Meee 83

Deposits penetrated. by wells. cc seesicrecs cate teieaiailaiewy piss oe cos LOOSE STAR ea Renal 84

Ap ee. dzdaro ios sae Aan utters Ding a dettge Gabe kenige hs vows tabawaniiminne aeae eS Eeee 85

JAMECO STayel as... -ertanee eee eee eh aS ecg ae neeNeae seo see ne ee Gieerd soe ore Gime 85
INeitine sc iso rata gheaiais o.9 3 Genet ee dive ew a 0 ane & app a la te Bw a aly cede eee eats lla chat tates 85
GCharattety ss .vs 225 .epcguewee eeu s sess fa aegageaddeewey ots 4 ese eeuingsealdeeeaesseeeees 85
Hource Ot materiales os. leek eee sd be eaeke cate ea oe EG Bates eee soe kaeeene 88
Relations to older deposits: 2 sis iss sede cc enneasidcegadid ese 2804.09 4 niceeds gab esi a eseauenieds 88
SUCHE 2:2 sees 222 eae ued 2 odds J eantneakg ae FEE SS yee RE uc erences 88
IDIStEIUEIOD Sc 2.2 <tiee2 ooo aS SS Be 28 aon otenareels RadllcaveStd-3 se ne aera aia ada iets 89

Possible surface exposures..........--22-02-- 2-000 e eee eee ee eee 89
TaCOb Milles. cease aatena sweaty Dosa ER IISA NN the RNC Ses 89
Mailiords Pointe snc cenzcccabeax'ys-02 5 rsd 2 anstatoeeteanieieianeele Stdatersid ate Aa aRMS Aten he a aatdews 89
Monta ke Point. sues tngncamenias = cwalcels Sam tatte eum mire sects ae aod debtors seeseeees 89
Hog Neckvcx: ss eenseuededecxsyees<x25 opnturcemeed dave ys: si 4 eae dee ses sede 89
Gardimers Telan duce itt ee ula ae aus tee aa eater Age es de shit later bs case 89

Deposits penetrated by welle.s ees she gees acieunie ecu eS walominalemesian 2s Fe Smeke 90
Wome Nelo 2 isco 2 5. acangadeahs sieoe Medes Aa seeete caste Siae ale ot £ bee O aye eae oe oe ean 90
Plum, Gull, and Fishers islands .......-........22.2 222-2000: 0 220 c eee eee eee eee eee 91

AB Orcs naa yee2ccieet Sea WAioleceee tei 2 cates 2 Py REG Caer ees 1884 Semmens Bee oaEa 92

Gardiners Cy iestsc23 229% phananddninnesteh Ditta03 coMpeemconsads sees s Came eaeEe ene aos 92
INGI Cie es aha Ge eee omecamcee se Sue be eed ene net Bek geate ween ee ees ade 92
Charaieters ac. cons seis ace cee ae tial Sl wales atethatancleeaexe eggs Seem SS ooo 93
Source of material.......... Powe disease soos gp sepcieeeeleGeeE ee netted GeMeeaaees oie acces 94
Relationtorolder deposits 0 p-ecesesgrceds est eeatunsetees ded eset iy pegaddae hee bScceqmnes 94
Character’of the upper contacts... v2 sect cs ics es toe vheesmee se oe eee Qeneeeune asoeeeeecere 95
Stricture: + -s2c0%22 220s cee eeeece hie Soe Ses Shs Shee kwdeeeeS dae bc 5 Atoms eneea ae xinien 95
DIStrIPMtODe sold sees elope otiean eeu ee esc ad cae ele Se eae 2 oes e eee ee eeeee uae 96

SUPT CENEX OSUTCS scciois acacia onsale iad S526 cid Sy. $ hve unmleiceiguted area Se eae Dhaene dasete ele yavats Meochn 96
Hempstead Hanotco.2asJaespinn 2a: Ge dhs atenemenaneettGuelg: Sa wechbasg be eines 96
Rocky Point, Cold Spring: Warbore sc... .cnescecgoccsiseeiiene ev poy eee eee’ seu cs 96
MWNGVGING Chey S11 ea pamiasesbeat be SS oe see enBeLer acs acl earileD te ee 96
Hato N@¢hks 52 teacracesamas ib ate ax oe ah de eeglaeheie ys See dos cca debise oe ce cence 97
Woodhull Landing ....c2.0e..c.sey<'ne x qaeteeeibeeencta et deeds sates ieee eee SSS 97
Rocky Point Landing: ..:202tsseensvex2s¢ecepecucdiek ts aitrsakekuwnanns aie Decrees tee 97
Hallock Landing) jo: :egdv eran Seecbs toss get enetneenme td -ceeueeeces Peete nea -. OT
Reamoke Pomitec. fo isccacc eases eo nad 2 saanacee ee Sees alaaeeatvenne acs veered. 0 98
Jacob aM 245322665 cet cel unkielos s aay eee a oeteBeuleees ve maekage ¥ehs $a maeleed 98
Brow Hille) 2o2...5.2casnanancdewe nae oR aAS a Adtlaveeene g emi tiets v nad ahucteilna 98
Robins Usland se.222annnanieceseGiGuetnn y namoe dee te dee cetcicuaiiie Yt a cgotemeed 98
South shore of Great Peconic Bay...--.. 2.220.022 concen eee eee ee ee ee 99
Hog Necks .o. 002.25 seme teng vere teu et yes deel asig ied fa ceaeeskasektas ye ae Seats ees 99
ae Mantes esas eed oc ke avai sackitioe era satemeaees wee oe couabweieuitece 99
MOM GAT Ke cig a coh estes INA 2 cig ola Sypdng alten are ROW Gashaulinbaon “od cea BR eens & 99
Gard iniens: Uslaiids2% x. nysndwedehe cont ele paren cca adel calc hd cncvdi enue e ale ox oe ge ate 100
Pl Ilan dye sere neyo ae cries vas once Rule sed eeapee hes Jao dann k wy kote 100
CONTENTS, VIL

Stratigraphic geology—Continued.
Quaternary system—Continved.
Pleistocene series—Continued.
Gardiners clay—Continued.

Distribution—Continued Page.
Deposits penetrated Iv wells........ sim eae td aig o-SReae ea sly eens DERG EME o Corian aaa 102
NOCc oc veseee ce 4 nse aerebeee ee sess 4 Sade ee ee eee soos beens ye eso eee 104
SACOM SAIC ete se estes Seeigats Sede ore a Se Satispshaes eae Pedic H Beaauayoussani’ Ys HAGE Ree EOE C ORR 106
ANG IMG aos fers ae Seeii2ee ep acnajn Sete c Sa RNs Sante ws OIG MEA aces ae Raat aa aC AES 106
CAPA Ctetiie.os cet ne nontemoeeedt scam castanhSencaaseeodedsad caer ere aeceaeamem ee eoer meer 107
DOuUree: Of Material acrecpnsca ceils aes oe Alaniareeekduans ode eacsievange edngite. tate aie Rahal ware ealee elehae 107
Relation *tovolderd eposltsi..vise14 oeieras Meee ea opaseae shee es oleae se oememeucee nce sayas 107
Character of the upper contactsscssceus cxadswacedaua eyes es paueedee dae ooeusesaeeee ws eb aee 107
DUUOUUN Os oh oo ote a vere sssiarayepeis eee Sissd 4 Musica deoheaguecd base b Po See eee FTES FP Dba eee Me AEES 108
Distributioniss5: ashes. cghaeeeunecst stan ann Gaeshul esses] in apeennhSaelases eateeeiseceas 108
Surisce Cx posuPesyiccsecncsau ses c a mated ces ie us} PRC aRS SG eT ea eeeeewe ee 108
College Points cc eoe ep TR eee eats noes HERE MSS aoa vn Salo aceRR ee 108

Port. W dshing ton ctecsquecv sere eielglnns Hod aturnceisae sous va sae eiee ewes tdaedees 108
Hempstead Harborscssrsss< sass noeeemticn sys ne doa eiaekser nee = Sb aseueeenesee ieee 108

Ory ster ay seis dynes oes sacl eels Chee ed a 6 Geno RS Pa aes Oe 108

Lloyd and: Baton weeks. oc vnsiec veicce wield 22 52 cet ae eooaaed Pass ba ade eldee cdc 109
Northport:to: Port Jetierson 22.340 cncaseseawsy ces chaeminemeinacas- dade damaniasdeened 109

Port Jefferson to Wading River_...............-22--- 2022-2222 e eee eee eee eee eee 109

Wading River to:Orlent: Pot s2.c2cccacecuuces os pe cea sled wewewe ve ced seen eeeeueus 109

Robins -and'S helter island s)s..<«ciaeaserseqsiciesel coc ss uve hero vides Siddeete voce sles dee atebioves 110
Gardiners-Islanid:.3.cie2 sete wn ja attnnceemelie ved oa kmnise dewey ee heb ee Se epiieedele ns 110

South Blukelzigeg cue i 2 on code ona U id aie aul A oat een awe Ne eons eg 111

Plum Tela jpn be o vs ook eee ae ee BES Senha weds od bo hp amebiosele lil

Bivelver'g Tis) iri hiss ta i 8 repeats eS ce tages hau yacavbes daeaUale ued Eek Dk dep 112
Deposits penetrated by wells........-. 020-222 ee eee ee ce eee eee cee eee eens 112

DAE Fein sp AS SAC re Bee oy eMC laace Bae Cet ct che byical NaS ete GUEVARA ED ee alan nay 113
Manhasset fommatiens <n o2ccnccccsnaes icon mee none Gere Se eees SoperetnTE Kee Sees se etmaeaen 114
INET oC SG SNe ae cena cag ead tea ae arco SSSA TENET Fees“ SaU ESD Ena PSE pete dna Sten gnc Te son 114
SUD GLIGVAST OTA Beet cere nsrcaet pees ceo orate oi stat TRAP NNN feat Marae ava ea rd chested Matas tekat crema echhasetiead 115
General distribution augas sau es 22 ay phe pees: ed nes waneRmane see Meese eee 115
Occurrence north of the Harbor Hill moraine.............2...0.00 002002 e eee cee eee 115
Western Long Island 2s: 20)se252esndacceahw eet oo o2cakaienaaccenGa be aeesec au ewece 115

Great and Manhasset necks, North Hempstead..............0..2.-.200- 0022 e cece eee 115
Hempstead Harbor to Oyster Bay................... sa ee neces Rageiedanns Aanaee 116

Oyster Bay to: Miller Place: 224 :incsec0% se camseawaauae ne ec ena ceaiawaacienetea eee 2 116
Occurrence between the Harbor Hill and Ronkonkoma moraines...............-...-.-- 116
POSH VA LO BL ON teacher Ach ch created ls nha: cvavsa tang HeLa cane bladetalecvte ela neni cactaeeyats 116

Huntin ptoninecionl.as2i.2 see vie ues donee a baee evs sa wraeeecuon eases se cea 116

SMIth town Tes OH ace teu ae ene bs seas AeEGER Rae seeds exw eeee Senses s paaeee 116

Port. Jefferson: repiON we.c.c.c2 ves ees so54o atewe dang c oo e Oona beh ey eeeee as bee l anes e Daken! 116

Rocky. Pointreri0ns..c.4ss0 se oss bance ceeitaduuad os bo hens diatla tuned biedeeelawoes 117

Wading: River recon.) ssssciie ss oc2.c.cc. 08 Semsawaded Be a6 ns A AR ASMA CAOREe ae ESAS 117

Middle: Island t6010it.....c..cccananc2 a4 acavmennaeeraeennt< ont mumteeiean xb eke eces aes 117

Fresh Pond Landing region.........2.. 222.2222 eee eee eee eee eee 117

RUE ESE STON a wach: svsstsrtec asa avavsiba si anhavahs iotensicka, eee rota ele ie lela chabchen deeaisnave( ars Dele haeleran lanes 117
Mattituck recionics- ssn joc y onc cas Woeenlaees 2 aoe eG eee Mee ee eeen ess SRS 117

North shore from Mattituck Inlet to Orient Point........................-.----.--- 117
Peninsulas of the North Fluke and Shelter Island.......................-.-.------- 117
Peninsulas of the South Fluke...........22.222-02 2020202002002 2 cece eee eee eee 118
Occurrence south of the Ronkonkoma moraine.................02555-..2000 200002 e eee 118
Tempstedd terion: 3..scccccsccie yaa eee BES Ree ee Dat ena s 2h OSL eee ade 118
Bethpage region and Half Hollow Hills........... be Sead aye etc HORA EEN tev atetecetsastatel Peter 118
Weyandanch to Central Wslip jones ess connie tiebey sc sectsh Mee Rea Ee eoeercds Soe 118

Central Islip to Yaphank.......2....2. 2002022022 2c ee en eee eee 118
Yaphank to Shinnecock Canal....2 2.2. sascanddeky sbe5 pos Fdduked nyse esa sense cue 118
Bridgehampton region..... ddl dd $58 2d (bra wiesuensielenshe Bete Lt Bape DALES ARRON 119
Amagansett region...........2...2.---.- RoWATiE GAS Aas cee Same eee eS aie 419

Deposits penetrated by Welli.c. casio. eee vs cenmeecwes vied eee Mae eee ede eee 119
VIIT

CONTENTS.
Stratigraphic geology—Continued.
Quaternary system—Continued.
Pleistocene series—Continued.
Manhasset formation—Continued.

General distribution—Continued. Page.
Special features of the distribution of the Manhasset formation.....-.-.----------+-+----- i19
North-shore belt ...0c2cc5202 2220225. ceaecpeneceaee cs sewers HERES E ei oe ete eee iis

Wilde elem Wel cscscacaie ou acu uncien siteiodemensenidvacs badsdemmbeeddauecs seers da

poutle Blk Weliica-ceuac seve sescesde Uadeaumucommenatacussqnacecearemarssenesaes Teh

Herod gravel member. oa-cteceue ve vy cess cayg x ececcmumaeuivoiisnni ae Guanes hosanerase ss 86eees 121
ING Cs ndge eects uh: SetSwene ose Ride 56 bs BER HA a oe le ee a ee eel eee Stee 121
Character sss ca ccinsic ce deus ceed be cers Leb biGeanuaee eee yey sees «Pewee apes ee tea rele 121
Western Long Island. ......-.-..-2.2..220 20022202 cence eee eee eee i21

Central and eastern Long Island............-.-2--2---2- 20-00-22 etree teeter eee 122

SOUP Of MAterIall a2. .ced murine bead cay emaunnaadne ae oint Sh sates aaeeee aes Pee eens 123
Western Long Islatid <2. .4cccccaseciacsenneanmeoeree soe aes Milk bee Ste Sse TS 123

Central and eastern Long Island............ 2.0.0. .00 20020022 eee eee eee 123
Relation to-other deposits... 2.20: e024 2 eadavsouewecaee pad eye Rls eee DOERR eT ee Et 124
SUC hare biti ane ctnceanranea Ar ae is 5c oid a een ara Runa tae wean sees Beene tease tee 124

LSE DUE IO Mi ety aencnth gpa ta x We ae a RR Baar daa Bataan aie abi nce RES MPA 125
East River to Little Neck Bay... 2.02.22. -ccseenedaae ouees ee eae e a eee cee eees 125

Great and Manhasset necks, North Hempstead .............-..--------+-2---2+2+-0-- 125
Hempstead Harbor to Oyster Bay.............2.2.22-22- 02220200 e eee eee MAdaiee as 125

Tioyd Neck to. Northport...2< 22222022 4sacnscddidesetineee ss 92 teases etenunemanues ose8 125
Northport to Port Jefferson...............0020. 20020 c cee ee eee eee eee eee 125

Port Jefferson to Orient Point................-.2.220 00. e cece eee eee eee 126
Bethpape terrace s.°c2mecccnc cae ec oe Mea mes eee Se Sane eae 126

Bas teria dong Ns) dst. 2as.seiecs sooner oa dees Nosetaachatsecnno steve ais as RSS Ga SR a Recetas 127

Roc kawaysAnid 96sec cash te tele «ta etee CEB BEUM cove 2h selacclmns Suabhnde ee asset 127

South Pluler. cn. avewwens ss saeeod pweee eo easieeees sea ses pe omen Ue eee eens 125

Robins Island asausen se eexe ld vekddaeded yee ake dees uly 22 ese ds FAMeRee hee eke 128

Shelter Tsland 5 sa. vxcve sees ope a bey ey eet bGew eae EEE EE SE DAG SP Salsmcwietund o¥eeee es 129
Gardiners Island..............-- 2-2-2200. 22 eee eee eee eee 129

Blinn, Tela ose disei lsd he Fo. $508 4 ae cea tees ode os See anit. geeeened Ae ead Ae 129

Hisheral lisland ojo seins oe-26 Gan seh aQamaeneea scans 12tebe ahasenteeeuaienetoue 130
Deposits: penetrated. by wells. 0.3 ove2.css2qneniasascarnenetiss sess puapomia ye ere nae 130
I i pian daceapreeearcae eae Sen Ee WES SERNA Hee Wu OSG di acataes matics 132
Montatik till miembet ss, ctoiissedie gan nde 546245 eR aeedeeecee nda bes eeeeaame ste adlats 132
NIMC: cre sedizs oan temnamadaiea AER e tthe ba Ean mneR Beem py a eee ae Shatslette Minsle gle eeigia ae 132
Character. 2022 ss ccs ncwuscciceeee ye ee ees es $e ewecoeeoe ess oes ed enledeeuisee ees zee dae 132
General compositiontes. cccccscceu se ses secs cartes vcmdiuneny goleed FRBOREERE EEE S oeuce 132

‘Till and eravel Phases. ..:s; sate cease eee ss eel egw ele eee ss sagaeneeeins os oc dcee 133
EQMIMNAVON: ccc scewcauccies ev orvenea todos emus seu swe means tL wees ok 133
Cementatlon i. vaseeececaniec : opr ee ws aes eeeieaine ty aes Joe ede Boe Laden dee 133

GolOPiccinted + cesswactacs cheeses cee sess Zee Soubeca loess: ca babaedaceiwearenvoced 133
OxidatiOnwiy:s sc. semeeteadedey vuvers ch shen odeiee soe 220 5 eeneaeonaa sa edariae 134

Source of materiale one se neiereedewe eye Lota 08 nadakhidiedGe arses gee raadecs bones oe 134
Relationsto other deposits. ......-..- 2... 22.00.02 e eee eee eee 134
UMC HUTO sacs ste Sine d see peta Mesias oo 8 Sie. oe beam e So DSTO Sos ea RA eaten 134
DISH DUTON cao secays tedemnsnoniia Eee he sae See seeee ese opt awEbal gues sedan anon 135
‘West of Little Neck Bayes cccce uy secs sie s sais vemeeny es sees ¢4xveuiytbelng-oee tenner 135

Great and Manhasset necks, North Hempstead...............2...0.2.0.0.-220---222. 135
Hempstead Harbor to Oyster Bay..............2200 0020000 135

Lloyd, Necks saxicerettiterutds = test agacinoe diss Seles Sedin 24 evens note waaay 136

West NeGkiy ¢ ejasa eure op oa: sue este aseak Me ba2 acca cigmancteb nace due Weenie 137

Little Neck, Huntington: .0.0252 22.2 2 aidneapenctecat eevee sa nawedbees eveacdens dick 137

Haton Neck and VACinity.. c.c2s 25.32.24 A neeamnmnecagaineeee one oAuawlee een oS sa Laetninie s 137

HOre DalOU Ca 2g aie tutes clases Oe dan an Sato he ie ow wee he i ab em gl ee 137

OMI Own. Bay Teslonls 4: eeansvews Siw se se leaned ye Yaa Lecicheldics eoaaunraewnetens 137

Crane Neck and Oldfield points. ...........2.0 000000000 oe cece ccc eee ee. 137

Port Jefferson to Wading River..... 22.2222. cece eee. 138

Wading River to Fresh Pond Landing........... 2.000.000. 00 cece eee eee eee 138

Hriars Head: . <. ssc ecsaecieewkas ys na: 4: i sakwaeanas ooeieeeoadca RA ae eos 138
Roanoke Landing to Orient Point.............00 000000. c eee cee eee cece cece eee. 139
CONTENTS, x

Stratigraphic geology—Continued.
Quaternary system—Continued.
Pleistocene series—Continued.
Manhasset formation—Continued.
Montauk till member—Continued.

Distribution—Continued. Page.
Half Hollow Hills:ssis.ees.0se.ccceeeeeeueae tac te sade acc vobx dedeebeeeee seas 141
Middle Island region.............. Bien ea SeY BS oman eiakle Hens iiatereans gee ass 141
Red :Ceédar Politic coccsonmche de Quod seeders ance mageiakises + 5se nbeGueweun baed ise 141
Shinnecock Hills and vicinity................0 00.0202. 0 00 eee eee eee eee eee e eee 142
JOSIP NOCk sectors acai cies sintmingacnelsd does s tne doeddanals ale eee ee ES ES 142
Hop Neck covctesseuwesesss cegusweseekeee ids tag Sunstein ee de eceedeueiakicey sess 142
Cedar Point.» :.asende sss sseaeeveceses tose ds cd Simneeeaeks eas pzavegeasiaxsedses 142
Hog Creek, Poititecscise 2 Ss5G crs gpiaass 2245 40s tacit evil an Gk Sua bedda Sse osd 142
Montauk penimisuliiscn 2 onc jegeceaeltieeleed 2h26 tote HME. Lee ee hy A eee bie akd 143
RODS Tela ceccccaesvi cc omoncaiacsettacas moneatiad Odd dea daamnsnes ete tans 145
Shelter Islands ciaistsnciss eens tesa seo ee as samt Ee Se eeeeeee SEES 145
Gardiners Islands .ic.'icice:. cos os sesecmisbaitses Sova an gncptawieues seek eaieeeeEearen Ans 146
Plum Wslandsicecveceseesxe esas ceudwcheeen sede: ee deneedeaie ss esos desececae eyes 146
Fishers Island iieacs seoses 222 ou cameehese evs os2 nde seebecdees Peeks ce eeiveeedae eee 147
Deposits: penctrated! by. wells. 2c 0 cceadces esc os Sesion ehecemie oes eaeemtabeene rete 147

BE scisnss saa 2 Sebeicvole Riwie va ES dest avetemayeumemnoand doe BE. ac ravbehlcsiasia dee ad Sa Sad aaron eee eee 149

Hempstead gravel member.....-...---------- 2-22-22 2c ee eee ee ee eee eee ee 150

NOM: jentrtncns one ceeserey SOEs vad eee edee ee secu E age os ee eee 150

Characters: scissncticieaaas oes sese UpRotees Sees Wage PSA Re a LL Coe eeeeeeae nes 150

Sourceliol Materials .cciiote ss. 2 cols wsciteichaecieine dls seed eMac dees pee ciclciale eases see 151

Relations to:older deposits. sesso s.nace vaneceaay vas regs iMoney oes voces eaeeaieee Yes 151

SHUCUIPe nosh ener ete 25 cae ey oes esd 3s teresa eee seg eedetee ee iS. 151

Distribwtionis..c3 4.2 sees ns ee ded che dieun debe Shc si ecmeehe eee SSSA Cae Sone cle pea ae s 151
Relation of Hempstead gravel member and Montauk till member................-.... 151
West.of Little Neck Bay... ssacesoeencoces-. dh etdaesene sates sae cteceeeneees 152
Great and Manhasset necks, North Hempstead................--.-2-..-2------+------- 152
Oyster, Bays as..ceas Sic ee Do veasmenns bas he ema exewmamene anes ceca anaen osetcen ess 152
DloydsNe@kicuciiecs: eecds sieriaudee pees eae ag Rede rea ees Dees see eet tes 152
hhittle Neck, Huntingtons, «:sc2cejiceurstes es cease dec Mane cadele de oe meus caddeltae ayes 153
Smithtown Bay regions cnc.cescc2s%eeees es cece sstenwdscdenee seeesse rene eaciess 153
Port Jefferson to Wading Rivers. . ss. sss0 +24 se+-s2 execs sees ves see ses busteesaeess 153
Frias Head. 3200s sss eanetetes Wee es os seep see Sauce eee t eee eee eee ns 153
Roanoke Landing and Jacob Hill............... 0.0.0.0 e eee eee eee eee eee 154
Oregon Hills and) VGN ss sce coca ale2 oo: i adamaaanscahGdes ? bandSscteeeekWak he 154
Rocky Point ncansstdicds tie nob eeiinat ato .ae BORceGReWesGaser esc canna aenanises 154
Riverhead to Sag: Warborie.c sccassceccgees tess sips ecaeeae year va emesanemGis 154
Hog Creek: Poin tie sisre ciate x stetsisislcoscanieae iene Suiatesattaniiatlds de weas oaecieeeede ue 155
Montauk: peninsula... 22 cvcxeviccttecwws +s sea ae Datedeuidauae sores 4c ceemecedea eye 155
Adjacent islandsic: s2c00: wesueeseesdsawes tesa ceembanteetaus bere ue sede eenedsey es 156
Deposits penetrated by welle..coc.sssccaws pees sean gewceeddese cesses ete teeeeee 2:4 156

NGG: prcins caiusume caustics 23 Adages Sec weine Shee s miacereemletsag said Ame epee SONS EES 157

Vaneyard formation: 220500222 nc netinnssaiecasesa cee cetecieeeis Arsehaies Skee aacaeen beeieseas 157
WASCONSINUOTI a5 aniiceectnclacit oa 6c Qi attyeriie eR hone desea 2 hcieesyempuelee yh ee Howse PAD ANSHSAe es 158
Phe till SheCticeccenca Sethi ace RERAMAelh eee he ode nee ORE LALOR As ci Sa eoR eRe aoe 158

Character ji 0nccccc ie dee casseenneraee dade t ceeaenenes beac ape Lawes bmRRREE REESE eee 158

Sourceiof:material...oc2 es caeteececsesswae yess oe smenencinaes egtfpo nase aaa aoe eos 159

Relations and structure. ... .ccccsscecesss sence erineenteie yey eee See Senet 160

Distribu tonsa: saves vewse eee eeisawhwoaees soe ewes Heeticlaegaleile wok ee eee e eevedalade Mee eee ee 160
Greater New YOrkk. << s<smiscteeerss We eos eee keeway 2.2 bs '5.d dee a tS 160
Little Neck Bay to: Oyster Bayes: sscasese< 2 scsasmeecedsceys sex tstdadeieeed¢eee wes. 161
Oyster Bay to Port Jefierson sec. cc.ccecleoseccae tanned see se Solent tuneacaeddeelse ess 161
Cold Spring: Hearborregon, cosc seceuiecs se ooea s aNOtee oes teeeds AeyeRdne ees 36 161
Dix, Hills A .24ch<atcd.s ahosee eee inetaus ios ci eins 225 Ceol BAG eben etaae, “162
Smithtown “‘driftless: ava... ccwcces cee esses ene eareeada vies ce eee semen sas 162
Middle Island regions... 2cadeee ce et Pee inde Sart seed ey Mele Hie Sa geea eee ene eee 162
Peconic: River reelonis. sveccexieayers st igiets lets cs eine mick ee lolatecs Cokes 2 Hace De ae 162
Riverhead to Orient: Points... 2000. sexeesss sce vnvedec see ee ese seaereneeegeeereseses 162
Adjacent islands and the South Fluke...............-2...-22-2---2-2.-222-----2------ 162
South of the Ronkonkoma moraine. ............-....--+-+---22---222-2020 2-22 ee eee 163
x CONTENTS,

Stratigraphic geology—Continued. :
Quaternary system—Continued.
Pleistocene series—Continued.

Wisconsin drift—Continued. Page.
Ronkonkomasmoraiie: 4 <s0: doar esse ess 4 ete aah lcs y cea eme MeletUe RE He Hoe ESSE 163
NAMI CLs Jeena s Advts yy ooo adc ee Reon s hs ac semana Mathes teased 163
Gharacteror malerialss.cencee 4 se ee ove oe d see ee acide SE eee Deg ped PRMD SERRE Rabe e Heeler 163

Source of material. << .2c.6 deb ooso5 cae4 be ahseenegnnuae ee oes es SEER eee 164
Relations to older deposits. ..-..... 2.0.0.2 02 eee e eee eee ee ee eee e eee e renee 164

DISH WHO sa. 6. 2.2.4..6.texnacioncs ousted oe one eee cue enateeeee dae 22085 GUaaS Rees eeeee ee 164
Outwash from ice along Ronkonkoma moraine...........---------2- 2-0 -0ee rete e eee eres 166

CO CCUTTEN CO aes ate eect AEA Ae esa oat tota eather ake eae oe Ae eleea aaa he ee 166
Character of materiale. acurrctiniiguedveece 2 seen ne adddemtinaeseesneala cera dessa t.oee8 166

Soutee Ohkamaberials ce wewladac pe Sake rete ate Sd arare aon dle me phy Seti cseaion als 25a abe a cae oe aestmrmeeantle AD 167
Relations to older deposits: -2o+cssece03 see oo eye 5se¢eeneduse eect es 2s eeeseencwe wees 167
DTSCH PU LOIN fey ag fate pops wes atau A ena alate aaah Se leh A wn ni ne Nia ee ze guenatend eho nie ee OS 167

Harbor Hill moraines cee ose Ses Se casc anaes SERb Sa SSS E EG Ram ESOS tea eRe eee ees 168
NSIC L es hentia ees eeiae cay A AGO aa tae tae cat tonic hits go Sirag wih Itc aes 168
Character and source of material...............2.222 022222 169
Relations to Older déposite..22..ccccexceseys vcs needs eiaicdseceasae cee teaeeemnnondeeee es 169

Distrib tiGn sax iaaqr sie Me cette ews 2 Rela soe mse Ras e Ramee eens aenSeoeeee aS 169
Outwash from ice along Harbor Hill moraine. _.......--...-.----- Bp adige (osit rn aaah een ah 172
General characteristics......-- ea RE Iterated J aa epithe dads anne oe x eS 172

VIB ETE A CMOIG east fogs oe alcscs eA MARA A Aedes hate apn oiaid es Palalalalal a etched Sty cited Ndeckaiesn's = ase eyetenan seed: fo 173
INerrowertO JamisdCdse nt oe <2 x cote ele ay aig en oe Ups alae ge aie waa cekewninls 173
Roslyo;Hempstead repion. 0.302550. f ae 22) ae eeaege ey ot ces eee y 173
Wheatley-Cold Spring region.................------------/ sseplathete neeaee Eta eee he 173
Huntington-Babylon region............... 0.202022 e eee eee eee eee eee 173

SMU tOWn REGION. soos 5.0 aN Ages Aoad Pod $226 beck Nags Ei4 Laat 174

Port. Jefferson: region. =: .s<scensasnncsceneeeesccie se seweeeswsss as RAR # ceeper 174

Rocky Point and Riverhead area.......... Sow -niass avn S espatetearanayanmeeny SS ole as esa eAS 174

North nWk@ rset. De aoe ee ed Mites Sei meee RARE Ais Bladakas ose haraast a atte Nt 174
Qutwashichanne ls yas ans sss clone oa @aveRBONe ceed ae pee sae QaSOHBeeReee che Beneeeees 175

Roslyn channel -. 00: -2c2-9 pe sstudeesees eh ek ea oes Sees eeee ee esae ey ESes pede ane 175

Melville chamin elat. 2. -< oun: verre yee vey vice Jesaoetese eee eens beeen’ 175
Centerport-Babylon chante). <0 ..c0ecucaaee es sees sis4seeyase-keceeeesé cabs --- 175

Conmeétqiiot chemiel 5.2004, euro ci et ceeaeev ees gee nese esa heinvde end Watkerenes 175

Carimans River channels. ccc cicecicntie sates eacenc ae Ga hmiintue so o5 Pee eae eae 176

Retreatal deposits...........--- Had ea hada tebe usa ieNE DD Le LISS Seas EE ASE REISS ot tact bee eeaee re 176
RGCENt BENE okays dod doeneee LS ze otk Gat easeta eRe 142 be tea SO ames eae epee sake cane 176
EXteDt cae eweomssene eoet2 teed Samm isied eeweas paved Rae ete recas tees ds ae camtcivgy 6 ee 176
Streammde posite: 25 5ceeccede tenn ncs cage aeeciewe leds Sel dec Seeneniescee eee t plan aulemtegh eee ses 177
Deposits inetréam channels: 2. aestscaneteacceae st eset Lace aeaoniematent o2 so dacheyetecey ose 177
IAMivaall fatig? mcs clciatew Ae asec Sais Gaeta Ie SE ie BS Sie S ISS enedioin ak ens ne Sete geet Ss 177
Deltasecs node i mctaet cet tao 2 dnt mse abe eee sl cea edge Oey ee one seas heSyhined oad 177
Maritie de positescie2 eos es cacesea ve teedegaeebn anes ese oes veenigERehGee oe ote op pea cea ese ee eene 177
Beaches ang Spits cov: = 5 s¢4 seamen eaten eee es she eemea ued Baa ea Hacseeameena eee 177
Conniectimp beaches i222 5.28 asia acer aoe. es Coates bie oo 3.40 oelne mae tee ots 178
Saal aprts and HOOKS: fe. cewe wevicdas eihalsoo Pies aed oped tosaeeemakes 2ecnent Seeaa/es san aoa 179
Magnetic and garnetiferous sands..........-..- 2-22-2222 eee eee eee eee eee 179
Wind d 6 posits soca no sccm 2x nonbabecWeinue.s S220 aL eseeeer ceed a een Re neha alta pa a ad SA 22 180
Character and general distribution................222. 20-22 e ee fee cece eee eee eee 180
Dunes at Napeagué Beach ..-....2222cecer ss ce ecees ceeeenevene ieee dd cbaneeeadeveeety amas 181
Dunes at Easthampton.........-..--.-...-.---- pr oGdeeeeeeersen te Su cete (esi CuK anes damecon 181
Dunes of the great south beaches. ...... 2.222.222.2222 181
Dunes at: Shinnecock Fils... ices veces easedee cand see Succes acide debe cc cemeiemiacte aden agence 181
‘Dimes oF the Morth Coasts set2 o.cueycers BaP aa 8a8 2 aoe dlenane ae er eebene miele satedden oe 182
Dunes in the interior of the island..............--..2222-....--2--- Ree tp atch clan BA 8S ads 182
Moarabid oposite’. occcscoux:sacuc eaetnanbnuuneades met eecmobidinns t lcs SRA alent ss qnaai aba, 183
Bresh marshes. :002 acces usnasenacteq ysis eds eee ey eg oe exe Fah ya teat: Oo 183

  

Marshes of the south shore...........2... 2202202002 gece ene e eee GS SM che ae, Sere angen ere 183
Marshes in the valleys of the south side....--.... 2.202.222 183
Marshes near artificial ponds......... 2-2-2220. 183

Marshes in obstructed channels.........2..2.220000 000.20 c eee eee eee eee ee 183
CONTENTS. XI

Stratigraphic geology—Continued.
Quaternary system—Continued.
Recent series—Continued.
Marsh deposits—Continued.

 

Fresh marshes—Continued. Page.
Marshes in-kettles)...-.'3.cc.ccdane > oc544 easntdeeace bvpsseseeaneeee see esaguaenes ae eee 184
Marslies belittid beach este .cncacce5 x3cxa ax marenennutes ner date betnece seas ae aenduene snes se 184
Intend un 6:itiareh 68s jcccowack vine ca hoe cea ee ea REE See sa mbOReeeedie ees em mSeeade ee 184
altars es\n..deewk's ¢c:dssaanvditieetecn’s «aa¥e adeadewweien dsr stGuigeesedannt Ye seamamessmcee et 184
Marshes of the south shore. .........-..-..---+---------- rs ye ise eiein le ng a favg'e Ghatsianslyg eas oe 184
Marshes of the south-shore bays............-- 200202 e eee eee eee eee eee eee eee e tees 185
Marshes of the north-shore reentrants............--- 202-220 cece ee ee eee eee eee eee 185
Summary of geologic features, by localities..............5-.2 20.2202 e cee ete 185
Geologic history..... IS farses Yona casas cael SreesARCa A aMeD ah cseat oa at ars Bence PR RMON aaa een dpa cigs St a Ea SPOR IEG 192
Pre-Cretaceous:eventercs: sons costings ss aigmaeaeee tans oe PASM eee Sees eee ny Dae ehS Geel Es wees 192
Cretaceous €VeNtSs2c2.erced eexcesscamneeees s¥etesss ceteebenscae eeraa la al Apia arte ak: 2 conten aieachslaiohitere 193
Terblary 6Vents: .o..:ecvuss9s04 sz Ageeeaeeeead yess i sex Boeeeeiea tees yest lesamnetedeeer tise deeesectate 194
HocCenerepochise saiace wed nce vesc dmc eauaualsa Sie eds ee eae nawek es oe Se ee eee fest et eveaeiee 194
MigCem ese pOCh xe ye saci ee vio 5 osc Gesaeenueae Raha dS Segue oa is io Abg ee Sons MAGI SESS een ene 194
Early Pliocene epoch. « 2.2 225.155 enntctenanga std bbe hegeeeabin thie sh eeigiieesea see edb awed 194
Late Pliocene (?) epoch (Lafayette formation).........-....2......-2 2222-2200 e eee eee eee eee 194
Post-Lafayetteserosloniens osu ncitson cece scines ied ees eal deme isan ye Oe desk Eee eee eee 195
Quaternary events se.cniac se S2e eps 2c celeb ecaeis yee eg eeisydeh ekee sss spe ceca ghee Oates: see cides 195
Pleistocene: poch a. cis seas steseerek oe ued bb eeses oa veeeoeteeewes Ee es 43 seeReeceeage yy i e<eia oecese 195
Mannetto glacialistage. 22 ovviswceecdvae pees ees elaadeecshed der eee ss ess needs eeeeneeses vas nee 195
Post-Mannetto interglacial stage.........- 2.2222. -- eee eee eee eee eee teens eeeees 196
Jamleco Placialsta ee x <2. peice he dsiaiednaas en Binds sie ORL eiieeisd aes Vee a emahemnee SoS eek ees 197
Gardiners:interglactal stage. ccics.c.ds.c2 2 ph5528 24 nub dceseienter £24 25 244 ose ened eo Pbee ena ecoeie 197
Jacob transitional stages o.niecnccreenegcsce.c cons Remtadeeualee Ss otoenka embacinoneciaeavces cayteule 198
Manhasset elacialistages 2:cccacacccotesx2 ciccateemenaonesceeanage cong cmimnemnanmesecssnenne 199
Herod glacial substage............-. SSS RE DSSS Ret AS 199
Montauk glacial stibetages cain oid eine ais eeerciciettrctnd aeccdece = a's eogue ig eotieisiiinteieeG [ee eae ng eclehny 199
Rirstradvance: of the tC nncyason cas woes Pee Ma dMnde sg tae soe edeotetinels: es eceaadss 199
Position Of 16e- Maret snc oc.n aitowdaeeGsmas yes +h 254c0e4 pAeaaeeee oe 6 ves eens 199
Erosion by the Montauk ice sheet.......-........002020 00202200 e eee eee eee eee 200
Accumulation of the earlier deposits of the Montauk till member. ................-- 200
Folding during Montauk substage........... 2.20.20. 22020 e een e eee ee eee eee 201
DECOM Gaia sig ySeeteceenssictstace 2s SOc ye Ba AR paras BI. a8 TOMO MES ae ame ee 201
Anticlinal nature of the fluke ridges...........-.0.--22.--222- 220-2 e cee eee e eee ee 201
Possible causes of the flexures...........2-2..02--+--0--2-220-0-+- See ee 202
Min Ot Warpln Gass 522s teccomienesmcaeeet em uaraSt ste seca ee eRe eRAS Gee He eee 205
Open and closédfoldss.. 22. ccccceccncckeucaeese res esecescieewiewery ponieidekiat, caroatg 205
First recession of Montauk le@. .coccnscanseueceaces £62022 sc cpeeecicn saddens bes ee eae 207
Readvance of the: Montaukiice x «cc ecco. ge ecice nee peg ee esse vesdevesseeeonenseey ----- 208°
Hempstead glacial substage..-.....-..--------------+++--- {ea peMsaeeeeieeReRe Sy odes sed see 208
Final retreat of the Montauk ice.........-22.....0 200202 e eee eee eee eee eee 208
Vineyard interglacial stages. on. isstescectocp ade awe casei eseeedete Stee deese ees 8526 tienes 208
TEFOSIOD AS sciicndie Seis erase cuaiveyeciclonsyo aoe SH S:80s,80 2 2: a Seakensneiegede leads aoe. se e's ad 2d aye acaueeatucuels eee Saas a 208
Deposition......--..- 209
Wisconsin glacial stage --' 209
First: advance of the 1c@s2. 22... a2snge0scee cece seen es ese Haeeeaescemeatase ees bee oe eae 209
Firstsrecession of the ices .:, .2+.+sasaentesacench ees coe se eu tit aceweeee eee ose ges cette 211
Readwvanee: of the glaciers: 2 coe. sgnocaciseled siemaesiee ace dois emeuiledahamese sass see eden 211
Final'retreat; of the ice: +. - 22.24 2c eee yeeekeeiewe cle pe nese aega tote teeters ue ce eae seeeees 212
Recentiepochin)..: cidisioimacwuoe st : 240 seanaesedeeta dees ee Yet oe eemeadeee eee dee ess asde cea 212
‘Worlsioftwind ‘and waiters ofc: ve iacaas dee ecbedetereryses lek eee Aeeweiiece vere su led seaedele 212
Subsidence Gf the: land ac. onda aus ae cep anticamecenda ye ones oa cea ee Bad een n ee Chee ee et eenedee 212
WVIC ONCE: crmecseccinseneae 28S an be Goelpeie mated bE DRGea Shea amhereIee i o 2.9. a eanoRewes 212
Goncluslong:.asssnsscee st eee oes oe tesa mad ens 64.04 Ge RHASRORREEOE EES 2a oh chee oh 215
Lengths of Pleistocene and Recent stages and substages.......-..--------.-+---.----2-2-0-2-0-- 216
Summary of Pleistocene and Recent orogenic movements.........-..-.---------++---2-2-222-5- 217
Mannetto depression: 2 2.2+-4sseecergesstbees ete vee eee omiseneebeabe yee recess steeedeenes 217
PRost-Mannetto uplitt.... soso esses sees <dediciey ey seer et 33 eerieeeSieine ees sone es ae eeeee anes 218

JAMMSCO Ge PrOBMON riences Posto eee te ceusyes sh eaed Semen ea eee Ae ona 218
XII

CONTENTS,

Geologic history——Continued.
Quaternary events—Continued.

Recent epoch—Continued.

Summary of Pleistocene and Recent orogenic movements—Continued. Page.
Gardiners Uplifteeve sx sua cd 5 lvtatoesenee os Goer be ole abbr erates ee Aa adeiaels 219
Jacobvde pression eas os ds eee eenacaeide tas HE BS DoRL Eee He eee nee CoCo Eee 219
Herod and Montauk depression..............00 0.000000 cece cee e eee eee eee enter tees 219
Hemipstead viplifs:.0228 isc 22 cess 22.5. Go Ricdoemeawan er pede sas bhonvnded gicaxey pees: saree 219
Vineyard tiplite.< 2-citidecas c2224c0cenacmannantenneeres geo oe ate nd panadauauu be otwe seanes 219
Wisconsin depression. .....-..---...- Bove ea Spat gtk fo fate NON ee ne eases nt Rae a eg 219
RECON MOVEMEN tS s.2sc 6 2 oc oes os cetaicladeaeeloebeu eyes cebu snsaunernameemed ode oe 2 Se ae 219
Correlations of the Long Island Pleistocene formations............02-..2 0000 c cece eee eee eee tee eee eee 219
Probable extension of the formations along the New England coast.............---.-.2--2220+ eee eee eee eee? 219
Mammetto ora vel ais ctr ndAiyerc tvetonen ay welny whens Siig aceasta eet et <a ae eens tin in a lial eae 219
JamMece Pray ello... 1 o.. Vsceeeeewe hee ee soe bade <4 24d acsoeaeguegueead Daees beaae se HEBER eeee ee Y ee 220
Gar dinerssCl aye. gsrscsieo ttle gest ohe o See eb ERG as heaiedectstdtdesp Oe Boe SSS EAE AS A Ge ea aes ELEEE EE 220
J ACO BANC por taperels. wee H areqey seed Saeuaenees isle Ao oud eee Ove emntee ame ARO a Depo ae 220
Manihassetiorimationt.cnincicaddes cceucnatere Meine es ee iiad oe Seem eee enamine ERaes ee dene Heomaneaine: 220
Herod srawvel tem ber crincetne aces eee k tle gow aes aes + eS SEER soe Ste eee Seems 220
Montauk till Membervccccccccceece Hado2e so5 dias waded nedsMaesn se oases oom eek aotens oe 221
Hempstead gravelumeém here :..ccusecacima voces oe esses a teegiemiavngeee mae cae oe wane aise serene = 221
Mine yardseroslom: Witer valli sets cntsts ciereictals oi Barse stay ole Sars o's eee o patie eeiietaers soon soe dire pea ASE ES 221
‘Wisconsin driftsi. sss 5s. o:eanivencctumweaxe eye saedaceG $64.55 SeteneaGoetee te oth aed se oieeeseseder + 222
Correlation with the New Jersey nonglacial formations......-...........-. Sagiddartibgsiaesenies ERE Ade Coenen 222
General Cond ions) 2. ded teat ice Veo oon ved eansteae cane wade eS aetiee POs 2 Hess aaageeetees 222
Correll atiisy,.i- c.ha sis cizis 5 3/5 5 occisiasa/Sripcvanstsindne saad sk SPP oP aie ee odd bee DETR eR GOS dt Seed nS eyneNOoN AS 298
Lower Cape May terrace. ..........--...--- re Reel Glsses2a2 2c kk 8k apogee eae eei ne een tees 222
Higher Cape May terrace._......-...---..-- AGOUNURIS AROSE SAA NAD academies tinh na desea ee AOE 229
Intermediate stream depositsen: .acne.sccccacnede tes os scan Saemenoecsee pte e eet nal eee eens 223
Pensaukenfor Mati ots 2 scnanccsecma see ce = eeu ei eles Riga cheiane fac eae 21g Oe as Sis OREO 223
Bridgeton formation cen ccos cansrexsmisiare anemia se eo es Bes ses eases anes ss og ep RRR ES 223
TndexX...5 : =v saitseooncGeee yy eee ey gees seins eek bs pee een da eee toes ed 54 Sees Sate 225
ILLUSTRATIONS.
Page.
PLate' J. Geologic mapof Long Island, N. V.--.c2s00.esc00es eae anacaeas tem ee ee eee cniideeemeadecsees In pocket.
I; Lopopraphicumap of Joong. Island, Ni V wc seccns cc sccm smominiwee s Js: nse geeemneeoaGadsescenss In pocket.
III. Topographic map of Mannetto Hills region..........--.--2-2--0 2-02-0222 - eee eee ee eee eee 28
IV. Topographic map of Great and Manhasset necks.....-...2.-22 202-0000 2 222 e cee eee eee 30
V. A, Outwash plain from ice along Harbor Hill moraine; B, Bowldery part of Harbor Hill moraine near
Creed mor ajdan5e5 sic steels chs Sth OEY eis ero do std ah eased anya yeuned BSE AN Spay G2. Ae esepegy Oiedeeie Vie wie ck k 32
VI. Topographic features of Long Island: A, Upper and lower Manhasset plateaus near Hempstead Harbor;
B, Till moraine near Jamaica; C, Sand and gravel moraine southwest of Riverhead; D, Mannetto,
Manhasset, morainal, and outwash topography near Wheatley...............0020002.022eeeeee cee ee 32
VII. Topographic features of Long Island: A, Simple morainal ridge near Hauppauge; B, Depressed mo-
raine and outwash near Port Jefferson; C’, Parallel “fosse” channels on Montauk peninsula ........ 34
VIII. Pseudomoraine (dunes) near Friars Head: A, Distant view; B Section..................-2..2...-... 34
IX. Topographic features of Long Island: A, Kettle valley and kettle chain near Bridgehampton; B,
Kettle valley near Fresh Pond Landing; C, Kettle valleys, kettle chains, and pre-Wisconsin
drainage lines northwest of Riverhead..............2..00. 0020 cece eee eee eee ec eee eee. 42
X. Topographic features near Smithtown and Lake Ronkonkoma..................2.-2..--2-22-02----2.. 46
XI. Topographic features of Long Island: A, Pre-Wisconsin erosion scarp near Creedmoor; B, Recent
erosion scarp of north coast; C. Branching kettle valley with reversed drainage near Mattituck;
D, Slightly modified and overridden scarps near Brooklyn................-020-0-2----2- 2c eee ee 52
XII. General view of great landslip area at Broken Ground, northeast of Northport...................... 54

XIII.

Broken Ground landslip area, northeast of Northport: 4, Inner scarp and tilted block; B, Upturned
Cretaceous clays at base of landslip mass.......... 220.00. c eee cece cee cece eee cece ceeeeeece

55
Puate XIV.
XV.

XVI.

XVII.
XVIII.
XIX.

AX,

XXI.
XXII.
XXIII.

XXIV.

XXV

XXVI.

XXVII.

Figure 1.
Di

On & Ore OO

10.
ll.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
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24.
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27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.

ILLUSTRATIONS. XIII

Page.
A, Main scarp at Broken Ground landslip area, northeast of Northport; B, Cretaceous deposits
OnwelO Vd: NECK: kata Sec maces cl aoe Stren ena e se eae eeae emia 56
Map showing position of bedrock in western Long Island...............22----- 20-200 e eee cere eee 66
Map showing the elevation of the Cretaceous surface in western Long Island..........--.------- 76
A, Structure of Cretaceous clays on Little Neck, Huntington; B, Large decomposed erratic
bowlder i lid Mannie ttG Taw el sinc cesenes 12 mabeled alee ee ea cm snedeaeeud oe lad deneomems eee 2ex 82
A, Upturned Gardiners clay and Jacob sand on east coast of Gardiners Island; B, Overturned fold of

Jacob sand lying on Herod gravel member of Manhasset formation, east coast at Gardiners Island. 110
al, Folded beds of Manhasset. formation near Tom Point, Port Washington; B, Banded Montauk

till member of Manhasset formation near Friars Head ..........--2..220- 20-2002 e ee ee eee eee 114
Topographic features near Middle Island..........2...2. 2.020 e eee eee eee ee ee eee renee eneee 116
A, Outwash topography near Southampton; B, Manhassetand outwash topography near Amagansett. 118
1, Contact of Wisconsin till with Montauk till memberat Lloyd Neck; B, Gravels (Montauk member

of Manhasset formation?) on Lloyd Neck ...........2-. 222200 e eee eee eee eee ences 136
{, Unconformable contact between Hempstead (?) gravel member of Manhasset formation and

Cretaceous deposits on Little Neck, Huntington; B, Manhasset gravel folded by overriding ice. 152
i, Typical bowlder beach on North Fluke; B, Banded Wisnoneln till on old gravels (Man-

nesta, Wax: WSs 25.5 se, dnd ciencedeie hele ey < Sa Sox 8s ercanehSamid Riles Sa Sad ead Seen eres BO eS 162
. Hooked sand spit at entrance to Smithtown Harbor.........-....-..----+---2-0--20-2-- eee eee eee 178

A, Undermined peat on coast near Prospect Point, Manhasset Neck; B, Semidune surface in
imtéenor-ofisland: near. Selden: s2- 5 e.2ck 8 beceedeedacéais Soe eae Se wew nant Pees adams 182
A, B, Mud cones marking orifices of springs in mud flats near Douglaston.............--.--.---- 183
Index map of Long Island and southern New England.................-.---------2-----2-----+5 1,
Map of the eastern United States, showing physiographic provinces.............---.-.------2---- 2
. Manhasset plateau and the superimposed moraine as seen from Long Island Sound.............-.- 22
. North=south profile.of Long Taland. : 2... scscciicccncged ooh ce eeeesinbe ses ceweseee oes gegen 22
. Relations of Cretaceous, Mannetto, Manhasset, and present north-shore scarps.............-.----- 25
. Relation between the original and the present cross section of north-shore valleys...........--..--- 26
. Sketch showing location of the upper and lower Manhasset plateaus from Douglaston to Oyster Bay. . 30

. Sketch showing location of the upper and lower Manhasset plateaus in the Lloyd and Eaton necks
NOCION verve v tes ssa evvmnee eddy ey i sb eheeexeeeeeee Hes tesa eee gaeenseteeee ey eee bs peREGeeeee 31

. Section showing relations of Manhasset plateaus and deposits along the north shore in western Long
Eslanide) tecet cca cc ed scene eet cmap aie cee earings we eno lage cakes ates CU ahah de ae 31
Section showing mode of formation and profiles of morainal cones.......-....--.----2--+--+-+----+-- 32
Profiles; of miorainal cOnese.cucuis 2. 5 o2eSe hb ouiscaeekie foi 52836 Madde ooo 22 60005 ane 32
Section showing relation between depressed moraine and outwash........--...--2..-.2-----20--- 34
Hypothetical drainage system in loose gravels before being covered by ice...........-.....-.---.- 35
Hypothetical condition of drainage system of figure 13, after being overridden by glacial ice.......- 35
Profile of a compound outwash fan of successive-plain type. .......-2.-2-0-0..202002220- 2022 eee eee 37
Normal:profile of tall moraines 242. 0decevvsecace vue y vines scaly eraragedeeeee yey 254422 eeesdes 38
Normal profile of stratified moraine........... 22.22.2202 20220 -oeeeeeeeeee 38
Section illustrating the formation of a kettle from a buried ice mass..............2---------22---- 39
Section illustrating the formation of a kettle from a projecting ice mass...............-2--2--2+---- 39
Section illustrating the relation between the slopes of kettle sides and the shape of melted ice mass. . 39
Section illustrating the relation between the slopes of kettle sides and the shape of melted ice mass. . 39
Section illustrating the formation of kettle terraces by the melting of ice masses of especial shapes. 40
Section illustrating the formation of depositional terraces between ice mass and kettle wall........ 41
Profile of terraced kettle near Lake Grove.......-..-..----2.-0-- 00-20 e 2c eee eee eee 41
Profile. of kettle with) outwash TW scsc.so.eenew ses Joc mcaneseea cease isan cuereapebesiee sss 41
Kettle: Timsas : vangceoctieer eyes sramansiseeeee ey: eee e sg gieseeg eat nak be ees eres cage ens ees 41
Outwash rim adjoining kettle 2 miles northwest of Southampton..................2.2....-2---.- 41
Pre-Wisconsin drainage system in Manhasset formation...............2022-22-2202 000 eee eee eee 42
Kettle valley system remaining after the melting of Wisconsin ice masses.........-.-.--.-.--.--- 42
Cross section along the line A-B of figure 28, showing residual ice masses partly buried by outwash. - 42
Cross section along the line A-B of figure 29, after melting of ice masses...............-...-....2- 42
Profile along the course of the kettle valleys of figure 29..........2.....22.200200000222220-220202- 42
Profilé-of kettle plainsenccce yey 224s. cenedsee rss: reise saeaneoeby sys ered ens AEE Rad ord ded 43
Profile showing a channel between kettles.......-......... 20-00 e cece eee eee eee eee eee AT
Profile showing relation of inner and outer fosses to moraine.............-.-..2...-2.2020-02-4-- 47
Profile showing fosse at inner base of moraine near Duck Pond Point............2............... 47
Profile of inner-fosse channels west of Fort Pond Bay, Montauk peninsula .......................- 48

Sections of terraced channel leading westward from Lake Ronkonkoma..............-...2..2.-.- 49
XIV

Fieure 39.
40.
41.
42.
43.
44,
45.
46.
47.
48,
49.
50.
51,
52.

53.
54,
55.
56.
57.
58.
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61.
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69.
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88.
89.
90.
91.
92.
93.
94.
95.
96.
97. §
98.
99.

ILLUSTRATIONS,

Forms of oiltwash: Valleyss..c.icecccscan eso oeebsecedemccewunea Hie gage eeUeeDeeaeyees sei HES
Profile showing relative steepness of east and west banks of Long Island valleys..-.-.------------
Section illustrating formation of amphitheaters by spring sapping.....-..-------------+++22e2eeeee
Plan of hopper or amphitheater at an early stage..............-2----2-2-2 eee eee eee
Plan of transitional form between a hopper and a normal drainage system.....-.-.-------+----++---
Plan showing character of notching in bluffs of the northern coast in eastern Long Island........-.
Section illustrating the relation of height of hanging valleys to stage of erosion of bluffs......--.--
Section illustrating the notching of hanging valleys..............----22--222ecee cece ceestec ert
Section illustrating the obstruction of valleys by landslides............---------+++++¢220-2ec cee
Section of refilled ravine of the north coast...............0. 00-222 e ee eee eect etree
Section showing the nature of displacement in the larger landslides......-...---.-----+--+-----++-
Map showing Cretaceous structure and location of submarine channels of Long Island Sound....---
Map of the submarine channel and canyon of Hudson River.........---.---------+---+-+2- reece
Cross section showing relations of the broader valleys and sharp canyon of the submarine Hudson
CHATMGIS: oii. oie sie os cleaigutainbmsk. oa jedusemloee ss coals a oe Cee eee eames vies os s ee oReReaee
Section showing relations of the submarine Hudson channels and their fillings.......-.-.---------
Sections from Hudson River to Long Island.................22.- 2-20-2222 eee eee eee ete eee
Columnar section of the Cretaceous formations of Long Island..........-...-----------++------+---
Map showing known distribution of Cretaceous formations on western Long Island ........--------
Section showing general relations of deposits in the Mannetto Hills region.........-..--.-----+----
Section from point near Ridgeway, Brooklyn, to Valley Stream..............--------------2-+--+-
Section 24 miles southwest of Montauk Light...........2.-2..2-.0-002- 20022 eee ee eee eee
Section near the middle of the northeast shore of Gardiners Island
Sections néar Browns Poitit:vs-snedesy se csk ds sa ceeteasiesGeeewe see veg gccsorddeenmmer eee beas
Section from Wards Island to Barnum Island...........-...-..----2--+-- 22222202 eee eee tees
Section near Eastern Plain Point, Gardiners Island...............-------2+--202 2222 e eee eee ee
Section near Jacob Hill, showing overturned fold of Gardiners clay
Section at Rocky Point, west of Cold Spring Harbor
Section north of West Beach, Eaton Neck.. : Prete ee ein d Beh nae
Section half a mile west of Rocky Point Landing, nontheast of Miller Place. fs tpg ss oie aum aye
Section near Rocky Point Landing, northeast of Miller Place
Section west of Hallock Landing... 22.02 csccceseesteneesey be v Pad po oe peeeeeentaasnnes sve eee
Section a quarter of a mile east of Roanoke Landing................------22--22-2--2202-2 2222s
Section three-quarters of a mile east of Roanoke Landing
Section near Jacob Hills.cye neces sedis meas nasseeeseoeee Verda s oeUels oo Roe Antenne sees es eR
Section at Brown Hills; mear‘Orient oc. ec seensseedsses s oee25¢ 26 eemeseeeeeeee yeees she bases
Section on east side of Robins Island
Section on east side of Robins Island............-..--2-- 2222-22022 20 eee eee eee
Section half a mile west of False Point, Montauk
Section near Cherry Hill Point, Gardiners Island........-......-220..2-2- 2-22-2222 22 - eee eee eee
Section a quarter of a mile east of northwest end of bluffs on northeast coast of Gardiners Island... .
Section three-quarters of a mile east of northwest end of bluffs on northeast coast of Gardiners Island.
Section near Whale Hill, Gardiners Island..............2..-.-2-.-220222-2 2220020 e eee eee eee eee
Section near south end of Bostwick Bay, Gardiners Island
Section on south-sidevof Plum: Island .c.cncconuces cca heey 2255444 SeeemeeeaSeeee ¥ eee bad eciewemics
Index map to localities on Fishers Island..............-.2.2. 2022-2222 ee eee eee eee eee eee
North-south section at Clay Point, Fishers Island
Generalized section of Fishers Island

Section 14 miles southwest of Montauk Light.............22..0020 020020 e eee cece cece eee
Section north of Weeks Point, Hempstead Harbor..........-..2..2 20-20 000 cece eve eee ee eee eeeee
Section a quarter of a mile west of Hallock Landing
Section near Woodville Landing. ........-2. 22. .2222. 202020022 c eee eee eee eee
Section at landing west of Jacob Point
ILLUSTRATIONS. xV

Page.
Ficure 100. Section near west end of bluffs on northeast shore of Gardiners Island..............2--222-+e0e-- 110
101. Section half a mile east of west end of bluffs on northeast coast of Gardiners Island. ............. 110
102. Section half a mile west of landing, Plum Island..................... mipuelasinhee aes Sa aiaheennions 111
103. Section along middle of south side of Plum Island.................0.00 00000 e cece eee cece eee eee 111
104. Section east of Fort Terry, south side of Plum Island.............0.0. 0.000 eee cece cece eee c ee eee 111
105. Section east of Fort Terry, south side of Plum Island.............. 0.02.2. cee cece ee ee cee eee e ee 111
106. Bluff section at Isabella Beach, Fishers Island...............0.0.02e2 ccc eee eeeceeceeeererecees 112
107. Cross sections showing structure of Long Island...........22...0000000 cee cece cence eee cece eee 120
108. Diagram of vertical pseudobedding in Herod gravel member................-.2--2-220e2eeeeeeee 122
109. Section near Quince Tree Landing, Montauk........ 2.0.0... 0 000 c cece ccc eee ene e eee eee 124
110. Section on the coast north of Fort Salonga... 22.2.0... 2.0.00. c ccc eceee cee n eee tees 125
111. Section half a mile east of Woodhull Landing.................0.00 0022002 e eee seein salen Pes 125
112. Section a quarter of a mile west of Hallock Landing........... 2.02.02. 2000 eee eee cee ceeceeeene 126
118. Section west of Herod Point............ 00.000 ccc ee ene ee cence eee eee tueeeees 126
114. Section near Paine Landing.-..... 2... 222.2202 02 e eect e eee eens 126
115» Section near: Mriars; Head acces octa aes dodscagend4 vadeiseeeraleeeeceeesesawonwanadaceadedtense 126
116. Section 1 mile southwest of Duck Pond Point............ 2.222000 c cece ee cece cece eee eee eens 126
117. Section northwest of Shinnecock Canal............ 000.000.2000 eee eee eee eee eee eee eee eee ee 126
18. Section northwest of Shinnecock Canal........ 22.0.2. 2.200 eo cece cece eee eee eee 127
119. Section east of Cedar Point, northeast of Sag Harbor...............2.22202002-0202 002s avaes ee 127
120. Section between Cedar Point and Sammys Beach, northeast of Sag Harbor.......... Ry Ane eeean 428
121. Section east of Cedar Point, northeast of Sag Harbor.......-...-..222220-2-022 2220 c cece eee eee 128
122. Section east of Cedar Point, northeast of Sag Harbor................0.0.0.00 000202 e ee eee cece eee 128
123. Section west of Sammys Beach.....-............-0- 2-020 -2eec eee cee eee 128
124. Section near Culloden Point, Montauk.................... Cine ee EME neeee ceee eee 128
125. Section 1 mile north of Quince Tree Landing, Montauk................0..00 20.00.0020 cece e ee eee 128
126. Section 1} miles north of Quince Tree Landing, Montauk...................20.220...202-eeeeee 128
127. Section on west side of Robins Island.......-........2.2220220 200002 c eee eee eee eee 129
128. Section on east side of Robins Island..............-..-.. 20-2022 0 20 eee cece eee 129
129. Section half a mile south of west end of bluff on northeast coast of Gardiners Island. ............. 129
130. Section near point at south end of Tobacco Lot Bay.................2-2.-. 20202222 e eee eee 129
131. Section near lighthouse at west end of Plum Island..................0..220.-200- 200200222 eee 130
132. Details of faulting in Herod gravel member near west end of blufis on south side of Plum Island.. 130
133. East-west section in clay pit on Fishers Island...............--. 2202.02.22 eee eee eee eee 130
134. Section through hill three-quarters of a mile northeast of east end of Isabella Beach, Fishers Island. 130
135. Section parallel with beach at headland three-quarters of a mile northeast of east end of Isabella
Beach, Wishers.Aslands ..2.02ccneguaaacciandaeoe ens 1s2soidact oleae atmcceed SE solar oan aes 130
136. Section one-third of a mile east of College Point........................0222 20222 ee 135
137. Section at Barker Point, Manhasset Neck.....-......2-022.0. 20022202 e eee eee eee eee 135
138, Section east of Lloyd Point, Lloyd Neck............22- 22.20.20 e cece cence ee eee eae 136
139. Section midway between Nissequogue River and Stony Brook Harbor...................-.....- 137
140. Section showing details of the Montauk-Herod contact at the locality shown in figure 139......... 137
141. Roadside section near Stony Brook station................2..-0-.22 025022022022 137
142. Section of pinnacle of Montauk till member near Friars Head ............-2.2.222222.-0-..02-0-02- 139
143... S6Ction Near: Friars Heads u.c.c.0 92 2.5 atu o Ss Was nueaennclens 3402.08 das aba SA DERE oe eee eek 139
144. Columnar section east of Roanoke Landing....................20-. 2002020202200 e eee eee ee 139
145. Section half a mile east of Luce Landing. ..........2....0.....2-22-2-.---. Sede ae ch chet adeted eaters ate 140
146. Section three-quarters of a mile cast of Luce Landing..................2..2.0.0022-0222-200-02220+ 140
147; Sectionsat-OreoonEL uss, + aueeees 2's ve sani ss ciddadoawiasceh dist gadis dees seage SAAS SREREROVE REELS ces 140
148... Section mear Duck Pond Pointsnccesd tava dceceh ans rys ee pene sse ea eas SORSAERE RENNES Sete sewe 140
149. Section a quarter of a mile south of Inlet Point................ 20.0... 2 222s ees = 140
150. Section 2 miles northwast of Shinnecock Canal........2...--02205-5-. 02000 e eee eee 142
151. Section on west side of Hog Neck, northwest of Sag Harbor. .................2.0.0000..0-2222.- 142
152. Section on west side of Hog Neck, northwest of Sag Harbor..............--..0--.0--.0..222202- 142
153. Section near Hog Creek Point, on South Fluke...................2.00 2222022 e eee. = 142
154. Section near Hog Creek Point, on South Fluke........-.----.. 2... ...22 00020 6 eee eee 143
155. Section 1 mile west of Rocky Point, Montauk.............22.20 0000002 o eee 143
156. Section 1 mile west of Rocky Point, Montauk...............0.0. 000600002 143
157. Section half a mile south of Culloden Point, Montauk..............0.00.0020 02 eee 143
158., Section east of Montauk Wight: <i ..<0<02..¢23 CAB GGURI RE: Seb El ce ge See ese GPs. bicunads 143
159. Section southedstof Montauk Dight....2 23.25: ceccuidaccdsg sis dec Shecayauun ao Bee obedens Rae 144
160. Section 14 miles southwest of Montauk Light................ 22-6022. 2 262 144
XVI

Fieure 161.
162.
163.
164.
165.
166.
167.
168.
169.
170.
Ti,
172.
173.
174.
175.
176.
177.
178.
179.
180.
181.
182.
L833.
184.
185.
186.
187.
188.
189.
190.
191.
192.
193.
194.
195.
196.
197.
198.
199.
200.

201.
202.
203.

204.
205.

ILLUSTRATIONS,

Page.
Section 13 miles southwest of Montauk Light............22...0-2.2202 02002 e eee eee eee 144
Section 2 miles southwest of Montauk Light.........0..0...0.. 002-22 e eee ee cette eee 144
Section on south side of Montauk peninsula between Napeague and Hither Plain life-saving stations. 145
Section on south side of Montauk peninsula between Napeague and Hither Plain life-saving stations. 145
Section on east side of Robins Island. ....-.--.-----.-0- 222-20 e eee eee ee eee eens 145
Section on east side of Robins Island. .......-..-.--------- 2-20-22 e eee erence reece 145
Section at south end of Bostwick Bay, Gardiners Island..........-.-----------+-----2-2e-reetee 146
Section near north end of bluffs on northeast shore of Gardiners Island.........--.--------++- 146
Séctioneast:of Whale Hill... 2.23424 032 eccccecaclagee ees fey 2 dimes eely eye es ee eter ce ee 146
Section near west end of bluffs on south side of Plum Island..............----------+----+---+++5 146
Section east of Fort Terry, Plum Island...........-.----- 2-22-2202 eee eee eee eee eee e eee 146
Section east of Fort Terry, Plum Island.........-..-.--.--- +--+ -- 22-22 eee eee e eee eee eee ee eee 147
Artificial section near the steamboat landing on west side of West Harbor, Fishers Island....-.. 147
Section cast of Montauk Lights cases 222 cecl gictisiiw cesta s os eee eed nese laos etic 151
Section 1 mile northwest of East Fort Point, Lloyd Neck.........-...-------------+---+-+---+-+ 152
Section northwest of East Fort Point, Lloyd Neck........-.....-2----- 22-22-22 eee eee eee eee 152
Section in clay pit near end of Little Neck, opposite Northport ......-....--------++-++-++-+-+-- 153
Section iéar Friars: Head! oc. cence set. peed ce cieuete eso: Pes aeeneeeere vce se eeue weeoS 153
Columnar section between Friars Head and Roanoke Landing... ....-...--..---------++--+-+--- 153
Columnar section near Roanoke Landing.......-...----.-22-222---- 2202 cece 153
Section west of Jacob Hill ac wossiaans peo4 ab aeheetleeenSe $68 Cates LAAs Shes Ge SS 154
Section. westiot Jacob Hill..5.2..<0cecc¢enencessnnnecdencaseeeeresided st Gomewadne ef fasGe Qatate 154
Section northwest of Shinnecock Canal.....-...-.-.-- 222-2222 eee eee ee eee 154
Section on Jessup Neck, west of Sag Harbor. ...-.-.--..---.0- 222-2020 eee eee eee 154
Section on Jessup Neck, west of Sag Harbor. ..22. passecwun cores sss ee wa reumee ules: ve es came 155
Section near Fireplace, South Fluke’. ...02: 2201+: seseewssua= ee noc esse es ener eeeeet bees ese seee 155
Section near Culloden Point, Montauk. ...--...-...-.-..-- 222-2022 e eee cee ene eee eee 155
Section 1 mile west of False Point, Montauk_.......-.-.......-2----22--22-2--222-+ 22-22-22 eee 155
Section south of Montauk Light.........-...-22. 20-22-2205 22 e nee 155
Section 24 miles east of Ditch Plain, Montauk...,......-...-..2-2.0. 0202000 e eee eee eee eee eee 156
Section half a mile east of Ditch Plain, Montauk..............-.--..2..0.022022 20020002 e eee 156
Section west of Ditch Plain, Montauk.............-.-. 2222202002222 eee eee 156
Section on west side of Robins Island...........-...-.------ 2-0-2222 e eee eee 156
Section on west side of Robins Island...............-0...-..2202022 2-22 eee eee eee 157
Section showing till ridge at head of valleys opening to the north. ..........2-..-222..22-22-2-. 161
Profile of Carmans River outwash channel near Yaphank...-...--...------------------2--2-20e 168
Kettle rim of till near highway between Mattituck and Cutchogue........-..2-.2-2-22.20.----24- 174
Diagram illustrating compression of beds through rearrangement of grains. .......-2-.2.--.--..--. 202
Diagram showing supposed compression of beds under ice load in the Long Island region. 5 204
Diagram showing supposed influence of Cretaceous masses in controlling the compression or the
Pleistocene: deposits under 166 ldad 2. <2. yeceemeremeacGatis ois e.nidee tee se eee exieeindies 204
Profile of imperfect 40-foot terrace east of Fort Pond, Montauk. ...........2.2.2.-.2---202-2-002 208
Section at top of bluffs between Woodhull and Rocky Point landings .................22.....-- 210
Sketch map showing relative positions of ice during the Ronkonkoma and Harbor Hill substages
of the: Wisconsin: stage-scesecgeu de veces se Sead Sordeuoedee ss ooo so Gadaieeedeaw ae « oociwoeeeees 210
Position of land with reference to present sea level in the Pleistocene stages and substages......... 218
Diagram showing the relations of the higher and lower Cape May terraces to the so-called ‘‘Trenton
gravel” along Delaware River in New Jersey. .......-- 0.22.2 eee eee eee eee eee eee eee eee 222
INSERT.
Page.

Approximate correlations of the Pleistocene formations of Long Island with deposits of other areas............ 220
THE GEOLOGY OF LONG ISLAND, NEW YORK.

By Myron L. Futter.

INTRODUCTION.

Location.—Long Island, New York, is the largest island adjoining the coast of the United
States proper. It is 118 miles long, extending from the Narrows at the entrance of New York
Harbor (longitude 74° 2’ W.) to a point nearly due south of the eastern boundary of Connecticut
(about 71° 50’ W.). Its maximum width is about 20 miles. The island is included in the
State of New York, but only a few miles of its shore line is adjacent to the mainland portion
of that State, more than seven-eighths of its total length lying off the Connecticut shore (fig. 1).

Geologic relations.—In its general geologic relations Long Island belongs to the inner part
of the Atlantic Coastal Plain (fig. 2), the line between the deposits of this plain and the meta-
morphic rocks upon and against which the sediments were laid down crossing the extreme west
end of the island near Long Island City. The basal or fundamental deposits are of Cretaceous
age and correspond to beds of similar age in New Jersey and the region farther south. They
appear at a considerable number of
points in the western half of the
island but in the eastern part are
nowhere seen at the surface. No
equivalents of the Tertiary deposits
of the mainland have been definitely
recognized, although some loose
sands possibly referable to the Ter-
tiary period have been noted at one
point.

Only a part of the deposits of
the island are true coastal-plain de-
posits, the greater portion of both
the surface and the underlying mate-
rials throughout the island being of ee
Pleistocene age and representing the f&. frLa® poe
morainal and outwash accumula- C— oo po ae
tions associated with the continental idee ;
glaciers (fig. 2). The two morainal
ridges, which are among the most conspicuous features of this area and which together
form ‘‘the backbone of the island,’ are the direct continuation of the series of moraines of
Wisconsin age which are traceable almost continuously from the Rocky Mountains to New
Jersey and thence through Long Island and the islands on the east as far as Nantucket and
Cape Cod. The various beds making up the considerable thickness of Pleistocene accumula-
tions beneath the ridges mentioned and above the Cretaceous formations likewise represent
older drift sheets of the central United States on the west and the Pleistocene formations of the
New England coast on the northeast.

Purpose of this investigation.—The investigation of the geology of Long Island was under-
taken in connection with a study of the underground waters of the island made by the United

1629°—14——2 a

 

  

CapeCod
ar,

    
   

 
  
  

Fa NS
J i 7 foe
SNAG ishers | Marthas
a ePlumIs QBlock! Vineyard Nantucket
— ga hGardiners |
As?" Montauk Pt

9 cBAN

 

 

 

Figure 1.—Index map of Long Island and southern New England.
2 GEOLOGY OF LONG ISLAND.

States Geological Survey in cooperation with the Commission on Additional Water Supply of
New York City. During the progress of the work many new geologic facts were developed,
some of which demanded extensive modifications of the views previously held as to the structure
and geologic history of the island. In fact, a complete revision of the geology became necessary
in order that the observations on the underground waters might be thoroughly understood.
This geologic work was conducted in connection with the water investigation during 1903, most
of the roads on the island being traversed and a very large number of well records collected.
Geologic work was continued during several weeks in 1904 and again for a few days in 1905, to
complete a study of bluff sections along the north shore and to establish the correlation of the
Long Island deposits with other Pleistocene deposits on the east and west.

Status of Pleistocene
correlation.—From the able
studies of Chamberlin, Cal-
vin, Leverett, and other
United States and Canadian
geologists, the Pleistocene
deposits of the interior of
North America have been
differentiated and their ac-
cumulation in a series of
four or more successive
glacial stages has been es-
tablished. East of Ohio,
however, because the last or
Wisconsin invasion in many
places advanced farther
than the earlier ice sheets—
removing, covering, or other-
wise obscuring their depos-
its—little has been done
toward the differentiation
and correlation of the drifts.
A fringe of old, deeply
weathered drift stretching
across Pennsylvania and
New Jersey, it is true, has
long been recognized outside
of the Wisconsin moraine
and because of the weath-
ered state of its materials
has been provisionally cor-
related with the Kansan or
pre-Kansan. On Long Is-
land Woodworth! recog-
nized an earlier drift underlying the Wisconsin and separated from it by a distinct erosion
unconformity, but beyond correlating it with the Columbia group of the Coastal Plain he made
no attempt to assign it to a definite stage. On Block Island, Marthas Vineyard, Nantucket, and
Cape Cod three glacial stages with intervening interglacial stages were recognized and a part of
the Pleistocene history was deciphered.’ The invasions were designated the first, second, and

 

 

------- Limits of ice invasion

 

 

 

FIGURE 2.—Map of the eastern United States showing physiographic provinces.

 

1 Woodworth, J. B., Pleistocene geology of portions of Nassau County and Borough of Queens: Bull. New York State Mus. No. 48,1901, p. 624.

2 Woodworth, J. B., Geology and geography of the clays, in Shaler, N. S., Woodworth, J. B., and Marbut, C. F., Glacial brick clays of Rhode
Island and southeastern Massachusetts: Seventeenth Ann. Rept. U. 8. Geol. Survey, pt. 1, 1896, pp. 975-988, Shaler, N. S., Geology of the Cape
Cod district: Eighteenth Ann. Rept. U. 8, Geol. Survey, pt. 2, 1898, pp. 497-593.

»
INTRODUCTION, 3

third glacial stages, but no attempt was made to correlate them with the stages of the Missis-
sippi and Ohio valleys, which in fact had not then been fully worked out. No further attempt
at differentiation or correlation was made until the problem was taken up by the writer and
his party in 1903, the question of equivalency of the eastern and central glacial deposits
remaining one of the great unsolved problems of Pleistocene correlation in this country.

Results of the work.—The results cf the work begun by the writer and assistants in 1903
and continued in 1904 and 1905 have been the apparent establishment for the eastern region
of all but one (the Iowan) of the five principal glacial stages recognized in central United States,
the recognition of one or more substages, the discovery of criteria for differentiating the deposits
of each stage, and the unraveling to a large extent of the complicated history of the region.
The evidences in regard to the conditions and history of the principal glacial and interglacial
stages on Long Island appear to be fully as clear and conclusive as those in any single area
of the earlier studied regions of the interior.

Scope of this report-—The investigations along the New York and New England coasts
have brought out the facts that the formations of the Pleistocene epoch were nowhere so well
developed and the sequence of events is nowhere so clearly set forth as on Long Island, which
in fact may be considered as affording the type section of the earlier glacial deposits of the
coastal zone. All stages except the Iowan are here represented. In the present report the
Long Island section is discussed in considerable detail to supply a basis of comparison with
similar deposits elsewhere. This systematic discussion is followed by a short tabular summary
of the geographic distribution of exposures, for the benefit of teachers and others interested in
the physiography and geology of special localities, and by a chapter on correlation, in which
the equivalency of the deposits of Long Island to glacial deposits elsewhere, especially to those
of the New England coast, is considered.

Field work and acknowledgments.—As already stated, the geologic work was undertaken in
connection with a cooperative investigation of the water resources of Long Island by the United
States Geological Survey and the New York Commission on Additional Water Supply in 1903
and was continued independently of the commission in 1904 and 1905. The ground-water
investigation included a careful collection of well records, of which about 1,500—-many of them
accompanied by samples of the materials penetrated—were procured. Other geologic work in
1903 included traverses of practically every road outside of the portion of the island included
in Greater New York and many visits to special localities, mainly in connection with the studies
of ground water. In 1904 a traverse was made of the north shore from Port Jefferson to Orient
Point and of the shores of Great and Little Peconic, Gardiners, and other smaller bays to Montauk
Point, during which the bluff sections were examined in great detail and fossils were collected
at a number of points. Gardiners, Plum, and Fishers islands, portions of the Elizabeth Islands,
Marthas Vineyard, Nantucket, and Cape Cod were also visited. In 1905 the investigations
covered the bluffs along the north shore of Long Island from Port Jefferson westward, the coast
of Rhode Island from Watch Hill to Point Judith, and a number of previously unexamined
points on the Massachusetts coast as far north as Boston.

Valuable assistance in the work was rendered by a number of geologists. A.C. Veatch,
to whom the investigation of the underground waters was assigned, rendered especially valuable
service in the collection of well records and samples, and D. W. Johnson contributed largely to
the success of the areal investigations. Much paleontologic information in regard to the
Cretaceous was furnished by Arthur Hollick, and Pleistocene fossils from several localities were
identified by W. H. Dall. Aid in the geologic investigations on Long Island was also rendered
by Isaiah Bowman and B. L. Johnson. In Rhode Island and Massachusetts F. G. Clapp assisted
largely in establishing the Pleistocene correlations. For the interpretations and conclusions
based on the bluff sections of Long Island and on the work done in the Elizabeth Islands and on
Marthas Vineyard and Nantucket, as well as for most of those reached elsewhere in Massachu-

setts, the writer is alone responsible.
4 GEOLOGY OF LONG ISLAND.

DEVELOPMENT OF THE GEOLOGIC LITERATURE ON LONG ISLAND.
GENERAL TREND.

The earliest publication relating to the geology of Long Island of which the writer has
information appeared about 1750. From that date until 1800 little seems to have been written,
but between 1800 and 1827 a number of contributions on the geology of the island were published.
In 1837 the preliminary results of the examination by the New York Geological Survey appeared,
marking a new epoch in its literature, and a few years later the classic report on the first district
was published. From this time until 1878 a considerable number of papers, mainly descriptive,
of Cretaceous and other fossils were issued, but little advance was made in the study of the
younger deposits. Beginning with 1878 the drift received much attention, and many papers
of importance appeared, in which, however, the glacial epoch was regarded either as a unit or
as two or more stages of indefinite age. The work of differentiation and classification of the
drifts, which began in 1901, opened the latest period in the literature of the island.

From the preceding outline it is apparent that there have been several phases or periods in
the development of the study of the geology of the island as expressed by its literature, which
for convenience may be described by terms indicating the characteristic trend of the papers
published during the respective periods, as (1) alluvial phase, (2) diluvial phase, (3) early
paleontologic phase, (4) early drift phase, and (5) later drift phase.

LITERATURE FROM 1750 TO 1837 (ALLUVIAL PHASE).

The period from 1750 to 1837 covers the beginning of the study of Long Island geology.
In it the first geologic examinations of the island were made and the first classification and
correlations of its deposits were attempted. It was not a period of detailed field examinations,
most of the published observations being records of private travels, with occasional attempts
at interpretation, but it was marked by the appearance of the first geologic map.

To Dupont de Nemours is credited the first statement on the geology of the island that
has been found. In a publication’ appearing about 1750 he said that Long Island, although
not a delta in form is one in reality, being formed by marine currents depositing the fluviatile
alluvium brought down by Hudson, Passaic, Hackensack, and Raritan rivers. This early
reference is much more in harmony with present views than those referring the island to the
‘primitive formation,’ which immediately followed it. We now know that the southern
two-thirds of the island, if not a delta as postulated by De Nemours, is at least made up largely
of confluvial deltas from glacial streams.

The next writer of note dealing with Long Island appears to be Samuel L. Mitchill. Writ-
ing in 1800,” he referred the part of the island north of the “spine” (on the basis of the granitic
bowlders which are abundant along the north coast) to the ‘primitive formation.” His paper
gave a summary of the topography of the island and the erosion that was going on, stating
that the island has been separated from the mainland by the encroachment of the salt water
during the lapse of ages. He also discussed the marshes and beaches, the character, distribu-
tion, and immense size of the bowlders, and the occurrence of marine fossils in wells. Mitchill
gave a further description of the bowlders in a paper appearing in 1802° and expressed the
belief that Plum, Gull, and Fisher islands on the north and Block Island on the south were once
connected respectively with Orient and Montauk points. This is t ‘ti ecognition of the
essential continuity of the ridges later known as the inner and outer#foraines.

In 1809 appeared the first geologic map of the United States, accompanied by an explana-
tory paper by William Maclure.* The map bears the note “By Samuel G. Lewis,” but it appears
to have been based on Maclure’s observations, and is generally known as the Maclure map.
On it the north half of the island is shown as “alluvial ® a term then applied to all the uncon-
solidated beds of the Coastal Plain. This is also stated in the text.

! Quelques mémoirs sur différens sujets, quoted by W. W. Mather, Geology of New York, pt. 1, 1848, p. 150.
; a o sketch of the mineralogical history of the State of New York: Med, Repository, vol. 1, 2d ed., 1800, pp. 279-303, 431-439; vol. 3, 1800, pp.

3 Mitohill, S. L., A sketch of the mineralogical history of the State of New York: Med. Repository, vol. 5, 1802, pp. 212-215.
4 Observations on the geology of the United States: Trans. Am. Philos. Soc., vol. 6, 1809, pp. 411-428.
GEOLOGIC LITERATURE, 5

Mitchill, who a few years before had assigned the north side of the island to the “primi-
tive formation,” reversed his opinion in 1811 and stated that all of the material was alluvial
except near “‘Hurlgate’”’ (Hell Gate), citing the occurrence of shells in deep wells as evidence
of such origin.! This appears to be the first reference to the fossiliferous silts now known as
Gardiners clay. Seven years later Mitchill reiterated the conclusion as to the alluvial origin
of the island and cited additional instances of buried shells.2 In the same paper, in describing
the northernmost ridge, he called attention to the superimposition of bowlders (Wisconsin) over
the “‘marine deposits” (Manhasset formation). This may possibly be taken as the first subdi-
vision of the deposits of the island.

In an account of his travels Timothy Dwight,’ then president of Yale, noted the difference
between the rounded character of the fragments over most of the island and their angularity
west of Jamaica and at Montauk, this being the second distinction on Long Island of the deposits
afterwards known as stratified drift and till. The hills at Shinnecock, which by many later
writers have been regarded as moraines, were described by Dwight as being at that time bare
hills of drifting sand. The island he regarded as having been formed as a bar by the Gulf
Stream, which swept inward during the Deluge. Buried shells and logs of wood are described
as occurring at several points.

Writing in 1824, John Finch said‘ that, no rivers are competent to deposit such masses
of alluvial material as are found on Long Island, which he considered as being the northern
extension of the Tertiary, the ridges, however, being referred to as “‘diluvial.”” The whole
island was considered to be underlain by sand, gravel, and clays containing fossil shells
(Venus, Ostrea, Murex, etc.) and tree trunks, and these beds were correlated with the clays at
Amboy, N. J.

In 1827 S. G. Morton arranged and published certain notes of Lardner Vanuxem,’ who
recognized the ‘‘Secondary”’ (the equivalent of the present Cretaceous of the island) in addition
to the Tertiary already recognized.

LITERATURE FROM 1837 TO 1842 (DILUVIAL PHASE).

The period from 1837 to 1842, though the shortest of the five into which the geologic lit-
erature of Long Island has been divided, is nevertheless among the most important, being
marked by the publication of the results of the first systematic field examination of the island—
that by the first Geological Survey of New York. It is characterized by detailed observations
rather than by inferences, and in it the complexity of the geologic history of the island was
for the first time distinctly recognized. Little further progress in solving the problems of
that history could be made as long as the hypothetical ‘‘diluvial process,” the exact nature
of which few pretended to comprehend fully, was appealed to as an explanation of the origin
of the island.

A report on the preliminary reconnaissance of the island by W. W. Mather,® geologist
of the first district of New York, appeared in 1837 and included discussions of the economic
geology, erosion features, bars and spits, landslides, dunes, erratic bowlders, clays, and the
occurrences of fossils and lignite in deposits penetrated by wells. A year later’ further descrip-
tions of the geologic features and processes were published. Mather’s discussions of the
extension of marshes, the occurrence of submerged tree stumps, the encroachments of the
sea, the formation of heaches, spits, and bars, the occurrence of garnet and magnetite sands,
and the distribution of bowlders are of special interest, as is also his prediction as to the ulti-
mate value of the peat deposits of the island.

 

1 Mitchill, S. L., An amendment proposed to the geological chart of the United States: Am. Mineralog. Jour., vol. 1, 1814, pp. 129-133; Geology
of Long Island: Idem, pp. 261-263.

2 Mitchill, S. L., Observations on the geology of North America, appendix to Cuvier’s Essay on the theory of the earth (tr. by Robt. Jameson),
New York, 1818, pp. 379-382.

3 Travels in New England and New York, vol. 3, 1822, pp. 283-336.

4 Geological essay on the Tertiary formations in America: Am. Jour. Sci., 1st ser., vol. 7, 1824, pp. 31-43.

5 Geological observations on the Secondary, Tertiary, and Alluvial formations of the Atlantic coast of the United States of America: Jour. Acad.
Nat. Sci. Philadelphia, vol. 4, pt. 1, 1827, pp. 59-71.

6 First Ann. Rept. New York Geol. Survey, 1837, pp. 61-95.

7 Mather, W. W., Second Ann. Rept. New York Geol. Survey, 1838, pp. 121-184.
6 GEOLOGY OF LONG ISLAND.

Four years afterward appeared the classic report on the First district,! which contained a
detailed discussion of Long Island. In this report, in addition to more complete discussions
of the processes and phenomena treated in the earlier reports, a classification of the deposits
of the island was attempted and its origin was considered. The materials were divided into
two systems—the Long Island system, called ‘‘Upper Secondary” and made to include the
Cretaceous and Tertiary formations, and the Quaternary system, comprising the Alluvial,
Quaternary, and Drift divisions. The principal mass of the island, including the white clays,
was held to be older than Tertiary, the lower beds being regarded as equivalents of the Creta-
ceous deposits of New Jersey, Delaware, and Maryland. The colored clays above the white
clay, which were believed to underlie the whole island, were recognized as older than the surface
drift and were referred to the Tertiary. This was the earliest recognition of a clay floor such as
that described by later geologists, although it is now known that two clays of widely different
age and stratigraphic position were considered by Mather as one. After the deposition of the
later clays (Gardiners clay) they were folded, as if by the lateral pressure of slides, after which
they were denuded (Montauk ice erosion) before the deposition of the drift (Wisconsin) uncon-
formably on their surfaces.2, In the “Drift division” overlying the folded clays was included
a thick deposit of what is now known as till (Montauk till member of Manhasset formation),
and above this came the “Quaternary division,’ embracing the more recent clay and sand
deposits of Long, Staten, and New York islands (Hempstead gravel member of Manhasset
formation and later deposits). ‘‘Some bowlder and drift deposits (Wisconsin) overlie this
formation, but the main drift deposit, which was usually called alluvium, erratic block group,
bowlder system, etc. (Montauk till member), underlies this formation.”* The ‘‘Quaternary
division’’ had three members, the lower being a blue clay, the middle a gray to buff clay, and
the upper a sand. The clays were correlated with those of the Hudson and Champiain valleys.
There is little doubt, however, that the three members are really to be correlated, respectively,
with what are now called the Gardiners clay, the Jacob sand, and the Herod gravel member
of the Manhasset formation. Their assignment to a position above the main drift (Montauk
till member of Manhasset formation) was doubtless due to the absence of this member of the
Manhasset formation in Mather’s type localities—an absence that is not at all uncommon.

Two drifts were also distinctly recognized elsewhere in Mather’s report. In speaking of the
‘Drift division”’ he said: ‘‘It is believed there is abundance of evidence of two epochs of strong
currents, with a period of considerable duration of comparative repose between them.” + This
statement, which was lost sight of by subsequent writers, deserves recognition as one of the
earliest if not the first explicit assertion in America of the duality of the drift period. Mather’s
statement in regard to fossils is also full of significance. ‘‘Most of them without any doubt
occur below the drift, a few in the drift, and none or very few in the Quaternary deposits.” §

Mather’s conception seems to have been that the “lower drift’? (Montauk till member of
Manhasset formation) and the drift of the ridges (moraines) were the same and were deposited
simultaneously as irregular hills, over or about which the deposits of his “Quaternary division”
were laid down in standing water. After this a layer of pebbles, gravel, and bowlders, “which
was called the upper drift,” 4 was deposited over the whole. The deposits of his “ Alluvial
division,” including fluviatile, lacustrine, marsh, and marine beds, all of which are still accu-
mulating, completed the formations of the island. In explaining the origin of the drift Mather
postulated diluvial processes requiring the action of strong currents laden with floating bergs
and recognized two periods of great activity separated by a quieter period, in which the deposits
of his ‘Quaternary division” were laid down.

LITERATURE FROM 1843 TO 1878 (EARLY PALEONTOLOGIC PHASE).

After the publication of the report on the First district the drift deposits received little
further attention for a period of 35 years, Mather’s work during this period being accepted as
authoritative and extensively quoted.° Of the new scientific contributions during this period

 

i Mather, W. W., Geology of New York, pt. 1, 1843. 2 Idem, p. 272. 3 Idem, p. 123. 4 Idem, p. 158. 5 Tdem, p. 264.
6 Thompson, B. F., The history of Long Island from its discovery and settlement to the present time, 2 vols., New York, 1843.
GEOLOGIC LITERATURE. t

by far the greater number related to paleontology, although several physiographic papers of
importance appeared.

In Mather’s report the older clays of Long Island had been assigned, on the basis of simi-
larity to the New Jersey deposits, to the Cretaceous, but no fossils identifiable as Cretaceous
had been found. In the year in which the report appeared, however, a notice of the finding
by William C. Redfield of Exogyra costata in a well in the drift at Brooklyn Heights was pub-
lished. This was asserted to be the first authentic discovery of a Cretaceous fossil on the
island.t

Four years later notes on more recent fossils in the drift near Brooklyn were given in
another paper by Redfield.? In commenting on this paper the editor said that the writer brought
out the fact “that at least two periods of drift must be recognized, one of which was anterior
to the deposit of clay in the valleys first referred to, the second that during which the shells on
the summit of Montreal Island and Long Island were deposited.” In 1848 E. Desor * reported
shells in deposits of striated pebbles (Montauk member?) forming an anticline on the flanks
of which were inclined sand and clays (Herod gravel member of Manhasset formation, etc.).
Bouchepon ‘ thought the structure might be due to a change of conditions caused by a shifting
of the earth’s axis.

The next contribution on the geology of the island was by C. H. Davis,® who described the
action of currents on the configuration of the entrance of New York Harbor. In 1850 and
1851 appeared two papers by E. Desor,® who in the second of these papers explained certain
phenomena of folding in the drifts about Boston as due to the settling of the deposits following
the melting of buried ice masses, a conclusion of interest in view of the explanations later
advanced in regard to the folding on Long Island. In 1854 a further note on the drift at
Brooklyn was made by Redfield,’ who reported the finding of additional fossils and advanced
the view that the drift period was greatly protracted but was later than the time of the so-called
post-Tertiary (fossiliferous) deposits, which he regarded as marking a distinct epoch. Desor?
differed from Redfield on this point, arguing that the deposit at Brooklyn was simply an
exception to the common rule of Quaternary formations.

The year 1857 was marked by the appearance of an important paper by George H. Cook,’
who cited many instances of submerged timber and marshes, especially near Hempstead,
Babylon, and Islip. Cook showed that undercutting by the waves does not explain the occur-
rences, which are more likely due to a subsidence that is still going on at the rate of 2 feet in
a hundred years.

In an agricultural paper, published in 1859, Winston C. Watson ® referred all of the island
except the ledges near Hell Gate to alluvium, which he considered to have been formed by the
sea in the same manner as the present beaches.

Four years later Dana,” in the first edition of his Geology, placed the northern limit of
the Cretaceous at Staten Island. He seems inclined to refer the older deposits of Long Island
to the Tertiary, although recognizing the glacial origin of the surface formations. He also
illustrated the submarine valley off New York Harbor in connection with his discussion of
Triassic rocks, saying: ‘‘The border, now submerged, has therefore in former times been dry
land; it may have been partly so in the Triassic period.’’

 

1 Am. Jour. Sci., 1st ser., vol. 45, 1843, p. 156.

2 Redfield, W.C., On the remains of marine shells of existing species found interspersed in deep portions of the hills of drift and bowlders in
the heights of Brooklyn, on Long Island, near New York City: Am. Jour. Agr. and Sci., vol. 6, 1847, pp. 213-219; Am. Jour. Sci., 2d ser., vol. 5,
1848, pp. 110-111.

3 Proc. Boston Soc. Nat. Hist., vol. 2, 1848, p. 247.

4Idem, vol. 4, 1854, p. 180.

5 Geological action of the tidal and other currents of the ocean: Mem. Am. Acad. Arts and Sci., new ser., vol. 4, 1849.

6 Des alluvions marines et lacustres et du terrain erratique de l’Amérique du Nord: Bull. Soc. géol. France, 2d ser., vol. 7, 1850, pp. 623-631;
[On the origin of contorted strata of sand and clay]: Proc. Am, Acad. Arts and Sci., vol. 2, 1851, pp. 282-283.

7 Proc. Boston Soc. Nat. Hist., vol. 4, 1854, pp. 180-181.

8 On a subsidence of the land on the sea coast of New Jersey and Long Island: Am. Jour. Sci., 2d ser., vol. 24, 1857, pp. 341-354.

® The plains of Long Island: Trans. New York State Agr. Soc., vol. 9, 1859, pp. 485-505,

10 Dana, J. D., Manual of geology, 1863.
il Idem, pp. 441, 442.
8 GEOLOGY OF LONG ISLAND.

In 1867 Sanderson Smith! published the first description of the clays of Gardiners Island,
together with an account of the fossils, which, with one or two exceptions, were believed to
be of species still inhabiting the waters of the region, although as a whole they were charac-
teristic of a more northern locality.

Two years later Elias Lewis, jr.,? mentioned buried or submerged tree trunks and other
evidences of subsidence, which he estimated had amounted to about 53 feet.

J. S. Newberry ® in 1871 announced the finding in the drift of cemented sand tragments
resembling Triassic material but containing angiospermous leaves not known to exist before
the Cretaceous.

The geologic maps issued before 1873, including that of the New York State geologists
in 1842, that of Edward Hitchcock and Jules Marcou in 1853, that of H. D. Rogers in 1858,
and that of Sir W. E. Logan in 1868, but not that of William Maclure, had shown Long
Island as Tertiary or alluvium. In 1873 C. H. Hitchcock and W. P. Blake, on a map of the
United States prepared for the Ninth Census, showed the north shore of Long Island as Creta-
ceous. With this mapping Dana‘ took issue, stating that there were ‘no facts making the
region Cretaceous.” After receiving a letter of explanation from Hitchcock, Dana published
another note, mentioning the source of the data supporting the map (Mather’s observations)
but expressing doubts of their value’ A reply by Hitchcock® the following year quoted
Mather and Cook as to the equivalency of the Long Island beds with New Jersey deposits of
known Cretaceous age. No mention was made by Hitchcock or Dana of the evidences advanced
by Redfield or Newberry, but attention was called to them soon afterward by D. 8. Martin,’
and new evidences of angiospermous leaves were presented by Newberry 7 and of the occurrence
of Gryphea by J. J. Stevenson.? Dana,’ however, in 1875 reaffirmed his belief that the
Cretaceous does not extend under Long Island.

Before the discussion of the Cretaceous ceased, Elias Lewis, jr.,° had called attention to
the occurrence of clay bowlders up to 8 feet in diameter in the stratified sands and gravels
at Harbor Hill, “near Brooklyn.’ In 1875 Dana” published some very important observations
showing complexities in the New England drift similar to those on Long Island. He noted
striated bowlders under the clays and ‘‘stony beds” (apparently loose till) over the sands, the
clays having been folded and eroded before the sands were deposited. Some of Dana’s descrip-
tions are suggestive of a still older gravel, possibly to be correlated with the Mannetto gravel
of the present report. Unfortunately, he was content to refer most of the phenomena to
unexplained variations in the diluvial processes accompanying and following the glacial invasion
(which was regarded as a unit) and made little attempt to develop the history of the region.
Submergence was advocated to explain the higher deposits. In another paper" Dana stated
that the glacial ice probably passed over Long Island and out to the edge of deep water 80
miles farther south. The same statement appeared in the second edition of his “Manual of
geology.’”’ The Sound, which was previously of less depth, was considered to have been occu-
pied and partly eroded by large subglacial streams. Dana also believed that the land at that
time stood at least 100 feet higher than at present and that the temperature was so low that
marine life did not exist until after the retreat of the ice. The year 1875 was also marked
by the appearance of a paper by Gabriel Furman,” who mentioned the occurrence of fossil
shells and described the breaks in the South Beach, and of a bibliography of Long Island, by
H. Onderdonk, jr.,* which, however, contained few references to scientific publications.

 

 

1 Notice of a post-Pliocene deposit on Gardiners Island, Suffolk County, N. Y.: Annals New York Lyceum Nat. Hist., vol. 8, 1867, pp. 149-151
2 Evidences of coast depression along the shores of Long Island: Am. Naturalist, vol. 2, 1869, pp. 334-336. ; mee ;
3 Proc. New York Lyceum Nat. Hist., Ist ser., 1871, pp. 149-150.
4 Dana, J. D., Geological map of the United States, compiled for the Ninth Census by C. H. Hitchcock and W. P. Blake: Am. Jour. Sci.,3d
ser., vol. 6, 1873, pp. 64-66. . a
5 (Cretaceous of Long Island]: Idem, p. 305.
6 Hitchcock, C. H., Note upon the Cretaceous strata of Long Island: Proc. Am. Assoc. Adv. Sci., vol. 22, pt. 2, 1874, pp. 131-132.
1 Proc. New York Lyceum Nat. Hist., 2d ser., No.4, 1874, p. 127.
8 Dana, J. D., Manual of geology, 2d ed., 1875, p. 455.
9 Bowlder-like masses of clay in the Long Island drift: Pop. Sci. Monthly, vol. 2, 1873, p. 634.
10 On southern New England during the melting of the great glacier: Am. Jour. Sci., 3d ser., vol. 10, 1875, pp. 168-183.
11 Absence of marine life from Long Island Sound through the glacial and part of the Champlain periods: \m. Jour. Sci., 3d ser., vol. 10 1875
pp. 280-282. ay Petre 2
12 Antiquities of Long Island, New York, 1875, pp. 1-434.
13 Tdem, pp. 435-469, .
GEOLOGIC LITERATURE. 9

The next year, 1876, D. S. Martin‘ called attention to fossiliferous erratic bowlders of
Silurian age, which he thought were drifted to the region by floating ice. In the same year a
paper by Elias Lewis, jr.,? gave a detailed account of the drifting sands of the island, including
the composition, weathering, structure, rate of advance, destructiveness, and methods of con-
trolling the dunes.

In 1877 were published four more papers of interest by the same author. In the first *
he described the large valleys of the south side of the island, noting the absence of streams
competent to account for their formation, which be thought was more likely due to the action
of subglacial streams. The lack of postglacial erosion was emphasized in this paper for the
first time. Lewis regarded the land as having been submerged to a depth of 260 feet in glacial
time, for stratified deposits are found up to that level. In the second paper‘ he pointed out
the occurrence of thirty pronounced valleys between New York and Riverhead, some of which
were said to extend across the Great South Bay to the ocean. Most of these valleys are char-
acterized by a much steeper slope on the west or right-hand bank than on the east, and the
general trend was said to be west of south. Deflection by the earth’s rotation was suggested
as the cause. In the third paper® the ridge or “backbone” appears for the first time to be
definitely referred to the terminal moraine. A table of altitudes was given, and the suggestion
was made that the amount of submergence during the formation can be determined from ‘the
presence and position of modified drift upon these hills and along their slopes.” This suggestion
indicates that Lewis believed the moraine to be older than the drift plateau on the north or the
sloping plains on the south. The fourth paper * was devoted to the supposed changes of level
indicated by the deposits of stratified sands and gravel that are recognized at different levels
by the submerged tree trunks and peat beds still to be seen, by the fossils and lignite encoun-
tered in wells, and by the submarine channels off New York. The absence of bowlders on the
plains south of the moraine was supposed to be due to their destruction by the advancing
and receding shore lines. The present Montauk till member of the Manhasset formation was
recognized as a distinct bed of “coarse glacial rubble in deep beds without fossils, * * *
chiefly on the north side of the island.” Below this were placed the gravels (Herod gravel
member of Manhasset formation) and below the gravels the fossiliferous clays (Gardiners clay).

The epoch was closed in 1878 by a paper by J. S. Newberry,’ which, though a popular
review of the geology, contained the statement that Cretaceous rocks underlie a large part
of the island but that the finding of Tertiary beds is doubtful. In view of later developments
this statement is of significance.

LITERATURE FROM 1878 TO 1900 (EARLY DRIFT PHASE).

The fourth period in the literature of the island began in 1878 with the first detailed dis-
cussion by Upham of the geology on the basis of the modern glacial theory, and continued
until the work of differentiating the drifts was begun. Knowledge of the island in this period
was advanced mainly through studies of the drift by Upham and Merrill, although, largely
through the efforts of Hollick, there was a steady accumulation of paleontologic evidence as to
the distribution of the Cretaceous along the north shore. The folding of the clays of the island
and the formation of the submarine valley off New York also received a share of attention by
Merrill and Lindenkohl, and the efficiency of subglacial streams as supplying many of the
deposits and developing most of the existing topography of the island was advocated at short
intervals throughout a large part of the period by Bryson.

.Upham’s first discussion ® was devoted to a consideration of the moraines, which he described,
giving their heights. He predicted that their continuation would be found crossing New Jersey,

 

1 On the occurrence of Silurian fossils in the drift of Long Island: Am. Naturalist, vol. 10, 1876, p. 191.
2 The formation of sand dunes: Pop. Sci. Monthly, vol. 8, 1876, pp. 357-363.

8 On watercourses upon Long Island: Am. Jour. Sci., 3d ser., vol. 13, 1877, pp. 142-146.

4 Certain features of the valleys or watercourses of southern Long Island: Idem, pp. 215-216.

& Heights of Long Island: Idem, pp. 235-236.

6 Ups and downs of the Long Island coast: Pop. Sci. Monthly, vol. 10, 1877, pp. 434-446.

7 The geological history of New York island and harbor: Pop. Sci. Monthly, vol. 13, 1878, pp. 641-660.
8 Upham, Warren, Geology of New Hampshire, vol. 3, pt. 3, 1878, pp. 300-305.
10 GEOLOGY OF LONG ISLAND.

Pennsylvania, and Ohio, and differentiated the inner and outer moraines. In a second paper,’
appearing the following year, Upham carefully and in the main accurately described the
moraines, gave elevations, and discussed their composition. He mentioned the prevalence of
till west of Roslyn and its absence to the east, and described the Shinnecock Hills as composed
of gravel.2 He recognized two tills throughout Long Island and New England, the lower being
composed of thick, clayey, compact bluish material and the upper of thin, loose, oxidized mate-
rial. The stratified character of the drift now known as Montauk was noted. Upham regarded
the Wheatley Hills as composed of till and thought the Mannetto and Half Hollow hills to
have been deposited like kames or in ice-walled channels. Later there was a local advance of
the ice sheet, accompanied by the deposition of drift over these elevations. In this paper the
outwash character of the plains was recognized for the first time, the preglacial age of the clays
near Bethpage was announced, and the folding and beveling of the clays on Gardiners Island
were described. The change of the sands lying unconformably upon the clays to bowlder
drift and vice versa was noted, and the deposits were correlated with those at Montauk,
Bethpage, and Gay Head. Upham referred the Smithtown drainage system to erosion and
described the numerous ponds that occupy old drainage channels.

In the following year, 1880, appeared still another paper by Upham, in which he described
the extension of the ‘lower’ (Montauk till member of Manhasset formation) and “upper”
(Wisconsin) till over New England,’ stating that the “lower” till is from 2 to 50 feet thick and
forms the drumlins, and that the “upper” till usually occurs as a very uniform mantle 5 feet
or so in thickness. In this paper Upham discussed the moraines of Long Island but made little
addition to the data published in his preceding papers.

In 1883 N. L. Britton * gave an account of further discoveries of sandstone fragments con-
taining Cretaceous fossils and predicted that correlation with the Cretaceous sandstones of
New Jersey would be established. In the same year appeared the first of a long series of papers
by John Bryson, a local geologist.* In this and the following papers Bryson recorded his
conviction that there had been no change of level of the island since the ice age, and that the
deposits are the work of subglacial streams which built up the island as a barrier across the
courses of the Connecticut and other rivers that had previously flowed southward to the ocean.
The fossils are assumed to have been washed up by the currents. The subglacial waters were
thought to have been finally diverted toward the west, cutting the East River channel. The
year 1883 was also marked by the publication of T. C. Chamberlin’s paper on the terminal
moraine® with which the moraines of Long Island are correlated. Chamberlin showed two
moraines in the eastern part of the island, but made the northern one end abruptly not far
from Port Jefferson instead of connecting with the other. His descriptions appear to be based
entirely on the work of Upham, although in speaking of the southern plains he says: ‘These
plains are undoubtedly due to glacial waters escaping over the moraine during its formation.” 7

In 1884 G. K. Gilbert ® discussed quantitatively the effects of the earth’s rotation on the
deflection of streams, mentioning the steep right banks of the southward-flowing streams of
Long Island. He pointed out that the conditions in rapidly deepening channels and in adjusted
alluvial fans were not favorable to the action of this force. In 1885 A. Lindenkohl ® described
the deep submarine channel cut in blue clay for a distance of 100 miles from New York Bay,
the presence of a bar of sand across it 75 miles from Sandy Hook, and the very deep ravine at
the edge of the continental platform. He noted the fact that the channel is in line with the
continuation of the moraine in New Jersey and suggested that the channel marks the position
of the old ice front.

 

1 Upham, Warren, Terminal moraines of the North American ice sheet: Am. Jour. Sci., 3d ser., vol. 18, 1879, pp. 81-92, 197-209.

2Cf. Dwight, Timothy, Travels in New England and New York, vol. 3, 1822, pp. 283-336.

3 The succession of glacial deposits in New England: Proc. Am. Assoc. Adv. Sci., vol. 28, 1880, pp. 299-310.

4 Science, vol. 3, 1884, p. 25. é

5 The glacial phenomena of North America as studied on Long Island, New York: Geol. Mag., new ser., vol. 10, 1883, pp. 169-171.

6 Preliminary paper on the terminal moraine of the second glacial epoch: Third Ann. Rept. U.S. Geol. Survey, 1883, pp. 291-402.
* Idem, p.378. .

8 The sufficiency of terrestrial rotation for the deflection of streams: Am. Jour. Sci., 3d ser., vol. 27, 1884, pp. 427-432.

2 Geology of the sea bottom in the approaches to New York Bay: Am. Jour. Sci., 3d ser., vol. 29, 1885, pp. 475-480.
GEOLOGIC LITERATURE. 11

The year 1886 was an active one in Long Island geology. N. L. Britton described the
finding of fossil leaves, supposedly from the ‘Middle Cretaceous,” in the clays at Glen Cove,
and J. S. Newberry noted their occurrence at Glen Cove and Lloyd Neck.* =

The principal contributions of the year were made by F. J. H. Merrill, who published a
detailed paper on the geology of the island.? In this paper, which was based on a five weeks’
study of the region, he divided the deposits into clays, gravels, and till. Of the greater part of
the clays he said: ‘‘ From their character and position we may surmise that the brown and red
plastic clays of Huntington, Gardiners Island, and elsewhere belong to the age in question
[Tertiary], although he noted the impossibility, in the absence of any unconformity, of deter-
mining where the Tertiary stops and the Pleistocene begins. He recognized, however, the simi-
larity of the clays at Glen Cove to the Cretaceous of New Jersey, although he said: ‘If the Cre-
taceous formation extends under the whole of Long Island it must occur at a very great depth,
since deep sections at points east of Glen Cove do not record its presence.” The gravels under-
lying the till were said to be ‘equivalent to and indeed identical with the yellow drift or pre-
glacial drift of New Jersey.’”’ A belief in the superimposition of the moraine on the gravels
is possibly indicated by Merrill’s statements that till is not more than a few feet thick even
where the land is high. In describing Montauk Point he mentioned a great thickness of ‘‘ bowl-
der clay and hardpan of considerable depth covered by a shallow layer of till,” apparently
recognizing the existence of two till-like drifts. He regarded the shoving action of the ice
as accounting for the elevation of the fossiliferous beds, for the lifting that formed the “back-
bone,”’ and for the folding of the clays of the north shore and even of those south of the
moraine, as at West Deer Park. The deep valleys of the north coast he explained as ‘“ plowed
out by projecting spurs of ice.”” In regard to the amount of postglacial erosion Merrill differed
from nearly every other writer on the subject, assuming it to be very extensive.

In a second paper? Merrill discussed at greater length the folding produced by the ice,
reiterated many of the conclusions outlined above, and assigned an age much greater than that
of the ‘‘Champlain”’ to the stratified fossiliferous deposits.

In 1888 W J McGee,! in discussing the Columbia group, noted the occurrence of “subestua-
rine terraces” up to 250 feet above the sea and in interfluvial regions up to 400 feet. He recog-
nized the fact that their age is greater than that of the moraines and suggested their corre-
lation with the extra morainal drift and the gravel deposits of Long Island. The erosion
interval between their deposition and that of the later drift was regarded by McGee as of great
length. The southward deflection of the rivers of the Coastal Plain he supposed to have taken
place in Columbia time.

In the same year John Bryson * gave a partial record of a well at Woodhaven, near Jamaica
Bay. Although noting the presence of lignite he referred all the materials to a glacial origin.
This well was further discussed with full records in subsequent papers by Bryson ® and Lewis.”
Bryson considered the glacial materials to extend to 298 feet; Lewis to 213 feet. No greensand
was found. The great depth assigned to the glacial deposits is of interest in connection with
the assumption of W. O. Crosby and others as to the Tertiary age of the gravels.

In 1890 J. D. Dana ® described the channels in Long Island Sound, ascribing them to the
action of a Sound river, which passed through what is now the North Fluke, near Mattituck,
into Peconic Bay, and thence eastward to the ocean. Other streams passed out of the Sound
at its east end. The harbors of the north shore were ascribed to the action of subglacial streams.
The presence of Cretaceous deposits had up to that time been disputed, but Dana admitted that
they occurred in the foundations of the higher parts of the island and on the north shore. He

1 Fossil leaves in Staten Island and Long Island clay beds: Am. Jour. Sci., 3d ser., vol. 31, 1886, p. 403,

2 On the geology of Long Island: Annals New York Acad. Sci., vol. 3, 1886, pp. 341-364.

3 Some dynamic effects of the ice sheet: Proc. Am. Assoc. Adv. Sci., vol. 35, 1886, pp. 228-229.

4 Three formations of the middle Atlantic slope: ..m. Jour. Sci., 3d ser., vol. 35, 1888, pp. 367-388, 448-406.

6 Am. Geologist, vol. 2, 1888, pp. 136-137.

6 Bryson, John, Artesian well, Woodhaven, Long Island, New York: Am. Geologist, vol. 3, 1889, pp. 214-215.

1 Lewis, Elias, jr., Woodham [Woodhaven] artesian well on Long Island: Am. Jour. Sci., 3d ser., vol. 37, 1889, p. 233.

8 Long Island Sound in the Quaternary era, with observations on the submarine Hudson River channel: .\m. Jour. Sci., 3d ser., vol. 40, 1890,

pp. 425-437.
12 GEOLOGY OF LONG ISLAND.

referred to the ‘‘Champlain stage” the bed of bowlder clay (Montauk till member of Manhasset
formation), 10 to 150 feet thick, beneath the gravel. The channel off New York Harbor was
thought to have been cut in ‘‘Jura-Trias”’ time (the Cretaceous and Tertiary being, according
to Dana, absent in its vicinity), possibly during an uplift accompanying a semiglacial epoch
which he thought may have marked the close of the era. He quoted a letter from E. Lewis, jr.,
who presented evidences of well records showing that the Cretaceous clays, especially those at
Deer Park and Bethpage, extend but short distances beyond their surface exposures.1. David
White * mentioned the occurrence at Glen Cove of plant remains similar to those of the Creta-
ceous of Marthas Vineyard and correlated them with the flora of the claysof Amboy, N.J. J.S.
Newberry * agreed with White as to the correlations and stated that he had traced the clays
from New Jersey to Glen Cove and believed them to extend the whole length of the island.

In 1891 A. Lindenkohl,* in a second contribution on the channel off New York, referred the
erosion to glacial time and noted a subsequent subsidence of 210 feet. C. A. White,’ in a review
of published literature, recognized the presence of nonmarine Cretaceous deposits but was inclined
to doubt the evidence of marine shells. F. J. H. Merrill,® in a paper on the Hudson Valley,
ascribed the submarine channel to fluviatile rather than marine scour, suggested a ‘‘ post-Cham-
plain”’ submergence of 100 feet in New York, noted the occurrence of low terraces on Staten
Island and the mainland, and correlated the plains of the south side of Long Island with the
terrace of Hudson River, expressing his belief that a sloping plain could be cut on a rising or
sinking coast without the formation of beaches.

In 1892 W. H. Dall and G. D. Harris’ expressed the opinion, derived from a review of
published literature, that Cretaceous and probably Tertiary formations are present on Long
Island,

In 1893 McGee’s geologic map of the United States * gave the northern half of the island as
Cretaceous. Bryson ° published three papers, all in favor of‘the subglacial theory. In the first
he argued for the subglacial rather than submarine origin of the channels of the plains, as
Shaler had postulated for Marthas Vineyard. In the second he placed the ice limit south of the
island rather than at the moraines and correlated the Olympia mounds of Washington with the
Easthampton dunes, referring both to subglacial action. In the third he considered the Shinne-
cock Hills to be of kame origin and Peconic Bay to be due to the action of subglacial streams.
Heinrich Ries * followed Merrill in referring a large part of the clays of Long Island to the
Tertiary period, but accepted the Cretaceous age of those at Elm Point, Glen Cove, Mosquito
Inlet, Glenwood, and Northport. Ries pointed out the similarity of the clays of West Neck
and Center Island to those of Fishers Island and recognized their folded condition and position
beneath sand, which in turn is overlain by till. He recorded stems and leaves from the clays
of East Williston.

The year 1893 was also marked by the appearance of the first contributions by Arthur Hollick
on the Cretaceous formation of the island. In the first of these papers he argues, from the
evidence of the flora, for a former land connection with the New England islands and the main-
land. Long Island Sound he ascribed to ice erosion, the moraines to ice shove, and East River
and its channels to overflow from glacial streams behind the moraine, assisted by tidal scour.
The moraine was believed to have been cut through in the “Champlain” period of submergence

 

1Am, Jour. Sci., 3d ser., vol. 40, 1890, p. 430.

2 On Cretaceous plants from Marthas Vineyard: Am. Jour. Sci., 3d ser., vol. 39, 1890, pp. 93-101.

3 Bull. Geol. Soc. America, vol. 1, 1890, p. 555. e

4 Notes on the submarine channel of the Hudson River and other evidences of postglaci: i i i fant
eo a ee postglacial subsidence of the middle Atlantic coast region: .Am.

Correlation papers, Cretaceous: Bull. U. 8. Geol. Survey No. 82, 1891, pp. 84-86.

6 On the postglacial history of the Hudson River valley: Am. Jour. Sci., 3d ser., vol. 41, 1891, pp. 460-461,

Correlation papers, Neocene: Bull. U. 8. Geol. Survey No. 84, 1892, pp. 38-39.

8 Fourteenth Ann. Rept. U.S. Geol. Survey, pl. 2, 1894, Pl. Il.

° Bryson, John, The glacial geology of Marthas Vineyard compared with that of Long Island: Am. Geologist, vol. 11, 1893, pp. 210-212: The drift
mounds of Olympia and Long Island: Idem, vol. 12, 1893, pp. 127-129; Origin of Peconic Bay and Shinnecock Hills, Long Island: Tdern vol. 12
1893, pp. 402-403. occas

10 Notes on the clays of New York State and their economic value: Trans. New York Acad. Sei., vol. 12, 1893, pp. 40-47.

Plant distribution as a factor in the interpretation of geological phenomena, with-special reference to Long Island and vicinity: Trans. New
York Acad. Sci., vol. 12, 1893, pp. 189-202. =
GEOLOGIC LITERATURE, 13

and the detached islands to have been thus formed. In the second paper! Hollick gave a sum-
mary of the previous writings on the island and a list of Cretaceous fossils. In the third and
fourth papers ? he recorded the finding of a palmlike fossil and described the plant. He quoted
L. F. Ward as stating that the fragment is a Williamsonia and not a palm.

In 1894 four more papers by Hollick appeared. In the first * he described the distribution
of fossiliferous ferruginous sandstone in the drift mainly west of Port Jefferson, and of the silici-
fied Paleozoic fossils west of Lloyd Neck. These fossils occur mainly in the drift of the outer
moraine, having been picked up by the ice at its first advance. The thick gravels were appar-
ently considered by Hollick as the equivalent of the “yellow gravel” of New Jersey. In the
second and third papers‘ he reported further discoveries of Cretaceous flora at Eaton, Lloyd,
and Oak necks, Glen Cove, and Seacliff. In the fourth paper *® he described the occurrence of
pebbles containing Paleozoic fossils as far east as Eaton Neck, and on this evidence correlated
the gravels (Manhasset formation) with the ‘yellow gravel” of New Jersey, notwithstanding
their granitic character. He did not clearly indicate the age of the fossils but seems to have
regarded them as pre-Pleistocene. In 1894 also the finding of Cretaceous leaves in water-worn
sandstone fragments was recorded by C. L. Pollard,® andthe occurrence of microscopic organisms
of supposed Tertiary age in the clays at a large number of localities was reported by Heinrich
Ries.’ It is interesting to note that all these forms were found in beds which later work has
shown to be Cretaceous, and none in what are now known to be Pleistocene clays, either on Long
Island or on Fishers Island, although these clays were then thought by Ries to be Tertiary. A
second paper by Ries * describes the discovery of Cretaceous fossils at Little Neck, in Northport,
making it necessary to place the boundary farther south than had previously been done. In the
meantime W J McGee,’ who had investigated the unconformities of the Coastal Plain, reached
the conclusion that although there had been erosion, amounting to 200 or 300 feet, since the
Lafayette epoch, only about a foot had occurred since the Columbia. The Lafayette was
regarded as marine and as separated from the overlying Columbia by the greatest unconformity
of Neocene and Quaternary time. N.S. Shaler” gave considerable attention during the same
year to the cause of the folding in the clays and associated beds of the New York and New
England islands. He thought these folds to be similar to those of the Richmond Basin and to
be due to downfolding and the production of a trough in the underlying crystalline rocks, with
the resulting synclinorial structure in the softer beds—in fact as a part of the disturbance
marked in the Coastal Plain farther south by faulting which has been going on since the move-
ment in the Appalachians ceased. Shaler further stated that the folding can not be due to ice,
for the folds were eroded before the Wisconsin ice advance. The earlier ice invasions were not
then recognized by Shaler. Ries," in discussing the same phenomena on Fishers Island, referred
them to ice shove.

In 1895 A. M. Edwards” noted the finding of supposed fresh-water and marine Bacillariaces
of Miocene age in clays near Rockaway. The deposits are now known to be Pleistocene or
Recent, instead of Tertiary, as assumed by Edwards. Arthur Hollick,” in a paper on the folding

 

1 Preliminary contribution to our knowledge of the Cretaceous formation on Long Island and eastward: Trans. New York Acad. Sci., vol. 12,
1893, pp. 222-231.

2 A new fossil palm from the Cretaceous formation at Glen Cove, Long Island: Bull. Torrey Bot. Club, vol. 20, 1893, pp. 168-169; Some further
notes upon Serenopsis kempii: Idem, pp. 334-335.

3 Some further notes on the geology of the north shore of Long Island: Trans. New York Acad. Sci., vol. 13, 1894, pp. 122-130.

4 Additions to the paleobotany of the Cretaceous formation of Long Island: Bull. Torrey Bot. Club, vol. 21, 1894, pp. 49-65; Recent investiga-
tions in the Cretaceous formation on Long Island, New York: Proc. Am. Assoc. Adv. Sci., vol. 42, 1894, p. 175.

5 Notes on the northward extension of the yellow gravel in New Jersey, Staten Island, Long Island, and eastward: Proc. Am. Assoc. Adv.
Sci., vol. 42, 1894, pp. 175-176.

6 Trans. New York Acad. Sci., vol. 13, 1894, pp. 180-181.

7 Microscopic organisms in the clays of New York State: Idem, pp. 165-169.

8 On the occurrence of Cretaceous clays at Northport, Long Island: School of Mines Quart., vol. 15, 1894, pp. 354-355.

® Graphic comparison of post-Columbia and post-Lafayette erosion: Am. Geologist, vol. 12, 1894, p. 180.

10 Tertiary dislocations of the Atlantic coast of the United States: Am. Geologist, vol. 13, 1894, pp. 143-144; Notes on the Pleistocene distortions
of the Atlantic coast of the United States: Am. Jour. Sci., 3d ser., vol. 47, 1894, p. 138; Pleistocene distortions of the Atlantic seacoast: Bull. Geol.
Soc. America, vol. 5, 1894, pp. 199-202.

1 Trans. New York Acad. Sci., vol. 14, 1895, p. 20.

12 The occurrence of Tertiary clay on Long Island, New York: Am. Jour. Sci., 3d ser., vol. 50, 1895, p. 270.

13 Dislocations in certain portions of the Atlantic Coastal Plain strata and their probable causes: Trans. New York Acad. Sci., vol. 14, 1895,
pp. 8-20.
14 GEOLOGY OF LONG ISLAND.

of the clays and associated beds, noted that the disturbance is limited to the region covered by
ice and is essentially’ superficial. He could see no evidence of preglacial topography. The
“yellow gravel” (Manhasset formation) he regarded as the equivalent of the Lafayette. Hein-
rich Ries‘ referred a large number of the clay outcrops to the Tertiary, noting especially the
similarity of the clays of Center Island, West Neck, and Fishers Island, which are “probably of
the same age, possibly Tertiary.” He recognized, however, the Cretaceous age of most of the
clays of the north shore west of Northport. L. F. Ward,’ in discussing the New Jersey equiva-
lents of the Cretaceous of Long Island in the same year, referred them to the Lower Cretaceous.
J. S. Newberry,’ in writing on the clays of Amboy, N. J., correlated the clays of Long Island
with the basal Cretaceous as developed in New Jersey.

In 1896 N. H. Darton‘ published a geologic section across the west end of the island and
gave a number of well records. A. M. Edwards,® in a second paper on the Diatomaceex, de-
scribed the finding of 70 species near Far Rockaway in clays supposed then to be of Neocene
age but shown by late work to be unquestionably Pleistocene or Recent. Arthur Hollick pub-
lished two papers during the year. The first ® contained an account of the finding of lithologic
evidences of marl on the north shore near Oyster Bay, of Cretaceous mollusks in greensand
fragments in the drift at East New York, and of ferruginous concretions with mollusks in the
deposits at Montauk. The second paper’ presents the additional suggestion that the clays of
Little Neck near Northport have been pushed southward in a mass, as they should be north
instead of south of the marl, fragments of which were found at Center Island. There seems to
be some likelihood of error in such conclusions because of the assumption that fragments of
ferruginous sandstone are weathered masses of marly deposits. W J McGee,’ in another paper
on the erosion epochs, placed the great erosion following the deposition of the Lafayette in the
‘“‘Ozarkian”’ and assigned it to late Neocene time. He also recognized two interglacial periods
of erosion. L. F. Ward ” reintroduced the term “‘Island series,’’ originally proposed by Mather,
for the Cretaceous deposits of Long Island and correlated them on the evidence of the flora
with the clays of Raritan and Amboy, N. J. O. C. Marsh !° in the same year made the some-
what startling announcement, based on the Jurassic aspect of certain fossils found in Maryland,
that all the deposits hitherto regarded as Cretaceous should be referred to the Jurassic.

In 1897 John Bryson" noted erratics on the ‘‘kame moraine’’ near East Williston, the
first recognition of the outer moraine at this point. L.F. Ward” pointed out that the clays
of Amboy, N. J., with which the clays of Long Island had been correlated, were distinctly
younger than the Potomac of Maryland and Virginia. Lewis Woolman " published a number
of records of wells near the west end of the island.

In 1898 John Bryson " described some contorted drift with interbedded till [Montauk 2] in
Brooklyn. Arthur Hollick * assigned the clays of Amboy, on the evidence of their flora, to the
“Middle Cretaceous,” though not denying that the older Potomac might be Jurassic. In
another paper ** Hollick gave additional notes on the occurrence of lumps of Cretaceous clay,
some of them with fossils, in the drift, and on the finding of marl concretions on Montauk.
Warren Upham * described the submarine channel off New York, postulating an uplift to 3,000
feet at the end of the Tertiary period. He regarded the fossils of Gardiners Island as preglacial.

 

. Clay industries of New York: Bull. New York State Mus. Nat. Hist. No. 12, 1895.

2 The Potomac formation: Fifteenth Ann. Rept. U.S. Geol. Survey, 1895, pp. 345-346.

3 The flora of the Amboy clays: Mon. U. 8. Geol. Survey, vol. 26, 1895.

4 Artesian-well prospects in the Atlantic Coastal Plain region: Bull. U. S. Geol. Survey No. 138, 1896.

5 On the occurrence of Neocene marine Diatomace near New York: Am, Naturalist, vol. 30, 1896, pp. 212-216.
6 Geological notes, Long Island and Nantucket: Trans. New York Acad. Sci., vol. 15, 1896, pp. 3-10.

7 Recent discovery of the occurrence of marine Cretaceous strata on Long Island: Proc. Ain Assoc. Adv. Sci., vol. 44, 1896, pp. 133-135.

8 Two erosion epochs: Science, new ser., vol. 3, 1896, pp. 796-799.

9 Age of the Island series: Science, new ser., vol. 4, 1896, pp. 757-760.

10 The geology of Block Island: Am. Jour. Sci., 4th ser., Vol. 2, 1896, pp. 295-298, 375-377.

1 The Hempstead Plains, Long Island: Am. Geologist, vol. 20, 1897, pp. 61-65.

12 Prof. Fontaine and Dr. Newberry on the age of the Potomac formation: Science, new scr., vol. 5, 1897, pp. 411-423.

13 Artesian wells in Cretaceous strata on Long Island, New York: Iept. New Jersey Geol. Surv: ey for 1896, 1597, pp. 155-165.

14 Drift formations of Long Island: Am. Geologist, vol. 22, 1898, pp. 245-247.

15 The age of the Amboy clay series, as indicated by its flora: Am. Geologist, vol. 22, LSU, pp. 255-256; Science, new scr., vol. 8, 1898, pp. 467-168.
16 Geological notes, Long Island and Block Island: Trans. New York Acad. Sci., vol. 16, 1898, pp. 9-18.

17 Glacial history of the New England islands, Cape Cod, and Long Island: Am. Geologist, vol. 24, 1899, pp. 79-92.
GEOLOGIC LITERATURE. 15

He recognized an early ice advance, producing the folding, as occurring before the advance that
produced the moraines, and he suggested that the Kansan, Illinoian, Iowan, and early
Wisconsin stages of glaciation in the Mississippi Valley may have taken place between the
folding and the formation of moraines. The topography of the plateau and its deep valleys
Upham thought to be due to the deposition of gravel around ice blocks. He pointed out the
thinness of till near the limits of glaciation.

In 1900 W. O. Crosby ‘ stated the principal formations of the island to be (1) crystalline,
(2) Cretaceous, (3) Neocene Tertiary, and (4) terminal moraine. The surface gravels both
north and south of the moraine, although granitic in character, he correlated with the “yellow
gravels” of New Jersey and regarded as Lafayette. The ‘‘blue clay,’ which was supposed to
form a uniform floor beneath the gravels, he referred to the Chesapeake. The gray gravels,
notwithstanding their high percentage of granitic material, he likewise included in the Tertiary.
These three formations are probably to be correlated with the Manhasset, Gardiners, and Jameco
formations of the present report. Crosby supposed the Cretaceous to be confined to the north-
ern part of each neck of the north shore and the Tertiary to be farther south on the same necks
but going under the surface near the head of each bay or harbor. The exposures at East Willis-
ton, Bethpage, and West Deer Park he regarded as Tertiary and supposed to have been brought
up by the pressure and thrust of the ice sheet. He considered the north-shore scarp to have
been worn back by lateral tributaries of Connecticut and Housatonic rivers during an uplift of
3,000 feet preceding the ice advance.

In the same year F. J. H. Merrill? postulated an origin for the white Cretaceous clays of
Long Island from the decomposition of the Lower Silurian [Ordovician] limestone and argued
for the origin of Long Island Sound and East and North rivers through the solution of such
rocks. Heinrich Ries * published an account of the clays, which, however, was essentially the
same as an earlier paper.

LITERATURE FROM 1901 TO 1908 (LATER DRIFT PHASE).

Previous to 1901 no systematic studies of the island as a whole or of any considerable part
of it had been attempted, with the exception of Mather’s investigations from 1837 to 1843,
although the detailed reconnaissances of Upham and Merrill approached such studies in
character. In the period beginning with 1901, however, a number of reports have appeared
that have been based on detailed and systematic field observations covering not only the
surface deposits but also the underground geology as worked out from the records of many
hundreds of wells and borings. The attempt has been made, moreover, to approach the problem
from the standpoint of the student of geologic history and to apply knowledge of the drift
succession in other parts of the country to the differentiation of the deposits of Long Island.

The first publication of the period was the geologic map of Long Island,‘ based on field
work by J. B. Woodworth and J. E. Woodman and issued by the Geological Survey of New
York. On this map the moraines were mapped in detail, and the fact that the later moraine
crosses the older one near Lake Success was pointed out for the first time. The Westbury,
West (Mannetto), and Half Hollow hills, which later work has shown to be much older, were
shown as moraines, and the gravels of the ridge at Rockaway, now known to be Pleistocene,
were referred to the Tertiary. In the same year J. B. Woodworth * published the results of a
careful study of the Oyster Bay and Hempstead areas. He mapped the outcrops of Cretaceous
rocks and clearly pointed out the Pleistocene nature of the thick gravels of the north shore
(Manhasset formation) and the included bowlder bed (Montauk till member of Manhasset).
In the region north of the moraine these gravels were also carefully mapped and their probable
extension southward was indicated. Woodworth recorded the presence of underlying blackish
or bluish clays, but considered that they are ‘‘not certainly of glacial origin and perhaps to be

 

1 Outline of the geology of Long Island in its relation to the public water supplies: Tech. Quart., vol. 13, 1900, pp. 1/ 0-119.

2 Origin of the white and variegated clays of the north shore of Long Island: Annals New York Acad. Sci., vol. 12, 1900, pp. 113-116.
3 Clays of New York: Bull. New York State Mus. No. 35, 1900.

4 Geologic map of New York, 1901, Long Island and Lower Hudson sheets.

5 Pleistocene geology of portions of Nassau County and the Borough of Queens: Bull. New York State Mus. No. 4s, 1901, pp. 617-670.
16 GEOLOGY OF LONG ISLAND.

regarded as of Tertiary or older age.’’ He admitted that the altitude of much of the Cretaceous
material is due to ice shove but recognized a strong erosion unconformity between the Cre-
taceous and the Pleistocene. The bowlder bed in the Manhasset formation was recognized at
many points and its change laterally from till-like to stratified materials noted. He described in
detail the great erosion period following the early Pleistocene deposition but preceding the deposi-
tion of the last drift, which had not been recognized by Crosby and had been explicitly denied
by Hollick. The deposition of the high gravels at Harbor Hill Woodworth ascribed to subglacial
streams. He discussed thé straight face of the moraine west of Jamaica but reached no definite
conclusion as to its origin. He suggested that the Jamaica Bay depression is an original con-
structional feature of deposition and that the Rockaway ridge is a remnant of the Tertiary.
The moraine he distinctly recognized as superimposed on the Manhasset, representing simply
a local thickening of the tillsheet. The geologic history as outlined by Woodworth is as follows:
(1) Erosion of the Cretaceous, (2) deposition of earlier Columbia deposits (Herod gravel member
of Manhasset formation), (3) advance of the ice and deposition of the bowlder bed (Montauk
till member of Manhasset), (4) completion of the deposition of the Columbia (Hempstead gravel
member of Manhasset), (5) long period of erosion, (6) invasion by latest ice sheet (Wisconsin),
and (7) retreatal deposition in glacial lakes. While many of the points brought out were not
new, this paper was in many ways the most important that had yet appeared, as Woodworth
did not stop with general statements but systematically described and discussed. the various
deposits and differentiated them for the first time on a map.

A paper by G. B. Shattuck’ presented the following summary of the later Coastal Plain
history: (1) Subsidence and deposition of the Lafayette, (2) elevation and erosion of the
Lafayette, (3) subsidence and deposition of the Sunderland, (4) elevation and erosion of the
Sunderland, (5) subsidence and deposition of the Wicomico, (6) elevation and erosion of the
Wicomico, (7) subsidence and deposition of the Talbot, (8) elevation and erosion of the Talbot,
and (9) subsidence and deposition of the Recent deposits. Shattuck stated that because of the
difference in method of classification exact correlation with the New Jersey deposits could not
be made, and he presented a table in which he suggested the correlation of the Sunderland with
parts of Cape May, Pensauken, and Bridgeton; of the Wicomico also with parts of the Cape
May, Pensauken, and Bridgeton; and of the Talbot with parts of the Cape May and Pensauken.

In the following year, 1902, appeared the New York folio,? in which that part of Long
Island lying west of the area treated by Woodworth was fully described. In this folio an early
Pleistocene elevation, during which the submarine channel was excavated and the channels
of the East River were cut by a tributary stream, was assumed,’ and the possibility of earlier
glaciers similar to the last was suggested.‘ The possibility of old Pleistocene gravels correlat-
able with the Pensauken of New Jersey occurring beneath the late till of Staten Island was
pointed out,® but no mention of their occurrence on Long Island was made. At least two ice
advances were considered to have occurred in the region. The superimposition of the relatively
thin moraine on older deposits was likewise recognized. The steepness of its face west of
Jamaica was not attributed to marine erosion. The plains of the south side of the island were
described, and the fact that their topography is not that of normal outwash plains was pointed
out. The Rockaway ridge was attributed to marine action in late glacial or postglacial time, when
the land was somewhat depressed. Although at least two glacial invasions in the region were
admitted and the occurrence of stratified gravels below the Wisconsin till was noted, the existence
of any extensive deposits of an earlier stage does not appear to have been recognized, the
materials beneath the till apparently being referred to an earlier deposit of the same stage
instead of to a distinct deposition separated from the last ice invasion by a long period of erosion,
as postulated by Woodworth in the adjoining area on the east.

 

1 The Pleistocene problem of the north Atlantic Coastal Plain: Cire. Johns Hopkins Univ. No. 152, 1901; Am. Geologist, vol. 28, 1901, pp. 87-107.
2Merrill, F. J. H., and others, New York City folio (No. 83), Geol. Atlas U. S., U. 8. Geol. Survey, 1902.

3 Willis, Bailey, and Dodge, R. E., Physiographic features of the district: Idem, pp. 17-18.

4 Willis, Bailey, Outline of geologic history: Idem, pp. 2-3.

5 Salisbury, R. D., Pleistocene formations: Idem, pp. 11-17.
GEOLOGIC LITERATURE, 17

G. B. Shattuck! published a second paper during the year reiterating the Coastal Plain
subdivisions proposed in 1901.

In 1903 the present writer, assisted by A. C. Veatch and others, began a detailed study of
the geology and water resources of the island. Ina preliminary notice by Veatch,? who devoted
himself largely to collecting well records and studying underground geology,. the “uniform blue
clay floor” of supposed Chesapeake age, which had been postulated by Crosby and others, was
shown to be absent, and the presence of a deep buried valley across the island west of Jameco
was pointed out. In this notice tho present writer was credited with the discovery in the
Wheatley Hills of hitherto unrecognized gravel deposits [Mannetto] older than the Manhasset
formation and with the recognition of terraces of the Manhasset south of the moraine near
Bethpage. A detailed section at the top of the hill west of Melville was given, showing a con-
siderable thickness of quartz gravels containing a few weathered granitic pebbles and underlain
by sands, clays, “‘arkose,” etc., of pre-Pleistocene age. The dip of the Cretaceous was deter-
mined for the first time, well borings showing it to be about 65 feet to the mile in the direction
S. 23° BE.

In another paper * Fuller and Veatch called attention to the extension of the Cretaccous
to the Bethpage and Wyandance localities and to the discovery of greensand in the Millville
section. The absence of Tertiary deposits was noted, the older gravels having been determined
to be early Pleistocene. The supposed Chesapeake clays were separated into a number of
formations, all of Pleistocene age. Gravels of glacial origin and of supposed Kansan age were
noted beneath the early Pleistocene clay in the buried valley west of Jamaica. The occur-
rence of gravels of the Manhasset formation was recognized as far east as Montauk Point and
their age was given as probably Iowan. The thinness of the outwash is emphasized for the first
time. Later the present writer‘ discussed two of the pre-Wisconsin deposits in more detail.
The older, deeply weathered gravels of the Westbury or Wheatley Hills and the West or Man-
netto Hills were correlated with the Pensauken formation of New Jersey and assigned provision-
ally to water deposition during a pre-Kansan stage of glaciation, and their correlation with
McGee’s high-level Columbia of New Jersey and farther south and with the deposits of the
Monongahela and Alleghany terraces was suggested. The discovery of a glacially derived gravel
[Jameco] resting unconformably on the old weathered gravel [Mannetto] and of an extensive
bed of Pleistocene clay [Gardiners] directly above it and the recognition of an epoch of folding
by ice thrust were credited to Veatch, who assigned the glacial gravel to the Kansan, the clay
to the Yarmouth, and the folding to the [linoian stage. On the basis of these discoveries the
unfolded Manhasset was referred to the Iowan. Veatch,® in a paper published a few weeks
later, described the clays and old gravels of Gardiners Island, their contained fossils, and their
folding and erosion. He gave the following succession for Long Island: (1) Pensauken gravel
[Mannetto], glacial; (2) Jameco gravel, glacial; (3) Sankaty clay [Gardiners], interglacial; (4)
Manhasset, glacial; (5) Wisconsin, glacial. The correlations with the various glacial stages are
the same as in the preceding paper.

Four other papers relating to Long Island appeared during the year. E. P. Buffet ® dis-
cussed the topography, bowlders, and beaches from the standpoint of the geographer. Arthur
Hollick’? gave a list of paleontologic accessions from Glen Cove. Tleinrich Ries * referred the
clays of Staten, Long, and Fishers islands to the Cretaceous, no Pleistocene clays on Long Island
being mentioned. J. W. Spencer ® described the submarine channel off New York, stating that
its continuation may be inferred to a depth of 8,500 feet below the “‘cul-de-sac”’ of Lindenkohl.

 

1 The Pleistocene problem in Maryland: Science, new ser., vol. 15, 1902, pp. 906-907.

2 Notes on the geology of Long Island: Science, new ser., vol. 18, 1903, pp. 213-214.

3 Results of the resurvey of Long Island: Science, new ser., vol. 18, 1903, pp. 729-731.

4 Probable pre-Kansan and Iowan deposits of Long Island: Am. Geologist, vol. 32, 1903, pp. 308-312.

5 The diversity of the glacial period on Long Island: Jour. Geology, vol. 11, 1903, pp. 762-776.

6 Some glacial conditions and recent changes on Long Island: Jour. Geography, vol. 2, 1903, pp. 95-101.

7 Field work during 1901 in the Cretaceous beds of Long Island: Fifty-fifth Ann. Rept. New York State Mus., 1903, pp. r 48-r 51,
8 Clays of the United States east of the Mississippi River: Prof. Paper U.S. Geol. Survey No. 11, 1903, pp. 173-175.

9 Submarine valleys off the American coast and in the North Atlantic: Bull. Geol, Soc. America, vol. 14, 1903, p. 214.

1629°—14——3
18 GEOLOGY OF LONG ISLAND,

The cutting he thought to be mainly post-Miocene, although it may have begun earlier, being
completed in post-Lafayette but pre-Columbia time. The Connecticut he regarded as flowing
eastward, stating that there is no evidence of a channel across Long Island.

The year 1904 was characterized by a marked falling off in the literature dealing directly
with Long Island. Arthur Hollick' described a number of new discoveries of fossil plants,
including one from “Cretaceous shale” at Montauk Point. Jn a letter Dr. Hollick states that
this was not found in place and that the Cretaceous does not at the present time show above sea
level, hence his observations are really in accord with those of the present writer, who regards
all the deposits as Pleistocene. C. E. Peet,? who studied the drift of the Hudson Valley, found
masses of till both over and under the drift and clay bowlders within it, especially in the southern
part of the area. Over the clay he noted also in many places a gravel with an undulating topog-
raphy [Manhasset ?], the contact appearing as if the gravel had been pressed into the clay.

In 1905 W. H. Hobbs ? published two papers in which he gave a number of sections across
East River that showed the underlying rock to be mainly gneiss, with only two narrow local beds
of limestone. He therefore regarded the channel as due to faulting and jointing rather than
to solution of the limestone. In the same year the first presentation of the Pleistocene stages
now recognized was made by the present writer * in a paper on Fishers Island. Although this
paper did not deal primarily with the larger island, the Long Island succession was described
in detail; all the divisions except the Hempstead and Vineyard were recognized and names
were applied to the Gardiners, Jacob, Herod, and Montauk stages and substages. A further
contribution to the literature on the submarine Hudson channel was made by J. W. Spencer,®
who stated that he could trace it to a depth of about 9,000 feet below the surface of the sea.

Early in 1906 there appeared in Chamberlin and Salisbury’s text book ® a geologic map of
the United States compiled by Bailey Willis, on which the north side of Long Island is shown
as Cretaceous. The present writer’ summarized the Pleistocene stages of the region and
described the Long Island subdivisions and their equivalents on the mainland. An important
contribution was made by A. C. Veatch * in a chapter of the report giving the results of the
underground-water investigations by the United States Geological Survey. The Pleistocene
formations recognized were identical with those discussed in the earlier paper by the same
author in 1903, the new stages differentiated by the present writer, including the Jacob, Herod,
Montauk, and Hempstead of this report, not being recognized. Veatch’s report was prepared
two years previous to its publication and before the subdivisions mentioned had been differ-
entiated. Although no new stages were recognized, the paper was of importance as presenting
a detailed statement of the subdivisions as they had been worked out in the first season’s field
work and fuller descriptions than had been given in the preliminary papers of 1903. Correla-
tions were made with the deposits of Marthas Vineyard, but none were attempted with the
drifts of the central part of the country nor with the Pleistocene formations of the Atlantic
Coastal Plain. An important contribution to the knowledge of the Cretaceous deposits was
made, these accumulations being regarded as the equivalents of the Raritan and Matawan
formations of New Jersey and as being of Upper Cretaceous age. Veatch gave an extended
discussion of the origin of Long Island Sound, which he ascribed to excavation by a westward-
flowing stream crossing western Long Island and joining the submarine channel off Sandy Hook.
In the same year Arthur Hollick® added to the information regarding the Cretaceous, and
G. B. Shattuck’s final report on the Pleistocene deposits of Maryland was published, in which
he still further elaborated his views.

 

1 Additions to the paleobotany of the Cretaceous formation on Long Island, No. II: Bull. New York Bot. Garden, vol. 3, 1904, pp. 403-418,

2 Glacial and post glacial history of the /udson and Champlain valleys: Jour. Geology, vol. 12, 1904, pp. 415-469, 617-660. :

3 Origin of the channels surrounding Manhattan Island, New York: Bull. Geol. Soc. America, vol. 16, 1905, pp. 151-182; The configuration
of the rock floor of Greater New York: Bull. U. 8S. Geol. Survey No. 270, 1905, 93 pp. : =

4 Geology of Fishers Island, New York: Bull. Geol. Soc. America, vol. 16, 1905, pp. 367-390.

5 The submarine great canyon of the Hudson River: Am. Jour. Sci., 4th ser., vol. 19, 1905, pp. 1-15.

6 Chamberlin, T. C., and Salisbury, R. D., Geology, vol. 2, 1906, colored plate.

7 Glacial stages in southeastern New England and vicinity: Science, new ser., vol. 24, 1906, pp. 467-469.

8 Outline of the geology of Long Island: Prof. Paper U.S. Geol. Survey No. 44, 1906, pp. 15-52.

9 The Cretaceous flora of southern New York and New England: Mon. U. 8. Geol. Survey, vol. 50, 1906.

10 Pliocene and Pleistocene, Maryiand Geol. Survey, 1906.
GEOLOGIC LITERATURE. 19

No important papers bearing on the geology of Long Island were published in 1907, but
in 1908 appeared a paper by F. G. Clapp! that was of unusual interest as showing the existence
of the Long Island subdivisions or their equivalents in northern Massachusetts, in New Hamp-
shire, and throughout Maine. The latest contribution to Long Island geology at the time of
writing (1908) is an article by W. O. Crosby,? who reiterated his earlier belief in the unity of
the glacial epoch and assumed only a single invasion, the Wisconsin. He referred the Gar-
diners clay to a Tertiary cpoch (that of the Chesapeake group of the Miocene). The Pleistocene
character of its fossils as determined by W. H. Dall and other competent paleontologists and
the nonagreement of the deposits in character nor elevation with the adjacent Miocene
deposits of New Jersey were disregarded. The large amount of granitic material, which is
entirely at variance with the character of the Tertiary deposits elsewhere, especially with the
clayey and marly deposits of this age in New Jersey, and the presence of large erratic bowlders
in the Jameco and Mannetto were likewise regarded as without significance and these two
formations were referred to the Oligocene. The heavy Montauk member of the Manhasset
formation, several times as thick as the Wisconsin, was not recognized.

LITERATURE OF CONTEMPORARY PLEISTOCENE DEPOSITS IN NEW JERSEY.

In 1891 R. D. Salisbury published the first of a series of reports on the surface geology of
New Jersey which has a direct bearing on the geologic history of Long Island. In this report? he
compared the older extramorainic drift, which he regarded as the equivalent of the oldest. drift
of the interior, and the younger morainic drift. The weathering of the former he gives as at
least 30 feet, but that of the latter as only 2 or 3 feet. In the second report * he gave consider-
able attention to the ‘‘yellow gravels,” which were shown to be a complex series, in part of
Tertiary and in part of Pleistocene age, containing some apparently berg-dropped bowlders.
The essential completion of their present topography before the advent of the last ice sheet
is recognized. The following tentative stages are postulated: (1) Submergence to 400-foot
level and deposition of gravel; (2) elevation and long-continued erosion reducing the surface
by 120 to 150 feet; (3) depression to 150 feet below the present level, with deposition of gravel
and possibly the introduction of ice-rafted bowlders; (4) elevation and moderate erosion to
the present level; (5) slight depression and formation of low terraces, and (6) elevation of about
40 feet. In the third report * he applied the name Beacon Hill to older gravels and Pensauken
to the next younger. A new stage of submergence, marked by the deposition of loamy silts
(‘Jamesburg loam”) with complex nonerosion topography, was postulated as occurring after
the erosion of the Pensauken and before the deposition of the gravels of the low terraces. In
his fourth report ° Salisbury subdivided the Pensauken into a lower part, consisting of hori-
zontally stratified loamy arkose sand, and an upper part, consisting largely of irregularly strati-
fied lenticular beds of gravel which contain scattered ice-rafted bowlders and in which many of
the granitic pebbles are deeply weathered. The upper part is clayey in many places in the
northern part of New Jersey and presents vertical faces in artificial cuts, but this character
does not prevail farther south. With few exceptions the gravel is heterogeneous both physi-
cally and lithologically, its constituents ranging from half an inch to 4 feet in diameter (compare
with Montauk, p. 132). The ‘‘Jamesburg loam” was described as an imperfectly stratified
surface mantle, in places much bent and contorted as if shoving or thrusting action had taken
place. Its correlation with an older drift is suggested. Elsewhere Salisbury referred the
Pensauken definitely to the Lafayette, stating: ‘‘There can no longer be any doubt that the
Pensauken is the equivalent of the Lafayette formation of the south.” The report for 18951
was mainly descriptive of new localities, but the presence of clays in the Pensauken was noted,
and the questionable character of the evidence for the separation of the ‘Jamesburg loam”
pointed out. In the next report by Salisbury and G. N. Knapp,’ the noticeable till-like char-

 

1 Complexity of the glacial period in. northeastern New England: Bull. Geol. Soc. America, vol. 18, 1908, pp. 505-556.

2 Outline of the geology of Long Island: Science, new ser., vol. 28, 1908, p. 936.

3Preliminary paper on drift or Pleistocene formations of New Jersey: Rept. New Jersey Geol. Survey for 1891, pp. 35-108.
4Surface geology: Idem for 1892, pp. 33-166.

6Surface geology: Idem for 1893, pp. 33-328.

6 Surface geology: Idem for 1894, pp. 1-150.
20 GEOLOGY OF LONG ISLAND.

acter of certain parts of the Pensauken and the presence of striated bowlders were mentioned,
and a new subdivision of the Pensauken with Beacon Hill affinities was suggested. The Pen-
sauken was at this time regarded as glacial. In the report for 1897 * this subdivision was
specifically defined as a gravel, sand, and loam formation, locally clayey, distinctly higher
than the Pensauken, and intermediate in age between the Pensauken and the Beacon Hill.
The name Bridgeton was applied to it and it was tentatively correlated with the Lafayette;
the Pensauken was considered as ‘‘probably contemporaneous with an early glacial epoch
(Kansan or Albertan).”’ The ‘‘Jamesburg loam’”’ seems to be dropped from the list of forma-
tions, apparently for the reason that later work had shown it to be simply a surficial phase of
the older deposits. The report for 1898+ dealt largely with the Cape May formation, or the
terraces at 40 feet or thereabouts.

The physiographic history of the State was discussed in the report on physical geography,®
but nothing new was adduced.

A report by R. D. Salisbury, H. B. Kimmel, C. E. Peet, and G. N. Knapp ° gave an interest-
ing summary of the Pleistocene history of New Jersey. The ‘‘only glacial formations which
have been distinctly recognized in New Jersey are those of the Kansan (?) and Wisconsin
formations.”??7 The clays below sea level around Hackensack were regarded as equivalent
to the ‘Champlain and Hudson River clays.”” A post-Wisconsin submergence of 40 feet in
the southern part of the State was recognized and one of 100 feet in the northern part was sug-

gested.
THE PRESENT REPORT.

Although dealing with the pre-Pleistocene as well as the Pleistocene geology of the island,
the present report gives chief attention to the latter, largely because the new discoveries have
related mainly to the Pleistocene formations. The report attempts, however, to arrange the
Cretaceous beds for the first time in a number of groups, which are in general sufficiently dis-
tinctive lithologically to admit of the assignment of outcrops to their proper places with some
degree of certainty. Until information that will permit a more precise definition is available,
however, it does not appear desirable to apply new formation names to them. Their distribu-
tion is shown on Plate I (in pocket) and figure 56 (p. 69). The results of the Pleistocene work
are best shown by the following table, in which the stages recognized, their origin, the deposits
by which they are characterized, and their probable correlations with the deposits of central
United States are given.

 

1 Surface geology: Rept. New Jersey Geol. Survey for 1895, pp. 1-16.

2 Surface geology; Idem for 1896, pp. 1-24.

3 Surface geology: Idem for 1897, pp. 1-22.

4 Report on surface geology: Idem for 1898, pp. 1-42.

5 The physical geography of New Jersey: Final Rept. New Jersey Geol. Survey, vol. 4, 1895.
6 The glacial geology of New Jersey: Final Rept. New Jersey Geol. Survey, vol. 5, 1902.
7Tdem, p. 189.
GEOLOGIC LITERATURE. 2)

Pleistocene events on Long Island.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Probable time
. hick- uivalents in
Stage. Substage. Character. Represented hy— le 5 etal DA and
Ohio valleys,etc.
Harbor Hill Glacial Tlarbor Hill or inner moraine, and associated till and Feet.
: : outwash.
Wisconsin. Farly Wisconsin.
fe Ronkonkoma or outer moraine, and associated till
Ronkonkoma. Glacial. and outwash. ’
Vineyard Interglacial Great erosion unconformity, and Vineyard for- 8 Teen 0), ne
7 = . maiion, consisting of marine deposits and peat. Peorian (?).
Hempstead gravel member. 50-75
Hempstead. =
d Tce erosion unconformity.
3 as
a Montauk till member:
Manhasset. Glacial, = 1. Till. 0-60+
7 i . 2 2. Gravel.
Montauk. g 3. Till. Winoian.
5
Ss Ice erosion unconformity.
Herod. Herod gravel member. 50-75
- ~~ ~ *
Jacob. Transitional. Jacob sand. r
Gardiners. Interglacial. Gardiners clay. Yarmouth.
Jameco. Glacial. Jameco gravel. Kansan.
Post-Mannetto. Interglacial. Great erosion unconformity. Aftonian.
Mannetto. Glacial. Mannetto gravel. Pre-Kansan.

 

 

 

 

 

 

In addition to the detailed descriptions of the various deposits, the older Pleistocene sub-
divisions, including all those antedating the Wisconsin, are for the first time shown on a map.
The probable extension of the formations along the New England coast toward the northeast,
their correlations with the New Jersey formations, the detailed geologic history of the island,
the orogenic movements that have taken place upon it, and the relative length of its various
geologic stages also receive attention. Special consideration is given to the topographic and
physiographic features, including the various forms of Wisconsin drift, the submerged Sound
valley, and the submarine valley and canyon of Hudson River. The conclusion is reached that
the Sound is in no way related to the submarine channel heading off Sandy Hook but is the
result of eastward-draining streams. The cutting of the Hudson channels is referred to Pleisto-
cene rather than to Tertiary time. A table in which the points of interest are arranged geo-
graphically is provided to aid those who may have opportunities for field examinations in the
region.

: The Pleistocene deposits of Long Island are unusually complicated—their variations from
point to point, the existence of great unconformities at several horizons, and the general similar-
ity of many of the beds of different ages all combining to render the decipherment of their
history a work of great difficulty. No complete section is found at any one point, and in order
to establish the entire sequence it is necessary to patch together fragments of evidence from many
scattered localities. The main events of the geologic history, however, seem to be clear, and
inasmuch as they have been corroborated at many places in New England they may be regarded
as established. Mistakes in details are inevitable in so complicated a region, and no doubt in
the earlier parts of the investigation many things escaped observation which, if the work were
to be done over with the main events of the history as now established in mind, could not fail
Missing Page
Missing Page
24 GEOLOGY OF LONG ISLAND.

Wheatley and south of Huntington massive hills of irregular outline, some extending well to the
south of the northern ridge. These are the Westbury, Mannetto, Half Hollow, and Dix hills,
which are, as is explained elsewhere, different in age and origin from the ridges.

Off the south shore of the island is a long, more or less disconnected barrier beach inclosing
the broad but shallow Jamaica, Great South, Moriches, and Shinnecock bays and the great salt
marshes between Coney Island and Babylon. Along the north shore lesser bars, beaches, and
spits connect small islets with the main island or project into the numerous harbors and bays
or into the Sound. In fact, these beaches have now joined with the main body (Long Island)
what must originally have been about 15 distinct islands.

Although old channels abound on the island few have streams now flowing in them, and
most of these are of small size. At Smithtown, on the north side, at Riverhead, between the
two flukes, and near Yaphank and Great River stations on the south side are deeper channels
that cut the water table farther from the coast than the others; hence the streams flowing in them

are of greater volume.
FORM OF THE ISLAND.

AGENCIES INVOLVED.

Long Island is the resultant of opposed agencies of deposition and erosion. Marine cur-
rents, ice, and glacial streams have each played a part in both the upbuilding and the tearing
down of the island. That the deposits now above sea level are small compared to those once
existing in the region there is probably little doubt, indicating that since Cretaceous time ero-
sion has on the whole predominated over deposition. Although erosion is not now going on
very rapidly, the amount to be removed before the island is reduced to sea level is far less than
that removed in the past, and if conditions remain unchanged the time may yet come when the
island shall cease to exist. Notwithstanding the preponderance of erosion, however, the present
form of the island is due to constructional rather than to destructional agencies.

EAST RIVER.

The northern part of the shore line of the west end of Long Island is determined by East
River, a tidal channel connecting New York Harbor with Long Island Sound and separating
Long Tsland from Manhattan Island. The southern part of East River occupies a channel cut in
rock and the northern part meanders through deposits of drift. This channel has been discussed
by a number of writers. S.L. Mitchill* urged that Long Island must have been recently sepa-
rated from the mainland by the encroachment of salt water. John Bryson? referred its origin
to the erosive action of the escaping waters of subglacial streams. F. J. H. Merrill * suggested
that the rock channel was probably due to the solution of a belt of limestone. J.B. Woodworth 4
thought the escape of ponded glacial waters during the final ice retreat had something to do
with the shaping of the channel in the drift. Bailey Willis and R. E. Dodge® regarded it as
occupied by a tributary of the Hudson at the time of the excavation of the submarine channel.
W. H. Hobbs * presented sections showing the general absence of limestone and proposed faulting
and jointing as the explanation of the form of the rock channel. A. C. Veatch 7 made it the
site of a tributary of the Hudson in the post-Miocene erosion interval.

The present writer regards the rock channel to be due to mechanical erosion by streams
rather than to solution, as there seems to be too little limestone in the area to account for its
size or its configuration. Its form was most likely controlled by joints (or possibly fault planes)
or by the strike of the beds, with which the channel agrees closely in direction. It is not believed

 

1 Med. Repository, vol. 3, 1800, p. 329.

2 Geol. Mag., new ser., vol. 10, 1883, pp. 169-171.

« Annals New York Acad. Sci., vol. 12, 1900, pp. 113-116.

4 Bull. New York State Mus. No. 48, 1901, p. 658.

5 New York City folio (No. 83), Geol. Atlas U. S., U. 8. Geol. Survey, 1902,

6 Bull. Geol. Soc. America, vol. 16, 1905, pp. 151-182; The configuration of the rock floor of Greater New York: Bull. U. S. Geol. Survey No.

270, 1905.
7 Underground water resources of Long Island: Prof. Paper U. 8. Geol. Survey No. 44, 1906, Pl. VI.
PHYSIOGRAPHY. 25

that the present depression is due in any material degree to actual downfaulting. The northern
part of the channel seems to have been cut subsequent to the period of the Manhasset accumu-
lation, for the deposits of this formation, as shown by their remnants, undoubtedly overlapped
upon the mainland. The channel was completed before the Wisconsin ice advance, but the
escaping waters from this retreating ice sheet and the subsequent tidal scour probably did
much to clear out the deposits left by the last glacier. The stream that excavated the rock
channel seems to have been a short one, having no connection with the depression in which
the Sound lies.
NORTH SHORE SCARP.

From a point near the west end of the island eastward to Orient Point, Long Island Sound
is almost everywhere faced by a steep scarp, rising in places more than 100 feet above the water.
Superficially it is plainly of erosional origin, having the form of more or less fresh bluffs and
cliffs (p. 54): In reality, however, erosion has done little more than cut a narrow shelf into
the land mass and wear away a few projecting points.

The history of the scarp is both long and complicated. The beginning of a scarp along the
north side of Long Island dates back before the Pleistocene, to the time when the Tertiary
streams were beginning to excavate the Sound Valley. The direction of the streams and the
strike of the beds make it seem probable that even then a somewhat steep slope existed not
far from the line of the present north coast—a slope which, though deeply buried, is still trace-
able in places by well borings. It seems likely that in the succeeding early Pleistocene stage
(Mannetto) the ice margin rested along the erosional slope already formed, producing on its
retreat a steep ice-contact slope that rose at least 350 feet above the present sea level. In the
post-Mannetto stage, however, the active erosion, though deepening the Sound, everywhere

- attacked the scarp, with the result

es that it was nearly or completely ob-

{Manhasset sro scare a otto grave! literated in eastern Long Island, and
y WO pacers SESIP toward the west end only a few rem-
Cretaceous nants persisted at the terminations of

Se eh Pl go ls Se Sy projecting spurs of the old mass.

FIGURE 5.—Relations of Cretaceous, Mannetto, Manhasset, and present north-shore Such appear to have been the con-
scarps.

   
 
  

  

Sei

ditions at the advent of the Jameco
ice, which not only failed to add to the scarp but actually reduced its height by adding to the
filling of the Sound Valley, a process that was continued through the Gardiners and Jacob stages.
During the Manhasset invasion, on the other hand, the conditions seem to have been more like
those of the Mannetto, and although the ice at times advanced much farther south the margin
seems to have rested along the north side of the island for considerable periods, during which
the thick Manhasset formation, rising in places to a height of 200 feet above the present sea
level, was built up. At the same time the weight of the ice in the Sound region and its drag
or shove on the land combined to produce a notable folding that helped to intensify the scarp,
which was eventually left in the shape of an ice-contact slope on the retreat of the ice. The
scarp was afterward notched by the streams of the Vineyard interval of erosion, subdued and
rounded by the Wisconsin ice, and cut by the waves of the present Sound until finally it reached
its present form. The amount of the late wave erosion is considered in the discussion of the
bluffs (p. 54). The present conditions along the north shore in the western part of the island
are represented in figure 5, which brings out the buried Cretaceous and Mannetto scarps beneath

the Manhasset.
HARBORS OF THE NORTH SHORE.

The north coast along the western half of the island from Port Jefferson to New York
is indented by a series of harbors, including Flushing Bay, Little Neck Bay, Manhasset Bay,
Hempstead Harbor, Oyster Bay Harbor, Cold Spring Harbor, Huntington Harbor, Centerport
Harbor, Northport Harbor, Nissequogue Inlet, Stony Brook Harbor, and Port Jefferson Harbor.
These harbors range in length from about 2 miles (Northport and Centerport harbors, etc.)
26 GEOLOGY OF LONG ISLAND.

to about 5 miles (Hempstead Harbor, etc.), and their axes, with one or two exceptions, are
straight or gently curving. Each one is bordered by slopes rising somewhat steeply to an
altitude usually of 100 to 200 feet. Some of the indentations, as Port Jefferson, Stony
Brook, Northport, and Huntington harbors, end rather abruptly in amphitheater-like
terminations, but most of them extend inland for a number of miles beyond the limit reached
by the sea, gradually closing in to V-shaped terminations. The valleys are generally free from
conspicuous branching such as would be expected if they had been produced by the ordinary
process of stream erosion. There are, however, on the borders of each main valley many
small lateral valleys sloping toward the harbors, which, although more or less filled with late
drift, are distinctly recognizable. At Smithtown, where little late drift is present, a typical
dendritic drainage system is seen. (See topographic map, Pl. II, in pocket.) Like the others,
it is of pre-Wisconsin origin, as shown by glacial deposits, including an esker in the bottom
of the main valley.

The bluffs bordering the harbors consist as a rule of Manhasset materials, but well borings
and outcrops along the shores indicate that the necks between the harbors have Cretaceous
cores rising high above sea level. In other words, the present valleys, although generally cut
in the glacial gravels of the Manhasset formation, are coincident in location with older Cretaceous
valleys.

Much material bearing on the formation of the north shore harbors and valleys has been
published. W. W. Mather? noted the action of springs in converting sand into quicksand so
that large masses flowed from the bluffs. Elias Lewis, jr.,? also pointed out that many valleys
are due to spring sapping, but he held that the harbors were formed by erosion by subglacial
streams. Warren Upham ® referred the Smithtown drainage system to stream erosion.
John Bryson‘ followed Lewis in referring
the excavation of the harbors to subglacial
streams. F. J. H. Merrill® considered the
harbors to have been ‘‘plowed out by project-
— ing spurs of ice” and regarded the adjacent
FigurzE 6.—Relation between the original and the present cross section of elevations as due to ice thrust. Arthur Hol-

eee ee lick * and W. O. Crosby 7 agreed with Merrill.
J. B. Woodworth * distinctly recognized the stream origin of the valleys, although stating that
they had been modified, enlarged, and deepened by the action of the Wisconsin ice. <A. C.
Veatch ® brought out the fact that the present harbors, though not cut in Cretaceous forma-
tions, nevertheless coincide in location with buried Cretaceous valleys cut in pre-Jameco time.
The coincidence of location he explained as due to the concentration of underground waters in
the old depressions, giving rise to extensive spring sapping. Some modification by the Wis-
consin ice was recognized. The present writer agrees with Veatch, but would lay more
emphasis on ‘‘ice erosion,” for the valleys, except the one at Smithtown, are much too broad
in proportion to their length and terminate too bluntly to be characteristic of stream action.
The trunk valleys are also larger in proportion to the lateral channels than is called for by
normal stream erosion. Drift deposition (Wisconsin) has also obscured and obliterated many
of the old valleys, as at Lloyd Neck and in the region south of Huntington. The erosion is
regarded as the work of the basal part of the main ice sheet rather than the projecting lobes,
as was asserted by some of the earlier writers. The conditions are illustrated by figure 6.

 

 

1 Geology of New York, pt. 1, 1843, p. 32.
2 Am. Jour. Sci., 3d ser., vol. 13, 1877, pp. 142-146.
3 Idem, vol. 18, 1879, p. 201.
4The geological formation of Long Island, New York, 1885.
ctAnnals New York Acad. Sci., vol. 3, 1886, pp. 341-364.
Trans. New York Acad. Sci., vol. 14, 1895, pp. 8-20.
7 Tech. Quart., vol. 13, 1900, p. 105.
8 Bull. New York Siate Mus. No. 48, 1901, p. 636.
® Underground water resources of Long Island, New York: Prof. Paper U. 8. Geol. Survey No. 44, 1906, pp. 43-44.
PHYSIOGRAPHY, 27
SHORE LINE EAST OF PORT JEFFERSON.

West of Port Jefferson, as has been seen, the coast is highly irregular, being indented by
many deep bays and harbors. East of this locality, however, the shore is very regular, being
made up of long, gently curved reaches with here and there a headland barely projecting from
the general line. Throughout this stretch the contour of the coast has manifestly resulted
from the action of the waves and currents of the Sound, its regularity being the direct result
of its fairly uniform composition. For most of the distance the bluffs bordering the shore are
made up of sands and fine gravels, but in places there is a more resistant bed of till or of clay
which gives rise to a slight projection in the coast line. An exceptionally high bluff may also
give rise to such a projection, as at Woodhull Landing. The swell at Rocky Point Landing
is probably due to the presence of the Gardiners clay in the bluff, the one at Herod Point to
the Montauk till member of the Manhasset formation, that at Roanoke Point to both clay
and drift, that at Jacobs Point to the clay, those at Ducks Pond, Horton, Rocky, and Terry
points to thick beds of till (Montauk member ?), and the one at Mulford Point to the clay.

West of Port Jefferson the general trend of the coast is somewhat north of east. Here,
however, the coast makes a decided bend and for 20 miles runs due east, beyond which it trends
somewhat more northerly than at the west end. In these stretches the elevation of the bluffs
becomes less, decreasing from 150 feet near Port Jefferson to 100 feet north of Riverhead and
to less than 50 feet near Orient Point. It would seem almost as if the coast had been cut back
through the plateau portion of the Manhasset formation into the sloping part on the south.
If so, the original coast, as indicated by the eastward prolongation of a line along the Manhasset
crest, must have been 5 miles or more north of its present position. Of this, however, there is
no very definite evidence. A chart of the Sound shows no notable shoals such as should exist
if the land had been thus cut back. In fact, the only shallow places are off Woodhull Landing
and Herod, Roanoke, and Horton points and between Rocky and Terry points. Those at the
first three localities are spitlike projections; those at the last two have the form of offshore
shoals. None is situated more than about 14 miles offshore. Elsewhere the bottom of the
Sound is almost perfectly flat and affords little evidence of extensive erosion.

On turning to the island, however, it is found that, notwithstanding there has been no
greater deposition of the late drift i in the eastern part fon at points farther west and no more
opportunity for obscuring the old topography, large northward-draining valleys similar to
those west of Port Jeflerson are entirely absent. If such valleys ever existed, and there seems
to be no reason why they should not have been formed here as well as farther west, they must
have been obliterated by subsequent erosion of the coast line.

Tt is an interesting fact in this connection that the deep Sound channel, described elsewhere
(p. 56), follows the coast of this part of the island at a distance of about 4 miles. It is probable
that the land, if it ever extended much farther northward, did not reach beyond the line of
this channel. On the whole it seems likely that the coast in this region has been cut back for
several miles, but if so most of the erosion occurred in pre-Wisconsin time, possibly in a period
of relative submergence that followed the cutting of the Sound and Peconic Bay channels,
such as is assumed in the discussion of the shaping of the shores and islands of Peconic Bay.
The post-Wisconsin cutting is not believed to have exceeded half a mile.

PECONIC AND GARDINERS BAYS.

No single feature of the outline of the island-is more conspicuous than the great connecting
bays lying between the North and South flukes. (See topographic map, Pl. II, in pocket.)
Together these bays form a water body increasing in width from a few yards at tha mouth of
Peconic River to 14 miles near Gardiners Island, 27 miles farther east. The water body does not
increase uniformly in width throughout and is much broken by islands, the largest of which are
Shelter and Robins islands, and by projecting necks mostly connected with the mainland by
beaches, among which are Jessup and Hog necks, near Sag Harbor, on the south side, and Little
and Great Hog necks, in Southold, on the north side. These islands and necks all stand from
28 GEOLOGY OF LONG ISLAND.

50 to 100 feet or more above the present sea level and appear to be remnants of old land sur-
faces at these elevations. Their topography, as well as that of the part of the main island
adjoining the bays, seems to be in part constructional and in part due to stream erosion,
although greatly modified and obscured by the subsequent passage of ice sheets over its surface.
The contours of the shores, however, are due almost wholly to the action of currents and waves.

J. D. Dana? advanced the view that the Connecticut and other Sound drainage passed
southward across the North Fluke in the vicinity of Mattituck into Peconic Bay, but what
course it then took he did not state. Three years later John Bryson ” suggested that the further
course of this stream (which he assumed to have been subglacial) was through the depression
at Canoe Place, and stated his belief that Block Island Sound and Gardiners and Great and
Little Peconic bays are the result of subglacial stream erosion.

The drainage immediately preceding the last ice invasion was toward the chain of bays
from all directions. Peconic River entered from the west, as at present. Along the North
Fluke traces of pre-Wisconsin valleys leading southward may be seen at a number of points.
Mattituck Inlet, although now opening into the Sound, then took the drainage southward, as is
indicated by the marked convergence of the lateral valleys in that direction; but that it was not
the outlet of Connecticut River nor of any other stream of the mainland or Sound, as was stated
by Dana, is shown conclusively by its shallowness, narrowness, and the character of the tribu-
tary channels mentioned, which indicate that it formed the headwater portion of a minor
drainage system rather than the outlet of a large river. (See Pl. XI, C, p. 52.) On the South
Fluke, Sebonac Creek near Shinnecock, the Long Pond and Northwest Creek valleys near Sag
Harbor, and Threemile Harbor, are valleys produced by northward drainage.

The course of the trunk stream receiving this drainage can not be located with any cer-
tainty. The bottoms of the bays are irregular and do not appear to contain any submerged
channels. The deepest water at the present time is along the south side of Great Peconic Bay,
off the pomts of Robins Island and Little and Great Hog necks, and between Shelter Island
and the North Fluke, and this line may mark the course of the old drainage. It could hardly
have passed outward at Canoe Place, for the gap in the Manhasset at this point is only a few
hundred feet wide, nor through the shallow and circuitous passage south of Shelter Island.

All that can be definitely stated is that in the stage immediately preceding the last ice
advance Peconic River flowed essentially in its present course, that the drainage entered the
Peconic trough both from the north and the south, and that the waters passed eastward into
the ocean. The land at this time stood at least 150 feet higher than at present, as indicated
by the submarine channel east of Montauk (p. 60), but a submergence took place and much
marine erosion, marked by a shaping of the shores and a separation of the islands, occurred before
the advance of the Wisconsin ice. The ice, although modifying the topography in many ways,
probably did not materially alter the main features. Postglacial erosion has likewise done
little except to modify the contours of the shores.

Although the Peconic region was the site of a drainage system just before the Wisconsin
ice invasion, it is doubtful uf the depression owes its origin to stream erosion at that time. More
probably the basins are largely the result of nondeposition in Manhasset time because of their
occupation by ice masses around which the materials of the various necks and islands accu-
mulated. If such was the case, it is not unlikely that incipient depressions favorable to the
retention of the ice masses were early formed through differential compacting of the under-
lying materials by the weight of the ice sheet, through ice scouring, or through the uplift of
the North and South flukes by the dynamic action of the ice.

OUTLINE OF THE SOUTH SHORE.

If the extension of the land produced in postglacial time by the formation of marsh
deposits along the old shore is left out of account, the south coast of Long Island in its broader
aspects consists of a number of broad, gently curving, lobelike projections of sands or fine gravels.

 

1 Am. Jour. Sci., 3d ser., vol. 40, 1SU0, pp. 425-437. 2 Am. Geologist, vol. 12, 1893, pp. 402~403.
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 82 PLATE Ill

 

 

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1913
PHYSIOGRAPHY. 29

A small but strongly curved lobe extends between New York Harbor and Jamaica Bay. East
of this bay is the broad, flat lobate curve extending to South Oyster Bay, a distance of about
20 miles. The next lobe, which is of similar character, extends between Massapequa and
Babylon; another still smaller lobe extends between Babylon and Bayshore. Beyond this
point the shore is more broken and complex, but the general lobate character is visible as far
east as Southampton. Between the lobes and also cutting their margins nearly every half mile
are small estuaries a mile or so long and a quarter to half a mile wide or estuary-like valleys
now occupied by marshes. Some of these depressions are traversed by streams and others
are dry.

The lobes appear to have been formed by the deposition of materials carried out from
glaciers by glacial streams during the melting of the ice. West of Bayshore the lobes are
regular in outline and appear to owe their form largely to outwash from the last or Wisconsin
ice sheet at a time when the land stood nearly at its present level. Farther east they are less
regular, are cut by deep channels and bays, and lack to a considerable extent the even surface
characteristic of the western lobes. It seems probable that the lobes are due primarily to
deposition during an earlier ice advance, and that they were afterward subjected to erosion
and finally to partial burial by the less copious outwash during the Wisconsin invasion.

The coast from Southampton nearly to Montauk Point follows a nearly straight line inter-
secting old headlands and crossing old bays. It is in part due to erosion and in part to depo-
sition. In the vicinity of Southampton the land probably at one time extended half a mile to
a mile or more farther seaward than at present. Southeast of Bridgehampton it possibly
extended half a mile farther, at Apaquogue about the same, and between Easthampton and
Amagansett a mile or more. That the shore at Montauk has retreated considerably is unques-
tionable. The Montauk shoals, which lie about 2 miles south of the present shore, indicate
that the land probably once extended to that pomt. Much of the erosion may have occurred
before the Wisconsin ice advance, and the amount of cutting back in post-Wisconsin time may
be not over a mile and possibly less, although, as pointed out by W. W. Mather,’ not less than
2 acres is lost annually by erosion in this region.

The same waves and shore currents that truncated the headlands formed beaches, connecting
the projecting points and inclosing the so-called bays and ponds, most of which occupied old
drainage channels in the gravels. Some of the bays are still connected with the ocean by narrow
channels, but in most places the beaches are unbroken. The most important beach is Napeague
Beach, lying between Amagansett and Montauk Point, which has a length of 4 miles and a width
of 14 miles. The sands of the beaches have for the most part come from the erosion of the land
at the points mentioned, and the material not so used has been transported westward to the great
barrier beach described under Recent deposits (pp. 177-178).

SURFACE LINEAMENTS.

INFLUENCE OF THE CRETACEOUS.

The Cretaceous of Long Island is extensively developed, as brought out in the bluffs of
the north coast, where natural exposures are numerous, and in clay pits and wells in the interior.
As it comes to the surface at few places in the island, it has little or no direct influence
on the topography, the only possible exception that was noted being at High Hill, southwest
of Huntington (Pl. III), where the character of the drift suggests that the core of this high
knob may be Cretaceous, a supposition rendered not improbable by the finding of Cretaceous
material in a near-by well (No. 586, p. 84) at an elevation of over 300 feet. Although not
directly controlling the present topography, the Cretaceous core has nevertheless exerted a very
extended indirect influence upon it through control of the Mannetto deposition, which took place
over and around the Cretaceous remnants.

 

 

1Second Ann. Rept. New York Geol. Survey, 1838, p. 126.
30 GEOLOGY OF LONG ISLAND,

MANNETTO REMNANTS.

Mannetto plateau.—At only one point on Long Island, so far as is known, is any trace of the
original Mannetto surface left. Beginning a little south of the peak known as High Hill, near
the north end of the Mannetto Hills, and continuing southward to a point about half a mile
north of Bethpage, a distance of about 3 miles, is a narrow plateau, one-fourth to one-half a
mile wide, constituting the flat crest of the hills (P]. III). It ranges in altitude from about 330
feet at the north end to 270 feet at the south end and is believed to be a part of the original
Mannetto surface. Whether the slope is original or is due to differential tilting is not known,
but the writer is inclined to consider it original.

Hills of Mannetto gravel.—Outside of the Mannetto Hills the Mannetto gravel is com-
monly represented only by irregular hills, although traces of the plateau level are observ-
able in the Dix Hills. In general, however, erosion has reduced this mass to a series of radiating
spurs. Near Wheatley the erosion is even more advanced, and nothing but an irregular group
of hills remains, as shown by Plate VI, D (p. 32) and the description on page 82. Similar but
more isolated masses of the Mannetto gravel are believed, from the character of the overlying
drift, to control largely the
topography at Harbor Hill,
at Roslyn, and in the knobs
rising above the Manhasset
surface on Manhasset Neck
(p. 82 and PI. IV).

 

MANHASSET SURFACE.

Higher plateaus.—The
Manhasset surface shows con-
siderable diversity of contour,
both original and subsequent
forms being extensively rep-
resented in it, the former by
the great plateaus and the
latter by the deep valleys and
sharp bluffs. The plateaus,
although recognized by few
of the earlier writers, princi-
pally because of the till coat-
ing and the semimorainal

Figure 7.—Sketch showing location of the upper and lower Manhasset plateaus from Douglas- aspect of the surface, become,
PEER ale when the physiography of the
island is studied in detail, one of the most conspicuous and important of its topographic
features. Although they are spoken of as plateaus it must not be thought that the surface of
the Manhasset formation is continuous or perfectly flat for any great distance. As a matter
of fact, the plateau is deeply indented or even separated into detached parts by the deep bays
and harbors, some of which extend back nearly or quite to the moraine, and is almost every-
where deeply trenched by stream valleys and characterized by superficial irregularities due to
the deposition of a mantle of morainal outwash or other drift over its surface. The continuity
of the plateau surface is also broken along the axis of Manhasset Neck by knobs of older material
projecting to a height of 60 feet or more above the plateau level (Pl. IV).

The plateaus fall into three belts—the north-shore belt, extending from the vicinity of New
York to Orient Point; the Middle Island belt, extending from Rockaway Ridge through Beth-
page and Half Hollow hills, the highlands near Middle Island and south of Riverhead, and the
islands and necks of the north side of Great and Little Peconic bays to Shelter and possibly
to Gardiners Island; and the South Fluke belt, extending from its junction with the Middle Island
belt south of Riverhead eastward along the South Fluke to Montauk. Each of the belts is

  

 

 

    

   

 

  

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1
Scale 62500
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Contour interval 20 feet
Datum is mean sea level

1913

LE News
PHYSIOGRAPHY, él

described at length on pages 119-121, and their characteristics are shown in detail by the topo-
graphic map (PI. II, in pocket).

Lower plateau or terrace.—A peculiarity of the northern plateau belt in western Long Island
is its double character or development at two distinct levels, as brought out by figures 7 and 8
and by Plate IV. The lower terrace, which lies along the coast, ranges from 1 to 6 miles in
breadth and has a maximum elevation of a little over 100 feet; back of this surface and usually
separated from it by a more or less distinct though gentle scarp lies a higher plateau at 180 to
200 feet, reaching back to the moraine and beyond. The significance of the lower plateau is
somewhat obscure. The charac-
ter of its surface and especially BONG FSLAND
of the slope between it and the a
higher plateau is somewhat sug-
gestive of wave work. The sur-
roundings at certain points, how-
ever, as at Glenwood Landing
on Hempstead Harbor, where
the terrace is unusually well de-
veloped (Pl. VI, A, p. 32), would
seem to preclude such action, it
being hardly conceivable that
the waves of a confined body of
water hardly more than half a
mile wide could have cut back a
terrace nearly a mile in breadth
in deposits rising a hundred feet —Fieurz 8 —Sketeh showing location of the upper and lower Manhasset plateaus in the
above the water level. Aside IDE ER Nene OTE
from the fact that this theory would require a subsidence of at least 100 feet in post-Manhasset
time, a movement of which there is elsewhere no record, examination shows that this plateau has
a drainage topography fully as far advanced, considering its lower level, as that of the upper
plateau and indicating equal antiquity.

The material of the lower plateau is clearly Manhasset and is, at least locally, the Montauk
till member of the Manhasset, extending nearly or quite to sea level and therefore considerably
below the level of the Montauk member in the gravel pits farther south on Hempstead Harbor,
the conditions being similar to those shown in the generalized north-south section in figure 9.
The explanation that the writer regards as most probable is that which assumes the lower
plateau or terrace to be an original feature formed in connection with the Montauk ice invasion.
On the first approach of the ice the margin probably lay
in the Sound not far north of the present coast line (fig.
ae 9, a), and in front of it the Herod gravel member of the
So eens Manhasset formation was laid down. On the actual in-
Figure 9Section showing relations of Manhasset Pl = Vasion of the region the ice reached somewhat farther

teaus and deposits along the north shore in western Long .
Island. u, Present bluff scarp at coast; b, modified ice south, passing over the Herod gravel member at least to

Contset etary Delween highend low Manbaseipiaiees the head. of Hempstead Harbor, as indicated by the
bowlder bed capping the gravel. On its recession or on its subsequent readvance its margin
rested along the line now marked by the scarp separating the low plateau from the high plateau
(fig. 9, 6), and in front of it were laid down the higher gravels (Hempstead member of Manhas-
set formation). This sequence of events explains the presence of the Montauk till member near
the surface and the general absence of the Hempstead gravel member along the coast, the lobate
form of the landward edge of the lower plateau, the similar erosion features of the two plateaus,
the nature of the separating scarp (ice contact), the peculiar position of the terrace at Glenwood
Landing (due to an ice tongue in Hempstead Harbor), and the greater disturbance exhibited
by the material of the lower plateau (due to more prolonged shove and drag by the ice).

 

       

 

 

 

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32 GEOLOGY OF LONG ISLAND,

MORAINES.
MORAINES OF STRATIFIED DRIFT.

EXTENT AND GENERAL CHARACTER.

The moraines of Long Island have in the past been almost invariably regarded as the cul-
minating physiographic members of the region, and although later work shows them to be
subordinate to the Manhasset they are nevertheless striking features of the topography (PI.
V, A), rising in many places 100 to 150 feet above the surrounding level and reaching a maximum
elevation of 410 feet above the sea. They are also of notable extent, stretching the entire
length of the island without any considerable break. Topographically they may still be con-
sidered as constituting the “backbone” of the island, but it should be borne in mind that this
is a superficial and not a structural relation,
for the moraines are not a part of the foun-
dation of the island but are only ridges rest-
Figure 10.—Section showing mode of formation and profiles of morainal ane On the Manhasset surface. : é

cones. u, Point of emergence of feeder; b, steep débris fan; c, isolated cone The moraines show great diversity in

of regular contour; d, irregular cone; e, confluent cones; k, kettle. form from point to point according to the
nature of the material composing them and the conditions of its deposition, nearly all the com-
mon types of morainal accumulations being represented. They are described in detail in the
section on stratigraphic geology (pp. 163, 168), and it is necessary to consider here only the
special types and minor features of the morainal deposits.

 

 

MORAINAL CONES.

Isolated cones.—The isolated morainal cones represent one of the simplest forms of morainal
accumulation, seemingly being the result of deposition by waters issuing from the ice front at
a single pomt and at a considerable elevation above the base (fig. 10, a). The volume of the
feeder must of necessity be very small and incapable of transporting material far beyond the limits
of the confined ice channel, for a larger volume would soon cut down to the base of the ice and
form a normal outwash channel. Both the character of the deposition and the elevated posi-
tion of the feeding channels, therefore,
point to small rivulets as the source of 3 c @
material of the morainal cones. When Le
first formed the deposits had the form of Figure 11.—Profiles of morainal cones. a, Isolated cone; b, semicone; e, conflu-
a steep fan or semicone (fig. 10, 6), but on ent cones of similar magnitude; d, confluent cones of various sizes.
the retreat of the glacier the part lying
next to the ice was let down and a more or less irregular cone resulted. Some of the cones are
rounded and have fairly regular slopes (fig. 10, c). Kettles may occur in any part of the cones but
are most likely to be found near the margins (fig. 10, #). Considerable till is likely to be present
on the ice-contact face.

A cone completely isolated from the surrounding moraine (fig. 10, ¢) is not often seen. The
best apparent examples are found at High Hill, at the north end of the Mannetto Hills, and in
the unnamed hill immediately west of this point (PI. III, p. 28). Both of these are sharp knobs
resting directly upon the Mannetto or the Cretaceous plateau, above which they rise 100 feet,
and they have practically no connection with adjacent morainal accumulations. It should be
noted, however, that the knobs mentioned are possibly not entirely morainal and that they may
contain cores of older material.

Confluent cones.—All gradations from the isolated cones that are described above (fig. 11, a)
through semidetached cones (fig. 11, 6) to completely confluent cones (fig. 11, ¢, d) are repre-
sented on the island. Their origin is essentially the same, each knob or cone representing the
discharge either of a single rivulet or of a number of closely adjacent rivulets. Confluent cones
result from the proximity of the contributory streams, which causes their deposits to impinge
on one another and become united into a ridge in which the component parts are represented
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 82 PLATE V

 

 

 

 

 

B. BOWLDERY PART OF HARBOR HILL MORAINE NEAR CREEDMOOR.
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 82 PLATE VI

 

 

 

 

 

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TOPOGRAPHIC FEATURES OF LONG ISLAND, NEW YORK

 

 

 

: Scale 62500
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1913
PH YSIOGRAPHY. 33

by the several knobs. Where the feeders are of essentially the same capacity the result is to
build up a ridge of fairly uniform height (fig. 11, c), but where they are of unequal transporting
power the ridge is uneven, with one or more knobs representing the chief sources of sediment
rising high above the others (fig. 11, d).

Examples of confluent cones are so numerous that a list of all those on the island would
cover many pages; in fact considerable parts of the inner moraine and a large part of the outer
moraine are made up of rows or groups of such deposits. One of the best examples of a con-
fluent ridge of fairly uniform height is that southeast of Hauppauge or northeast of Central
Islip (Pl. VII, A). Bald Hill, 4 miles southwest of Riverhead, affords an example of a cone
Tising prominently above its neighbors (Pl. VI, (). In fact, Bald Hill approaches the isolated

cones in form.
MORAINAL RIDGES.

Simple ridges——The simplest morainal ridge is that formed by confluent outwash cones
along a stationary ice margin in the manner outlined in the preceding section. Such ridges have
a simple cross section, as shown atc, figure 10. The best large-scale example is that mentioned
as occurring southeast of Hauppauge.

Double ridges—Inasmuch as the ice front is seldom entirely stationary during the upbuild-
ing of a moraine, there is commonly a tendency to repetition of the ridges. The simplest form
of moraine resulting from this tendency is a double ridge such as those shown in profile at ¢
and d in figure 10, each ridge consisting of the confluent cones formed at a given position of the
ice margin. The best example of a double ridge of this character separated by a flat outwash
deposit was noted on the road crossing the moraine half a mile southwest of Woodbury or 14
miles southwest of Cold Spring station.

Compound ridges—Simple and double ridges are the exception among the moraines of
Long Island, as elsewhere, the normal form being a compound ridge of considerable breadth,
as shown in profile at ¢ in figure 10. The formation of a ridge of this type differs in no essential
way from that of the ridges described above, except that the cones composing it are confluent
with those before and behind them as well as with those at their sides—a result following from
changes in the position of the ice margin smaller than those giving rise to the double ridges. In
general compound ridges are the result of deposition during a number of successive slight
recessions of the glacial margin. The ice may also have temporarily advanced, overriding
part of the earlier deposits and disturbing them more or less, thus giving rise to abnormal forms
of relief. Under such conditions many ice blocks would become detached and buried beneath
the drift, causing on melting the numerous kettles that almost everywhere characterize deposits
of this type. The long-continued presence of the ice favored the incorporation of considerable
till both within and on the ice-contact face and the scattering of bowlders over the surface. In
fact, the conditions were such as to develop a most diversified morainal topography—high
knobs, ridges, and gravel heaps of all shapes and sizes alternating confusedly with equally
irregular basins, troughs, and deep, angular kettles. This complexity is brought out by the
topographic sketch, Plate VI, C.

The greater part of the southern moraine is made up of compound ridges of the type
described. Among the especially characteristic portions may be mentioned that lying south of
Peconic River between Manorville and Riverhead, that north of East Quogue, and that between
Hampton Park, north of Southampton, and Sag Harbor.

DEPRESSED MORAINES.

There is some doubt as to the propriety of applying the term ‘“‘depressed’’ to moraines,
as well as to that of considering the particular form of accumulation which it here denotes as a
moraine at all. Yet this form occurs in so many places on the island that some term is needed
for it, and the one given above was selected as best indicating its nature. In brief, the term is
applied to irregular marginal accumulations developed along the ice front in line with the
normal morainal ridges but failing to rise above the adjacent outwash. The ‘‘depression”’ is

1629°—14—4
34 GEOLOGY OF LONG ISLAND.

due rather to the nonaccumulation of morainal material than to an excess of outwash. The
conditions of its formation are brought out in figure 12. Its mode of formation differs from
that of the normal stratified moraine chiefly in the size and carrying capacity of the glacial
streams that formed it, the water issuing in large volumes instead of rivulets and forming broad
outwash aprons instead of the ordinary cones and ridges. The total accumulations, however,
are not necessarily greater than those in front of the normal moraine. The topography of the
depressed moraine is ordinarily similar to that of the compound ridges, exhibiting the same
irregular kettle and knob as-
pect. In some places, where
the morainal deposits are thin,
the accumulations have little
more than blocked the previ-
ously existing valleys of the

Figure 12.—Section showing relation between depressed moraine and outwash. a, Head of underlying land surfaces - and
outwash plain; b, exposed part of depressed ine; d buried t of di d =
Dp , OXD' p pressed moraine; c, supposed buried part of depresse: many kettles of larg e size and

moraine; d, normal profile of moraine.
; great depth remain.

The most conspicuous depressed moraines along the northern ridge are in the region east
of Port Jefferson station, where the kettle valleys above described are also best represented
(Pl. VII, B). In the southern ridge the depressed moraines are best seen at the gaps in the
hills between Yaphank and Shinnecock, although good examples are found near Ronkonkoma,
farther west, and at several points between Sag Harbor and Easthampton, on the east. In
some localities the morainal material is scanty and the north edge of the outwash approaches
the simple ice-contact slope in form.

 

 

DEPRESSED MORAINE OUTWASH

TILL MORAINES.

GENERAL FEATURES.

The topography of the moraines of Long Island varies widely according to the character
of the materials of which the ridges are composed, those made up largely of till differing greatly
from those composed mainly of stratified material. The presence of till in a moraine indicates
deposition in direct contact with the ice, partly perhaps beneath its marginal portions, hence
many such accumulations take on the subdued contours characteristic of formations overridden
and rounded by glacial ice. Under such conditions the tendency is to form a more or less con-
tinuous belt made up of small masses exhibiting something of the ridge form and separated by
intervening troughs or basins. The ridges are lower and more rounded and have gentler slopes
than the stratified moraines, and the depressions are more regular and shallower and have less
steep sides. Another feature of the till moraines is the essentially continuous character of the
ridges, gaps such as those found in stratified moraines at many places (where they mark the
emergence of glacial streams) being relatively rare. Cones and sharp ridges of drift are practi-
cally unknown. The till type of moraine is best developed in that part of Long Island included
in Greater New York (Pl. VI, B, p. 32).

MORAINES DUE TO ICE SHOVE AND DRAG.

Little evidence of the competency of ice shove as a cause of morainal accumulation is
afforded by existing glaciers, the tendency nearly everywhere being for the ice to override a
mass of material in its path and drag it away little by little instead of pushing it along. At
times, however, the ice evidently developed a tremendous power to push (pp. 201-207), the
result of which was the formation of immense folds in the overridden material, some of them
reaching an elevation of 100 or 150 feet, and the development of numerous faults, in both of
which the positions of large masses of material were noticeably shifted.

This shoving action was most conspicuous during the Montauk ice invasion, but was also
developed to a considerable extent in the Wisconsin stage, during which the moraines under
82 PLATE VII

 

 

 

   
 

 

 

 

 

 

 

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER

73°10"
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A. SIMPLE MORAINAL RIDGE NEAR HAUPPAUGE oho

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73°05 BB. DEPRESSED MORAINE AND OUTWASH NEAR PORT JEFFERSON 73°00
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Contour interval 20 feet.
Datum is mean sea level

1913

=

2 Miles

TOPOGRAPHIC FEATURES OF LONG ISLAND, NEW YORK
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 82 PLATE VIII

 

 

 

 

 

 

 

 

 

PSEUDOMORAINE (DUNES) NEAR FRIARS HEAD.
A. Distant view; B. Section.
PHYSIOGRAPHY, 35

discussion were formed. The action was most pronounced where the ice encountered scarps
or other marked irregularities of surface, such as projections from hills or ridges between valleys,
especially where the trend of the topographic features was at a considerable angle with the ice
movement, as shown in figure 13. Under such conditions the previous topography was in many
places greatly modified, partly by the shoving of the points, as near A, figure 13, partly by the
pushing up of material in converging valleys, as at B, and partly by the breaking down of divides
and the dragging of the material into the adjacent valley, as at C. Thus in the figure a ridge
would cross the valley at A, both sides of the valley would be broken down, a small ridge and
kettle would be formed at B and a larger one at C, the result being a topography such as is
shown in figure 14. These figures show how the ice in passing over a region of diversified
topography changes the surface to the morainal type, consisting of
irregular hills and kettles.
Examples of topography of this type, which is truly morainal,
inasmuch as there has been an actual movement and redeposition
of material, abound on Long Island, being observable at dozens of
points scattered over the Manhasset plateau north of the main ridge
of the Harbor Hill moraine and especially on Great Neck between
Huntington and Centerport harbors, where there are several drift-
obstructed valleys. Other good examples are afforded by the Shin-
necock Hills and the hills between Napeague and Fort Pond bays,
Montauk. In neither of these localities, however, are the surface
irregularities due entirely to ice shove, a mantle of dune sand mate-
rially altering the surface relief of the Shinnecock if not of the Montauk Frevre 13.—Hypothetieal drainage
hills. The former were covered with drifting sand hills when visited —_ ‘¥stem in loose gravels before being
‘ i covered by ice. A,B, C,and D are
by Timothy Dwight as late as 1822. at the same points as in figure 14; ar-
A second type of ridges due to ice shove but not truly of morainal Ws shew knee mr mueye:
character, although the resulting topography has a decidedly morainal
aspect, is produced by folding. The best development of this type is found on Gardiners Island,
where the folds form several topographic ridges of considerable size. These ridges rise and fall,
bend, separate, unite, cross, and merge into one another with an irregularity simulating that of
a moraine, although generally preserving a marked alignment of features parallel with the ice
margin. Considerable material has at the same time been trans-
ported or removed by the ice. Taken as a whole, the structure must
be regarded, as intermediate between a true fold and an ice-shoved
moraine similar to that between the Shinnecock Hills and Montauk

Point.
PSEUDOMORAINES.

Tn the class of pseudomoraines are included certain ridges of the
north shore which, although not of glacial origin, are so intimately
associated with the moraines and so closely resemble them that
they demand consideration here.

3 From a point a little east of Port Jefferson to Orient Point
Oe the morainal ridge hugs the coast, capping the tops of the bluffs
overridden by glacial ice. Points, that line the shore. The ridge is practically continuous, and at
Foe ee eae ates first sight the moraine appears for the most part unbroken. At a
number of places, however, sections along valleys cutting the ridge

show that, although it possesses a kettle and knob topography indistinguishable from that of a
moraine, it is in reality composed entirely of wind-blown sands (PI. VIIT), the true moraine
being entirely absent. In fact, it is not unlikely that considerable areas of the ridges mapped
as moraines are only pseudomoraines composed of dune sand, although they may contain a core

of morainal drift.

 
36 GEOLOGY OF LONG ISLAND.

OUTWASH DEPOSITS.

EXTENT.

The outwash is the most extensive of the Wisconsin deposits on Long Island. At first
sight, in fact, it appears to cover fully two-thirds of the surface of the island, but closer exami-
nation shows that the great plains stretching southward from the morainal ridges are in reality
composite surfaces made up of outwash and projecting swells of older materials (Manhasset).
Notwithstanding its wide extent, the outwash as a whole is not normally developed, the Man-
hasset formation even where buried exerting through its kettle valleys and allied features (p. 42)
a considerable influence on the topography. Locally, however, especially near the moraines,
several typical forms of outwash plains are represented.

OUTWASH DEPOSITS ADJACENT TO MORAINES.

SIMPLE FANS.

The simplest form of outwash accumulation is the fan-shaped deposit made by water
issuing from the ice front at a single point. These fans are closely related to the isolated cones
described in the discussion of the moraines but differ from them in that the points of emergence
of the feeding streams were usually lower down in the ice, and the volume of outflow and conse-
quently the transporting power were materially greater. The amount of water in the streams
forming the simple fans was, nevertheless, not very great, the streams deploying almost imme-
diately on their emergence from the glacial sheet and depositing close to the margin the material
brought in suspension from the ice. The fans thus formed are usually small, being from half a
mile to a mile or two in diameter, and have a comparatively steep slope, not uncommonly reach-
ing 40 to 60 feetina mile. They lie at short intervals along the southern moraine, the individual
fans, although confluent at their outer margins, still being distinctly recognizable. Along the
northern moraine the plains are flatter, and the component fans are usually distinguishable
only with difficulty. In general the fans head against the morainal ridges rather than at gaps
in them, the streams that came through the gaps apparently being more powerful than those
that produce the fans and carrying their load to a greater distance before depositing it. The
normal outline of an outwash fan is semicircular, but very few fans have this simple form, the
direction of currents, the variation in the supply of material, and the character of the under-
lying surface all tending to produce unsymmetrical outlines. The individual fans are not
commonly of a magnitude to be brought out with any degree of clearness by 20-foot contours,
but indications of them may, nevertheless, be seen at many points on the topographic map.
They are especially noticeable along that part of the moraine lying south of Peconic River.

CONFLUENT FANS.

In the same way that the simple fan is related to the isolated morainal cone the group of
confluent fans is related to the confluent cones and ridges of the moraines and like them repre-
sents the discharge of a number of adjacent contributory streams. The spacing of the con-
fluent fans, however, is not necessarily so close as that of the confluent cones, the greater spread
of the fans allowing them to unite at much greater distances from their heads. The spacing of
many of the confluent fans is less than a mile, but the feeders of some were several miles apart.
All gradations in the form of the confluent fans, from those in which the individual fans of the
group barely touch at the edges to almost completely confluent forms, are observed on the
island, but even in the groups of the latter type the heads of the component members can in
places be distinguished. The confluent outwash groups range from 1 mile to 6 miles or more
in diameter. The slope ranges from 40 feet in a mile near the moraines to 15 or 20 feet a few
miles away.

The best example of such a group of fans on Long Island is probably the plain bordering
the Ronkonkoma moraine from the Half Hollow Hills eastward to Central Islip station, which
embraces eight or more separate fans, at least five heading along the south side of the Dix
PH YSIOGRAPHY. 87

Hills and three or more along the moraine cast of the gap north of Edgewood, the principal
centers of dispersion being north of Edgewood, Brentwood, and Central Islip stations, respect-
ively. (See topographic map, Pl. IT, in pocket.) Another fine group of confluent fans is
found in the vicinity of Hicksville, the component parts heading at gaps in the moraine
instead of against the moraine, as is more common. Other typical groups center in the vicinity
of Prospect Park, Brooklyn, and near Richmond Hill, west of Jamaica. The great fan groups
of eastern Long Island are so broken and modified by Manhasset remnants that their typical
character is lost.
OUTWASH DEPOSITS DISTANT FROM MORAINES.

CONFLUENT PLAINS.

In the same manner in which the fans unite to form groups the groups eventually unite
into broad confluent outwash plains. The union of the groups commonly takes place at a dis-
tance of 2 or 3 miles from the moraine, but the distance may be considerably greater where
the groups are separated by older ridges, as at the Mannetto Hulls, where the Hempstead and
Huntington-Babylon groups do not unite until they reach a point 6 miles south of the moraine.
The lobate character of the contours, which is strongly marked in the fan groups (see Pl. UH,
in pocket), becomes less distinct in the confluent plains, the contours taking on broader curves.
Thus in the Hempstead, Westbury, East Williston, and New Hyde Park groups, which unite
to form the Hempstead Plains, the lobate contours are very noticeable, but in the resulting
plain the individual curves disappear and the contours, aside from the minor bends at the
drainage creases, show only a single broad curve, best indicated by the coast line extending
from Jamaica east to Massapequa, a distance of 16 miles. The slope of the plains decreases
progressively from the heads of the fans near the moraine and is commonly reduced to less than
15 feet and in many places to hardly more than 10 feet in a mile along the shore. Where the
outwash plain is well developed one may look over its flat floorlike surface for miles without
observing any irregularities other than its channels.

The individual, outwash plains, such as the Hempstead Plains, unite with other plains,
such as those of Babylon and Islip, to form a broad outwash belt reaching for many miles along
the south side of the island. The greatest stretch of pure outwash (free or nearly free from
Manhasset projections) is formed by the union of the plains mentioned, the extent of the belt
from west to east being over 30 miles.

- If the composite plains (Manhasset and outwash) east of Connetquot River are combined
with these more typical plains they form an almost uninterrupted outwash plain from Brooklyn
to Promised Land, a distance of more than 100 miles.

COMPOUND FANS.

The term compound is applied to certain groups of fans differing from the normal con-

fluent type. Among the more important of these compound forms are those termed successive
fans, which are analogous to the double and compound ridges of the moraines, being formed by
deposition at successive stages of retreat of the ice margin. The chief points of difference are
the greater volume of water taking part in their
formation and the greater distance between the (ee ee ee
stages of halt. The relations of successive fans to  Ficure 15—Profile of a compound outwash fan of suocessive-
one another is shown in cross section in figure 15. Plain type.
Suggestions of fans of this type were observed at a number of points, but few show a develop-
ment as strongly marked as that indicated by the figure. One of the most accessible examples
is found on the road south of Selden, where two or more southward-sloping fans with relations
similar to those shown in the figure are seen.

SECONDARY OUTWASH FEATURES.

Besides the broader outwash features described in the foregoing sections there are many
minor features that modify the general topography. Chief among these are the channels and
38 GEOLOGY OF LONG ISLAND.

valleys that cross the plains at short intervals. Many of these are sharply defined and of
considerable width, several being a mile or more across. The various types, representing several
distinct modes of formation, are described on pages 45-48.

Next to the valleys, the most important of the modifying features of the outwash area are
those portions of the Manhasset surface which project above the outwash at many points.
The continuity of the outwash surface is also broken by many kettles representing buried ice
masses, which are considered at length in the next section. Still another source of irregularity
is the extramorainal fosse described in connection with the other types of valleys (p. 47).

KETTLES.

To its glacial kettles Long Island owes many of its most pleasing features, including the
hollows and basins which help to make the north shore an attractive residence district, the
lakelets among its hills, the broad fresh-water ponds, such as Lake Ronkonkoma, and appar-
ently even certain of its bays. In few regions is more diversity of type exhibited by kettles;
in fact, it is difficult to imagine a greater range of form than is found on Long Island. This
diversity 3 is due to the differences in the conditions of their origin.

KETTLES OF THE TILL MORAINES.

As pointed out in the discussion of the topography of the till moraines (p. 34), the basins
in deposits of this type are relatively shallow and have gently sloping sides and comparatively
regular outlines, their flowing contours bemg strongly contrasted with the highly irregular
outlines of the stratified moraines. This
characteristic 1s brought out by the cross
fa 1 section shown in figure 16, a comparison

of which with that of figure 17 will show
the difference in profiles between the two types of kettles. So marked are the differences that
they are even brought out by the 20-foot contours of the topographic map. Plate VI, B (p. 32),
is a reproduction on an enlarged scale of a portion of the topographic map showing the till
moraine north of Jamaica, and Plate VI, C,, represents a typical portion of the stratified moraine
south of Riverhead.

The kettles of the till moraines usually mark the depressions between two accumulations
of different stages rather than the sites of buried or projecting ice blocks, and have much less
range in size than those of the stratified ridges. In fact, a kettle less than 100 feet or more
than a quarter of a mile in diameter is exceptional in a till moraine. The tendency is toward
elongated forms with the major axes parallel with the ice margin. Depths of more than 30
feet are rare, and the kettles are relatively isolated.

 

KETTLES OF THE STRATIFIED MORAINES.

As can be inferred from the conditions of formation of the stratified ridges (p. 33), their
kettles are both more diverse and more numerous than those in the till moraines. Although
shallow basins similar to those of the till ridges occasionally occur, the great majority of the
kettles are relatively deep and steep-sided, the normal con-
tour being similar to that shown in cross section in figure 17,
which is in marked contrast to that of the till moraine, fig- ;
ure 16. The kettles of the stratified moraines represent in + : :

* z ' % IGURE 17,—Normal profile of stratified moraine.
part the depressions left by melting ice blocks, in part the
hollows between successive ridges or other forms of stratified accumulation, and in part depres-
sions between heaps of ice-shoved materials. They have, therefore, a very great range, both
in size and in form. Basins hardly 15 feet in diameter are observed here and there; and, on
the other hand, some of the kettles have a diameter of one-fourth of a mile or more. In
outline the kettles are equally varied, all forms from rounded depressions of the Lake Ron-
konkoma type to elongated and branching kettles such as Great Pond, south of Riverhead,
PHYSIOGRAPHY. 39

being observed. The elongation, however, does not usually bear any close relation to the
trend of the ice margin, and few linear groupings are noticeable, the common tendency being
to an arrangement in crowded groups, as in the hills south of Riverhead. (See Pl. VI, C.)

KETTLES OF THE OUTWASH DEPOSITS.
KETTLES FROM BURIED ICE BLOCKS.

The simplest and least conspicuous of the kettles are those resulting from buried blocks
of ice. The manner of their formation is brought out by figure 18, in which a represents an
ice mass buried beneath the stratified outwash, 6. On the melt-
ing of the ice the overlying sands or gravels are let down upon
the underlying surface, as at c. The lower layers of the out-
wash are broken down into a confused mass, but the higher beds sha

. A FiGuRE 18.—Section illustrating the formation
show only moderate sagging, and the surface is marked by a © otakettlofrom a buried ice mass. wu, Buried
shallow basin with gently sloping sides, d. This is the typical aa b, suntan seman inne
form of buried-block kettles, but where the ice masses are larger eRe ae ee
and the covering of outwash relatively thin the kettles are of
greater depth and their sides much steeper. In fact, all gradations between kettles from
small buried blocks and those from large projecting masses are found. The kettles originating
from completely buried blocks have as a class one dis-
tinctive characteristic, namely, the universal absence of
bowlders from their surfaces; but as bowlders are likewise
Ficure 10,—Section illustrating the formation ota lacking in many projecting-block kettles (where the ice was

kettle from a projecting ice mass. a, Projecting free from englacial rock masses), this characteristic does not

sree Ae aati from the melting of afford a criterion for the recognition of individual buried-

block basins. Other negative characteristics of kettles of

this class are the absence of rims, either of till or outwash, the absence of terrace or shore
features, and the absence of drainage channels leading outward from the depressions.

 

 

 

KETTLES FROM PROJECTING ICE MASSEs.

Formation.—The most characteristic and conspicuous of the outwash depressions are the
kettles that result from the melting of large ice masses rising above the level of the surrounding
outwash, as shown at a, figure 19. During the melting of
masses of this type the materials banked against the ice are
let down and the débris contained within the ice is set free
and is left strewn over the bottom and sides of the kettle,

as at 0, figure 19. Few kettles of this type are entirely free Ficune 20.—Section illustrating the relation be-

% tween the slopes of kettle sides and the shape of
from bowlders. melted ice mass. a-a, Steep kettleside resulting
Steepness of sides.—The material let down as a broken _ tromsteep ice face; b-b, gentle kettle side result-

mass around the perimeter of the depression rests with its #7 Spins ire face
surface at an angle which depends to a large extent on the profile of the ice border. Where
the ice presented a vertical face the material on slumping took the steepest angle possible, its
“angle of repose”’ giving slopes as high as 30° to
35° in some kettles (fig. 20, a-a); but where the
ice presented a sloping face the material when
let down lay at a much lower angle (fig. 20, b-b).
tt tela odin: Sapa aces stn eve bee Where the ice faces were regular the kettle sides
resulting from melting of regular ice margin; 8-2, irregular slope are likewise regular (fig. 21, a-a); but where the
secultine tron The msl inp or eregrlen SOT RIEI mass of ice was irregular the slopes that resulted
from its melting are correspondingly irregular (fig. 21, 6-0).
Form.—The shape of the outwash kettles is of great irregularity, every form from simple
circular or oval to highly branching (Pl. XX, p. 116) or long linear channels being noted. Some
of the more conspicuous kettles are listed on the next page.

 

 

 

 
40 GEOLOGY OF LONG ISLAND.

Typical kettles of Long Island.

Circular or oval:

Lake Ronkonkoma, 14 miles north of Ronkonkoma station.
Irregular oval:

Lake Success, 2 miles south of Manhasset.

Artist Lake, 1 mile east of Middle Island.

Swan Pond, 2 miles northeast of Manorville.

Great Pond, 2 miles southwest of Riverhead.

Watermill Pond, near Watermill.

Poxabogue Pond, 1 mile east of Bridgehampton.
Branching:

Kettles, southeast of Huntington station.

Kettles, southwest of Huntington station.

Kettles, 2 miles southwest of Rocky Point.

Dix Pond kettle, 1 mile southeast of Wading River.

Long Pond kettle, 2 miles southwest of Wading River.

Mattituck Inlet, near Mattituck.
Linear:

Kettle, 2 miles west of Middle Island.

Kettle, 1 mile south of Fresh Pond.

Scuttle Hole, 2 miles northwest of Bridgehampton.

Size—The normal outwash kettles range in diameter from a few rods to about a mile. In
many of the linear kettles, however, as seen in the table on page 43, the longer axes are from
2 to 4 miles in length. Although the
great bays between the North and
South flukes are not typical kettles,
there is reason to believe that they
owe their existence to nondeposition
of outwash drift resulting to a certain,
extent from the presence of large ice masses in these basins. In a way, therefore, Great and
Little Peconic bays may possibly be regarded as kettles, in which case the maximum diameter
of such depressions would be increased to nearly 6 miles.

Depth.—Many kettles of the outwash deposits are of considerable depth, their bottoms
standing from 20 to 60 feet or more below the surrounding region. Examples of the deeper
kettles are given in the following list:

 

 

Figure 22.—Section illustrating the formation of kettle terraces by the melting of ice
masses of especial shapes. a-a, Imperfect terrace; b-b, regular terrace; c, ice mass.

Deeper kettles of Long Island.

 

 

  

ee

ol sur-

rounding Depth.
surface.

: Feet. Feet.

Lake Ronkonkoma, 1 mile north of Ronkonkoma station.................-. 222220222 cece eee eee eee eee ees 107 50

Kettle, 1 mile south of New Village..........----- Sats 160 85

Kettle, 1 mile southwest of Rocky Point station. . haere 130 80

Kettle, 1 mile southeast of Wading River station eer eas 105 82

Kettle, 4 mile northeast of Baiting Hollow.................0.2-2e cece eee e ee ence nce eee nee eee e eee ce en eee eee eee eeeeeaeenenees 110 80

Scuttle Hole, 2 miles northwest of Bridgehampton. 0.4 .o.c2c-weccin os couteamnnas seeaeieits pene ee ndwa ead AER eeows eekaiemee oe 70 40

 

 

 

Terraced ketiles—By terraced kettles are meant those showing flat benches on their sides
at levels intermediate between the bottom and the rim. They appear to have at least three
possible modes of formation. Probably the most common mode is by the melting of basal
projections of the ice masses, as shown in figure 22. Few such terraces are perfect, most of
them showing some irregularity that betrays their origin.

A second type is due to the shrinkage of the ice mass (a, fig. 23) and the deposition of
materials set free from the melting of the remaining block (0, fig. 23) in the space (c, fig. 23)
between it and the inclosing outwash. It is difficult in the absence of sections to verify the:
existence of the conditions indicated, but that the ice may carry sufficient detritus to form such
a terrace is proved by the presence of local outwash rims in a number of places. The amount
PHYSIOGRAPHY, 41

of drift in the lower part of glacial ice is almost invariably greater than in the higher parts,
hence sufficient material to form a terrace within a kettle might be set free, even where no out-
wash rim was formed by the melting of the upper portion of the ice.

A third type of terrace
seems to have resulted from
erosion in the free space
between the shrinking ice mass

and the kettle walls, due either

to the action, of waves upon, the  Ficure 23.—Section illustrating the formation of depositional terraces between ice mass and

1 ‘ hi kettle wall. a, Original profile of ice mass; b, later form of melting ice mass; c, sands and
gravel or sandy sides or to the gravels deposited between ice and kettle wall.

sweeping of currents around the
perimeter of the ice block toward the drainage channel which leads away from the kettle. Ter-

racing of this sort is of minor importance except where combined with deposition, as in the type
last described.

Terraces were observed in a considerable number of kettles,
especially in the eastern part of the island. As this region was
examined without a map (before the topographic survey by the

FIGURE 24.—Profileof terraced kettlenear United States Geological Survey), it is generally impossible to
eS give locations with sufficient accuracy to make them of value.

Some very distinct terraces may be seen where the road crosses the deep kettle valley three-
fourths of a mile northwest of Lake Grove and about 3 miles east of Smithtown Branch
(fig. 24). Kettle terraces, however, are not usually persistent, and these die out within a few
hundred feet.

Kettle rvms.—Elevated rims are formed
around the edge of certain kettles by mate-
rials set free by the melting of the ice masses
to which the kettles are due. Three forms
have been recognized. The most common form is probably the outwash fan (a, fig. 25) formed
by the spreading out of fine materials over the surrounding outwash by rills from the melting
ice. These fans are generally so flat as to be recognized with difficulty, but the slopes of
some are steep and the fans are easily recognized when
seen in profile.

A second form, much less common than the preced-
ing, is represented by more or less conical heaps (a, fig.
26), analogous to the cones of a moraine (p. 32) and
formed by small rills issuing from the ice several feet
above the surface of the outwash plain.

The third form is similar to the second and consists of irregular heaps of till or lines of bow]-
ders (b, fig. 26) that have slid from the ice face as it melted, without the intervention of water.

In the absence of sections it is difficult to
distinguish rims of the second and third types,
but the first type is more readily recognized. si ;

The best example was reported by D. W. John-  "°V"* 27 —Ohuwssh Go se ia
son at a point near the gap in the moraine about

2 miles northwest of Southampton. The drawing representing this kettle rim in Mr. Johnson's
notes is reproduced in figure 27, in which the view is northwest, the direction of movement of the
outwash being toward the northeast. The notes of Mr. Johnson also record “ delta-like scallops,
probably the discharge of melting ice blocks” near the north end of the Scuttle Hole kettle valley
northwest of Bridgehampton. An example of what appears to be a till knoll is found bordering
a kettle about a mile southwest of Cutchogue on the road to Mattituck, at an elevation of about
15 feet above the surrounding plain. Knolls of drift of intermediate or indeterminate types
border the kettle valleys between Riverhead and Baiting Hollow and the kettles at the fair-
ground southeast of Huntington station.

 

 

 

FIGURE 25.—Profile of kettle with outwash rim (a).

 

FIGuRE 26.—Kettle rims. a, Till rim; 6, bowlder rim.

 
42 GEOLOGY OF LONG ISLAND.
DOUBLE KETTLES AND KETTLE CHAINS.

Double kettles are exceedingly numerous on Long Island; in fact they probably outnumber
the simple isolated kettles. Examples are shown at many points on the topographic map. Twin
lakes are present in many such kettles. Not only are double kettles com-
mon, but triple kettles are not unusual and in some places, as in the area
northwest of Riverhead (Pl. IX, C) and in the Scuttle
Hole locality northwest of Bridgehampton (Pl. IX, A),

a considerable number of more or less connected kettles,
which may be here appropriately called kettle chains, are
found. A F
Fieve 29.-2Pré-Wiseonsin In the double kettles and kettle chains the barriers |

drainage system in Man- separating the component members are nowhere as high

hasset formation. A-B, : : *

Lineof section offigure3o, 8 the surrounding plains, as a rule being not more than leah aie

15 or 20 feet above the kettle bottoms. Generally these system remaining after

separating ridges retain their original irregular or rounded contour, but — *hemeltingof Wisconsin
well-defined notches cut by flowing waters connect some adjacent kettles. tod tonblgee Ae
The channel mentioned in the description of the Scuttle Hole kettle, below,
is typical of the class.

     

KETTLE VALLEYS.

(Outwash
Ice oa “<a lee
Manhasset formation

 

ere ere In no other part of the glaciated area of
America which has come under the writer’s
FIGURE 30.—Cross section along the line A-B of figure 28, showing re- observation are kettle valleys so well developed.
sidual ice masses partly buried by outwash. They are, in fact, among the most distinctive
topographic features of Long Island. Briefly,
they may be defined as long linear or branching kettles marking the positions of snow or ice
masses that Jay in the valleys of a previous surface and were covered with outwash. The con-
ditions of their formation are brought out by
figures 28 to 32. Figure 28 shows in plan a
normal drainage topography, such as character-
ized the Manhasset surface at many points Figure 31.—Cross section along the line A-B of figure 29 after melting
before the advent of the Wisconsin ice sheet. ee
Figure 30 is a cross section along the line A-B of figure 28, showing the valleys occupied by
snow ice or by residual ice masses left by the glacier during a recession, together with a covering
of outwash spread over valleys and ridges alike.
CLIC EES Outwash level Figure 31 shows a profile along the same line

| Manhasset for

   

 

 

Outwash

   
  

 

 

Manhasset formation

 

      
     

mation =| after the melting of the ice masses of the valleys.
Where the ice filling a valley was of uniform
thickness and melted at a uniform rate, an open
valley resulted, but where the icc was of irregular thickness and melted at differing rates in
different parts the overlying outwash was let down more or less irregularly, being thin or lack-
ing in some places and of considerable thickness in others. Where it was thick the old valleys
have been almost invariably more or less obstructed and have been converted into a series of
elongated kettles, as shown in profile in figure 32 and by the contours in figure 29. The kettle
valleys of Long Island are not only numerous but Jarge. Some of the more prominent are listed
in the table on page 43.
The Scuttle Hole kettle channel is described in the field notes of D. W. Johnson, as follows:
It leads directly southeast [from its head near the moraine] with slight meanders to the big kettle and pond [near
the railroad]. The gorge is from 20 to 25 feet wide at the bottom, which is flat except where cut by a little trench of
recent erosion. The sides are abrupt. The gorge ranges in depth from 6 to 8 feet at its [upper] end to 20 or 25 feet,
where it opens into the big kettle. It has two [or more] insignificant lateral branches, both from the north and only a
few rods long. The channel is cut sharply into the outwash plain, there being no slope toward it [other than the

sides of the valley]. At the east end is a broad shallow kettle. This latter served asa receptacle into which the waters
accumulated [coming from the northwest portion and cutting the minor trench mentioned].

FiGuRE 32,—Profile along the course of the kettle valleys of figure 29.
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 82 PLATE IK

 

 

 
  
   

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LONG ISLAND
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A. KETTLE VALLEY AND KETTLE B. KETTLE VALLEY NEAR FRESH

 
    

72°40'

 

 
     

 

72% ©. KETTLE VALLEYS , KETTLE CHAINS,AND PRE-WISCONSIN DRAINAGE 72°40’

 

 

 

        

ao x i ey A ek hol ~ ¥ ) 1
{ { e/ )/ ( Cl) Colt | [ ) A

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LINES NORTHWEST OF RIVERHEAD

 

 

TOPOGRAPHIC FEATURES OF LONG ISLAND, NEW YORK" "°”

poe hanes
Scale 62500
oO L 2 Miles
ae

———————

a
2

 

Contour interval 20 feet.
Datum is mean sea level,

1913
PHYSIOGRAPHY. 43

Large kettle valleys of Long Island.

 

 

 

 

   
  
  

 

   

Location. ; Character. ee om

0: : il th “i :
ne mile southeast of Huntington station (Fairground)..... frreguilar, completely Closed, . + savacesnsssuuesgeesens waveads on mi baewdnes ¥ 1
One mile west of Middle Isl aid iii isis Baia omblie Reactor: Long, narrow, branching, partly closed ae XX, p. 116)...... ait 4
aaa ae nor of Middle Island ........... -.-| Irregular branching, partly closed (Pl, XX)............-+ 2
ne- in mile east of Middle Island ......... By Lieu partly closed, containing Artist Lake (Pl, XX).. 1
Vicini ¥ and north of Lake Ronkonkoma. . on Be ly irregular, practically closed kettle-valley system (Pl 3
Two a southwest of Rocky Point....................... rregular, completely closed (Pl. XX)........-- 222 20eee eee ee eeeeeee se 2
Two a es ee ge of W. acted River eteilen. eh cae kettle-valley system, partly closed, containing Long Lake 2
One ae ee ere of Wading River. --.| Branching, contains Deep Pond, completely ¢ closed. . 2
One mile south of Fresh Pon Landing. ---| Valley, partly open, es ettle chain (Pl. IX, B).. 3
Three miles northwest of Riverhead. . ony] Ot Chain UPL LX 5 Oy a escny cxcnedene®eaenceen - 4
Near Matuituele CUDNO 0) a asec nlsaureg ne are mee ane steeds Reece Branching, reversed pater (BIT, OC) cgonce nysienciied dreblvceniie date 2
Two miles northwest of Bridgehampton (Scuttle Hole) ..._. Kettle chain and valley, mainly closed PL IX, 4) cvehtieielsie Sind debi. o Ba 3

 

PITTED OR KETTLE PLAINS.

The term kettle plains i is here applied to those plains in which kettles are so numerous as to
be the controlling factor in the topography. All gradations between isolated kettles (a, fig. 33)
and kettles so closely crowded
that only the higher rims reach
to the level of the surrounding

plain (3, fig. 33) are found on the
. FicureE 33.—Profile of kettle plain. a, Isolated kettle; b, divide between kettles rising just
island. In fact, not a few of the to level of plain; c, kettle surface with no remnants rising to surface of plain.

pitted or kettle plains grade off

into irregular surfaces on which no trace of the original plain is Jeft (c, fig. 33). Where the
kettles are more or less isolated and are separated by flat outwash areas, as in the plains
west of Cold Spring station and southwest of Huntington station (Fairground), the kettle-
plain character is very apparent, but where they are more crowded the significance of the
topography is less easily recognized. In such places the sky line affords the most reliable
clue. If on looking from one of the higher points, such as 0 in figure 33, it is found that, not-
withstanding the absence of flat remnants, the rounded knobs rise to a nearly uniform elevation
(as they do in the direction of a) it is usually safe to assume that the surface is a pitted plain.
An occasional flat-topped remnant makes the recognition much easier. The region northwest
and west of Riverhead, the district about Bridgehampton, and the country between Riverhead
and Mattituck are among the best examples of kettle plains.

 

 

 

KETTLES OF DOUBTFUL ORIGIN.

About 24 miles northwest of Babylon, east of the road leading toward the Half Hollow
Hills, is a shallow kettle large enough to be shown on the topographic map, and a number of
smaller basins are hidden by the underbrush of the vicinity. Other distinct kettles were
noted in the vicinity of Farmingdale. The former are more than 10 miles and the latter
8 miles from the moraine from which the outwash issued and 5 to 7 miles south of the outer
moraine. There are no evidences that the glacial ice ever extended to this region, and even
if it did there would seem to be no possibility that ice blocks would have persisted from a
period antedating the oldest moraine until near the close of the building of the youngest.
Moreover, in the older outwash of this part of the island there are no kettles. Therefore, as there
are no evidences of an extramorainal ice invasion or of snow-ice masses during the upbuild-
ing of the earlier outwash, it would seem that the kettles, whatever may be their cause,
were developed during the formation of the later outwash deposits themselves. The accumu-
lation of snow or snow ice in channels temporarily dry and the freezing of the smaller deploy-
ing rivulets of the broad outwash fan and the burial of the ice thus formed by subsequent
deposits suggest themselves as possible causes. It is to be noted, however, that the basins
44 GEOLOGY OF LONG ISLAND.

are all small and that they lack the sharp and irregular slopes that characterize most of the
kettles of Long Island, and it may be that they have resulted from some unknown peculiarity
of deposition. Similar depressions have, in fact, been noted by the writer in the flood-plain
deposits of Mississippi, Ohio, and Wabash rivers, in whose formation ice has played no part.

KETTLES OF THE MANHASSET SURFACE,

Kettles on the Manhasset surface are exceedingly numerous and may be divided into
those due to ice shove and drag, including obstructed and modified valleys, and those due to
deposition. In the obstructed or modified valleys resulting from ice shove or drag there has
been invariably a reworking or readjustment of materials, the accumulations being essentially
morainal. The formation of kettles in this manner has been discussed in connection with
moraines (p. 35, figs. 13 and 14). The kettles due to deposition are represented by the kettle
valleys and kettle chains described in the preceding section.

PSEUDOKETTLES.

Besides the true kettles, comprising hollows between glacial ridges and basins left by
melting ice masses, there are on the island several other forms of undrained depressions. Among
these may be mentioned the unfilled areas between the moraines and the confluent outwash
fans (p. 47), the sharp-angled, kettle-like basins and troughs of the sand-dune areas, and the
irregular depressions in Jandslide surfaces. In wet seasons small pools form in the landslide
depressions and small shallow temporary ponds gather among the dunes.

VALLEYS.

The valleys of Long Island exhibit a wide range of form according to the conditions under
which they were produced. The types include those formed by glacial waters as well as those
made by ordinary streams; all ages from early Pleistocene to Recent are represented, and both
original and modified forms are found.

PRE-MANNETTO VALLEYS

The oldest valleys on Long Island of which a record exists are those eroded in the Cre-
taceous formations before the deposition of the Mannetto gravel, but as these were completely
filled by the gravel deposits they have no direct topographic expression at the present time.
Nevertheless, as is pointed out elsewhere (p. 29), they exerted an important indirect influence
on the subsequent topography by their control of Mannetto deposition. The deposits of the
Mannetto reached lesser elevations in the broad, low Cretaceous lowlands than over the higher
surfaces, as a result of which the post-Mannetto erosion tended to follow the lines of the earlier
drainage.

VALLEYS IN MANNETTO GRAVEL.

The valleys of the Mannetto gravel differ greatly in extent, all sizes, from the small notches
around the borders of the plateau remnants, as in the Mannetto Hills (PI. III, p. 28), to broad
lowlands many miles across, being represented. Of the latter, the so-called Jameco Valley,
crossing the island from north to south in the region between Hempstead and Brooklyn and
occupied by the Jameco gravel, is the best example, but inasmuch as it is a buried valley rather
than a feature of the present topography it need not be considered further.

Intermediate between the larger and smaller valleys mentioned are the valleys of the hills.
In the Wheatley Hills, the most westerly considerable remnant of the Mannetto gravel, the valleys
radiate to the southwest, south, and southeast from the crest near Wheatley village (Pl. VI, D,
p- 32). Originally the valleys were probably deep and V-shaped and were separated by fairly
straight, flat-topped interstream ridges, probably not unlike those in the younger deposits on
the south side of the Half Hollow Hills (north and northwest of Wyandanch), valley depths of
100 and 150 feet being not improbable. Owing to the passage of the various ice sheets over
them, however, the valley walls have been broken down, the minor ravines largely obliterated,
PHYSIOGRAPHY, 45

and the main valleys obstructed and more or less filled with both till and stratified drift, giving
the whole area a decidedly morainal superficial aspect, although the major contours, as brought
out by the topographic map, are plainly due to erosion. The hills apparently represent a
Mannetto surface dissected to the extent that the valleys met from all directions about a central
crest and were separated by sharp ridges. The crest and ridges probably stood not far from
the level of the original Mannetto surface, but little or nothing in the shape of flats at this
altitude appears to exist. It is to be noted that the valleys on the north side of the hills have
been completely obliterated by the ice sheets and their deposits.

The Dix Hills and the small mass of hills northwest of them are very similar in their topog-
raphy to those near Wheatley, showing the same obscured or obliterated valleys on the north
side, the same modified and partly filled valleys on the south, and the same superficial morainal
topographic features. The dissection appears, however, to have been less advanced than in
the Wheatley Hills, and it is probable that in the central part of the Dix Hills there were several
remnants of the original Mannetto surface standing at an elevation of about 300 feet and having
a considerable extent, although less than in the Mannetto Hills.

The Mannetto Hills afford the best-preserved examples of unmodified valleys in the Man-
netto gravel, as only the north end of the hills was overridden by ice. The rough parallelism
of the valleys and the lack of conspicuous branching, features which are so noticeable in the
Wheatley Hills (Pl. VI, D, p. 32) and on the southeast side of the Dix Hills, are even more
conspicuous on the Mannetto Hills, especially on their west flanks (Pl. III, p. 28). All the
valleys have served as channels to conduct glacial drainage southward from the ice front as it
laid along the moraine, hence they are considerably modified from the pre-Wisconsin forms.
Several fine terraces may be seen in the valleys north and northeast of Plainview. It is notice-
able that many of the longitudinal divides separating the valleys are reduced considerably
below the 280 to 300 foot level (that of the Mannetto surface), although a few remnants, usually
flat topped, occur well out on the spurs, as is shown by the topographic map. The chief remnant
is found in the flat-topped ridge, in places of considerable width, stretching southward from the
moraine to the vicinity of Bethpage.

The valleys of the Mannetto gravel above described were mainly developed in the post-
Mannetto stage, immediately following the Mannetto deposition, for the distribution of the
succeeding formations, including the Jameco, Gardiners, Jacob, and Manhasset, shows that
relatively little further erosion took place after that stage, although trenching continued near
the heads of the streams among the hills, as in the Wheatley, Mannetto, and Dix masses, until
the covering of the hills by Wisconsin drift and to a less extent until the present time. The
valleys of the east side of the Mannetto Hills extend considerably below the level of the Man-
hasset. (as represented in the Bethpage and Half Hollow Hill remnants) and therefore belong
to a post-Manhasset period of erosion.

OLDER VALLEYS IN THE MANHASSET FORMATION.

The valleys in the Manhasset formation are everywhere conspicuous features, cutting the
formation from its surface at an elevation of 200 feet or less to a point considerably below
sea level. As post-Wisconsin erosion has accomplished little more than a slight notching of
the bluffs and steeper hillsides, practically all the valleys shown on the topographic map belong
to the older or pre-Wisconsin group. Most of them do not, however, show the original forms,
for, with the exception of the Nissequogue Valley near Smithtown (Pl. X, p. 46), there is
nowhere in Long Island a Manhasset valley of notable size that has not been materially modi-
fied by ice action or the deposition of glacial débris. In many valleys, however, the modifica-
tion was confined largely to the deposition of a superficial mantle of drift which, although
giving rise to minor irregularities that in places simulate low morainal accumulations on the
valley sides, does not obliterate the chief characteristics. The valley at Glencove, that of
Mill Neck Creek, other valleys near Oyster Bay, the Cold Spring valley, and the valleys east
of Northport are examples of this class.
46 GEOLOGY OF LONG ISLAND.

When the action of the ice was more energetic or the deposition took place on a larger
scale, many old valleys were obstructed and even partly obliterated, the remarkable kettle
valleys described in detail on page 42 being produced.

The western half of the Nissequogue Valley at Smithtown is in an area practically free
from Wisconsin drift and was protected from erosion by a filling of snow or ice. We have
here, therefore, a practically unmodified remnant of the original Manhasset drainage system
with its deep, sharp trenches and branching valleys. It is not unlikely that such systems
existed at many other points on the island but have been materially modified by the passage
of the ice over them or by more or less complete burial beneath Wisconsin drift. Remnants of
such modified systems are found north of Lake Ronkonkoma (PI. X), in the vicinity of Middle
Island (Pl. XX, p. 116), near Wading River, and northwest of Riverhead (PI. IX, (, p. 42).

South of the Ronkonkoma moraine the Manhasset valleys are represented by the short
V-shaped valleys cutting the Mannetto and Half Hollow hills and by the broad, shallow, ill-
defined valleys leading southward to the coast in regions where the Wisconsin outwash is thin.
The valleys of the hills mentioned may be taken as representing a type of short valleys such as
were probably developed also in the high bluffs at many places along the north shore; they are
now represented by the valleys at the heads of Huntington, Centerport, Stony Brook, and other
harbors.

It is difficult to describe with any degree of accuracy the broader Manhasset valleys south
of the moraine, as it is generally impossible, even on the ground, to differentiate sharply between
the Manhasset and the outwash gravels. The Manhasset topography was in general low, with
broad, gently rounded divides and perhaps equally ill-defined valleys, the outlines of: which
were still more obscured by the deposition of the subsequent outwash. A somewhat sharply
marked valley, however, appears to have led southwestward from the vicinity of Lake Ron-
konkoma, uniting with another valley from the region east of Hauppauge at a point a little
north of the railroad, whence it extended southward along the course of the present Connetquot
River. (See Pl. II, in pocket.) Apparently its sides rose steeply to a height -.of 30 feet or
more above its bottom, and it had many tributary valleys, especially from the east. A smaller
valley probably entered the sea near Patchogue, and another large one, exceeding even the
Connetquot channel in size, extended southward from Yaphank. This valley had a width
of over 3 miles in places and was bordered by bluffs or steep slopes, probably rising originally
in places to heights of not less than 80 feet above its bottom. Even after receiving the filling
of outwash from ice along the Ronkonkoma moraine the bottom still stood, near the site of the
railroad, at least 50 feet below the surrounding Manhasset surface.

VALLEYS ASSOCIATED WITH THE MORAINES.

Minor channels —The simplest class of valleys of the moraines are the small wash channels
extending down the sides of the morainal cones and ridges. The stratified morainal deposits
were for the most part built up from small rivulets that were alternately overloaded and under-
loaded with glacial débris. When overloaded the water quickly deployed and ran down the
surface of the deposits in many streamlets, effecting but little erosion. On the other hand,
when underloaded the water, instead of spreading and depositing, tended to deepen some one
of the many channels of the deploying rivulets and to concentrate itself in that single channel,
which was soon enlarged into a valley of some magnitude. The tendency to form such channels
was probably most pronounced in the closing stages of morainal building.

The water in its passage downward followed the natural hollows in the moraine, here
entering a kettle and there passing around some knoll. At the start the channels were therefore
of considerable irregularity, but as their development continued they tended to straighten, the
minor bends being obliterated and only the long, swinging curves remaining. The channels
are commonly from 15 to 50 feet wide, although some are wider, and are generally flat-bottomed,
though some are slightly trenched by subsequent erosion. The sides are commonly steep and
in places rise to a height of 30 feet or more. Remnants of terraces are scen locally, but few are
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PHYSIOGRAPHY. 47

well developed. The slope of the channels is commonly between 1 to 50 and 1 to 25, or 100 to
200 feet to the mile. Many groups of channels have a semiradial development from some central
height, but as a rule the channels extending southward are much better developed than those
running in other directions. The best areas for tracing such channels are in the great irregular
hills of the Ronkonkoma moraine south of Peconic River (Pl. VI, (, p. 32), southeast of River-
head, and between Hampton Park (Southampton) and Sag Harbor.

Kettle channels.—The small erosion channels that mark the pathways of waters escaping
from an ice block into an adjoiming kettle or from one kettle into another (fig. 34) are described
and examples are given in connection with
kettles (p. 42). They should not be con-
founded with the kettle valleys, which are
of entirely different origin.

Outflow channels—The pronounced valleys leading through the morainal ridges and
commonly cut to the level of the outwash plains bordering the moraines on the south are known
as outflow channels. Through them flowed large glacial streams issuing from the ice margin
or from the waters impounded between the ice front and the moraines; hence their origin
differed in several essential particulars from that of the minor channels just described. They
are relatively broad, few being less than 100 feet wide and some from one-fourth to three-fourths
of a mile. The smaller channels commonly merge into outwash fans, of which they were the
feeders, but the larger ones are generally prolonged as definite valleys across the outwash plains,
being, in fact, the heads of the outwash channels described on page 48. The floors of the channels
are mostly flat, with perhaps a small central furrow marking a late phase of outflow or with low
terraces on one or both sides of the valleys. In general the higher points of the valley walls are
constructional (morainal) rather than destructional, indicating that the gaps are mainly original
features and are not due to erosion by waters forcing their way across the moraine. The
locations of the most prominent of the outflow channels are indicated on the geologic map,
Plate I (in pocket).

Outer morainal fosse—On Long Island, as elsewhere, it is not unusual to find at the base
of the outer border of the moraine a longitudinal depression or fosse lying between the ridge
and the adjoining outwash plain (fig. 35). This feature is not especially well marked on the
island, although some good local examples are seen. None are very deep, 5 to 10 feet being a
common depth, although a few are deeper. Most of them appear to represent unfilled depres-
sions behind the outwash fans, the tendency to deposit being least marked along the moraine
at right angles to the direction of the emerging stream. Fosses due to this cause are without
erosion features and commonly show by their topography their constructional origin. Other
fosses, however, have the form of somewhat indefinite channels, as if occupied and modified
by outflowing waters at some period subsequent to their formation. It is even possible that
, some are of the nature of true outwash
channels and mark the positions of out-
wash streams that happened to occupy
at the closing stages of outflow positions
next the moraine.

Inner morainal fosse.—The inner fosse, although perhaps not so common as the outer on
Long Island, is a much more striking feature. In its simplest form it is a channel running along
the inner face of the moraine, apparently due to
the lateral flow of water between the ice and the Moraine
moraine (fig. 35). What is probably a channel of = games
this type is shown at a in figure 36, from field notes Be ne tenet eee eee
of D. W. Johnson, who says: ‘This depression [near yetr puck Pond Point. (After sketeh by D. W. Johneon.)
Duck Pond Point, Mattituck] is peculiarly constant
for a considerable distance east and west,’’ making a sharp trench in the inner face of the,

moraine.

 

 

 

 

FIGURE 34.—Profile showing a channel between kettles.

 

Younger outwash Innerfosse Moraine Outer fosse Older outwash

FIGURE 35.—Profile showing relation of inner and outer fosses to moraine.

  
     

 
48 GEOLOGY OF LONG ISLAND.

The most remarkable fosses of this type occur on the north side of the Montauk Peninsula,
between Fort Pond and Napeague bays, 14 to 34 miles west of Montauk station, where there is
a succession of channels having a northeast-southwest direction parallel to the moraine. The
channels, although too crowded for accurate delineation, are clearly indicated on Plate VII,
C (p. 34). An examination of this map will show four main channels cutting the 100-foot
terrace north of the moraine (dotted) and just southwest of Fort Pond Bay (A). These channels,
which are the deepest and most conspicuous of the fosses, open to the southwest upon a bench
of about 60 feet elevation and northeastward they extend to sea level. They are flat-bottomed,
steep-sided erosion channels and appear to have been outlets for waters issuing from the ice
margin at successive halts and escaping into Fort Pond Bay and thence through the pond
depression into the ocean. Figure 37 shows a cross section of the moraine and terrace with the
fosse channels. Indications of smaller channels on the lower slopes of the terrace are seen
between the railroad and the shore south of Rocky Point (B, Pl. VII, C).

Asecond group of channels is found southwest of the first but draining in the opposite direc-
tion, to the southwest. The more southerly channels of this group appear to have carried
the escaping waters to a gap leading southward across the moraine (C, Pl. VI, C) 2 miles west
of Hither Plain life-saving station, whereas the more northerly drained into a channel (D, Pl.
VII, C) leading westward to Napeague Bay near Quince Tree Landing, whence the water escaped
to the ocean through the gap now closed by the long connecting beach.

As indicated by their form the main features of the fosse channels described are erosional,
but there is some reason to believe that their position and to some extent their form and depth
may be due to folding. Thus on Cape Cod, where the walls of similar channels are shown in
cross section in the bluffs, they are seen to represent actual folds whose troughs were simply
widened and otherwise shaped by outflowing waters. In the absence of sections, however, it
is impossible to determine what part, if any, folding has played in the formation of the Montauk
channels.

One of the largest of the closed inner-fosse depressions is that lying along the north face of
the Ronkonkoma moraine from a point near Lake Grove, north of Lake Ronkonkoma, eastward
through New Village, Selden, and Coram to Middle Island, a distance of nearly 10 miles. Its
extent and outline are both well brought out by the 100-foot contour of the topographic map,
although this contour does not quite close. The northern slopes of the fosse are gentle, being
formed mainly by the Manhasset surface with its shallow drainage creases more or less modified
by their outwash fillings. The south flanks are steeper, bemg formed by the inner face of the
Ronkonkoma moraine. In the eastern part the bottom is marked by the great kettle valleys
of the Middle Island region. The
fosse has no surface drainage,
the waters falling upon its sides

and bottom escaping by under-
FiGuRE 37.—Profile of inner-fosse channels west of Fort Pond Bay, Montauk peninsula ground percolation throu gh the
(Pl. VII, C, A). a, Small channel on lower slope of terrace.

   
 

 
   

Terrace level

<--74 Moraine

 

 

sands beneath the moraine.

The fosse now occupied by Peconic River is fully as large as the one just described and is
of the same general character, although it is an open instead of being a closed depression.
Lying lower than the other, its bottom cuts the water table, giving rise to the river that enters
Great Peconic Bay at Riverhead.

OUTWASH CHANNELS,

The outwash channels, which include all the drainage depressions of the outwash deposits,
are among the most interesting of the topographic features of the island, presenting in their
various types, forms, and relations many attractive problems.

RELATION TO MORAINES.

Most of the larger and more important of the outwash channels head in gaps in the moraine,
being the continuations of the outflow channels described in connection with the morainal
PHYSIOGRAPHY. 49

valleys. Among the most important of these may be mentioned the one leading southward
from the Harbor Hill moraine at Roslyn and the Centerport-Babylon channel leading south-
ward from the same moraine near Greenlawn; there are also many smaller unmapped channels
heading in gaps in the moraine between Yaphank and Montauk. (See geologic map, Pl. I, in
pocket.)

Besides the larger and better-defined channels there are a considerable number of smaller
drainage lines heading either against the moraine or at one of the minor morainal channels.
Some of these can be seen by tramping a mile or two almost anywhere along the south base
of the Ronkonkoma moraine, but they are less common in front of the Ilarbor Hill ridge.

Channels of a third class start. at points on the outwash plain some distance from the mo-
raines and are apparently formed not by definite streams issuing from the moraine but by the
gradual gathering together of waters from various sources, including those that had previously
deployed and deposited their suspended material. The channels developing near Melville be-
tween the Mannetto and Half Hollow hills are good examples of this class.

A fourth class is due to the collection of the outwash waters through the agency of an older
topography instead of by normal conditions pertaining to outwash accumulation. Such chan-
nels are exceedingly numerous on Long Island. Good examples are afforded by the channels
uniting to form Carmans River between Middle Island and Yaphank, the streamless valleys lead-
ing to Peconic River west of Riverhead, and the many valleys
leading to the estuaries of Moriches and Shinnecock bays. oP Nee ay ee

Channels of still another class, represented by the great
Connetquot channel leading southward from Smithtown Branch, PT ee
originated in ice masses not resting against the moraine but are
otherwise similar to those heading at the morainal gaps.

RELATION TO KETTLES.
A. considerable number of minor outwash channels head ee

in kettles, but as a rule the water from melting ice blocks

was too small in amount to cut deeply into the gravels, and YO
few such channels are large enough to be shown on the FisvRe 38.—Sections of terraced channel lead-

: E ing westward from Lake Ronkonkoma.

topographic map. They are probably most abundant in

the kettle-valley region northwest of Riverhead, but similar channels lead from the lower
kettles southeast of Scuttle Hole, near Bridgehampton (Pl. IX, A, p. 42). A larger and.
very sharp and definite channel leads westward from Lake Ronkonkoma and joins the
main Connetquot channel (Pl. X, p. 46). As the Connetquot channel issued from a large ice
mass occupying the Nissequogue Valley, it may itself be regarded as originating in a kettle,
although the kettle was finally left open.

FORMS OF CHANNELS.

The valleys of the outwash are of two distinct types—true erosion valleys and interfan
creases. The former are well-defined channels with flat bottoms, terraced borders, and stecp
banks (fig. 38); the latter are broad, shallow sags between two confluent outwash fans repre-
sented on the map by bends in the contours, but many of them hardly apparent to the eye.
The two types occur in combination at many places, however, and at such places the faint
interfan creases are accentuated by true channels, as in the region between Edgewood and Cen-
tral Islip stations. Channels of this type are most conspicuous at a distance from the moraine.

Terraces are of widespread occurrence in connection with the outwash valleys, there being
probably very few such channels that in the course of a mile do not show something in the
shape of a terrace. A given terrace, however, is as a rule not persistent for any great distance,
generally dying out in a few hundred yards and being replaced by another at a higher or lower
level. So far as observed there is no uniformity in their number or elevation. They appear

1629°—14—_5
50 GEOLOGY OF LONG ISLAND.

to be rather accidental remnants left at various altitudes during the practically uninterrupted
period of downeutting. So numerous are the terraces that specific mention would be without
value. The type is illustrated in figure 38, which shows cross sections at intervals of about one-
eighth of a mile in the channel leading westward from Lake Ronkonkoma to the main Connet-
quot Channel (Pl. XN, p. 46).

Although the bottoms of outwash channels are commonly flat there are numerous excep-
tions. The most common irregularity seems to be a low, rounded, barlike ridge along the
center, such as that shown in figure 39, a, which represents the profile of a large channel along
the road just south of Commack. The bars are commonly of no great extent, dying out gradu-
ally both up and down the channels. In places two or more overlap en échelon and others are
more or less confluent and irregular. All gradations between normal bars and the ridges and
terraces separating the double channels described in the next paragraph are found.

It appears that in some places after the deposition of

i the bars above described the volume of water became lessened

a and was no longer able to fill the whole of the original chan-

nel but divided into two small streams, one flowing on each

SN ey side of the bar. These streams gradually cut for them-
b selves separate channels, the intervening bar eventually

ee a being left as a ridge, as shown in figure 39, b, which repre-

sents in cross section a southwestward-leading channel about

14 miles north and a little west of Lake Ronkonkoma.
Ficure 39.—Forms of outwash valleys. a, Channel A
with bar south of Commack; b, ridged channel 1} It seems to have happened not infrequently that dur-

miles north of Lake Ronkonkoma; ¢,doublechan- ing the closing stages of outflow the waters of the broader
nel 1 mile west of Holtsville station.
outwash channels were reduced to two small streams, one of
which hugged one bank and one the other. These streams also cut subordinate channels, which
were separated by a broad, flat terrace representing the uneroded part of the floor of the larger
outwash valley, as shown in figure 39, ¢, which is a profile across a small channel 1 mile west of
Holtsville station and a quarter of a mile south of the railroad. A similar and larger double
channel is shown in the outwash valley between the Mannetto and Half Hollow hills, each side
of which is marked by a broad, sharp channel that is well brought out by the geologic map
(PL. I, in pocket).

The slope of the bottoms of the valleys is usually gentle and uniform from the moraines to
the sea, the rate being commonly from 10 to 15 feet to the mile but flattening in the lower mile or
two, apparently owing to a slight sinking of the
land, which has permitted the lower parts of the
valleys to be occupied by estuarics of the sea and
has caused a slackening of the drainage.

As long ago as 1877 Elias Lewis, jr.,* called
attention to the greater average steepness of the
right-hand or westerly banks of the outwash
channels as compared to the easterly or left- FicuRe 40.—Profile showing relative steepness of east (left) and west
hand banks (fig. 40), stating that the difference Se renter eeu
had been long noted by travelers and referring it to the earth’s rotation, as a consequence of
which the streams are thrown against the westerly banks. Seven years later G. K. Gilbert? dis-
cussed the deflective force duc to the earth’s rotation, limiting it to streams of slight fall and
citing the Long Island streams as good examples. The observations of the writer and his
assistants seem to indicate that probably four-fifths of the ordinary shallow valleys of the out-
wash plains lying south of the outer moraine have steeper banks on the west than on the east
side. In some valleys the difference is as marked as that shown in figure 40, but in others it
is hardly appreciable. The development, however, must be recognized as remarkable when the
weakness of the force is considered.

Local exceptions to the general rule of steep westerly banks were observed, but the only
notable ones are in the relatively deep valleys formed where the outwash streams have cut

entle left bank
Steep right, bank

|

 

 

1 Am. Jour. Sci., 3d ser., vol. 13, 1877, pp. 215-216. 2 Am. Jour. Sci., 3d ser., vol. 27, 1884, pp. 427-432.
PHYSIOGRAPHY, 51

into the Manhasset formation. In such valleys the steepness of the bank depends on the curva-
ture of the streams, being greatest on the outside of the bends. In straight reaches the banks
are of nearly equal slope.

Although the cutting of the valleys of this type began in Wisconsin time, the erosion and
shaping of the banks has extended to the present day, especially along the south shore, where
the water table comes to the surface and supplies the short streams with water.

Many of the outwash valleys have been partly obstructed by the formation of deltas across
the main valleys at the mouths of tributary streams. Usually the flow of water in the larger
valleys has been sufficient to cut through the deltas, but
here and there the obstructions have not yet been over-
come, and wet weather ponds of considerable size accu-
mulate behind the barriers. The best example of an
obstructed valley with ponded water observed was on the
northeast-southwest road three-fourths of a mile north- _ | /
west of Lake Ronkonkoma, where a marshy pond over a ne eae Ge tee
quarter of a mile in length was seen in 1903. gence of the spring; b, profile of resulting hopper.

     

Sealevel LY

POST-WISCONSIN VALLEYS.

NATURE AND EXTENT OF EROSION.

Little work has been done in post-Wisconsin time by the larger streams of Long Island other
than local widening of their valleys, for their channels had already been extended to or below
the level of the sea when the Wisconsin ice sheet retreated before the opening of the present
period. The principal recent changes have been accomplished by subordinate agencies, the
chief of which are ‘‘spring sapping’’ and rivulet erosion, the former represented by numerous
amphitheaters and the latter by short ravines and gullies in the bluffs and by
small notches in the older valley floors.

FORMS OF THE VALLEYS.

Amphitheaters —Wherever a body of clay or other impervious substance
underlies a mass of porous material and comes to the surface at or near drain-
age level (a, fig. 41), there is formed a series of springs often perennial and
Figure 42—Planofhop- Copious in volume. At such places part of the overlying incoherent sand is

per or amphitheater at almost always carried away, the action being limited at first to the immediate

Bigg aa vicinity of the point of emergence of the spring (a, fig. 41) but extending
later farther and farther back until finally a great hopper-shaped excavation or amphitheater
results, as shown in profile in figure 41 and in plan in figure 42.

In the early stages the hoppers or amphitheaters are of nearly circular outline, but as the
sapping progresses the erosion tends to become uneven through the influence either of inequali-
ties in the underlying impervious stratum, or of variations in the character of the material in
which the hopper is cut, or of other causes affecting the distribution of
drainage lines. As a consequence of unequal sapping, erosion goes on
faster at some points than at others, and an unsymmetrical amphithea-
ter soon results (fig. 43). The irregularity continues to increase until a
normal drainage system is produced. Few if any such systems, how-
ever, have been developed on Long Island in post-Wisconsin time. Hop-
pers 200 to 300 feet in diameter and 100 feet or more deep are seen at
many points along the north shore, especially from Wading River east-
ward to Mattituck Inlet. Figure 43,—Plan of transitional

Notched cliffs —The notched cliffs are produced by an agency work- Cae a pe
ing from above instead of from beneath, as in the hoppers, the under- -
lying clay and its attendant springs being absent. The notching is greatly facilitated by the
incoherent nature of the deposits of the Manhasset formation, in which most of the notches are
cut, but is retarded by the porous character of this material, which causes it to absorb the
waters before they can unite and form streams of much vigor. Many of the notches start at

 
52 GEOLOGY OF LONG ISLAND,

close intervals and develop into a succession of sharp, V-shaped parallel ravines separated by
narrow rounded ridges giving a serrate plan and profile to the bluffs at many places, especially
along the edges of the lower bluffs in the eastern half of
pe ee key, the island (fig. 44).
Notched mergin” of bluffs Hanging valleys—Where the shore line has remained
Figure 44.—Plan showing character of notching in ynchanged for a series of years the ravines enter the sea
bluffs of the northern coast in eastern Long Island. ; :
at grade. As a whole, however, the coast is undergoing
somewhat rapid erosion by the waves, a single storm not infrequently cutting several feet or
even a rod or more into the base of the bluffs and leaving a large number of the ravines as
hanging valleys with floors 5 to 10 feet above the beach (a, fig. 45). Where the stream erosion
is slight the wave action may continue predominant for a long series of years or even perma-
nently, in which case the action of the waves
is cumulative and the valley enters at pro-
gressively higher points (6, c, and d, fig. 45)
until perhaps only a slight notch at the upper
edge of the cliff remains (e, fig . 45). Figure 45.—Section illustrating the relation of height of hanging valleys

As goon as th e hanging valleys are formed be an of erosion of bluffs. ua, b,c, d, and e, Successive positions of

. 3 s; a-e, floor of valley.
by the cutting back of the cliffs their reexca-
vation by storm waters is begun, usually with a relatively narrow notch in their bottoms having
a somewhat steeper grade than the older valley. (See fig. 46.) At the same time a steep fan
is built up against the bluff at the point where the storm waters issue from it @, fig. 46).

Examples of hanging valleys are usually
very numerous, especially within the first year or
two after a severe northerly storm, and all the
types described may generally be seen in a walk
Figure 46.—Section illustrating the notching of hanging valleys. u, of a few miles along the beach, especially in the
b, c, Original floor of valley; 6, d, slope of channel of newly cut notch. region eset at Port Tsfheravini: Thie mon of
the examples noted during the progress of the field work would, because of the constant changes
in the bluffs, be of little value.

Obstructed ravines —Many of the ravines cut in the deposits of the north shore are more or
less obstructed by materials brought in since their formation. Probably the most common
cause of obstruction is the building of a delta or fan across a ravine
from materials supplied by a tributary channel entering at a high
angle. Such obstructions, however, are commonly due to local
causes, such as a sudden increase of débris in a tributary, but are
usually soon cut away. Another common cause of obstruction,
especially in the sharper ravines, is the caving of the incoherent
banks, letting down an irregular mass of sand, till, and other ma-
terial (fig. 47). Several good examples were seen in 1903 in the region between Fresh Pond
Landing and a point north of Riverhead.

Refilled ravines —Many ravines have been partly refilled with deposits having the relations
shown in figure 48. This refilling appears to be due to the waters becoming overloaded in the
later part of the ravine’s history, a condition apparently caused
by a decrease of rainfall and run-off. In brief, it is assumed
that the original ravine was cut at a time of heavy run-off, per-
haps during a storm or series of storms, and that the filling has
taken place during a period of ordinary rains in which the run-off
has been insufficient to sweep the material to the sea. The dif-
ferences in run-off are doubtless due to irregular and accidental
local variations in precipitation and other conditions, rather than to any real climatic change.
A single heavy and continued downfall of rain may at any time sweep the valleys clear of their
fillings and even cut them deeper than they were originally. Valleys of this type are constantly
changing, but examples can probably be found along the coast near Fresh Pond Landing.

 

   

 

 

 

 

 

Figure 47.—Section illustrating the
obstruction of valleys by landslides.

 

 

FIGURE 48,—Section of refilled ravine of the
north coast.
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TOPOGRAPHIC FEATURES OF LONG ISLAND, NEW YORK

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1913
PHYSIOGRAPHY. 53

INLAND SCARPS.

PRINCIPAL EXAMPLES,

Inland scarps of considerable prominence occur at several places on the island, some being
of glacial and others of subaerial origin. The most important are the scarp facing the Connet-
quot outwash channel south of Smithtown Branch, those facing the valley between the Mannetto
and Half Hollow hills, and the one stretching along the south side of the Harbor Hill moraine
west of its junction with the outer or Ronkonkoma moraine south of Manhasset Bay. (See
Pl. II, in pocket.) The Connetquot scarp has been described and its origin has been discussed
in detail on page 46. The scarps between the Mannetto and Half Hollow hills owe some of their
features to stream erosion beginning as early as the close of Mannetto deposition, but the greater
part of the valleys and ravines that now notch the edges of these scarps are clearly post-
Manhasset, for they cut into and extend well below the surface of that formation. A further
shaping, including the planing away of projecting spurs, resulted from the action of the waters
of the broad Wisconsin outwash channel passing between the hills, and the final minor notching
is the result of post-Wisconsin erosion.

THE GREAT INLAND SCARP OF WESTERN LONG ISLAND.

CHARACTER,

A well-marked scarp beginning at Lake Success, near the eastern boundary of the Borough
of Queens, where the outer or Ronkonkoma moraine is crossed by the inner or Harbor Hill
moraine, extends westward in almost a straight line to Fort Hamilton at the Narrows, a distance
of about 20 miles, with a height of 60 to 100 feet above the outwash deposits bordering it on
the south (Pl. XI, A). An examination of its face shows the surface material to be mainly
till, some sections near the top of the bluff containing 20 to 30 feet or more of this material.
Nevertheless records of wells put down a little back from the edge of the scarp generally show
relatively little till, the drill soon passing into stratified sand or gravel, possibly a part of the
moraine but more probably part of the Manhasset formation of which fine exposures north of
the moraine are known to occur at this level. In Prospect Park, Brooklyn, more or less folded
strata of sand and gravel, probably Manhasset, have been exposed from time to time. It is
believed that a complete cross section would show the bluff to consist mainly of stratified gravel
of the Manhasset formation, with a mantle of till varying in thickness from a few feet near Lake
Success to 30 feet or more at points in Brooklyn, lying unconformably over its top and face.
This till appears to be late Wisconsin, hence the scarp that it mantles must have been formed
before that time.

Additional evidence as to the age of the original scarp is afforded by the notches in its
face. From Lake Success to the vicinity of Hollis the notches are generally small and simple
with little branching, and such notches are characteristic of most parts of the scarp. North-
west of Hollis, near Maple Grove, north of Woodhaven, and at several points west of East New
York, especially near Prospect Park, Brooklyn, the notches are larger and resemble the dendritic
systems characteristic of drainage development. In fact, it seems fairly clear that such was
their origin. They are not postglacial features, however, for they have every appearance of
being clogged and partly obliterated by the deposition of till.

In addition to the larger convexities, such as that north of Hollis, projecting swells of
till and other material pushed forward by the ice occur here and there. J.B. Woodworth ¢ in
describing the scarp says:

West of Prospect Park the morainal front maintains its lineal course toward New York Narrows, but with a rather
bulging frontal slope composed of stratified gravels. As seen in pits open in the season of 1900 these stratified gravels

rise up steeply from the northern margin of the frontal plain, then bend downward into a large kettle hole in the
deposit. The attitude of the beds suggests frontal shoving on the part of the ice.

 

1 Bull. New York State Mus. Nat. Hist., No. 48, 1901, p. 649.
54 GEOLOGY OF LONG ISLAND.

ORIGIN.

That the original scarp was cut in deposits antedating the later Wisconsin drift (probably
in the Manhasset formation), that it is the result of erosion, that it was subsequently buried
by a mantle of late Wisconsin till, and that it has suffered little subsequent erosion, seem clear.
The fact that its origin antedates the deposition of the latest drift explains why the scarp lacks
the abruptness that would be expected if the cutting had been post-Wisconsin, and why no
beaches or terraces have ever been found. The range in elevation of the base of the scarp
from 240 feet near Lake Success to 60 feet near East New York, which has always been a
stumblingblock in the way of accepting the theory of its recent marine origin, is due to the
natural slope of the outwash plains built against it, the line of contact with these plains bemg
in no sense a warped shore line.

The origin of this scarp appears to be clearly indicated by its topography, every feature
of which is duplicated elsewhere on the island under conditions apparently admitting of the
absolute determination of origin. The original scarp differed in no way from the bluffs at
dozens of points on the north shore, and the drift-covered face and partly filled valleys have
counterparts at many places. This is strikingly brought out by the maps given on Plate XI,
A and B, which represent respectively a part of the morainal scarp near Creedmoor, and a part
of the north shore near Miller Place, east of Port Jefferson. The same steep bluffs with minor
indentations are seen in each locality, and the valleys cutting them are almost identical in
character. The only difference in the topography, in fact, is the slightly steeper face at the
Miller Place locality, due to the fact that there is no coating of till on the face of the bluff,
which is being rapidly cut by the waves at the present time. There is little reason to doubt
that the inland scarp under discussion is, in its main features, of marine origin but has been
modified by late drift. (See Pl. SI, D.) There seems to be no ground for regarding it, as
some have, as a morainal front, for it has few of the characteristics of a moraine exéept in its
most superficial features.

How high the land stood when the scarp was formed can not be told. From the depth of
channels in the vicinity of the island (see p. 59), it is known that the land stood considerably
higher in relation to the sea in the Vineyard interval than at present. The fact that Cretaceous
formations are found at a depth of about 100 feet, or about 25 feet below sea level in a well
in front of the scarp at Hollis, shows, however, that unless the mass encountered represents an
offshore island, the land could not have stood more than 25 feet higher than at present.

SHORE BLUFFS.

There is hardly a point on Long Island at which the highlands reach the coast where the
shore is not bordered by bluffs, this being true of the bays and harbors as well as of the exposed
coast line. The condition of the bluffs varies greatly from place to place, however, all gradations
being observed from nearly vertical cliffs such as border the south coast west of Montauk light
to relatively gentle slopes (25° to 35°) completely covered with trees. On the open coast
probably four-fifths of the bluffs are free from vegetable growth, and perhaps a tenth are
sufficiently free from talus to admit of the determination of their composition and structure
from top to bottom. The remainder are clothed with grass or trees or artificially covered.
In the harbors about half of the cliffs are covered with vegetation and half free from it. Harbor
cliffs are, however, seldom free from talus, but even in the talus-covered cliffs the general
structure can usually be made out by a little digging.

The condition of the bluffs often changes materially within a short time. The whole line
along a coast may be modified by a single storm, which in some places eats into the bluffs and
elsewhere throws up barriers of sand or gravel in front of them, according to the direction of
the wind, the angle of impact of the waves, and the nature of the currents set up at the time.
The barriers built up along the beaches in front of the bluffs persist until they are removed by
storms or currents from other directions than those of the storms which formed them. Some
of them last for many years—long enough for the cliffs behind them to become covered with
grass or even forests—but sooner or later the cutting begins again and the cliffs are under-
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BROKEN GROUND LANDSLIP AREA, NORTHEAST OF NORTHPORT.

flandslip mass.

 

A. Inner scarp and tilted block RB. Upturned Cretaceous clays at hase
Photographs by GN. Knap.
PH YSIOGRAPHY. 55

mined, landslides take place, and earth and tree trunks are mingled in confused heaps. (See
‘Landslides,’ below.)

The cliffs are best preserved where coherent materials, such as the Gardiners clay, Jacob
sand, and Montauk till members of the Manhasset formation outcrop in the bluffs (Pls. XIX,
B, p. 114; XXII, A, p. 136), and are least well preserved in the sands and gravels of the Man-
hasset (Pl. XX, p. 116). At the time of the examination of the shore line in 1904 the best
exposures were on Gardiners Island, on Robins Island, and on the south coast of Montauk from
Napeague Bay to the lighthouse. Fine exposures were also found on the south side of Great
Peconic Bay, on the two large necks east of Sag Harbor, and especially along the north coast
from Port Jefferson to Orient Point. Good exposures were seen northeast of Northport and
on Eaton and Lloyd necks. West of Oyster Bay, although there were a few good exposures,
as at Rocky Point and on the east side of Hempstead Harbor, the bluffs are prevailingly low
and are in many places artificially covered. The south shore, except the Montauk Peninsula
and the part of Shinnecock Bay south of the Shinnecock Hills, is essentially free from cliffs,
although it has some bluffs 4 or 5 feet high.

LANDSLIDES.

Landslides may be ranked among the conspicuous features of Long Island, occurring, as
would be expected, at many points on the steep bluffs of the north shore. Some of them rep-
resent a mere slipping of the surface of the bluffs, whereas in others the land is affected for many
hundred feet back from the shore (Pl. XII). The slides are of a number of different types and
are due to a variety of causes, the more important of which are noted below.

CAUSES.

Work of waves.—The action of waves is the direct cause of many of the landslides of
the island and the indirect cause of most of the others. The whole north shore, the shores
between the flukes, and the south shore between Montauk Point and Napeague Beach are
exposed to the full action of the waves, which during storms, cut rapidly into the bluffs. When
the cutting begins in the softer material, such as the Manhasset formation, the talus that has
gradually accumulated since the last preceding storm commences to slide downward and is
soon removed by the waves. The undisturbed drift itself is then attacked, and this, being gen-
erally loose and uncemented, crumbles as soon as a vertical face of a few feet is produced, often
setting the entire face of the sandy bluff in motion, tilting or overturning the trees, shrubs, or
plants that may have obtained a foothold upon it. A similar result often follows stream erosion
on the sides of some of the small but sharp ravines of the north shore.

If the material is till, especially the partly cemented Montauk type, the erosion is somewhat
different. The material does not crumble rapidly, and the waves often make progress only by
tearing it away bit by bit until they produce a vertical or even overhanging face. Faces over-
hanging as much as 3 or 4 feet have been observed. When this stage is reached a new process,
which may be called scaling, begins, the material peeling off in vertical layers or scales. Some
of these layers are thin, but in places vertical slabs, the largest 20 feet or more high and 1 or 2
feet thick, become detached. The most typical examples of these slides, if they may be called
slides, are seen at Montauk Point.

Work of springs.—The action of spring sapping on Long Island, which is a very prevalent
cause of landslides, was described as long ago as 1843 by Mather. Springs act in two ways—
by adding water to the finer sands and converting them to quicksands and by actual erosion by
the streams proceeding from them. Commonly both processes go on together.

The gravels of the north shore are saturated by waters that ordinarily reach the sea between
high and low tide by seepage without appearing at the surface elsewhere. Under these usual
conditions few or no slides seem to be produced, for the water table is at some distance below
the beach, and the quicksands, if any are formed, are prevented from escaping by the overlying
material. But where an impervious layer holds the ground water in the bluff at a level higher
than the beach, the sands may be changed to quicksands and flow seaward, allowing the over-
lying material to sink and producing landslides of considerable size. The action is generally
56 GEOLOGY OF LONG ISLAND,

localized and produces hopper-shaped instead of linear slides. At this stage the water of the
spring begins its erosion, carrying the material brought down by the slide to the beach while
new slides bring down additional masses to take the place of the first. The pronounced amphi-
theaters on the north coast and many of the short, sharp valleys are produced in this way.
Movements of clays.—The slides produced by the flowage and slipping of clays are by far
the most conspicuous slides on the island, because of the considerable areas they cover and the
confusion of the resulting topography. Many of the clays when wet are very plastic, and there
is probably considerable flowage of those in the steeper bluffs under the weight of superincum-
bent deposits, although this is difficult to prove because of the absence of good cross sections.
If not the cause of the landslides it is certainly an effect, for there are many places where the
plastic clays have been pressed out upon the beach in contorted masses, as shown in Plate XIII, B.
The sliding of the layers of clay on their bedding planes
is also doubtless an important cause of landslides, but here
also no evidence has been found to show to what extent
this movement actually takes place. Sliding may occur
also along curved fractures, as shown in figure 49. Such a

movement is suggested by the conditions shown in Plate

FIGguRE 49.—Section showing the nature of dis- s ]
placement in the larger landslides and the or. TLL, A, although there is no reason why either of the
gin of the scarps shown in Plates XII, x11, other causes should not have produced the same effect.
A, and XIV, A. a, Original profile; b, profile me
atietaliupiies q.dlipaing windiaes: The sliding of sand beds over wet clays has been suggested
as another cause of slides, but observation on Long Island
seems to indicate that ordinarily no such slipping takes place. In every clay slide observed
the clay beds themselves seem to have moved, as indicated by the contorted structure they

have assumed.

 

DETAILS OF LANDSLIDES,

The Broken Ground slide, the largest on the island (1904), is situated on the Sound shore,
3 miles northeast of Northport and 1 mile north of Fort Salonga.t| The north face of the hill,
which has an elevation of 100 feet, has been converted by the slides into a confused jumble of
earth masses and prostrate trees. On passing northward over the crest one suddenly comes to a
fault scarp varying in height from 5 feet at the ends to 30 or 40 feet at the center (Pl. XIV, A).
At the base of the scarp is a broad shelf 50 yards across, representing the surface that was dropped
by the fault (Pl. XIII, A). Beyond this is a succession of slip faults separating narrow tilted
blocks, the whole grading off to the more confused earth heaps at the base (Pl. XIII, B). In
1904 many of the faults were still open to a depth of 5 to 10 feet. The whole disturbed area
has a length of nearly half a mile and a width between an eighth and a quarter of a mile.

The other landslides on the island are relatively small, only the faces of the bluffs com-
monly being affected. It is obvious that any storm would be likely to remove old slides of
this character and produce new ones, hence detailed descriptions would have little value. It
may be said, however, that extensive slides may be looked for at any point where clays are cut
by the sea. These localities are indicated on the geologic map (PI. I, in pocket). Among the
places where more or less definite slides were observed in 1904 may be mentioned the west shore
of Eaton Neck (where Cretaceous clays outcrop); Woodhull Landing near Miller Place, west
of Hulse Landing, Jacobs Point, Luce Landing, and Jacob Hill (Gardiners clay); Oregon Hills

and Mulford Point (till).
SUBMARINE FEATURES.

LONG ISLAND SOUND.

The great Sound valley.—After the close of Cretaceous deposition in the Long Island region
there was, as has been seen, an interval of nondeposition during most of Eocene time. The
extent of the uplift in this interval, if any, and the amount of erosion are not known, but it does
not appear to be represented by any great unconformity. During Miocene time the land, at
least in the southern part of Long Island, was below sea level, and enough deposits were laid

 

1 Incorrectly located by Veatch (Prof. Paper U. 8S. Geol. Survey No. 44, Pl. VII) as northeast of Huntington.
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 42 PLATE XIV

 

 

 

 

 

MAIN SCARP AT BROKEN GROUND LANDSLIP AREA, NORTHEAST OF NORTHPORT.
Photograph by G N Knapp.

 

; \x te
3 He ; ; ~——

tio

 

 

 

 

B. CRETACEOUS DEPOSITS ON LLOYD NECK.

Showing composition and structure. Photograph by G@ N Knapp.
: PHYSIOGRAPHY. 57

down to bury in large measure the erosion topography developed in the Eocene epoch. It is
believed that up to this time the Cretaceous deposits existed as an essentially continuous sheet
with its northern border overlapping upon the crystalline rocks of the Connecticut shore, and
that the Miocene deposits rested on the Cretaceous with their shoreward margin somewhere in
the southern third or half of Long Island.

In the Pliocene epoch the region was greatly reduced by erosion, in which both streams and
the ocean took part. A.C. Veatch! believes that during the early part of this period (pre-
Lafayette) Housatonic and Connecticut rivers continued to flow southward across the Coastal
Plain but developed, through the agency of tributaries along the contact of the Cretaceous with
the crystalline rocks, more or less marked lateral valleys with northward-facing scarps. These
lateral valleys were partly filled but not obliterated by the Lafayette deposits, but the narrow
valleys leading southward through the ridge are considered by Veatch to have been more nearly
effaced. The post-Lafayette uplift he apparently regards as accompanied by a tilting toward
the southwest, which caused Housatonic and Connecticut rivers to be deflected westward,
passing across the site of Long Island in the vicinity of Jamaica Bay near the west end and,
after uniting with the Hudson a few miles beyond, running southeastward in what is usually
known as the submarine Hudson channel. Veatch’s maps show that he supposes this course
to have been maintained after the Mannetto deposition, amounting to 300 or 400 feet or more,
and to have been deflected only after the deposition of the Manhasset formation (Tisbury of
Veatch). To the erosion by the streams mentioned, acting through this long period, Veatch
refers the development of Long Island Sound.

To the writer the history seems to be somewhat different. After the post-Miocene uplift
the streams, as stated by Veatch, probably continued southward across the Coastal Plain to the
ocean and very likely developed lateral valleys along the contact with the crystalline rocks.
Any opinion as to what happened in the Long Island region in Lafayette and post-Lafayette
time must be entirely speculative, for no Lafayette deposits have been identified, and there
is no evidence yet available for distinguishing between the post-Miocene and post-Lafayette
erosion periods.

The Mannetto deposition amounted to more than 300 feet and possibly more than 500 feet
and in central Long Island appears to have buried all the older deposits, with the possible excep-
tion of those on High Hill, south of Huntington, where, though nothing but drift shows at the
surface of the hill, the topographic features suggest that it may have a core of Cretaceous mate-
rial. The Mannetto deposits would have completely obliterated any valley across Long Island
that might have existed. If the drainage in post-Mannetto time took the course indicated by
Veatch, it must have marked the beginning of a new cycle that was entirely independent of the
earlier and did not inherit the courses of its streams.

The distribution and elevation of the Cretaceous deposits of western Long Island indicate
that, in all probability, no conspicuous valley with its bottom much below the present sea level
was ever formed across the island in the Jamaica-Jameco region. These deposits appear to be
above sea level from a point east of Smithtown to a point north of Jamaica. At Whitestone
they are less than 20 feet below sea level, and at College Point they appear to be less than 85
feet below sea level. The distance between the point of observation north of Jamaica and that
at Whitestone is 2 miles, and that between Whitestone or College Point and the outcrops of
crystalline rocks on the mainland is 1 mile. The intervening channel is only about 60 feet deep.
There is, therefore, no room for any but a narrow and correspondingly shallow channel through
the island at this point, there being no break comparable in size to the broad Sound supposedly
due to erosion by the same streams. It would be strange if the stream that in its upper
part eroded a valley from 10 to 20 miles wide should have a valley only 1 or 2 miles in width
near its mouth.

The Sound is broadest at a pomt southeast of New Haven, where it has a width of over 20
miles. From this point it tapers gradually westward until only the narrow East River separates

 

1 Prof. Paper U. S. Geol. Survey No. 44, 1906, pp. 28-32.
58 GEOLOGY OF LONG ISLAND,

Long Island from the mainland. A more significant feature, however, is the similar form of
the area inclosed between the mainland and the Cretaceous remnants lying above sea level on
the island. At Eaton Neck the breadth of the strip between the Cretaceous boundary and the
crystalline rocks is 8 miles, at Lloyd Neck 7, at Glen Cove 5, and at Elm Point 3 miles. At
Whitestone the Cretaceous, which is here only 20 feet below sea level, is only about a mile from
the crystalline rocks. If normally developed by subaerial erosion, such a valley could be pro-
duced only by a stream system draining eastward.

That the Sound is in the main the result of such erosion rather than of ice scour is probable,
as the Pleistocene deposits of Long Island, although derived principally from the Sound, would
not obliterate it if returned. Moreover most of the drift above sea level in the eastern part of
the island appears to have been derived not from the Cretaceous deposits but rather from the
mainland or from older glacial deposits lying in the Cretaceous trough. This trough is not the
result of ice erosion, as is shown by the absence of corresponding glacial accumulations, and the
great depth to the Cretaceous surface (555 feet below sea level in a well at Greenport) must there-
fore be referred to stream work. Other well records throw light on the eastward deepening
of the buried Cretaceous valley—the Sound valley, as it may be called.

In a map based on such records Veatch ! shows the Cretaceous to be at or within a few feet
of sea level in the vicinity of the north coast from College Point eastward to the vicinity of Stony
Brook. <A well record, as stated above, shows it to be about 550 feet below sea level at Green-
port, but at Fishers Island, still farther east, the top of the Cretaceous seems to be only 260
feet below sea level. None of these points, except perhaps the Greenport well, are in the pres-
ent Sound valley, and there is no means of estimating the depth of the old valley except by
prolonging northward the observed decline of the Cretaceous surface, as brought out by well
records, and the present depth of the Sound, a method which is of course far from satisfactory.
In the hills north of Old Westbury this surface has an elevation of about 230 feet. Thence
it declines northward, being slightly below sea level at the coast. The same rate of fall would
give it a depth of at least 100 feet in the center of the Sound. Jn the Mannetto Hills it is elevated
about 300 feet, and it declines to sea level at Lloyd Neck, a rate which would carry it to 150
feet below sea level in the Sound. The water as a matter of fact is more than 100 feet deep
at this point. At Westhampton the Cretaceous is about 150 feet below sea level, whereas at
Riverhead, S miles to the north, it was not recognized in a well 300 feet deep. At Bridgehamp-
ton it seems to have been encountered about 75 feet below sea level, although 12 miles
farther north, at Greenport, it was reported about 550 feet below sea level.

There seems, therefore, to be a broad buried valley in the Cretaceous surface in the Sound
region, having a width of a mile or two near the west end of the island and opening out east-
ward to a width of about 20 miles near New Haven. The valley seems to deepen east-
ward from 100 feet or less near College Point to at least 550 feet in the vicinity of Green-
port. Its southern rim is pretty uniformly from 300 to 400 feet higher than the lowest
point of the valley. The shallowness of the Cretaceous on Fishers Island would seem to
indicate that the axis of the valley passed south of this point.

The present valley of the Sound seems to be due principally to stream erosion, assisted,
however, by a certain amount of ice scour. It appears to have been cut entirely in the uncon-
solidated Pleistocene and Cretaceous deposits, there being, so far as known, no corresponding
depression in the underlying rock surface nor other evidence to support the theory of limestone
solution advanced by F. J. H. Merrill? on the basis of the composition of the clay.

Later channels —The bottom of Long Island Sound as a whole is remarkably even, in most
places sloping gently southward from the Connecticut shore at the rate of 10 or 20 fect to the
mile for about two-thirds of the way across the Sound, and rising somewhat more steeply to the
Long Island coast. The level bottom is, however, as was long ago pointed out by Dana,’ inter-

 

1Veatch, A, C., op. cit., Pl. IIT
2 Annals New York Acad. Sci., vol. 12, 1900, pp. 113-116.
5 Trans. Connecticut Acad. Arts and Sci., vol. 2, 1870, pp. 65 et seq.; Am. Jour. Sci.,3d ser., vol. 10, 1875, pp. 280-282; vol. 40, 1890, pp. 425-437.
PHYSIOGRAPHY, 59

rupted by a number of more or less channel-like depressions. The most conspicuous of these
extends eastward from a point about north of Oyster Bay and is from 25 to 50 feet deeper than
the surrounding bottom (fig.50). Ata point north of the head of Great Peconic Bay it bends
slightly southward and is lost in the shallow water of the Long Island coast. Dana considered
that it passed across the site of
the island near Mattituck, but
of this there is little evidence, as
the present valley at this point
is of other origin. (See p. 28.)
Another channel-like depres-
sion starts a few miles north-
west of the point where the first
ends and extends northeast-
ward to a point beyond Little
Gull Island, where it divides,
one branch passing south and
the other north of Valiant Reef.
In this vicinity depths of 50 to
55 fathoms, or 300 to 330 feet,
are recorded, although on each
side of the channel the water
is relatively shallow. East of j
Valiant Reef there are four ;
branches; one passes north of 2
Block Island and the others ‘
start in a southeasterly direc- -
tion and are lost in the shoals
north and northeast of Mon-
tauk Point. This digitate sys-
tem of channels converges west-
ward, and if it is the work of
streams would indicate a west-
ward drainage. The digitate
portions occur only in what is
known as the ‘‘Race,”’ a local-
ity of severe tidal scour, and
their form may have resulted
from tidal action. It is diffi-
cult, however, to account for
the channels in the broader
parts of the Sound in this way,
for they do not follow lines
of especially strong currents.
Moreover, the general relations
as brought out in figure 50
strongly suggest stream origin.
If they were cut by streams
they are, in all probability, to
be referred to the Vineyard erosion interval, as they are at a much higher level than the
post-Mannetto land surface, which was developed at the last preceding stage of uplift, and
there has been no post-Vineyard elevation sufficient to account for their depth. An earlier
time than the Vineyard is also precluded by the tremendous ice scour and subsequent deposition

 

 

an

a es

 

 

Hy, _
Hy
Noa
Montauk
Pt
Gntank

Fishers !
20 Miles

  
      
 
  
 

 

a

oy" 1

 

aw

  
   
  

(ai A

Island Sound and vicinity

=
10

Submarine channels of Long =

SNe
GF
helter

*® Sag Harbor

s

Easthampton
outhampton
P

sea jevel,in feet

(Veatch, 1904)

7700

sand; figures give

i
y

Gr¢
- “sO gies mag
ra Neu,
NS
ee |
A
Ay
oft the Lloyd
depths below

 

 

das

proximate contours on to)

L
Eastport #

Ss

 

73°

New Haven

 

 

30°
FIGURE 50.—Map showing Cretaceous structure and location of submarine channels of Long Island Sound.

South Norwalk
Stamford ’

74°

 

 

 

 

 

 

 

 

 

 

 

 

 
60 GEOLOGY OF LONG ISLAND.

characterizing the Montauk ice invasion. The point of outlet of the system, if one really
existed, is unknown, but the absence of any break in the Manhasset deposition indicates that
the outlet could have been only at the extreme west end of the island, probably beneath the
present lowlands in the vicin-
ity of Long Island City or
even along East River.
Starting at a point 7 miles
east of Montauk Point, ora
little over halfway to Block
Island, a submerged channel,
50 feet deep in places, extends
southeastward for nearly 10
miles. Its upper partis only
about a quarter of a mile
wide, and it is characterized
by swings and other features
of atruestreamchannel. It
seems to be lost at a depth
of 20 to 25 fathoms, hence at
the time of its formation the
land apparently stood 120 to
150 feet higher. A shallow
depression connects this
channel with one of the de-
pressions southeast of the
Race, but it seems to be
nothing more than a tidal
connection.
Conclusions.—The excava-
tion of the Cretaceous de-
posits began in the post-Mio-
cene period of erosion, but
whether the valley then
formed persisted through the
Lafayette accumulation (if
any took place in this region)
and the Mannetto deposition
isnot known. The valley or
its successor appears to have
been completed, however, in
the post-Mannetto stage of
erosion. It was partly filled
during the Jameco, Gardi-
ners, Jacob, and Manhasset
stages of deposition but was
10 See 10 Zo Miles not obliterated, and at the
Figure 51.—Map of the submarine channel and canyon of Hudson River. By J. W. Spencer. close of the Manhasset stage
Figures indicate depth in feet. it seems to have been occu-
pied by a westward-draining river system, which excavated the submerged channels. At the
same time a well-defined channel leading southward between Montauk and Block Island was
formed. In the last ice advance the valleys were partly filled and otherwise modified by the
action of the overriding ice and by the accompanying deposition, and in recent time tidal
scour has done much to change the character of the channels.

 
PHYSIOGRAPHY.

SUBMARINE CHANNELS OF THE HUDSON.

GENERAL CONDITIONS.

61

Channel of the continental shelf—Since the northern part of the continental shelf was first
charted the so-called submarine channel of the Hudson has aroused much interest among both
geologists and geographers, and many papers describing it and discussing its origin have been

published. It may be described briefly as a submerged valley leading
across the continental platform from a point a few miles cast of Sandy
Hook southeastward to the margin of the shelf, 55 miles from the beginning
(fig. 51). Beyond this margin a sharp canyon-like notch extends down
the escarpment to a depth of a mile
reer OF more below the surface of the sca.’
The measurements of this channel
given in the texts or shown on the
maps by different writers do not en-
tirely agree with one another, hence
Yj 7009 it is necessary to cite authority for
(oo aise the figures used. The depth of this
FIGURE 52.—Cross section showing relations of the broad- channel at the start is about 15
er valleys and sharp canyon of the submarine Hudson fathoms, or 5 or 6 fathoms below
channels. By J. W. Spencer. a :
the adjoining sea bottom; at 10 miles
out the depth is 8 fathoms below the surrounding bottom, and at 20, 30,
and 40 miles about 15 fathoms. Beyond the 40-mile point, owing to a
steepening of the inclination of the platform, the slope of the channel
being unchanged, the depth decreases and the bottom of the channel is
only about 8 fathoms below the level of the adjacent bottom at the 50-
fathom contour, 45 miles out. Immediately beyond this point, however,
is the beginning of the narrow but deep outer canyon or notch, which is
marked by an abrupt drop from 288 feet to 1,008 feet. This is followed by
a gentle slope extending about 6 miles, at the end of which a second drop
of about 400 feet takes place. A third drop of about 500 fcet occurs about
12 miles from the head of the canyon, the total depth then reached being
about 2,292 feet, or about 2,050 feet below the continental platform. The
soundings at this point (fig. 52) seem to indicate the presence of shelves
on the sides of the canyon, at a depth of about 1,250 feet, the origin of
which is obscure. At 31 miles the depth of the canyon has increased to
4,800 feet, or 3,800 feet below the surrounding sea bottom. Spencer on
his map (fig. 51) extends the canyon 43 miles farther, to a depth of 6,000
feet, and indicates a shallower valley-like depression extending to a distance
of 71 miles from the head of the gorge, or to a depth of 9,000 feet,? but the
evidence for the extension beyond the depth of 4,800 feet does not appear
to be conclusive. A section showing the relations of the various channels
is given in figure 53.

Hudson River rock channel.—Intimately related to the submarine
channel just described is the rock channel of Hudson River. That this
channel lies much deeper than the present river bottom and is covered
with thick accumulations of drift is well known, but unfortunately infor-
mation as to its exact depth is not available. The greatest depth yet
recorded (1908) is near Storm King Mountain, where the bottom appears
to be about 650 feet below sea level.’ At New York City the greatest

Sea Zevel

 

 

1000
2000

3000

  

 

Sea level

Bottom of channel cut in Manhasset formation

Rock wall of channel
-

 

 

  

SHOT OT Oy

EEK

eR

 
  
   
   
   

é
f

a, Manhasset formation, partly in channel; b, Jameco gravel, Gardiners

clay, and Jacob sand; c, outer canyon of late post-Mannetto stage; d, Cretaceous and later deposits.

FIGURE 53.—Section showing relations of the submarine Hudson channels and their fillings.

depth recorded is about 300 feet, but there is room for a narrow gorge of greater depth between
the soundings. Local erosion by ice to a depth of several hundred feet in the unusually hard

 

1 Map by J. W. Spencer, Am. Jour. Sci., 4th ser., vol. 19, 1905, p. 2.
2 Spencer, J. W., op. cit., pp. 6-7.
3 Kemp, J. F., Am. Jour. Sci., 4th ser., vol. 26, 1908, p. 320.
62 GEOLOGY OF LONG ISLAND.

rocks near Storm King (although the softer rocks of the vicinity were relatively little eroded)
does not afford a satisfactory explanation of the depth at this point, and it is equally unsatis-
factory to assume that a warping of 350 feet has taken place between this point and New
York. As examinations have shown that there is no other possible outlet for the old Hudson
waters, it seems probable, although not certain, that a buried canyon at least 700 feet in depth
must exist somewhere beneath the Hudson at New York City.

HISTORY OF THE CHANNELS,

Agencies of formation.—In considering the history of the submarine channels it is necessary
to start with an assumption as to the agencies to which their origin is due. The principal
basis for this ‘assumption must necessarily be the form and course of the channels themselves.
From the soundings, which have been taken at unusually close intervals, probably closer than
over any other submarine area of equal extent on our coasts, it is possible to contour the sea
bottom with an accuracy comparable almost to that of topographic maps of the land surface.
Not only are the broader features of the trough and the adjacent sea bottom brought out
but many minor details, such as the accelerations of slope and the presence of shelves on the
sides of the deeper canyons, are plainly shown.

The cross section of the submarine valley from Sandy Hook to the edge of the continental
platform may be said to be practically identical in character with that of the normal streams
which to-day cross the emerged portions of the Coastal Plain along the adjacent coasts. The
sloping sides and nearly flat bottom of the submarine channel correspond with the similar
gently sloping highlands that border the terrestrial streams and their alluvial bottoms. Like-
wise, the curves and bends of the submarine channel differ in no material way from the similar
sinuosities of the present Coastal Plain streams.

The form and course of the trough, the presence of sand in the channel, although the
surrounding sea bottom consists of clay, and the physical connection with the present Hudson
River channel, except for the narrow bar of relatively recent deposits obscuring the channel
between Sandy Hook and New York, all seem to point to a fluviatile origin. Inasmuch as
such a channel could not be shaped by any process at work in the ocean, so far as known to
science, and as it has none of the characteristics of a fault depression, the writer has been
led to ascribe tentatively the origin of the shallower channel to subaerial stream action when
the land stood from 300 to 350 feet above its present level with reference to the sea.

The origin of the deep canyon-like gorge extending seaward from the outer end of the
shallower channel seems to be less certain. As shown hy the map? (fig. 51) and section (fig. 52),
the gorge exhibits, both as regards its course and the character of its cross section, the normal
characteristics of an erosion notch cut back in the mesa-like edge of the continental platform,
and the sharp drops or falls at intervals in its bottom are equally characteristic of young erosion.
Furthermore, it seems to represent the continuation of the inner, shallower channel, which
the writer considers to be due probably to stream erosion. Like the inner channel, it appears
to have none of the charactcristics of a fault fissure. It can not be considered a depression
such as might be caused by the slumping of the materials along the steepened margin of the
continental shelf, for such a depression would necessarily be approximately parallel with instead
of at right angles to the margin of the platform. Submarine scour as a cause of canyon cutting
appears to be entirely out of the question.

The theory that the gorge was excavated by stream erosion would involve an elevation
of several thousand feet at the time of the erosion—not less than 4,806 fect being required
by the depth of the floor of the lower part of the gorge, as shown in figure 51. The writer, in com-
mon with most other geologists, is loath to acknowledge the occurrence of any such elevation
at this point in Pleistocene or late Tertiary time. It is not impossible, however, that in the
reaction from the belief in great and rapid oscillations of level, held by many geologists a few

1 Tt should be stated that the character of the channels was not determined from the few soundings shown on the map, but from a very large
number of soundings, which could not be indicated readily because of the small scale of the drawing.
PHYSIOGRAPHY, 63

years ago, the pendulum has swung too far, and the present tendency may be to minimize the
evidences for such oscillations. Notwithstanding the violent assumption of elevation involved,
the form and character of the gorge itsclf appear to be more nearly those which normally result
from stream erosion than from any other known agency. The writer docs not wish to be con-
sidered as advocating the assumption of excessive elevation in general, and especially he does
not wish to advocate it as an explanation of the broad troughlike submarine depressions of this
and other localities that have been cited by some writers as crosion features, and even in the
present instance he would go no further than to point out the apparent significance of the
channel features.

The principal features to be accounted for in a consideration of the history of the channel
and canyon are (1) the rock gorge of the present Hudson River, presumably cut to « depth
of about 700 feet below sea level; (2) a broad outer depression, in the bottom of which the
canyon notch is found; (3) the cutting of the deep outer canyon; (4) the filling of the first
deep channel of the Hudson; (5) the cutting of the present shallow, upper submarine channel;
and (6) the partial filling of the inner end of the upper channel.

Cutting of the 700-foot channel.—The rock gorge of Hudson River proper, which is
assumed to be about 700 feet deep in the vicinity of New York, appears to be filled solely
with Pleistocene materials, as indicated by the Storm King and other borings; hence, unless
earlier beds had been deposited and subsequently removed by glacial ice, its cutting ‘is
to be referred to a date later than that of the deposition of the latest Tertiary beds in this
region. It was probably cut at a much later date, for the Mannetto gravel (pre-Kansan 2),
which accumulated to a height of 300 feet above the present sea level in western Long Island,
seems to have been originally continuous with the Bridgeton formation of New Jersey, which
is built up to at least 200 feet above sea level in the northern part of that State. After the
deposition of the gravel, however, there was a period of uplift and erosion in which the Man-
netto was cut to a depth of at least 300 feet below sea level, as shown by the depth of the
buried Jameco channel of Long Island. The great length of this period of erosion, indicated
by the almost complete removal of the thick Mannetto gravel from the Long Island region,
is in harmony with the time required for the cutting of the Hudson River rock gorge. Inasmuch
as there are in the later deposits no unconformities that would indicate prolonged elevation
of similar degree, it seems that the date of the cutting of the rock channel may be referred
with a considerable degree of certainty to the long post-Mannetto (Aftonian ?) interval.

It is not beyond the limits of possibility, however, that the 700-foot channel may be some-
what older than the post-Mannetto and pre-Jameco. Although the Mannetto gravel and
Bridgeton formation were presumably continuous and stood at a considerable clevation above
the sea in the region of the upper part of the present channel, it is not impossible that they
were in part glacial outwashes from localized centers of dispersion, and in that case a gap
might have been left in the region of New York City in which a pre-Mannetto channel might
have persisted.

The channel began at some point well above New York City, for soundings to a depth
of 650 feet in its fillings have been made as far north as Storm King Mountain, 50 miles above.
the city! It extended southward and southeastward probably to the edge of the continental
shelf. Possibly the land along the northern part was more elevated than that near the coast,
and the excavation was therefore less near the sea than farther up the valley. That the gorge
was excavated to a depth of more than 300 feet in the vicinity of New York City, however,
has been established by borings, and a channel of at least that depth, if not of 700 feet, appar-
ently must be assumed as having been formed across the continental shelf.

The broad outer depression —Well-marked shelves occur at intervals on both sides of the
canyon portion of the submarine channel, from the inner to the outer end. (See fig. 52, p. 61.)
They are not continuous, however, the total space occupied being only about half the length

 

1 Kemp, J. F., Our knowledge of the filled channel in the Hudson of the Highlands and the submerged gorge on the continental shelf: Science,
new ser., vol. 29, 1909, p. 279.
64 GEOLOGY OF LONG ISLAND,

of the gorge, and some of those at up-channel points are lower than those at down-channel
points. Inasmuch as their absence can not be accounted for by incompleteness of soundings,
it does not seem likely that the shelves represent an old valley marking a separate epoch in the
history of the channels, as their appearance at first suggests.

The outer canyon.—The narrow, steep-sided, and deep outer canyon, although it is the most
marked feature of the submarine channel system, would appear to require, if due to stream
erosion, but a relatively short period for its formation, as compared with that needed for the
excavation of the long rock gorge of the Hudson. This fact is emphasized by the great drops
or falls in its bed, which could not exist had the period of canyon cutting been as long as that
of the rock gorge. Probably it extended but little north of its present head, for there appears
to be little evidence, to judge from the contours of the bottom, of anything more than a slight
filling by later deposits.

So far as its observed features indicate, the outer canyon might have been formed during
either the post-Mannetto or the Vineyard interval of erosion. The soundings, however, seem
to show that it was to some extent filled at its head by the great series of deposits that obliterated
the continuation of the 700-foot channel; hence it must apparently be referred to the same
general period of erosion as that channel. If due to stream erosion at all, it must be referred
to an elevation of great magnitude, occurring at the close of the post-Mannetto erosion stage,
but of so transient a character that the chief work of erosion consisted of a notching of the edge
of the continental shelf, the land back of this point being but little affected.

Obliteration of the earlier channels —The post-Mannetto erosion was followed by a long period
of deposition, as shown by the thick conformable series of deposits, including the Jameco gravel,
Gardiners clay, and Jacob sand. During this period, so far as known, the sea bottom in the
vicinity of the channel remained constantly below sea level. The deposits, which have a
thickness of 200 feet or more on Long Island, doubtless extended far to the south and largely
buried the early channel. The obliteration was probably completed by the outwash of the
several stages of Manhasset deposition, including the Herod gravel member, the Montauk
till member, and the Hempstead gravel member, which, although not having anything like
the maximum thickness of 300 feet observed on the island, doubtless formed a sheet of con-
siderable thickness.

Cutting of the present upper channel—The upper channel has a depth at its outer end of
only about 350 feet, hence an elevation of the land of this amount will explain its formation.
As no time break is indicated in the deposits of Long Island from the beginning of the Jameco
to the close of the Hempstead deposition, and as there are nowhere on the island, even on
the exposed coasts, any erosion channels referable to Wisconsin or post-Wisconsin elevation,
the formation of the upper channel is most logically referred to the Vineyard interval of erosion,
following the Manhasset deposition. The valleys in the Manhasset deposits, although some-
what modified and partly filled with Wisconsin aceumulations, arc known to extend some
distance below sea level at many points along the north shore, indicating a higher position
of the land than at present. These valleys, most of which mark small intermittent streams,
naturally are not nearly so deep as the channel formed by the large Hudson stream, and in
themselves indicate little as to the absolute elevation of the land, which is shown only by the
submarine channels such as that of the Hudson.

Filling of the upper channel.—The upper channel has been largely obliterated north of
Sandy Hook, in part by the Wisconsin outwash and in part through the shifting of the sands
by the littoral currents that nowsweep along the coast. Its termination is somewhat indefinite,
but where last recognized seems to point toward Jamaica Bay. As the Manhasset deposits
contain no gap or channel marking the position of any outflowing stream, the bend seems to
be without significance, so far as Long Island is concerned, and is probably simply one of
several bends between Sandy Hook and North River at New York.
GEOLOGY OF LONG ISLAND. 65

STRATIGRAPHIC GEOLOGY.
METHOD OF MAPPING.

The geologic map accompanying this report (Pl. I, in pocket) sets forth the present state
of knowledge of the geology of Long Island so far as it can be represented with the data at
hand. It is to be noted, however, that here as elsewhere the glacial deposits of one type in
places grade insensibly into those of another with no sharp line of demarcation. As boundaries
are necessary they have been placed where they seem, all things considered, to bring out best
the relations it is desired to show, even if no exact line can be recognized in the field. Other
real inaccuracies in detail have doubtless resulted from the fact that a large part of. the work
in the interior of the island was done before the topographic survey was completed and without
any accurate base, as a consequence of which many features could be located only with difficulty,
if at all, on the new base. More or less generalization has also been unavoidable because of
the small scale of the map.

This map shows the outcrops of the older Pleistocene beds as exposed in the bluffs in 1903
and 1904, but as the condition of the exposures is constantly changing many sections then
observed will now be found to be destroyed and their places to be taken by exposures not then
visible. There will also be much difficulty in distinguishing some of the beds in certain locali-
ties. For instance, the Wisconsin till and the Montauk till member of the Manhasset forma-
tion in some places so closely approach each other in character that it is difficult to separate
them when in contact, and they may appear as a single unit. It is for this reason that the
Montauk member is not shown as occurring on the North Fluke, although in all probability it
is present in the greater part of the length of the bluffs. Again, where the Montauk member is
composed of reworked Gardiners clay, it is almost impossible to distinguish it from the true clay
except in the few places where granite pebbles have been incorporated in the reworked mass.

In mapping the outwash areas considerable generalization has been necessary, as all grada-
tions between pure outwash and nearly pure Manhasset occur. From the relations of the two
deposits it is to be expected that Manhasset remnants may be found here and there projecting
above the areas shown as outwash, and in some of the compound areas it may be difficult to
detect any outwash. In fact, in many such areas the outwash is confined to a few channels.

The geologic map is not strictly a lithologic map, the attempt being made to bring out the
history and relations of the deposits by means of a system of solid underprints representing
the fundamental formations with overprints showing the superficial deposits.

The dune areas are probably much more extensive than is indicated, although the mantle
is thin in places and the underlying deposits may show through. Where the developments
are weak the topography is not striking, and owing to the covering of forest and the absence
of sections, the full extent of the old dune areas is very difficult to determine,

PRE-CRETACEOUS ROCKS.!

The basement deposits of Long Island, originally considered in large part “Primitive” or
composed fundamentally of metamorphic rocks, have been successively classed or mapped as
alluvium, diluvium, Tertiary and drift, and Cretaceous and drift. The early conception of
simplicity of the drift has likewise been abandoned, and where one formation was originally
known. at least five are now differentiated and a complex series of events is recognized.

The pre-Cretaceous rocks of Long Island consist chiefly of pre-Cambrian gneiss with
intruded dikes of granite and a little dolomitic limestone. The gneiss, which is known as the
Fordham gneiss, is of a gray color and is made up of bands rarely exceeding 2 inches in thick-
ness. The bands differ widely in composition, some being highly quartzose, others biotitic, and
still others pegmatitic. The banding stands at a very high angle and strikes about N. 25° E
being parallel with the course of that part of East River near Blackwells Island. The gneiss forms
the western shore of Long Island from Lawrence Point southward to Newtown Creek. The
dikes occur as narrow intrusions of gray and reddish granite, usually parallel to the band-

 

1 For a more detailed description see Merrill, F. J. H., New York City folio (No. 83), Geol. Atlas U. S., U. S. Geol. Survey, 1902.
1629°—14——_6

-
66 GEOLOGY OF LONG ISLAND.

ing of the gneiss, and, being somewhat more resistant than the surrounding rock, have given
rise to many of the islands of upper East River. Many small dikes occur in the vicinity of
Ravenswood, and there are pegmatitic masses of considerable size at Hunters Point.

The dolomite, which is known as the Stockbridge dolomite, consists of alternating layers
of coarsely crystalline dolomite and limestone. It is well bedded, the layers standing at high
angles and striking parallel to the gneiss. It is mapped by Merrill as a narrow band crossing
the neck west of Astoria and has been encountered in at least two borings in Hast River.

Whether the Fordham gneiss is of sedimentary or igneous origin is not known, for the
metamorphism that it has undergone has been sufficient to destroy all its sedimentary features,
if any ever existed. It is, as already stated, of pre-Cambrian age. The Stockbridge dolomite
is clearly of sedimentary origin and is regarded as being of Cambrian and Ordovician age. The
granitic and pegmatitic intrusions in the gneiss are younger than the dolomite, for they cut
the Hudson schist (Ordovician), which overlies it, and are therefore of Ordovician or later age.

These rocks have been compressed into close folds in which the beds stand nearly vertical,
as shown in figure 54. There is considerable evidence that faulting has frequently taken place

in the region, that

~ pct 72
8 é é _ 5 ge the structure of the
z a 3 2 2s .
a 3 5 gE = gc rocks ismore complex
8 = % z = 2 : ‘
3 £ = 3g & 2 § than is shown in the
| | | i 11 sections, and that it
v_Sh Sh fgn $ fgn_-€Ss Sea level

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TFA STIS AUT TROT may even have had
NTT RM WNT ON x
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a considerable influ-
ence on the topo-
graphic expression
of the East River
region.

The metamorphic
rocks are seen at the
surface only in anar-
row strip along East
¢ % 1: 2 miles River, at the extreme

Figure 34.—Sections from Hudson River to Long Island, showing in a general way the folded and erodea West end of the island,
character of the bedrock underlying Long Island. (After Merrill, 1902.) fgn, Fordham gneiss (pre-Cam- t th
brian); €Ss, Stockbridge dolomite (Cambrian and Ordovician); Sh, Hudson schist (Ordovician). bu ey have been

Ss fgn Sea level
r a Wanna
K A

   
    

 

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. HA
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encountered ina large
number of wells in Brooklyn, in Long Island City, and at several points eastward to Wood-
haven and northeastward to Manhasset Neck. From these occurrences it is possible to contour
the rock surface roughly, as shown in Plate XV The contours show that this surface slopes
southeastward at an average rate of about 100 feet to the mile for a distance of 5 miles or
more. Many minor irregularities are brought out by wells that are close together, but on the
whole the slope seems to be very even in the western part of the island. At Greenport, near
the east end, the slope is considerably less, rock being encountered at a depth of 670 feet ata
point 11 miles from the outcrops on the mainland. The statements in regard to the well on
Fishers Island are conflicting, the depth to rock being given as 150 feet, 204 feet, and 281 feet.t

CRETACEOUS SYSTEM.

The discoveries of fossils by which the existence of Cretaceous deposits was established
have been described in the review of geologic literature (pp. 4-22). The well records collected
in connection with the recent work and the discovery of evidences for separating the
Pleistocene from the Cretaceous clays, with which they had often been included, have made it
possible to determine the character and distribution of the Cretaceous beds within fairly close
limits. The well records have already been published in Veatch’s report.

 

1 Prof. Paper U. 8. Geol. Survey No. 44, 1906, pp. 17, 167, 337. 2Idem, pp. I1t et seq.
U.S. GEOLOGICAL SURVEY

PROFESSIONAL PAPER 82 PLATE XV

 

 

LEGEND

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MAP SHOWING POSITION OF BEDROCK IN WESTERN LONG ISLAND.

By A. C. Veatch.

 
CRETACEOUS SYSTEM. 67
OHARACTER OF THE DEPOSITS.

The Cretaceous deposits of Long Island differ extremely in composition within short dis-
tances. One well may show several hundred feet of clay and an adjoining well may show an
equal amount of sand. Nevertheless there appears to be a certain general sequence, which is
shown in the columnar section forming figure 55.

The term ‘‘basal clays” is applied to those at the base of the Long Island Cretaceous sec-
tion as it has been disclosed by well borings, or in other words those lying beneath the Lloyd sand.
Relatively few sections of these lower beds are available, but they seem to consist rather uni-
formly of dirty white, gray, and blue clays, with a few beds of gray sand and some grayish
quicksands. Their total thickness probably ranges from 100 to 200 feet. The beds are no-
where exposed at the surface and are encountered in only a few of the wells near the west
end of the island.

Veatch* has given the name “Lloyd sand” to the bed of yellow to
white quartz gravel and sand with some clayey layers lying next above
the basal clays. This is the main Cretaceous water bed and is usually
about 80 or 90 feet thick. It does not outcrop anywhere at the surface
but is probably not much more than 100 feet below sea level near College
Point and in parts of Long Island City.

Above the Lloyd sand is a group called “red clays” but contain-
ing beds of yellow, salmon-colored, red, brown, chocolate-colored, and
black clays, with a few relatively thin beds of sand, the total thickness
ranging usually from 100 to 250 feet but in places exceeding 400 feet.
The clays are found in the wells of the north shore, and are to be seen
south of Mott Point, on Manhasset Neck, north of Glen Cove, and in the
beach below high water at Rocky Point, Cold Spring Harbor.

Above the colored clays is a bed of ‘white sand" and clay reach-
ing a thickness of at least 100 feet. This is the white arkose sand ex-
posed on the east side of Hempstead Harbor, near Sea Cliff, at Latting-
town, at Center Island, and on Lloyd and Eaton necks.

The white sands are overlain by about 75 feet of “yellow clays,” in-
terbedded with red and brown layers. These lighter clays crop out along
the shore of Cold Spring Harbor for more than a mile south of Lloyd

Beach.
Next above these clays stratigraphically are the dark slate-colored

clays of Little Neck and their chocolate-colored to black equivalents
along the Sound 4 miles northeast of Northport. These beds are ex- Foc24 Crystalline rocks
posed in many clay pits and are seen to be well stratified and to carry, gure 56—Cohmnar section
in the latter locality, numerous concretions. Several beds of light- of the Cretaceous formations
colored sand are included among the clays. The thickness of this group, ene
which is designated “dark clay’’ in figures 55 and 56, is estimated to be about 75 feet.
Nothing is seen of the Cretaceous between the north coast and the Dix Hills, 4 miles south
of the Little Neck outcrop, where undifferentiated beds of yellow, gray, and white clays of
probable Cretaceous age were encountered in a cistern. Five miles farther south, near
Wyandanch, there are considerable exposures; and at Bethpage and Farmingdale, a few miles
west of Wyandanch, thick beds of clay are exposed in the clay pits. Allowing a dip of 65 feet
to the mile, which is that observed at Oyster Bay, and allowing for a difference of 100 feet
between the surface elevations, we find that a stratigraphic interval of nearly 600 feet must inter-
vene between Little Neck and Bethpage. According to Veatch’s well records this interval is.occu-
pied mainly by yellowish sand, with a clay bed here and there, as at the base of the Dix Hills.

 

Marl (10 ft.)
Yellow sand (150 ft.)

 

     
 
    

Buff clay (100 ft.)

 

Undifferentiated (600 ft.)

Dark clay (75 ft.)
Yellow clay (76 ft.)

 

 

“| ‘White sand (100 ft.)

 

=| Red clays (200 ft.)

 

 

j Basal clays (150 ft.)

 

 

 

 

 

1 Op. cit., p. 21.
68 GEOLOGY OF LONG ISLAND.

A group that may be called ‘‘buff clays” includes the gray, salmon, and buff clays at Beth-
page and Farmingdale and the yellow, buff, and dirty-brown shaly clays near Wyandanch.
The observed thickness and the distribution of these clays indicate that their aggregate thick-
ness is, roughly, 100 fect.

Above the clays at Wyandanch and Bethpage is seen the “yellow sand.” ‘Talus slopes
of this sand also appear at many points on the hillsides, and it was seen in a roadside section
below the crest of the ridge west of Melville. A few clayey streaks occur in it, but the section,
so far as known, is sandy throughout a thickness of 150 feet.

On the crest of the ridge west of Melville, beginning about 41 feet from the top of the hill,
the following section was recorded by G. N. Knapp and the writer:

Section of marly beds near Melville.

 

Ft. in,
J. Sandy marly clay, greenish gray..-.......-- 2-26. 2eo eee nee eee 6
2. Ferruginous, partly indurated, marly clay, yellowish brown......-.-.--------+---+--+----- 6
3. Marly clay; greenish marl, with chocolate-colored clay base .....-----------+-+-++-++---+-- 1
4, Ferruginous (weathered) micaceous clay marl, yellowish brown .........-...--2+2+--2e----+ 6
5. Clay marl; fine green sand mixed with chocolate-colored clay and some quartz sand; typical
Merchantville of New Jersey (bed No. 1) ....-..-...--- 2-0-2 2-2-2222 ee reece eee eee 1
6. Weathered, somewhat sandy, semi-indurated clay marl, yellowish brown .....-... soke emtessye S 1
7... Clase toarl (same as.N6..5; SHOVE). -sicee 2-222 vs canine eonSee ences See a reechoeeaee ee eee sae 1
8. Iron plates alternating with marl, clayey sand, and gravel.....-.---.---------------+-++- 26
9. Coarse green marly sand and clay, with abundant green sand; some quartz pebbles one-fourth
to one-half inch in diameter; resembles arkose; weathered pits in lower half; like top of
Clay marls-of New Jersey iwcassieeeeeccgitekik nets sade s ceceee Guess eae es 3
11

These beds and some greenish clays observed by Veatch at 156 fect in wells at Quogue
and 155 feet in wells at Bridgehampton, at about the same stratigraphic horizon, are among
the few representatives of the marl series that have been found on Long Island. The marly
deposits of this section were first described by Veatch’ as arkose, but in his final report? were
referred to the marl series on the basis of the observations of G. N. Knapp and the writer.

DISTRIBUTION OF CRETACEOUS DEPOSITS.

SURFACE OUTCROPS,

Elm Point.—The westernmost important showing of Cretaceous beds on Long Island is
situated at Elm Point, on the west side of Great Neck, between Manhasset and Little Neck
bays, in North Hempstead Township. The Cretaceous deposits at this place consist of about
30 feet of dark-gray clay containing a few lignitic fragments, overlain by 15 to 20 feet of
Pleistocene gravel and till.

Thomaston.—A small exposure of sand and other material may be seen in a railway cut
between Thomaston and the head of Manhasset Bay, at the base of Great Neck.

West side of Hempstead Harbor.—The first indications of the Cretaceous in a journey north
from Roslyn are found a short distance north of the sand spit known as Bar Beach, where white
or yellowish Cretaceous clays are occasionally encountered in excavations at the bottoms of
gravel pits. A little farther north white clayey arkose sands and bleached quartz pebbles appear
amid the Pleistocene talus, and a considerable number of small exposures of the same material
are seen in places. The sands are cross-bedded, although on a small scale, and contain many
pinkish streaks. The Cretaceous also shows up to an elevation of 150 fect along the highway
leading from Hempstead Iarbor to Port Washington Harbor, about a mile north of Bar Beach.
In a section at the highest point the Cretaceous was found in 1903 to be upturned at a high angle,
the contact with the Pleistocene being absolutely vertical for the entire depth of the cut (about
25 feet). The materials here were mainly white, cream, and pink clays and sands. These belong
to the ‘‘white sands”’ of figure 56.

1 Veatch, A. C., Notes on the geology of Long Island: Science, new ser., vol. 18, 1903, pp. 213-214.
2 Veatch, A. C., and others, Underground water resources of Long Island, New York: Prof. Paper U. 8. Geol Survey No. 44, 1906, pp. 20-22,
CRETACEOUS SYSTEM. 69

Another good exposure is about half a mile south of Mott Point, where 15 feet of yellow-
ish and reddish clay was seen in the bluff in 1905, and beds of cream, salmon, red, and black
Cretaceous clays from 6 inches to several feet in thickness crop out on the beach between high
and low tide limits. They are referred to the red-clay bed of figure 56.

Glen Cove.—A little north of Glen Cove Landing there is an outcrop of contorted yellow,
pink, gray, and black plastic clays having crusts of hematitic sand and containing pyrite con-
cretions. They have an entirely different aspect from the gray and yellow sandy clays (Pleisto-
cene) between Weeks and Red Spring points and have yielded plant remains that establish their
Cretaceous age. The clays are hidden near the landing, but are well exposed a quarter of a mile
farther south and continue for many hundred feet. White, cream, yellow, red, purplish-red,
gray, and black clays occur in strong contortions in which granitic gravels appear to be involved,
for they clearly underlie the Cretaceous clay in overturned folds at one point: The beach is
covered with a shingle of hematitic sandstone plates. The outcrops belong to the red-clay bed
of figure 56 and are overlain by more or less of the succeeding white-sand bed.

 

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SS WN NS AN
Marly beds. Yellow sands Buff clays Undifferentiated Dark clays Yellow clays White sands. Red clays

Outcrop shown by, X
FIGuRE 56.—Map showing known distribution of Cretaceous formations on western Long Island. By M. L. Fuller. Legend arranged

in order of age—youngest formation at left, oldest at right.

Sea Cliff—tThe first outcrop seen near Sea Cliff was in a sand pit on the south side of Mos-
quito Cove, opposite Glen Cove. Here 10 feet of white cross-bedded Cretaceous sand occurs
unconformably below Mannetto gravel. At short intervals from this point to Sea Cliff there
are exposures of Cretaceous deposits, mainly glaring white sand and sandy clay. Thick sections
are to be seen in some of the big sand pits. Southward from. Mosquito Cove there are traces of

- white sand and clay in the bluffs for a distance of half a mile, but no good exposures occur. A
show of white clay occurs three-fourths of a mile south of Glenwood Landing. The materials
are referred to the white-sand bed of figure 56.

Lattingtown.—The exposure of Cretaceous near Lattingtown is in a clay pit, 6 or 7 feet
deep, situated just south of the highway, three-quarters of a mile southeast of the village, at
an elevation of 130 feet. The materials are whitish clay locally tinged with pik and salmon.
Little sand is present. They belong near the transition from the red clay to the white sand of
the section shown in figure 55.
70 GEOLOGY OF LONG ISLAND.

Mill Neck.—An outcrop in the railroad cut across the neck between Oyster Bay and Mill
Neck station is mapped by Woodworth but is not described. Its stratigraphic position appears
to be near the top of the white sand bed of figure 56.

Center Island —The best exposure of clays on Center Island was seen at Rocky Point at
the mouth of Cold Spring Harbor, where in the beach between high and low tide marks is a
series of ycllow and dark-gray to jet-black, very plastic clays, free from grit and similar to those
near Glen Cove and Mott Point, with which they are correlated. The darker clays seen in
the bluffs above tide level appear to be Pleistocene. On the west side of Center Island, just
south of the point where it is nearly bisected by the marsh, an artificial pit showed in 1905
several feet of white clay streaked with white and pink sand belonging to the white sand of
figure 56. White sand and grayish clay were also cut by the dredge in digging a basin a quarter
of a mile south of the neck connecting with the main island.

Cold Spring Harbor—There are two outcrops of Cretaceous materials on the west side
of Cold Spring Harbor, one about half a mile south of Coopers Bluff and the other opposite
the village of Cold Spring Harbor, half a mile northwest of the sand bar. The former shows
only a few feet of white clayey sand, possibly talus, but the latter shows 10 feet or more of
white sand and a considerable amount of yellow, white, and salmon-colored clays in the beach
between high and low water marks. The sand belongs to the white-sand bed of figure 56, and
the clays to the overlying yellow clays.

The best exposure on the east side of the harbor is in the large abandoned clay pits just
south of Lloyd Beach, connecting Lloyd and West necks. In the bottoms of the pits the
material seems to be light to dark gray clay, overlain by a considerable thickness of yellow
and red clays. Many local variations of color and composition occur. The deposits belong
to the yellow clay of figure 56. South of the pits red and white sands show in the beach at
intervals for a quarter of a mile, and yellow and white sands with scattered traces of clay occur
for the next three-quarters of a mile. These deposits are included with the Cretaceous on the
map, although there is some reason for thinking that they may be reworked material.

The following is a section of the deposits exposed in this vicinity as given by Merrill? in
1886. The correlations are by the present writer.

Section on Cold Spring Harbor.

Feet.
Wisconsin’ "Till and stratified gravel: cccowcccie coos as een cemgwedaas yee Nek oe deta oewe nee seeds 10
Manhasset formation: Quartz gravel. ...........---2.--.-. enataliibalaicteia sistas ie teas eee 45
Cretaceous:
Red and blue ‘‘loam” or sandy clay.............-.-22-0 2200000000 20
Distomaceousesarth:22 2-2. ass oso gassed seec tebe ke See en ges SESS ete OARAS Hide ate ue 3
Yellow and red stratified sand..............0.0 02000000 ee 20
Red Plastie ClaYn on. cseesteemarmeeeg eer ded eds pnedonsees Aon Le dd a4 SROMOe RSE eee 20
Brown plastic: clay’... sccicecscees os eeeg ye sgeteeeaesee sce tee eee tee eee eee tetera 25

Descriptions of the diatoms have been published by Ries. (See p. 78.)
Lloyd Neck.—The best exposure on Lloyd Neck is in a high bluff on the north side about
three-quarters of a mile east of Lloyd Point. The following section was exposed in 1903:

Section on Lloyd Neck.

Feet.

Dine sand): 2. veewecsuesoraveese essen dg oeeses saith Gis ia ova GRIArsraeayanvaue’s arena) elaheigl ah aeieetessgse 10

Brow nish loamy till (Wisconsin) <<... 205 oa ccimeriiiernyy sewer ducesebee ey esa zadseseeeue ene c ce 10
Gravel and buff sandy clay, merging locally into lenses of till (Manhasset formation, with lenses of

Montatke Gil meni bern. .c ie ees ane See Sede view Shak bm oepgpeigncntiegad-n bose POORER eaomEa areca 30

Bright-red clay mixed with overlying gravel (Montauk?)..........-.2.2..2..0200-222--000000--- 2

White and pinkish clayey cross-bedded sand (Cretaceous)......-....- 12.0022. 0 220 ee eee eee eee 48

The sand is somewhat arkosc-like, and much of it is finely cross-bedded. Its character is
shown in Plate XIV, B (p. 56). It belongs to the white-sand bed, figure 56.

Another exposure of clay is found in the bluff facing Cold Spring Harbor just north of the
north end of Lloyd Beach. For some distance along the beach at this pomt there is here and

 

1 Merrill, F. J. H., On the geology of Long Island: Annals New York Acad. Sci., vol. 3, 1886, p. 350.
ORETACEOUS SYSTEM. 71

there an outcrop of yellowish clay, more or less undulating or folded, dipping in places as much
as 35°. It is underlain by a bed of gravel, which is mainly quartz but yields a few pebbles of
decomposed granite, indicating that it is probably to be regarded as Pleistocene. The Cretaccous
should be only a few feet lower, however, and it may be exposed from time to time as the waves
cut into the beach or bluff.

Great Neck, Huntington —At the end of Great Neck, northeast of Halesite, there are a number
of exposures of Cretaceous deposits. Not far from the point where the highway reaches the
beach a light-gray plastic clay, with a tinge of pink, is seen at beach level. A little farther
along traces of chocolate-colored clays occur, followed in the next half mile by indications of
salmon-colored and light-gray clay. White and pinkish clays appear at a number of points,
the southernmost being just south of the little cove around which the road circles. The beds
appear to belong near the top of the yellow clays of figure 56 and were formerly extensively
worked.

Little Neck, Huntington Cretaceous beds are exposed on both sides of Little Neck for
half a mile south of Little Neck Point. On the west side little but white cross-bedded sands is
to be seen, although a dark-gray clay shows through the beach at one point. On the east
side, however, the Cretaceous is well shown, both in the bluffs and in the big sand and clay
pits. One pit contains 20 to 25 feet of coarse white Cretaceous sands, the materials being
stratified on a broad scale instead of cross-bedded, as is usual. Another pit shows 30 to 40 feet
of finely stratified and perfectly jointed black and gray clay containing large pyrite concretions
and many leaves and even lignitized tree trunks (Pl. XVII, A, p. 82). White clay is said to
underlie the dark clay but was not exposed in 1905. Twenty feet of gray and olive-colored
clays were exposed in a bluff a quarter of a mile south of the wharf at the sand pit in 1905 and
are referred to the dark clays of figure 56.

Eaton Neck.—The Cretaceous materials are best exposed on the west shore of Eaton Neck,
from Winkle Point on the south to a point about half a mile north of the north end of West
Beach. At Winkle Point the Cretaceous is represented by only a small show of pinkish sand,
but in a large amphitheater a quarter of a mile farther north, on Price Bend, more than 30 feet
of pink, yellow, and white sands with ferrugimous concretions and hematitic sandstone plates
are exposed. Half a mile farther north, and not far from the head of Price Bend, 20 feet of
pink and white sand is exposed in the bluffs. In the high bluff just north of West Beach there
is about 30 feet of similar material with a few clay streaks. Beginning a quarter of a mile
north of the bluff, 10 feet of brown and black micaceous clay overlain by yellow sand is seen
at intervals for half a mile. Three feet of white Cretaceous clays show on the east shore of
Eaton Neck about half a mile southeast of Eaton Neck Light. These beds fall mainly in the
white sands of figure 56.

Northeast of Northport——The most easterly exposure of the Cretaceous on Long Island is
on the Sound shore about 4 miles northeast of Northport or a mile north of Fort Salonga village.
Here great masses of chocolate-colored and dark-gray to black clays have been upturned on
the beach by landslides, and lighter-brown clays contaming numerous calcareous concretions
were to be seen in a clay pit opened in 1903. There seems to be at least 30 or 40 fect of the
clays at this point. They are referred to the dark-clay bed of figure 56.

Diz Hills —On the west base of the northern extension of the Dix Hills, 14 miles south
of Greenlawn, there is an exposure of yellow quartz gravel free from granite pebbles and under-
lain, as shown by a cistern, by at least 12 feet of white, gray, and yellowish clay. It is regarded
as Cretaceous and is referred to the undifferentiated beds of the standard section.

Wyandanch.—Cretaceous exposures occur in some old clay pits in a deep valley in the
Half Hollow Hills a little northwest of Wyandanch (West Deer Park). In the northernmost
pit the clays are much disturbed, being in places upturned at an angle of 30°, apparently as the
result of creep. The lowest deposits seen are nearly jet-black lignitiferous clay containing
large concretions or disseminated crystals of pyrite. Above this there are locally red and white
variegated clays. A deep, narrow pocket of yellow sand occurs in the surface of the clay, but
whether as an infolded mass or in a small erosion channel could not be determined. On top is
12 GEOLOGY OF LONG ISLAND.

a bed of structureless sand and pebbles and granitic fragments resembling till. Elsewhere in
the pit 10 to 15 feet of stratified yellow gravel was seen above the clay, and in an adjacent pit
from 10 to 15 feet of brownish-gray shaly clay occurred. There were some small granitic frag-
ments on the surface. A pit 800 feet south of the first exposed 5 feet of yellow gravel with gran-
itic fragments on the surface. Below this was 10 feet of white and buff sand, and at the base
10 feet of salmon-colored and white clay. The sections in these pits differed greatly, even at
points only a fow feet apart, and no generalized section can be given. The beds are correlated
with the buff clays of figure 56.

Farmingdale and Bethpage.—Clay is exposed in the pits of the brickyard just north of
Farmingdale. At the time of the writer’s visit from 20 to 35 feet of material was exposed.
This comprised an upper layer of structureless gravel resembling till, from 1 to 8 feet thick,
resting on a very irregular surface of gray, yellow, and pinkish clay having a maximum thick-
ness of 10 feet. Below this layer the clay was darker, ranging from chocolate-colored to dark
brown or nearly black. About 10 feet of this dark clay was exposed in 1903. The surface clays
are somewhat disturbed, the structure being accounted for by creep. They belong to the buff
clays of figure 56.

The conditions at the Bethpage pit are very similar to those at Farmingdale.

Melville—At the top of the ridge near Melville the following section is exposed.

Section near Melville.
Feet.

Yellowish gravel with rotten granitic pebbles. ..... Ci D AS 22d Ra aemiaecates melee RNG 40
Fine orange-colored sands (‘‘fluffy”)........2....0000 0002002 e ee eee ee eee eee 6
Marly sands! 23 one sepenanieea cee Ve oa ies arent tnwe eM Sees eee meeee on aaee as 11
Gray, red, and yellow variegated clay with sand layers 6 inches to 2 feet thick. ..........2.-.2... 13
Coarse white or yellowish clayey sand..........2..- 220-2222 e cece e cece eee eee ee eee ee 18

88

_ The yellowish gravel at the top is referred to the Pleistocene; the orange-colored sands,
which resemble the so-called “fluffy’’ sands of Miocene age near Kirkwood, N. J., may belong
to the Tertiary; the remainder is Cretaceous. Details of the marly beds have already been
given (p. 68). The clay series consists of about a foot of ferruginous platy sandstone at the
top, followed by 94 feet of irregularly bedded stiff, fatty, brittle gray clay blotched with red
and yellow streaks alternating with lamine or thin layers of sand, the sand layers being more
numerous near the base. At the bottom is 2! feet of orange-colored sand with some clay streaks
and a few ferruginous plates and layers stained with manganese. The lower sandy member
is horizontally but irregularly bedded, the bedding lines being darker and somewhat more
clayey than the rest. These beds are the highest Cretaceous deposits encountered at the sur-
face on the island and are to be referred to the marl stratum of figure 56.

CRETACEOUS DEPOSITS PENETRATED BY WELLS.

Evidence as to the character of the Cretaceous deposits below the surface must be derived
from well records. Fortunately many deep wells have been sunk on Long Island and a large
number of records were collected in connection with the studies of the water supply. Some
of the more typical of these records are presented here. One of the striking features brought
out by them is the large proportion of sand in the deposits, much more being shown than the
surface outcrops would seem to indicate. The records are quoted from A. C. Veatch,! and the
numbers are those used by him. The first record, which is that of a well in the northern part of
Brooklyn (Williamsburg), near East River, gives a representative section of the deposits at the
extreme west end of the island.

 

1 Prof. Paper U. 8. Geol. Survey No. 44, 1906, pp. 168-337.
CRETACEOUS SYSTEM, 73

66. Record of well at Meeker and Kingsland avenues, Brooklyn.

Feet.
MILEA SB FOUN Oise sipcerse SSR ha Re ws hhsalde dle enchauenbeneadya pq DOS ea deacess. shes Du Remeee 0-5
Wisconsin:
Blue clay with bowlders............2.0...0020 00020000020 c eee eee eee 5-16
Sand and small bowlders with water............0..0.0.00 0020000 c cece eee eee 16-32
DINGS CLAY 522k cAcayee adenserndt eee OO sei Oe eee Erk a REA ASAE NESS oR eS 32-72
Dio teerays Cla Veeco Stet cast casas tis LGU vctdes hee Ls ue Gy wae ghee ere a ee OS 72-180
Cretaceous:
Sand—not water bearities.: sexes es oi4544snenaedeaind 050765545 4aeedseee es eeee eee 180-180. 5
BOHOL ay oes se Pathondia lee eb aad Ae Ci Labia t BEA d ulead An EE Le 180. 5-205
Light-greenish clay, passing into dark-greenish clay containing small concretionary
TASS OS 5 a. 5 5 cncsicngiisseisindivs:spa ea a}evann alevsnshencyasenee nae code aveve lg a gialishanomiavevadn sx eid Sleletatees 205-215
Yellow and dark-colored sandy clay.............2..2..2202020 2020002 e eee eee 215-225
Pre-Cretaceous:
Rocke ties, Bebis tees sei ok Sas Sauce cet ee ced ebeSe eamae made a ses eke Sates 225-

The deposits thicken rapidly southward and eastward and even the deepest wells are far
from penetrating the full thickness of the Cretaceous. The following section shows the char-
acter of the beds penetrated at Long Beach, 18 miles southeast of Brooklyn.

373. Record of well of Long Beach Association at Long Beach.

Recent: : Feet.
White beach sand, with waterworn fragments of shells.....................2----2------ 0-36
Dirty-gray sand, with small quartz pebbles and particles of vegetable matter........... 36-40

Tisbury [Manhasset formation]:

Fine to coarse gray sand, with a few small quartz pebbles (salt water)...........-..... 40-50
Medium gray sand; no gravel. ......-.2..2-. 22-222 o eee eee eee 51-55
Grayish-yellow sand and small gravel, with a few greensand grains..................... 55-65
Weellowish=orayisande a4. soe te eek hh Pt atte ced aileitt Ba ASS aM foley al tate elas earns th 65-70
Orange-yellow sand and gravel, similar to Rockaway material. ..............-...-..-- 70-73

Sankaty [Jacob sand and Gardiners clay (?) ]:

Gray sand and gravel, similar to overlying bed in texture, but not iron stained......... 73-76
Large quartz gravel and pieces of blue clay containing sand and gravel.............-.- 76-82
Jameco:

Dark, multicolored coarse sand and gravel; considerable percentage of flattened shale
pebbles; only 50 to 60 per cent of quartz; some biotite; looks as if it might be asam-

ple taken from the Wisconsin moraine in the center of the island.................... 82-90
Cretaceous:

Black sand composed of fine gray quartz sand with a large percentage of lignite; some

FeS and §; several large pieces of lignitized wood at 99 feet.................-------- 90-99
Grayish sand with some free sulphur and a few particles of lignite............-..-.-... 99-107
White sand with occasional patches tinged lemon-yellow, perhaps due to iron stains; a

few particles of-free sulphur: ici.cccs0cs 22 <cocnagtinnemer ose see gge weet eseeees eee eee 107-111
Darkseray ‘silty sand sos xccdsnecdeak ves ses gees sok pre eeicietosece meen et aneeaetuies pes 111-119
White sand with small pieces of lignite; note on bottle says ‘120, petrified wood”.... 119-121
Very dark colored, clay (‘blue clay”)... 2: :222¢4:seeseeeedasaeaey eres yess see ee ees 121-135
Coarse gray clayey sand, with particles of sulphur. .............-..-.-----------+++-- 135-143
Medium dark-eray sand. (salt water). .o2..22 2+ pecan aeunea vers ee oodceente pte sane 143-145
Very coarse:dark-gray Sand 1.22 2-ce0nec +s carer etnenctiie eee re pe tes posse ee tees 145-156
Olive-green sand and small quartz gravel; some sulphur salt SALOT tanec pshn ho anoiatysiets 156-158
Very dark lead-colored clays... - 242-0. s sdeceeecumateaeeias ee ttteseseess Semegen res 158-174
White sand, containing at 190 feet a log of lignitized wood......-...---..-.-2+--.-+-+-- 174-192
White gravel and salt water... 22220224 sesadeaeteeseear erase ee te ne ewe iiieieean ee 192-196
Olay2 2 cdaiasceamansiebiins as 335500500 22 SRE ee a gee es ose eae se tes 196-200
Pin eisandsnocckeoxacace dead aces fags sig eeaeseseeles edi eeeee seeebee sds x eisouesteess 200-220
Solid blue clay; at 270 feet fresh water, sweet and chalybeate............-..2-.-.-.-- 220-270
White sand “aridiwoddersiseiescs 2 teens oneronanaee Ounce y C2 cre hs 58 Seeulaaeuarinssclannas 270-276
lay 2 os scend eee eecees ee vase: esse Petites ec adie Sands Poeed scar eeRaMEle dos 276-282
‘White sand and. W000 + -sixes sasnceess poet eeaedd Geta eats eee ese Ca@ReGeEe Sota 289-997
Blueidlayx.n.csscingecnsae Weend. 1244 paARRR ONO Stes eee eeu Tee geese dee 297-305
White sand, wood, and water............--.22+2 +2520 - 252-2 ere eee eee isin ee 305-308
Blue clay......-.--- 22-000 02202 eee eee eee eee tenet eee eens eters 308-317

White eand containing wood and artesian water.......-----..--+2+-+2--25--252-22-20-- 317-325
U4 GEOLOGY OF LONG ISLAND.

Cretaceous—Continued. Feet.
Blue ela yess cuedes Sada dds ietetaemi gered ts iia ver mati ekeekig tsi e2 yl pees 325-340
White sand and mineral water; has considerable CO., sparkling and effervescent. ..... 340-356
TC a yh acc tek obs iS che oars reel psp AN hay sna feel es A ptt Ae aes eee RES bok 356-360
White sand sand! pure. water: s.accnveudesensaneyy oe 2ecey paeienadiec ere se <heductueueaass 364-378
Blue clay............-.------- Eien esi S oahalanis Sse ORs DEA a Bee BSE EGG esheets 378-380
Wee Sept ec ec B.S wc U8 6 Bod oie PN SAIN GRAS EE SCG RNS SS Sache ED HE Lk se eal ina 380-381
WRITE CLA Yi2 8 Sata Siete ata eth dete pA IS GS Sh 2 Oto Syt Ct) RUM eats A... fe mens 381-383
Fine said: with Sresiait Wate. .sccccaacanncsasaeeeae ods $ 2 RieomeeGmEe Cae ees cee 383-386

The next section is that of a well on the north side of the island between Hempstead Harbor
and Oyster Bay, which cuts beds of a stratigraphically lower horizon.

470. Record of ('. O. Gates’s well near Peacock Point.

Pleistocene: Feet.
Pandan Saye ne aasshedi saad eee otek es ward wei allen idee amcor eres 0-40
Greenish-gray sandy clay, with a few quartz pebbles................-..-2-2---2.-+--- 45
Dark reddish brown sandy clay, with some biotite.............2.2..2---22.--2.2-2----- 60-80

Transition:

FINE: STAY SAN a cee jensen dares teoerdv gs oie mipegnigaea eewastssY a Vets gar ae de ae 90

Cretaceous (undifferentiated) :

Laminated reddish-brown sandy clay; no biotite................00000002 20200 ce eee eee 95

Very fine pinkish-white micaceous sand............2..2- 02.0000 e cece eee eee e eee eee 100
Light-gray medium micaceous sand..............-.2. 200-020 20 eee ee eee eee eee 105-130
Dark grayish brown sandy Clay.....-.-...2+s 02+ eeeeeeevesats ceeteseesseseeeaeencus 135
Pebbles of ferruginous sandstone......-. 2... 2222222222 c cence eee ence eee e eee 140

Laminated red and white clay. In the fragments furnished the laminations show very
great distortion; whether this is the natural condition of bed or is the result of the
method of taking samples is not known. Sample 17 contains a few fragments of a
lamellibranch, but the sample shows evidence of having been laid out on the ground
before it was packed in the bottle, and the shell may have been picked up there... ... 145-160
Briek-red,, very plastic:clay': wees ogecieseag aks 855024 ss4g saahideeaseued dokoas anecenes 165-190
Cretaceous (Lloyd sand):
Fine reddish sand; the red color seems to be due in a great measure to the red clay from

theroverlyine bed oc iac.c.022 .aedhiaotcoahechuniease oes eye gaonaesechu levers renee 195-210
Mediunt ligh tyellowr sand: . js cnnsaeastconneemins ee os da deesaeeekite tees ae 4 ances 215-225
Fine to coarse light-yellow quartz gravel, with a few fragments of white, chalky-looking

CHET sce oon enue: Se SiR eevee ot pienieuigeniegsiay een E es ge eabartcedegughes ces cned 230-

The following section shows the materials encountered in a well on Eaton Neck only a few
miles from the point where the Cretaceous surface descends permanently below sea level:

670. Record of L. A. Bevin’s well on Eaton Neck.

Pleistocene: Feet.
White sand and gravel, with a percentage of erratics...................2-------2----. 15-30

Cretaceous:
Medium-coarse white sand. ...... 2.222202. 2 2c coe ceeceecee cee e eee eee. 40
Sand and small pebbles with a rather pinkish cast...............0...2-..0--.-- 002-0. 50-75
Coarse: pinkish white sand a. 20.06 Sh \oea gee od cin dads Go Geman mamas oe Se Oe dela hus wudamenee ec ote 80
Medium white micaceous sand......... 222.2222. c ecco ccc c eee cece cece eee ence. 90-100
Very fine gray micaceous sand.....- 2.0.0.0. 060222 c cece cee ce cece cece cence cece 110
Medium to coarse white sand.............0.20 0-2 c cece cece cence cece ee cee cece cee. 120
Small angular quartz pebbles, evidently broken from larger ones....................... 130
Medium to coarse white sand...... 2-20.20. 0.0000 coco c eee cece cence eee. 130
Medium white-sand ciceccwees exis tsa tddeie naietined eoee dye Sag ave se eens edobseueucoi co: 150
Wihitevelayi CO AGliin® ) a. 2 wih aici hsucthotestnwee So Talia chtehede idai noes eS ata Oe pen tacustien 159-160
Small white quartz pebbles... 222.0... cece ee eee 165
Kine tay MN CaCeOUs RON «sn ccusnassgn howe gine vey a jacne qamaudaniuties aaswmad’ecminawnc 250-300
Medium-coarse White Gand occ os2ec 022 zee yddadeass 4 nedadis 4 savauuasnie Sainsuisisdjdeubeisies 215-240
Hiner white micaceous Rand sa «pecs vedios Ae qpalssiuuthes pet ee eee uimamveduce ee eeunet ones 250-300
Medium yellowish-white sand... 2.2.22 0 00000000 eee. 310-330

Fine sand and small quartz pebbles.......... 2.202000 0000 335-350
CRETACEOUS SYSTEM, 75

The two following sections show the character of the Cretaceous deposits underlying the
North and South flukes of Long Island:

892. Record of test well of Greenport waterworks, Greenport.

Feet,
Wisconsin: Yellow gravelly material..............0.2.00020 02002022 e eee ee eens 0-20
Tisbury [Manhasset formation]: Alternate series of sands and gravel..............2.2...-24- 20-100
Sankaty [Jacob sand and Gardiners clay (?)]: Brown clay similar to that in Sanford’s brick-

VAT spares aid Gibaavnretria nee eae eae agin Meow SIS ala teach Oe aM glee yale eae aigwinsam dee 100-150
Jamecor Win GwsaN ds. ite cecich less a wisgieeseaoebe es + ces 3. eee Soe cave eae --- 150-225
The well was then completed by Mr. E. K. Hutchinson, the only record kept being a few

samples in a test tube preserved by Mr. Fred Klip. These show the following materials:
Coarse yellow sand and gravel (probably glacial)...............0000.200.0200-002-00 eee 225-
Coarse: qUartZ: SON dia sasn cence eneeaee one how eda Maciel veg waatas ae cetaletarateats
Coarse quartz pebbles (one granite pebble)....................-.0.020-22220-02 0222 e eee
Ferruginous quartz conglomerate...........22--20-0-0 20-202 e eee eee eee —-555
Cretaceous:
White, highly mi¢a@eotisisand c.cc.e eres 2s sede os ecnantdaeleaae os e346 pudae aamaneeede 555-605
Pineswiite Sand 2. onc aus eueaeas Manas ate h OS Sosa ea Sane oan ause a aeMeeAEae 605-612
Brighttred-sand Bid li yeecs: sccanew nea taacumde o aeA ORDER MOS # Reena rea 612-619
Bicksréed Clay. «cso neacaceneaene ed ed eNedined aisha cece neha dau eine ss tai eetaeees 619-635
Yellow sandand elayinccaacasccucimcn ioe cous AAMAS SERMAMOERh shoes nage y PRRERORE 635-640
Wellowishawhite-clays sascecutemne maces oy zeae ates Oe aura eanhnY Soda ang Aleta 640-645
Salmon-Colored clay... \swenceewen ey nies ss sone nea eee eames ga eset een be execs 645—
Fine, rather dark quartz sand. .....--.-..-.-.-.-.--- eeu eins eRhERS SDD aoe eee GE tees
Pine dark-colored and j.0.c8c.8 seccece Fie 2S sao Ged eteAdncie alum EASIEST Se ea ade HEROS 650
Coarse quartz sand containing fresh water (Lloyd sand?)..............2.--.-22--22---- 650-670
Pre-Cretaceous:
SChistivccses sess ees Vaan ee dy tad eee he os Se we batmban peta Pet sew se ee eeaORS 670-690
897. Record of Sanford & Son’s well, Bridgehampton.
Tisbury [Manhasset formation]?: Gray micaceous clay, with a few small quartz pebbles... . 70
Sankaty [Jacob sand and Gardiners clay(?)]: Medium grayish-white sand and gravel, with

pieces of greenish clay containing fragments of shells...............-....-2---2.---- 100
Jameco:

Fine to medium orange-yellow sand.........2.-22. 22-2220. 2 eee eee eee eee eee 105
Orange-yellow gravel, apparently identical with that of the old glacial bed on Gardiners

Aslamdins S37 2ts teem cemarmares ee Rhee te dt Based Nadie Mleada ees aaiue pee ke bonhede 110
Very fine yellow silt, with orange gravel.................2. 002020 e eee eee eee eee — 112

Cretaceous:

Fine gray sand, with muscovite and lignite...........-....----+-.-.---+-++-+-+-+----- 115
Medium yellow sand, with fragments of shells. ............---.-.-2------+-----000-5- 140
Gray clayey sand, with fragments of shells.......-.-..---.--+-------+--+----- Vl iene. 140
Greenish-gray sandy clay, with fragments of shells.........-..----.-------+-+-+-+---- 155
Very fine dark-gray sand, with some coarse white quartz sand..............------.-.-. 165
Pine lightssriy-satid soc4escceses eo lees ood ameciohaenene te ebens te esee ee eee. 190
Fine to coarse light-gray sand with partly lignitized wood ..............-..-.--------- 210
Medium white micaceous sand..........-------2-.-. 2022-22 e eee eee eee eee 215
Fine light-gray sand with lignite. .............--.+-22- 22222222202 eee eee eee ee eee eee 222
Lignite and large flakes of muscovite....-..-.-.-.-------- +--+ +--+ 25-20-22 eee eee sees 231
Meditim white micaceous sand .....-.02. 2.22225 peste reetione eros ates es tees seeieeiy 235
White sand, muscovite, and lignitized wood.....-.-..+.-----++-+-+-+--+2-++++-- 5 ds Site tes 275-287
Fragments of iron pyrite..........----. 22-22-2022 2 222 eee eee eee eee ee eee eee 287-288
Fine to medium grayish-yellow sand......-...--- 2-02-22 .22 ee eee eee erect eee eee eee 288-300

The Cretaceous deposits, although visible at the surface at only a few points, are shown
by borings to extend under the whole island. In the eastern half of the island the borings are
too few in number to indicate anything beyond the general depth of the deposits, but in the
western part there are sufficient data to represent their position by rough contours, as in Plate
XVI, which differs from the similar map by Veatch * in that the deep valley of the ‘Sound
River” shown by him between Roslyn and Whitestone is omitted as not being indicated by the

 

1 Prof. Paper U. 8. Geol. Survey No. 44, 1906, Pl. IIT.
16 GEOLOGY OF LONG ISLAND,

records and outcrops, the contours near the coast are modified, and the Cretaceous area is
extended.

East of the area covered by the map the Cretaceous is encountered in wells at a number
of points, as shown in the following table based on the records of Veatch:+

Wells encountering Cretaceous deposits east of Setauket, Ronkonkoma, and Sayville.

 

 

  
  

  
 

No. Locality. Owner. aeeode.
Feet.
(71, | Mount Misery: Point’ csc. oe cas aceture as ceeeeeemes eine st lean snieare singe e.cicieie< 2 ielesslalanere ishzacit, nai dateteandonsisba ees, sesbeess aie ieee 110?
MIB: || PACCHORUC! ste eco o5 acs Sie ae Aeteceg leasing esses BOSE SE See City commission .... sini) Surmivarieelints cs tevtocecne yeas os epremeennidiate 99
GSb lessee MO sed ss sriernjeie idcsqapinicastste Race AN GEGEN Goede Mou wed aS dO ses vee ay 39
6 W SREP NEVA Oe 5 i 2h ose Se sie dey Rao suls ee SEERA Ginna desea ne niaidicttia Maids Le SERRE PLge tani ee Rete ate om Serene 40?
801 | Port Jefferson. . _.| J. L. Darling -. Sie enh ge ag see cts sgt a Be Ye eI ac ata 20?
BLL. as 2x Om anverseniy 4| OLD CMOrSOD: COj cc 2ieic cals vated Gist 2a gal eeatesluse of Adega Soetete 325
825 | Wardenclyffe- - zeal IN IKGIAYROSIA scence cma aiad-nd SaoAReiesae 26 we dau cecetias 135?
B58 i | QUO BUC 02 ns tc Aes ars redanaien stesecsiz sim cesiesctetanc eissseiae, xia. eee ee etereea are Hallock & Small...........-.-.-2-+--2-2-2-0---- fstise dese Seovuess: 150?
$59) foc ciee Ore) stareetienrtesmcetstiaie, ht goe nya etetcet es niin is stele anetehelaioisarmsts A.B. Hallock....... ai 156
860! | sas vx OO is ceo eres ua creatine exten rene inteiay a done eeletedaents Jo Wendellacsinsccaiicine : — a oe 200
802 | Greenporbecccsceorceccace: eereaeeimereaae es beet ace sedee: Waterworks. .... at se ace a 555
897: ||. Bridgsehampton)..:,- tis oh. x. ceucsemuashiasae es akekenseceeeS Sanford & Sons 115
910" || “Mishors TSANG jcc. sac wudiinis sa se meu aaanniea as eaetansiaceperunnie's Ferguson....--.....-. iat Se eeee es HES REE arte eas cee 260?

 

 

 

 

STRUCTURE OF THE CRETACEOUS BEDS.
DIP.

In nearly every place where Cretaceous deposits are exposed at the surface they are much
disturbed both by folding and faulting, it being not uncommon to find the beds standing nearly
vertical. Overturned folds occur at several points. Well records, however, show this to be
merely a surface condition, the beds at a slight depth having only a gentle and even slope to the
southeast.

From observations in wells on the depth of the Lloyd sand, which is about 200 feet below
the surface on the north shore, Veatch prepared a contoured structure map of the Cretaceous
which shows that in the Oyster Bay and Huntington region, on the north shore, the dip averages
80 fect to the mile. This is between three and four times as great as the dip in New Jersey
(22 feet) and is double that at Port Jefferson (40 feet). The dip probably decreases somewhat
rapidly toward the east and south.

FOLDING AND FAULTING.

As indicated above, nearly every outcrop of the Cretaceous shows marked evidences of dis-
turbance. In some places, as on the road across Manhasset Neck near Port Washington, the
beds are vertical and dips of 20° to 30° are very common and may be expected at any locality.
In general, folding is most conspicuous in the clays, which seem to have bent under the action
of the forces producing the disturbance, while the sands in many places were crushed to a
structureless mass. The effects of the disturbance are most conspicuous along the steep north-
ward-facing bluffs of the Sound shore, less so on the sides of the north-south harbors, and least
on the general upland surface, as in the sand pit on Little Neck. The surface disturbance is not
confined to the north side of the island, but is well shown at West Deer Park (Wyandanch),
south of the moraine.

The depth of the folding does not appear to be very great and probably there is little evidence
of disturbance at 50 fect below sea level even on the north coast. There are few closed folds like
those at Marthas Vineyard, where apparently a thickness of at least 500 feet is involved, although
small closed folds and contortions are seen here and there, as south of Glen Cove Landing, where
an overturned fold of Cretaceous clay is recumbent on Pleistocene gravels. Generally the dis-
turbance is marked either by a mere surface crumpling or by broad, low arches and shallow
troughs. In a few places detached masses of Cretaceous clay are found in the till. Faulting
is observed here and there.

 

1 Prof. Paper U. 8. Geol. Survey No. 44, i906, pp. 168-337.
 

 

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CRETACEOUS SYSTEM.
FORM OF THE CRETACEOUS SURFACE.

The general form of the top of the Cretaceous deposits has been indicated in the discussion
of the distribution of the deposits and is represented in Plate NVI. As shown by the map, the
Cretaceous surface has a fairly close agreement with the present surface over much of the western
part of the island. rising well above sea level in each of the necks and reaching almwst to the high-
est points of the island in the Mannetto (West), Half Hollow, and Dix hills. Long Island sound
is a broad, partly filled Cretaceous Valley. In fact, the Cretaceous depressions in general coin-
cide with the Pleistocene valleys and the Cretaceous ridges with the high Pleistocene ridges.
although it is known that there are many minor irregularities due to Cretaceous folds which
have no surface counterpart and it is probable that there are many minor buried valleys not
indicated on the surface. If the drift should be removed from the western half of the island,
the remaining land mass. though smaller, would differ only moderately from the present in
form.

AGE OF THE CRETACEOUS DEPOSITS.

STRATIGRAPHIC EVIDENCE.

The resemblance of the clays of Long Island to the similar beds of New Jersey led
Mather as early as 1843 to correlate them with the Raritan formation of that State. a correlation
which later work by Newberry. Hollick. and White tended to confirm. The stratigraphic evidence
disclosed by well records and surface observations in connection with the present work confirms
the conclusion of Ward that the flora of the deposits of Long Island is younger than that of
the clays of Amboy, N. J.. a local phase of the Raritan formation. and the beds are therefore
stratigraphically higher.

A means of direct stratigraphic correlation is afforded by the Lloyd sand, which is found in
the wells of both the north and south shores of Long Island and in New Jersey and is regarded
by A. C. Veatch as ‘‘a horizon in the Raritan about 200 feet below the base of the Matawan.”
This would indicate that the outcrops at Glen Cove and Sea Cliff, including the red clays and
white sands of the columnar section (fig. 55, p. 67), are uppermost Raritan, while the overlying
yellow and dark clays are the supposed equivalents of the Magothy and Matawan formations of
New Jersey. The leaf remains in the dark clays on Little Neck do not necessarily indicate the
deposits to be Raritan, as collections made by E. W. Berry in the Matawan show essentially the
same flora. Above the deposits which are believed to represent the Magothy and Matawan
there is a great thickness of alternating sands and clays. with some lignite : undifferentiated bed
of fig. 56°. and, although correlation with specific formations is impossible. they show a general
resemblance. especially as regards their sandy character, to the Matawan group (including the
Englishtown and Wenonah sands the Monmouth group (including the Mount Laurel and
Redbank sands’. and the Rancocas group (including the Vincentown sand) of New Jersey.
Well borings are sufficiently numerous to make it perfectly clear. however, that there are on
Long Island no thick greensand beds like those in New Jersey. their stratigraphic position
being occupied by the sands mentioned. The observations of Newberry, Hollick, White, and
Berry on the flora and the discovery of a probable Upper Cretaceous fauna in the Lloyd sand
seem to indicate that the Raritan. with which the lower beds of the Cretaceous of the island
are correlated. is basal Upper Cretaceous.

FOsSsILs.

A large number of Cretaceous fossils have been found on Long Island and are described in
papers by Newberry. Hollick. Ries. and others. but. except those of the outerops at Glen Cove.
Cold Spring Harbor, and Little Neck and those in the wells at Roslyn and Lloyd Point. the fossils
have been obtained from materials transported by glacial ice rather than from undisturbed Creta-
ceous beds. The following list of fossils from the island includes species other than those first
described from the island or those of questionable identification. The list of plants is furnished
by Arthur Hollick and that of marine forms by Mr. Hollick and A. C. Veatch.
78 GEOLOGY OF LONG ISLAND,

Cretaceous fossils from Long Island.

 

 

  

   
    
 
 
    
        
    
  
 
 
   
   
   
  
  
    
 

 

 

 

Locality. Name. Source.
Brooklyn, Clark St «2:20 24:ee0e00 WXOBYTAISD () pacesnas ates devnasine Gena cmatead BARRE tienes SORE ces: Drift.
Brooklyn, De Kalb Ave..............-. Juglans crassipes Heer... ..-....----+---++- 2222222 ee eee eee cere Do.
East. New York. ss éececenseace viva ssdins CTY PHBA VeSICULALIS! vey-sarcieiresasemscracicis e-vin aie aieats alsin. t sieusielateenis Sal soataceatios Do.

DOs, aceewswecenenesg sé os Seeeense ese Osttea larvascun ceccccee eve connie cedaciwe eines Rg HE eee Do.

DO seco veicdge geecnnieasix a seceeeeee Cuculles 8p (2) iescxcncsva cies ccey see nasneevecaseeuscesines cezeeeneese Do.

Da sisoca cei adsaconiein ud Shenae Ree OLMIS BOs caraoaunal pxy ae ta ae pi rep MUENa Se AREER EMS eers eePERwewe Do.
"Willams pure oo: coic,2-cisne cqteusinciemenisia Dalbergia TM MANS oe 2 cies icieassio cage eae aeiatig wicinedwlsu) moore aide Do.

BIG. POM bine dacedasaavhiccnsadavesan Liriodendropsis simplex Newhberry....-....---.--------0-e-ee eee ee eee Do.

ID Os ccktans eine Sveetis 26 Pee eee RASS Diospyros pees COT ion ecco gh oe cmc as AOR G coh atewatesey Cireeecen Do.

1D O)srs cractormmedaneen cite mais nideinimrncmsiak Magnoliaalternans Bleers..2cscaciieses eeaedacanks itateweds neaweeee Do.

ADD Oa mratsreten Se apee infaistnislemimociareieteeecve Ss Platanus newberryana Heer..........-...-.-0-2-- 0-22 e eee eee eee eee eee Do.
Manhasset Neck...........-...-2-2---+ Nelumbo kempii Hollick...... siaschavecs piensttaisialenstsiaiare Rina alpetatndarae aieed Cretaceous clays.
MOS Necasssexmacsoes aaa wadanu- es ee Perebra til a MOsas. ins cassis saaresiswayaiasisisiviswseactesissanstunvacmetewssccices Cretaceous in well.
Ee CULT as eesti eae ive eran aicince na hte a Salix protezefolia flexuosa Lesquereux.....-.-..-.--2.--2-2202-2+0-20-- Cretaceous clays (?).

Do. .--| Proteoides daphnogenoides Heer.........-.-----.------2-20-22e cece eee Do.

Do. .| Andromeda parlatorii Heer. -..... BS Do.

Do... -| Magnolia tenuifolia Lesquereux Do.

Glen Cove. .| Zizyphus elegans Hollick.. .-| Cretaceous clay.

DO icaiehesn son eoiceraschaien eee Aralia coriacea Velenovsky .........-----------20220- eee e eee eee eee Do.

DOsccsatnnnd see esnie-n ce Sesiees Andromeda flexuosa Newbelry........---.--25-20-020ee cece ee eee eee ee Do.

DOs Scespcrcrn mx errs eee SE SESE Premnophyllum trigonum Velenovsky ..............------2-22+22--- Do.

DOs 2 haemeeek eeu neater ms eee Sassafras hastatum Newberry (?)..-.---.----.2-.--2.--ee eee e eee eee Do.

DO wexsant: eis gseedinacaveemaaatac’ Laurus plutonia Beers a. cc 2 scccccesccesieaenwseasece cis cecinessisece ous Do.

DOs nicesecspeds somrecrenioecrraeniaacetniesine Sassafras acutilobum Lesquereux...............---2-222-2222- 2 eee eee Do.

DOS cee here pnt actin Pais Aca aoe Podozamites angustifolius (Eichwald) Schimper .............--...... Do.

DO e-exgieree ue oo eee ceremea ewe Diospyros primesva Heer. «wise see 2 eevee eeecaaeaees sesveuscaees 2525 Do.

DO e eeciseies sian osedoccesesiees 2282 Dammara microlepis Heer... .c0.0 sas ececessncsseiak Nida heWhend = Yoru Do.

DOs wee eee soe eect sa kate Myetophiy liar (Eucalyptus) geinitzi pia aa Sreac sath cea ea Aide aaa Do.

WO ee cpiaeeehaee aeolian Sapindus morrisoni Lesquereux...........-22--.2-22--20222022ee eee Do.

DO 2 tsssiese:siioe ca dsstieplccquisicenaie ceaiaisince B@Une0G RAMI HOWICK on cmenaienacitinnsaimninieite mes siiireinaitibcaeen sees Do.

DIG ais Ste RAE ate MOS ademas Magnolia speciosa Heer.......-..-..----- 0022-2 eee eee ene eee eee ee eee Do.

SD) Os Ais ses hoe hol e e heecderne se Magnolia capellinii Heer........22.........00. 0200220 e eee eee ee ee Do.

DO aase Se criestieeinatianteieeteeseceid POS CCS SD via c= Senees see cdcamseaae aeseeek eeecnaminncee ben eeeces fe ae Do.

TD O33 Messieiis Se tet abbr reonesien paves Liriodendropsis simplex Newhberry........-.-..----2.--220eeeeeeeeees Do.

Discreet cicahatn araduiceais eases OQUIOL A; SD occ cpssarctctam nsied oie aiciacronejoiers ining iba eine sic serai stance rcera alent Do.

Dosoris Island...........222-0-.-2----5+ Liriodendropsis simplex Newberry....-.....-....----202200-2---0---e Drift.
ae lometoes: New Derry ciz.cicctescir ac nic nerioaenenean ene yee rienie'os © Do.

Oak Neck Point..........-...2.2..22..5 Andromeda latifolia Newberry ...-....--..-2---2---.02eeecee cece eee Do.

Center Island... x :.cicnar cussions saves. Frenelopsis hoheneggeri (Ettingshausen) Schenk (?) eared eaten Do.

DO's visitas ee eaieemcesenimesete mene Quercus morrisoniana Lesquereux..-...........2-2-2--- cece eee eee eee Do.

DOs cneesueeeesveusceseusayeseensiess Magnolia capellinii Heer (Glen Cove)...............2..20-22002 eee ee Do.

Cold Spring Harbor. .......-.-...------ Species doubtful. ......... Re sccyiauwinicis se alvaiaan daqias eae uidesedaintnt Te Cretaceous clays.
Lloyd Nee kis ssc seven coshaencseaeec8e yrsine elongata Newberry .......-.---- 2-20 -0c eee eee eee eee eee rift.
Do Dalbergia rinkiana Heer... ........2--2 2222-0 eee eee eee cece eee Do.
Tricalycites papyraceus Newherry.............------2--ee cece eee eee Do.
OlAUSa AMETICANA 0... cred umsicnacie aarsie See's slaw BRIERE celeste Cretaceous in well.
Colutea primordialis Heer...............2202--2- 02 ec eee eee ee eee eee Drift.
Brachyphyllum macrocarpum Newberry.............--.-.-----2-00+ Cretaceous clays.
Laurus augusta Peers coc nc cise ccireeasanesissicte sotneowawecaacxamae os Do.
Gelastrusarctica Meet: .2.ce cementite aie nand sesamin eioueccrmeeen Do.
Paliurus integrifolius Hollick........ Do.
Eucalyptus (?) angustifolia Newberry. Do.
Tricalycites papyraceus Newberry. -.. Do.
Grypheea sp (?).....-.....--- od Do.
Turritella lippineotti Whitfield..............22.22022000 000002222 eee Do.
Drosimtis Pai WIEN ccc ac marninenieoun nace saphnacnenneninnn memnvnet nen aes ¢ Do.
2| Weniella inflata: (Conrad)... sis.cccsesjaysnne so eyrveerndenne soeeredieeeiied = Do.
.| Mnonseufaulensis CONTA. «ees wae sc oesede iphone ay sesnenweee s Do.
Corbulassp, (PY aii... cisions ce sete coopster dak 8 evaeeellsiayssasrcpaavsteeesesaisternmetia a Do.

 

 

 

In addition to the macroscopic fossils in the above table, a large number of diatoms, etc.,
have been enumerated by Ries‘ (identified by C. H. Kain and others). These were all obtained
at localities where Cretaceous deposits are known to occur, but none of the Pleistocene clays
have so far afforded them. The species are all fresh-water forms.

Cretaceous diatoms.

Wryandalichs: «2.200: Saco nestonuaitehe eo or oi s9 see ueneariee se Melosira granulata [Ehr.] Ralfs.
Northport. 2 2) eet dee cicicmns ievictetainisivtslc oe ssn gee gue eniak acs Melosira granulata [Ehr.] Ralfs.
Diatoma hyemale K. B.
Cocconema parvum W. Smith.
Center [sland <2. 32229 yeeros Ghar vls Soe a han senees Stephanodiscus niagaree Ehr.
Glen WOVE. 2525s a sa nntaeeie tea Rat eas 22udtecadeaeecne heats Melosira granulata [Ehr.] Ralfs.
Stephanodiscus niagarse Ehr.
Diatoma hyemale.
Melosira granulata [Ehr.] Ralfs.

1 Ries, Heinrich, Microscopic organisms in the clays of New York State: Trans. New York Acad. Sci., vol. 13, 1894, pp. 165-169.
TERTIARY (?) SYSTEM, 79

Cold Spring Harbor (diatom bed)................02.2.2..0.------ Stephanodiscus niagaree Ehr.
Epithemia turgida [Ehr.] Kutz.
Encyonema ventricosum Kutz.
Cymbella delicatula Kutz.
Cymbella cuspidata Kutz.
Navicula viridis Kutz.
Navicula cocconeiformis Greg.
Navicula major Kutz.
Navicula varians Greg.
Navicula lata Breb.
Eunotia monodon Ehr.
Gomphonema capitatum Ehr.
Stauroneis phoenecenteron Ehr.
Fragilaria construans Grun.
Synedra affinis K. B.

4 Campyloneis grevillei var. regalis.

Triceratium trifoliatium.

TERTIARY (?) SYSTEM.

DISTRIBUTION.

Long Island has never yielded any fossils of Tertiary age, the diatoms from Rockaway and
elsewhere described by A. M. Edwards‘ being from deposits that are clearly interglacial or
postglacial. Lithology and stratigraphy must therefore serve as guides in determining the
presence or absence of Tertiary deposits.

Eocene and Miocene deposits are definitely recognized in New Jersey and the Lafayette
formation is doubtless present, although it has not been clearly differentiated. The Eocene
(Shark River or upper marl) is a blue marl about 11 feet thick resting with a slightly discordant
dip on the beveled edges of the Cretaceous. It occurs in eastern New Jersey as a narrow strip
outcropping between the Miocene and Cretaceous beds and is intersected by the ocean at Deal
Beach. Though covered farther south by later deposits, it seems to be continuous across the
State in that direction. Its probable extension toward the northeast is suggested by fossils
found in the drift on Cape Cod. The Miocene is well developed across New Jersey, where it
includes the Kirkwood formation and the Cohansey sand, and it occurs on Marthas Vineyard
and possibly at Marshfield, near Plymouth, Mass. It appears probable that originally both
the Eocene and the Miocene extended across the Long Island area to the New England coast
and that their presence or absence to-day depends solely on the amount of erosion to which the
region has been subjected.

EOCENE (?) SERIES.

On Long Island a few feet of marl has been found at Melville and in the wells at Quogue
and Bridgehampton (p. 68). The stratigraphic position of the bed at Melville, which is the
only surface exposure, is very close to that at which the Eocene would occur if the Cretaceous
maintains the same thickness as in New Jersey, and itsstrike isasindicated on Plate II (in pocket).
The composition and the presence of the stony layers (see section, p. 68) agree closely with the
character of the Eocene in New Jersey, as described by Cook,’ who says “‘it is a mixture of green-
sand and light-colored earth; the upper 2 feet are quite hard and stony.’’ On the other hand,
it would be somewhat strange that one particular bed of the Eocene should be present where
the great mass of Cretaceous greensands are unrepresented. Thus, although it is possible that
the marls at Melville may be Eocene, it is at least equally probable that they are Cretaceous,
and they have been so correlated in the present report.

 

+ Am. Jour. Sci., 3d ser., vol. 50, 1895, p. 270; Am. Naturalist, vol. 30, 1896, pp. 212-216.
2 Cook, G. H., Geology of New Jersey, 1868, p. 275.
80 GEOLOGY OF LONG ISLAND.
MIOCENE (?) SERIES.

Resting on the marls just mentioned is a bed of loose yellowish quartz sand about 6 feet
thick and similar in character to the ‘‘fluffy’”’ Miocene sands (Kirkwood and Cohansey for-
mations) of New Jersey. It occurs at almost the exact position where the Miocene would be
expected and it may represent that series. On the other hand, sands of identically the same
character were observed in the Dix Hills at a much lower stratigraphic horizon, unless there
is an unconformity much greater than there is any reason to suppose, and very similar sands
were noted in the Cretaceous area at many points. On the map this sand is included with the
Cretaceous deposits.

PLIOCENE (?) SERIES.
LAFAYETTE (?) FORMATION.

At points farther south the Lafayette was deposited as a sheet overlapping on a slightly
eroded Cretaceous surface. If the structure of the Cretaceous beds is regular in the Long Island
region and if the topography is due solely to erosion, the Lafayette would be expected to occur
at the top of the Mannetto Hills, if at all. The only bed at this point with which it could be
correlated is the ‘‘fluffy’’ sand of the Melville section, which resembles the Kirkwood and
Cohansey formations of New Jersey much more closely than it does the Lafayette farther south.
The unconformity at the base of the overlying gravel of this section appears to be many hundred
feet, and the gravel could not well be correlated with the Lafayette even if it did not carry
erratic materials.

Overlying the Cretaceous clays at nearly every point, however, are more or less extensive
deposits of white or yellow sands. In some places they are conformable to the clays and clearly
a part of the Cretaceous, but elsewhere their relations are obscure and they may be of subse-
quent origin. They are not glacial, for they contain no erratic material. Some of them might
be Lafayette if the early Pliocene erosion was strong enough to develop a topographic relief of
200 to 250 feet, which is the range of elevation of the clays on which the sands rest. This is
much greater than the unconformity found farther south. There is, moreover, no conclusive
evidence that the sands are a separate formation. Sandy beds are abundant throughout the
Cretaceous of the island, and the materials may represent Cretaceous sands slightly disturbed
and crushed by the ice. On the whole it appears that although the Lafayette may occur, no
definite evidence has yet been obtained of its presence.

QUATERNARY SYSTEM.

PLEISTOCENE SERIES.

MANNETTO GRAVEL,
NAME.

The Mannetto gravel was named from the Mannetto Hills (West Hills), on the crest of
which just west of Melville some of the best exposures of this gravel on the island were found.
(See section, p. 68.) -

CHARACTER.

The Mannetto gravel, as is indicated in the table on page 21, is the earliest of the Pleistocene
deposits. It consists of stratified and in places cross-bedded gravels composed mainly of well-
rounded pebbles of quartz from half an inch to an inch in diameter mixed with coarse yellowish
quartz sand, but carrying everywhere a few deeply weathered granitic pebbles and scattered
large bowlders of crystalline rock, also deeply weathered or disintegrated. It includes a few thin
intercalated beds of yellowish clay. The granitic fragments can usually be crushed by the
fingers or by a slight blow of a hammer, and even the quartz is far more friable than fresh
fragments. The quartzose and stained character of the gravels, the deep weathering of the

pebbles, and the complex flow and plunge structure are the distinguishing features of the
formation.
QUATERNARY SYSTEM. 81

SOURCE OF MATERIAL,

The great predominance of quartz in the Mannetto gravel is at variance with the compo-
sition of the later glacial deposits, in which granites are very abundant. It seems likely that
this predominance arises from the nature of the formations of the Coastal Plain farther north.
Highly quartzose Cretaceous beds probably extended across what is now Long Island Sound,
overlapping the metamorphic rocks of Connecticut, and, being nearest, furnished a large part
of the materials of the Mannetto gravel, as compared to the relatively small portion furnished
by the more remote granitic rocks.

RELATIONS TO OLDER DEPOSITS.

Although only a few sections showing the contact between the Mannetto gravel and the
underlying beds have been discovered, there is no reasonable doubt as to their relations. In
the roadside section west of Melville already mentioned (p. 68) the Mannetto gravel rests
upon a thin bed of loose yellowish sand, probably of Cretaceous age, which in turn rests upon
impure marls. The Cretaceous deposits, however, do not continue to outcrop farther down
the hill, the surface consisting of horizontally stratified gravels of the Mannetto type. Their
relation is brought out in figure 57.

The conditions indicated by the figure are substantiated by observations on the general
relations of the older deposits in other parts of the island, especially at Sea Cliff, where an
unconformity between the Mannetto and the underlying Cretaceous sands was well exposed in
a large sand pit. To-
gether with the Melville
exposure and the num-
erous well records, this
establishes the existence
of a great erosion uncon-

formity antedating the FicurE 57.—Section showing general relations of deposits in the Mannetto Hills region. a, Manhasset
Mannetto deposition and formation with outwash mantle; b, Gardiners clay and Jacob sand; c, Jameco gravel; d, Mannetto
‘i : : gravel; e, Cretaceous deposits. The relations of the Jameco and Mannetto beneath the level of the
representing an interval

Gardiners are hypothetical.
of sufficient length to ad-
mit of the complete removal of the Tertiary deposits, if such were present, and the reduction
of the Cretaceous over the greater part of the island from a level at least as high as the crest
of the Mannetto ridge to and below the present level of the sea.

 

 

STRUCTURE.

The Mannetto gravel, so far as can be determined, lies horizontal wherever it is not dis-
turbed by landslides or by the drag or shove of the ice sheets by which it was afterward over-
ridden. This is shown by the horizontal bedding in the Melville section, in sections in Wheatley
Hill near Old Westbury, and in the deeper and undisturbed parts of the Little Neck section, and
by the extensive horizontal surface which it forms south of High Hill at the crest of the type
locality, the Mannetto Hills. Great care has to be exercised in determining the dip because of
irregularities of deposition due to the configuration of the underlying Cretaceous beds, as at
Sea Cliff, and to the flow and plunge or larger cross-bedding features.

At points along the coast and to a less extent in the Dix Hills the Mannetto has been more
or less disturbed and involved with other beds in the folding due to overriding ice. The flexures
may be small, as shown in Plate XXIV, B (p. 162), or they may be many hundred feet across
and correspondingly high, as at points on the north coast. The conditions under which the
folding was produced are discussed on page 201.

DISTRIBUTION.

The Mannetto gravel was in part removed by stream and ice erosion in the subsequent
interglacial and glacial stages and in part covered by thick deposits laid down upon it mainly
during the latter stage, so that it is now exposed only at a few points in the erosion remnants
of the Mannetto and other high hills or in bluff sections or artificial excavations on the north
shore.

1629°—14—_7
82 GEOLOGY OF LONG ISLAND.

OUTCROPS IN THE INTERIOR OF THE ISLAND.

Melville-—The finest exposure of the Mannetto yet found is that in the southern half
of the West or Mannetto Hills, outside of the moraine. In these hills the Mannetto gravel
appears to form an extensive terrace ranging from about 270 to 330 feet in height. The for-
mation could be best seen in 1903 at the side of the road leading from Melville to the crest
a mile west of that village. There 40 feet of somewhat irregularly stratified but not cross-
bedded buff to orange-colored gravel, mainly quartz with a few rotten granite and ferruginous
sandstone fragments, was found resting on the pre-Pleistocene deposits. Essentially horizontal
gravels of the same type, though somewhat less stained, are seen at intervals to the base of the
hill, their relations being as shown in figure 57.

South end of Mannetto Hills—Many sections of the Mannetto can be seen about the south
end of the Mannetto Hills, especially in the vicinity of Bethpage, Plainview, and Farmingdale.
In this region the old Mannetto topography was buried by subsequent deposits (Manhasset
formation) and the whole was then complexly eroded. As a consequence of this superimposed
topography the finding of the Mannetto can seldom be predicted from the altitude or form of
the surface. In general, however, the Mannetto tends to form the ridges and the Manhasset
tends to occur in terraces, as northeast of Betlipage.

Among the points at which the Mannetto gravel was recognized were the small projecting
ridge east of the road half a mile northwest of Plainview, the sand pit just northeast of the
Bethpage clay pit, sections on the east-west road a mile south of Plainview, and the cut made
by the east-west road through the hill a quarter of a mile north of Bethpage Junction. At the
last-named locality a fine unconformity, marked by a zone stained by iron and manganese,
was seen between the Mannetto and the overlying Manhasset. The steeper slopes of the Man-
netto Hills are commonly covered with talus defying identification.

Half Hollow Hills —¥rom road sections it seems probable that a large part of the mass of
the Half Hollow Hills also is made up of the Mannetto gravel, although no typical outcrops
were discovered. Yellowish sands, however, such as occur in this formation at many places,
were'seen in several road cuts. The top of these hills appears to consist of later Pleistocene
material, abounding in large and relatively fresh granitic fragments.

Dix Hills —The conditions in the Dix Hills are much the same as in the Half Hollow Hills,
although, owing to the morainal belt across the southern portion of the Dix Hills, exposures
of the Mannetto gravel are fewer. North of the moraine, especially in the hills southwest of
Elwood, several shallow cuts along the roads show Mannetto beneath later drift deposits.
Such 4n exposure is shown in Plate XXIV, B (p. 162).

Wheatley Hills —Between Wheatley village and Old Westbury is a group of hills projecting
southward from the moraine for 2 miles or more (Pl. VI, D, p. 32). Superficially these hills
are covered with, till of Wisconsin age, and they were classed by J. B. Woodworth ! and earlier
geologists with the moraine. On careful search, however, a number of excavations were found
a quarter of a mile north of Westbury Pond and elsewhere, which showed beneath the mantle
of drift typical orange-colored cross-bedded Mannetto gravel with its usual rotten granites.
Well borings in other parts of the hills seem to indicate that these conditions are general.

Knobs of the north-shore necks.—On the plateau surface of Manhasset Neck (Pl. IV, p. 30)
on the north shore, there are many well-defined knobs standing 20 to 60 feet above the general
surface. No cuts deep enough to expose the material in them beneath the Wisconsin drift
were discovered, but a study of the composition of the till, in which white quartz pebbles pre-
dominate, seems to indicate either.a Cretaceous or a Mannetto core, probably the latter, as well
records do not indicate that the Cretaceous rises to these elevations.

 

1 Bull. New York State Mus. Nat. Hist. No. 48, 1901, map.
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 82 PLATE XVII

 

 

 

 

 

 

 

 

B. LARGE DECOMPOSED ERRATIC BOWLDER IN MANNETTO GRAVEL.
MANNETTO GRAVEL. 83
OUTCROPS ON THE COAST.

Broken Ground.—Mannetto gravel of the usual quartzose type appears to occur in small
quantities overlying the Cretaceous clay at Broken Ground, near Northport, and to be involved
with the clay in the great landslides. This is the most easterly point at which the formation
has been recognized.

Eaton Neck.—The Mannetto is well exposed on Price Bend, about one-eighth of a mile
north of Winkle Point on Eaton Neck. The following section was measured:

Section near Winkle Point.

Wisconsin drift: Buff till with small bowlders..............0... 002000 c cence cece eee e eee 5
Mannetto gravel:
Yellow mealy sand with a few pebbles...........2.....0 2022-20 e eee cence eee eee eee eee eee 15
White and yellowish) clay.cccckaaycuwneah es red teece pet Co ASS cept AN lee 1
Sand and gravel with weathered erratic bowlders...............2.2020020eceee eee ce eee e eee 20
Cretaceous: Pink, yellow, and white sand with hematitic sandstone plates and concretions........ 30

The bowlders, one of which is shown in Plate XVII, B, were of acidic orthoclase
granite and ranged from 1 to 2 feet or more in diameter. They are completely rotted and fall
to pieces on pressure with the hand, so that none are seen in the talus, but a careful search
reveals a considerable number in the gravels.

A little north of the head of Price Bend another good exposure was seen, the Mannetto
here being overlain by 4 feet of a chocolate-colored clay. The contact is sharp and shows a
strong unconformity. Mannetto gravel is also to be seen at a number of places farther north
along the shore.

Iitile and Great necks, Huntington —Gravel, probably Mannetto, shows in the talus at a
considerable number of points on both the east and west sides of Little Neck near its north end
but was not recognized in the clay and sand pits. On Great Neck quartz gravels containing
weathered granite pebbles occur in outcrops and in the talus above the Cretaceous deposits
at a number of points near the entrance of Northport Bay.

Lloyd Neck.—On the north side of Lloyd Neck the Mannetto was apparently removed
by the erosive action of the Montauk ice, no indication of it being seen over the Cretaceous
outcrops at that place. Back of the south end of the beach southwest of Lloyd Point and at
the base of the bluff just north of Lloyd Beach, talus slopes, seemingly of Mannetto materials,
are seen. The section at this point is given to show the character of .the clayey phase of the

formation.
Section north of Lloyd Beach.
Feet.

Montauk till member of Manhasset formation (?): Interstratified yellowish clay and sand with an

occasional erratic up to 6 inches in diameter........... 222-222-2022 022 ee ee eee eee 2
Mannetto gravel:
Dark-oray Clay s.cseotsaeessceiyes ey eerenges eek es yelye es gee valeyvnise eS hina vey ee sees pees iy
Brigh t-yellow Clay: cscgcu ce etarsnasaneeeetatewed ee aeess es G3 eieeeeetegee eye des 34 Fan 1
Yellow clay with ferruginous sand and pebble layers...............-.-2..2..20-22-2--00--+- 2
Fine quartz gravel with iron and manganese stains; weathered granitic pebbles.............. 5
104

The beds are folded on east-west axes, the dips ranging from 5° to 30°.

Hempstead Harbor—The Mannetto gravel was seen resting on the white Cretaceous sands
in a number of thesand and gravel pits on the south side of Mosquito Inlet, at Hempstead Harbor.
In one of these, just across the stream from Glen Cove, an unconformity was exposed in 1905.
The old Cretaceous surface is marked by a dark band at the top of the steeply dipping sand.
The first Mannetto layers are whitish, owing to their materials being derived from the Creta-
ceous sands immediately underlying them, but in the upper part of the exposure the admixture
of foreign material gives them a darker color.

No other good exposure of the Mannetto was seen on Hempstead Harbor or at any point
farther west, but the talus slopes afford indications that the bluffs at a number of points south
of Sea Cliff are composed in part of Mannetto material. Indications of Mannetto material
84 GEOLOGY OF LONG ISLAND.

-

were noted in the drift on the knobs that rise above the general crest of Manhasset Neck and
suggest Mannetto cones. Mannetto gravel was seen above upturned Cretaceous clays in the
crest of the neck at a point due west of Sea Cliff.

DEPOSITS PENETRATED BY WELLS.

Owing to the small percentage of granitic material present in the Mannetto, it is distinguished
from the Cretaceous quartz gravels in wells only with difficulty. There is, however, good evi-
dence of its presence at a number of places, among which are those mentioned in the following
paragraphs. The figures in parentheses indicate the number assigned to the well by A. C.
Veatch in his report on the water resources of the island, in which detailed records may be
found.

The most westerly point at which probable Mannetto material was found was in a test
well at Fresh Meadow pumping station, south of Flushing (No. 231), where 7 feet of coarse
orange-colored sand and quartz gravel with a small amount of white chert was found 50 feet
below the surface. A 20-foot bed of medium-grained reddish-yellow sand with some crystalline
pebbles found at 125 feet in the well of W. K. Vanderbilt, jr., near Lake Success (No. 317), is
probably in part Mannetto. A 12-foot bed of hard coarse gravel at 62 feet in the R. L. Cottnett
well, near Old Westbury (No. 426), is also referred to this formation. The J. F. D. Lanier well,
in the same region (No. 427), penetrated 10 feet of Mannetto at the surface. Material that is
probably Mannetto occurs within 30 feet of the surface in the H. B. Duryea well, near Old
Westbury (No. 430), and at 90 and 106 feet in the E. D. Morgan wells (No. 431), in the Wheatley
Hills, which probably penetrate a buried valley.

In the S. Mortimer well, also in the Wheatley Hills (No. 434), the Mannetto appears to
extend from a point near the surface to a depth of 150 feet. Other wells in this region contain
probable Mannetto material as follows: Yellow quartz sand and gravel at 23 to 56 feet in the
W. P. Thompson well, near Old Westbury (No. 511); yellow gravel in the first 70 feet of the
J. H. Harriman well, in the Wheatley Hills; and fine sand to medium-sized yellowish quartz
gravel at 51 to 81 feet in the Jules Kunz well, near Jericho. In Mrs. J. Vowman’s well, near
Roslyn (No. 436), the formation is probably present as a coarse reddish gravel at 90 to 115 feet.

The orange-colored sand found at 73 to 92 feet in the L. C. Wier well (No. 481), at 73 to
126 feet in the E. Latting well (No. 483), and at 83 to 108 feet in the W. D. Guthrie well (No.
484), all near Lattingtown, may be Mannetto, although orange-colored Cretaceous gravels also
occur in that vicinity.

In the Mannetto Hills, according to Veatch, the following beds of the Mannetto gravel
were penetrated by the well of H. L. Stimpson. The correlations, which are Veatch’s, appear
to be based on the occurrence of decayed cherts, which are locally present in the Mannetto but
are rare in the Cretaceous.

586. Samples from H. L. Stimpson’s well in the West Hills.

Feet,
Wisconsin: Clayey sand and gravel with many compound pebbles.......................... 8- 20
Mannetto:
Orange-yellow quartz pebbles, with a very few fragments of compound rocks, the latter
probably derived from the overlying beds..................-.02020.0022.0-0-02---2--- 28
Orange-yellow quartz pebbles, with considerable sand and yellow clay and many frag-
ments of decayed white chert........2...2. 2.202.202 0 cece eee ee cence eee cece ee eee 40
White quartz sand, with much fine-grained red ironstone and decayed chert.........-.. 52
Cretaceous?:
White to light-yellow quartz sand and gravel containing fragmentsof decayed whitechert. 60-120
Fine to coarse reddish-yellow sand..........2.2.200020 2000000 cece cece cece eee e cess 125
Pine to. coarse white 6a dcncoetiedtecseucies os dnageeadeawesy eokas gececerh os See 130
Fine to coarse yellow sand............-2..2.02-222222-24. aoe Pon poe aaen eee 135
Medium yellow silty sand, with many small brown ferruginous nodules and a few pellets
OR CNY Mitor sedis) isto Eee 2 id au date ae oan. cenmmcwaennaeA ce nw oul amubeeueter en cence 140-145
Medium to coarse light-yellow sand, with many fragments of dark-brown ferruginous
BANS LONG as < taainise cme P Seah a axa ahead 2 W's oh Separate Caw yon eian cole bao ook Gos 150-155

 

1 Prof. Paper U.S. Geol. Survey No. 44, 1906, pp. 168-337.
JAMECO GRAVEL. 85

The Mannetto has not been definitely recognized in any of the wells on the eastern half of
the island.
AGE,

No absolute proof of the age of the Mannetto gravel has yet been found, although all evi-
dence seems to point to its post-Tertiary origin. The unconformity at its base is much greater
than any of the Tertiary unconformities in adjacent areas in New Jersey, even the pre-Miocene
unconformity or the pre-Lafayette unconformity farther south being small compared with it.
Moreover, it differs in many ways from the sandy Kirkwood, Cohansey, and Beacon. Hill forma-
tions of New Jersey. The Beacon Hill, for instance, carries many pebbles of rotten quartz and
chert, whereas the quartz pebbles of the Mannetto are relatively fresh. Again, the Beacon Hill
nowhere carries granitic pebbles, but they may be found in every exposure of the Mannetto.

The pre-Pleistocene formations, so far as observed at the surface, either on Long Island or
in New Jersey or in the Coastal Plain States farther south, are, except for scattered pebbles of
very acidic schist approaching quartzite in character, free from crystalline fragments. The
only apparent exception in the region under discussion is a granite fragment measuring 2 by 3}
inches reported from the Cretaceous at a depth of 335 feet in the well of E. D. Morgan, in the
Wheatley Hills.1. Inasmuch as surface outcrops have yielded nothing of the kind, although
well exposed at dozens of points, and especially in view of the well-known carelessness of drillers
and the possibility of the fragment dropping from a higher level in the well, its evidence must be
regarded as of doubtful value. The relative abundance of granites in the Mannetto suggests
the correlation of the formation with the Pleistocene rather than with older deposits. The
presence of erratic bowlders as much as 2 feet in diameter is also suggestive of glacial derivation,
for although it is true that such bowlders can be transported by floating trees or other agencies
besides ice, the fact that none are found in the hundreds of feet of Cretaceous and Tertiary
strata exposed at the surface on Long Island and in New Jersey or, with the exception of the
doubtful fragment mentioned above, in the thousand feet or more of such strata penetrated by
the drill makes some other method of transportation than floating trees more likely. The coarse
average texture of the Mannetto compared with that of the Cretaceous and Tertiary deposits
indicates that a considerable change in the conditions of deposition had taken place since the
latter were laid down. The structure of the Mannetto, especially the details of its cross-
bedding, and the smooth, gently sloping upper surface of its remnants in the Mannetto Hills,
is identical with that of parts of the outwash from Wisconsin ice, of-late Pleistocene time, and
suggests a similar origin. The degree of weathering is also suggestive, the decay of the granite
pebbles being what would be expected of an early Pleistocene deposit rather than a Tertiary
formation.

The available evidence as outlined above seems to warrant the inclusion of the Mannetto
in an early glacial stage of the Pleistocene series, although a strictly fluvial origin of the deposits
is not impossible. If the formation is glacial outwash, it was probably laid down early in
the Pleistocene epoch, as indicated by its weathered character and stratigraphic position with
reference to the associated deposits of the same epoch, most likely representing the pre-Kansan
invasion.

JAMECO GRAVEL.

NAME.
The term Jameco gravel, which was used by A. C. Veatch in his report on the water resources

of the island, was derived from the Jameco pumping station, near Jamaica South, 3 miles south
of Jamaica, in western Long Island, where the deposits were first recognized in the deep wells.

CHARACTER.
The Jameco gravel, although it has not been definitely recognized at the surface at any point

on, Long Island, has been encountered in a considerable number of wells. In its type locality,
in the area extending from Jamaica Bay northward toward Whitestone, it occupies a broad

 

1 Veatch, A. C., op cit., p. 259.
86 GEOLOGY OF LONG ISLAND.

depression in the underlying rocks (either Cretaceous or Mannetto). It is easily recognized
in the wells in this locality because of its striking dissimilarity to all other Pleistocene
beds (except the Montauk till member of the Manhasset formation) and to the Cretaceous
formations. The difference between the Jameco gravel and the Mannetto gravel is especially
marked. Although the older beds are prevailingly light-colored and composed principally of
quartz, the Jameco is generally a very coarse dark-colored gravel containing a predominance
of granitic pebbles with a few streaks of black or other dark sands or finer silts (wells Nos. 135,
195-206, 273, 290, and 291 of table, p. 90). The pebbles are well rounded and of different sizes,
some being nearly as large as cobbles, but toward the east they become finer, being commonly
from half an inch to 2 inches in diameter.

It should be noted that although on Long Island knowledge of the Jameco is derived
mostly from samples obtained from well borings, the gravels beneath the Gardiners clay are
well exposed at several points farther east, where folding has brought the beds to higher levels,
especially in the Nashaquitsa Cliffs, on Marthas Vineyard; near Highland Light, Truro, on
Cape Cod; and less perfectly between Balls Point and Clay Head, on Block Island. At most
of these localities the relatively high granitic content, the absence of notable staining and
cementation, the lack of marked weathering, and the strictly conformable contact with the
overlying Gardiners clay effectually preclude any possibility of confusion with the Mannetto.

The darkest phase of the gravel is rather local, being confined mainly to the old Cretaceous
valley mentioned. In Brooklyn and Williamsburg, which lie on the west of the valley, the
Jameco is usually reported as consisting of yellow or reddish sands and gravels, with a little
hardpan (in wells Nos. 5, 23, 37, 38, 62, and 65). On the shores of Long Island Sound the
material, as shown by the north coast wells (Nos. 351, 469, 527, 529, 530, 532, 539, 548, 548,
549, 613, 633, and 652), is almost invariably a light-colored sand or gravel, although black
sand (No. 545), brownish sands and gravel (Nos. 628, 629), and coarse granitic gravel (No. 654)
are reported in a few records. Along the east side of the buried valley on the south side of the
island, as at Valley Stream (No. 287), a sandy phase of the Jameco is developed locally, but
the formation seems to be generally absent east of Rockaway Ridge, although a bed of dark
clay and sand, probably the Jameco, is found beneath Muncie Island (No. 671). Near the
east. end of Long Island a yellow or white sand or gravel correlated with the same formation is
found beneath supposed Gardiners clay (Nos. 897, 901).

Where lithologic characteristics are not determinative, the formation is recognized by its
position below the fossiliferous Gardiners clay.

The following sections show the character of the Jameco gravel at a number of points.
The numbers refer to records in Veatch’s report, but the correlations are those of the writer.
The first is a record of a well west of the Cretaceous valley.

38. Record of well at Bartlett Street and Flushing Avenue, Brooklyn.

Recent: Feet.
Billed: pround 2ccscccscccemaae ences ai ¢ ident deta aeeeauiee’s oxo one oe NS Sater ive ree O- 8
Black: mareh Mud... es0npaaovvaeeeiey es eeu daeg setaens.cenese 2: 245 odaseaeancestacss 8- 9
Blue Clay sicwsscnwiee'y a venesehedegney see sss Sudwcacea dd s/o dea deamenoaucaetlecodeue 9- 15

Hempstead gravel member of Manhasset formation:

Light yellowish-brown sandy clay at......... 2.222.222.2222 0 cece cece eee eee ee 19
Bluish-gray, rather pure clay at........ 2.2.22... 2 cece ce eee eee 26

Montauk till member of Manhasset formation:

Highly erratic glacial gravel..........2...022 0200200 c ccc cece eee ee cece ee 31- 36
Medium erratic sand. «s-/c202 senectidsaa v2 eels ys sta asegeeaiuade dawanmevcumnons oy eecuy ex 36- 62
Enratic gravel mixed with blue clay........ 22.22.2020 2 2002200 c eee cece eee eee 62- 73
Herod gravel member of Manhasset formation: Coarse glacial sand...................-.... 73- 81
Jacob sand and Gardiners clay:
Impure bluish-gray sandy clay...........2........... Je PG ASE S Bae REAR ORR BG a HIG 87- 93
Yellowish-gray sand mixed with clay............2...0 20000000002 c eee c eee ee eee 93-108
Clean light-brown medium erratic sand........ 0.22.0. 00 00000020 e cece cece cece cele. 108-122
Bluish-pray sandy Cay 2 32.2 acawenondwatiweet eu pavemecklee ngs sae eeweeancecceee 122-124

Medium yellowish-brown clayey sand... ... 22.22.20... 00000. c eee cece cece eee eee 124-127
JAMECO GRAVEL. 87

Jameco gravel: Feet.
Coarse yellowish-brown clayey sand. .......2.0.0 0.02 cee cece eee c cece eee c cece cee eeeee 127-134
Very coarse dark-yellow clayey sand.........2.. 2.0. e cee cuee cece vecececececeeeseces 134-145
Very coarse reddish-yellow erratic sand. ..... 22.22.0000. 0 cece e eee eee eee cee e eee eeee 145-174
Coarse, highly erratic sand.........0..0.0 00 coc e cece cece ce cee cece ccc ceceeeseeseeree 174-175

The following well section is typical of the region of the Cretaceous valley:

204. Record of Brooklyn test well No. 3, Brooklyn Aqueduct and New York Avenue.

Feet.
Wisconsin: Reddish-yellow silty sand and gravel. ....... 2.2.2.2. 2.000202 eee e eee eee eee 0- 9
Manhasset formation:
Fine to coarse reddish-yellow sand with granitic pebbles in lower portion..........-.. 9- 45
Hiné.ligh eyellow: sand. eens: eee ey ss ws ue abanvetees gees ned sea yates Fees 45- 86
Gardiners clay: 5
Lead-colored clay...............02 22.22 ce cece eee eee eee Pee ciaphs mone Manlsamaee Toe ye 86-139
Hine dark era y'eilty Sand....41 sce ot snd-ae bod aksoaanieee te neu ban aaeneecenaetidescemns 139-158
Mediuindark-gray silty, 680d ac scsncne seercan nese bowie esageembonceeead aan ese ew 158-160
GTA YA Yer: See liane cate ed ecra 8 srercsaipeeieelstendy aia g ace srctausln Ne LaBare fee ale yaa oy Ast 160-201
Jameco gravel: Fine to coarse dark granitic silty sand........---.--.--2--0-2-2---2------- 201-277

The next record shows the characteristics of the deposits in the wells of the north shore.

652. Record of well of Huntington Light & Power Co. near Halesite.1

Recent: Feet.
Billed) oround ic. ancseanee ends 22 2 a iapidat ames hess o2.28 ee ctalban sales eon ea eS 0- 6
SWAMP CePOslt nnicecus cece dec scecenadesenautddee d2 ccd eseudigsmleuleetnadestss awn 6-10

Manhasset formation: Dark sand and gravel.......--.--.------ 22-22-2202 e cence eee eee eee 10-70

Gardiners clay: Blué: clay... 22-204 20 scscsseewacuaas ee ee ee es ee eeeeee eae ew ee od esis 70-71

Jameco (?) gravel: Light-yellowish gravel.............-.2.2-.--- 220-022 e eee eee eee eee eee 71-75

On the south shore east of the Cretaceous valley the succession is as follows:

187. Record of James Caffery’s well near Far Rockaway.

Feet.
Manhasset formation: Water-bearing strata, almost clear gravel.......... Bide ees eelneciorerses 0- 42
Gard inérs Clay 6: <2os028 decisis s peepee ee ecee eee eee tes ee ceeeee en eae at esse tec 42— 66
Jameco gravel:
Black sand with water which looked and tasted good................-...--22--22----- 66— 88
INomMrecord 3223 axa days 2s ais css es pees cece ow She ae Se eee ou a betas OE Eee oc aa 88-112

The character of the Jameco in the eastern part of the island is shown in the record of the
Bridgehampton well (No. 897) given on page 75.

In a number of wells at the Springfield pumping station wood is reported in the Jameco,
as well as in the Gardiners clay. This is indicated in the abbreviated records in the following
table, taken from the report of Veatch,! with the correlations of the writer.

Well sections at Springfieldapumping station.

 

 

Section.
Water-bearing
Well Blue clay
No. Sand with wood sand and

Wisconsin gravel; some
va Man- aun a at clay
hasset). « ardiners

| Gardiners). and Jameco).

 

Feet. Feet. Feet,

15 0-74 74-182 182-207
117-177
124-178
160-177 |
160-177
139-179,

132-156

 

 

 

 

 

1 Op. cit., p. 201.
88 GEOLOGY OF LONG ISLAND,

East of Long Island the Jameco occurs at a number of points. Veatch correlates the
yellowish sands and the bowlder-bearing deposits beneath certain of the clays on Gardiners
Island with the Jameco, but for the reasons given on page 90 the writer regards the presence
of true Jameco on that island as doubtful.

The stratification of the Jameco where the beds are exposed at the surface farther east is
fairly regular, cross-bedding being exceptional. An examination of the material at a number
of points shows that the pebbles have not undergone any great amount of decomposition, although
they are distinctly more weathered on the average than are the subsequent deposits. The
thickness of the beds is ordinarily not very great, rarely exceeding 100 feet, and thicknesses of
less than 50 feet are not uncommon. ,

SOURCE OF MATERIALS.

At the type locality in the buried Jameco channel the pebbles and even the smaller grains
of the Jameco gravel are prevailingly granitic in character and therefore must have been derived
from the crystalline area of the mainland on the north. The generally low percentage of quartz
indicates that very little material was derived from the Cretaceous, from the later Coastal
Plain formations, or from the Mannetto gravel, in all of which the pebbles are mainly quartz.
Outside of the buried valley mentioned, however, much more quartz is present in the Jameco
gravel, indicating that it must have received considerable contributions from the Cretaceous
formations or the Mannetto gravel.

RELATIONS TO OLDER DEPOSITS.

The Jameco gravel rests unconformably upon the older Mannetto and Cretaceous deposits
(fig. 57, p. 81), the principal portion on Long Island being laid down in the broad buried valley
underlying Jamaica Bay and the region to the north, toward Jameco, Jamaica, and Flushing.
Whether this old valley was cut wholly in Mannetto gravel or whether the erosion cut through
the Mannetto into the underlying Cretaceous is not clearly shown by the well records. In
either case the unconformity amounts to nearly or quite 600 feet, as there is that much differ-
ence between the altitude of the Mannetto plateau remnants and that of the bottom of the
buried valley occupied by the Jameco gravel in the region mentioned. Taken as a whole it
seems likely that the Jameco rests upon or abuts against both the Cretaceous and Mannetto
(fig. 57), although to judge from the severity of the pre-Jameco erosion, which seems to have
almost completely removed the Mannetto, the beds probably more commonly rest upon the
Cretaceous. In western Long Island the accumulation of the Jameco took place almost
entirely in the valley described. Farther east the deposits were banked against the north
side of the Cretaceous and Mannetto land masses, such as those of the Mannetto and Half
Hollow hill region, and in the extreme eastern part of the island they were spread out over
the lower and flatter Cretaceous surface which existed there.

STRUCTURE.

The structure of the Jameco gravel of Long Island must, in the absence of known surface
exposures, be inferred from the attitude of the overlying beds and from differences in the
elevation of the buried surface. Such criteria are, of course, of value only where uncon-
formities are absent. Although there is no direct evidence on Long Island that the overlying
beds are conformable with the Jameco, observations on Block Island, Marthas Vineyard, and
the Massachusetts coast, where the beds are perfectly conformable, indicate the probability of
similar conditions on Long Island. If this is assumed as a fact and conclusions are based on
the elevation of the Jameco surface or on the structure of the overlying Gardiners clay, it
appears that the Jameco beds, although nowhere far from the horizontal, are yet more or
less warped. In the region between Ridgeway, Brooklyn, and Valley Stream several undula-
tions from 50 to 100 feet in elevation are brought out by the borings (fig. 58), and beneath
Rockaway Ridge occurs a similar fold whose existence as a topographic feature ix due to this
JAMECO GRAVEL, 89

arch in the underlying beds. This and similar irregularities on the north shore of the island
are brought out by the depths in the table on page 90. Although the occurrence of the Jameco
at the surface on Gardiners Island appears doubtful, it is probably present locally at no great
distance below sea level and is doubtless involved in the strong folds which characterize all the
older deposits of that island.

DISTRIBUTION.

POSSIBLE SURFACE EXPOSURES.

At a number of points on Long Island and in its vicinity beds of sand or gravel underlie
the clays exposed in the bluffs. Sandy beds are in places intercalated with clayey strata in
the Gardiners clay, but in the absence
of well records it is not possible to de-
termine whether the clay seen is the
basal clay of the formation or one of
the upper members. In the former
case the sand or gravel would be re-
ferred to the Jameco; in the latter case

Forest stream (290)

Springfield (196)
No, 197
No.*292
No,.293
No, 289

New Lots (135)
No. 291

Pumping Sta.
No. 1327

I
Ww
i .
Baisleys (200)

jo. 141
No. 136
No, 195
No. 199
Jameco (201)
No. 203
No, 204
No. 205
No. 206
No. 287
No. 285

N

 

= 7 0
100

1
1
\
\
1

1
\
\
1
iS)

 

 

 

 

 

a ig Sar ag del | L200
it would be referred to the Gardiners. |” => ) 1300
The exposures may, however, be de- ee
scribed at this point. Miles 1 2 i 4 ee

 

Jacob ill.—In the bluffs of J acob Figure 58.—Section from point near Ridgeway, Brooklyn, to Valley Stream. 1,
Hill, which is situate d about 2 miles bic ‘ers 2, Manhasset formation; 3, Gardiners clay; 4, Jameco gravel; 5,
west of Mattituck, several conspicuous
pinnacles of contorted reddish or chocolate-colored sandy clays were seen just back of the beach
in 1904. The base was not well exposed, but the relations seem to be as indicated in figure
71 (p. 98). The gravel may be Jameco, but it seems more probable that the clay is involved in
an overturned fold resting on the Herod gravel member of the Manhasset formation.

Mulford Pownt.—A short distance west of Mulford Point and about 3 miles west of the
termination of the North Fluke at Orient Point a complexly folded exposure of Gardiners
clay was noted. At the time of the writer’s visit in 1904 nothing could be seen of the under-
lying beds, but Mather‘ in 1843 gave a section which seems to indicate that the clays are
underlain by sands, possibly to be correlated with the Jameco.

Montauk Point.—At a point about 24 miles west of Montauk Light a considerable thick-
ness of gray to greenish sand and fine gravel with some yellow gravel was exposed in 1904
beneath 10 feet of interlaminated sand and chocolate-
colored sandy clay, with the relations shown in figure
59. Most probably the material described belongs to
the Jacob sand, but it is not impossible that the sandy
clay belongs to the Gardiners clay, in which case the
underlying material would be Jameco.

FiguRE 59.—Section 2} miles southwest of Montauk Hog Neck.—On the west side of Hog Neck, 2 miles
aa B : ee ee northwest of Sag Harbor, is exposed a section that seems
clay; ¢, banded till (Montauk member of Manhasset to show beneath the Gardiners clay a considerable thick-
Mert ee ness of stratified gravels which would naturally be cor-

related with the Jameco gravel. The beds are strongly folded, however, and are probably

overturned, so that the gravel may be stratigraphically above the clays though below them in

the section. (See figs. 151 and 152, p. 142.)

Gardiners Island.—The stratigraphy of the Pleistocene deposits of Gardiners Island is
complicated by the severe folding to which all the beds except the Wisconsin have been sub-
jected, as well as by the somewhat unusual succession. Instead of the Gardiners clay being
represented by a single stratum, as in many localities both east and west of this island, it occurs
as a series of interbedded clays and sands; moreover, thin clays of very similar character

 

 

QO 100 Feet
Gresrenecncneneeteecenarvenniereennnienresaranenl

 

1 Mather, W. W., Geology of New York, pt. 1, 1843, pl. 4, fig. 5.
90 GEOLOGY OF LONG ISLAND.

occur in the Montauk till member of the Manhasset formation. Owing to the incompleteness
of the exposures or to the complexity of the folding, it is in many places impossible to deter-
mine the horizon of a particular clay bed, and the identification of the underlying sand beds
is still more difficult. For this reason the writer has found it impossible to identify positively
the Jameco on Gardiners Island. Veatch! describes and figures a section near the middle of
the northeast coast (diagram reproduced as fig. 60), in which a bed of gravel containing bowlders
of granitic rocks is shown between a red clay and a bed of fine gray micaceous sand regarded
as Cretaceous. To the writer, who examined the same exposure at a later date, it appeared
that the bowlders referred by Veatch to the Jameco are a superficial deposit (Montauk)
irregularly massed against an ancient bluff, and that the supposed Cretaceous sand is identical
with beds intercalated with the Gardiners clay at other points and is to be correlated with that
formation. The small unnumbered infolded bed between Nos. 4 and 5 has the appearance of
belonging to the Herod gravel member of the Manhasset, and No. 4 resembles the Jacob sand.
It would be strange if the Gardiners clay, which usually has a thickness of 30 to 100 feet and
is represented by a number of alter-
nating sands and clays, should at this
particular point be represented by a
single bed only a few feet thick. The
Jameco is thought to occupy its nor-
mal position below sea level, possibly

 

 

FIGURE 60.—Section near the middle of the northeast shore of Gardiners Island. 0, banked against the Cretaceous mass,

Black Cretaceous clay; 1, fine gray micaceous sand (Cretaceous); 2, Jameco gravel; the upper part of which is involved
3, red clay (Sankaty); 4, silty sand (Sankaty); 5, Wisconsin till and outwash gravel. : : :
Height of section, 60 feet. Section and nomenclature by A. C, Veatch. in the fold shown in the figur e. It is

very doubtful if any Jameco shows
above sea level on Gardiners Island. The folded bowlder-bearing beds which underlie certain
clays elsewhere on the island, and which are correlated with the Jameco by Veatch, belong
almost wholly to the Montauk till member of the Manhasset formation.
No beds that could be correlated with the Jameco gravel were noted on either Plum Island
or Fishers Island, although they doubtless occur below sea level.

c DEPOSITS PENETRATED BY WELLS.

Long Island.—The distribution of the Jameco gravel shown by the wells of Long Island is
concisely presented in the following table, which emphasizes, first, the concentration of the
coarse dark granitic gravel in the old Cretaceous depression north of Jamaica Bay; second,
the finer, more quartzose, and lighter-colored deposits on either side of the depression and on the
north shore; third, the general absence of the gravel from the south side of the old Cretaceous
land mass; and, fourth, its occurrence as a light quartzose gravel in the extreme eastern part

of the island.
Jameco gravel penetrated in wells of Long Island.

 

Depth of for-

 

 

  
    
  
 

No.a Locality. Owner or place. Ta tiOn Character of the deposit.
; Feet.
Rapid Transit Co........... 139-212 | ‘‘Hardpan’”’ with black stones and coarse sand.
5th Avenue and 18th Street - ’ 55-135 | Reddish-brown sand and gravel.
Bartlett Street and Harrison 150-165 | Coarse red sand.
venue.

Bartlett Street and Flushing 139-176 | Coarse yellow sand.

Avenue.
Ten Eyck Street..........-- 100 | Beach sand.

65 |..--- 0) csi seisciciciies .--| Porterand Maspeth avenues. 190 | Water-bearing gravel.
130 | Barren Island.... -| T. F. White Co............. a 130-220 | Reddish-brown sands with cobbles.

*.:| Dept. Water Supply.

135 | East New York.....-.
.-| Brooklyn waterworks

118-164 | Coarse dark granitic gravel.
136 | Aqueduct.......-- Br gr

128-191 | Dark reddish or yellowish sands and granitic gravels.

  

 

 

 

 

137 | East New York. DO eraisicceccvoinsscke an 141-149 | Coarse dark sgrauitio gravels.

141 occas (eer crercre Oras aiaraieasdiaie ge seisteinertier. 281-284 | Gray silt and granitic pebbles.

176 | North Beach... Bowery Bay Building Asso- 36- 82 | Coarse sand and me
ciation.

187 | Far Rockaway........| Jas. Caffery................. 66-112 | Black sand.

188 |...-. Osc eecintteeaquey Eh Tae SAIN, ic sia see seanmisncimre 65-190 | Fine to coarse sand and gravel.

a Numbers refer to well records in report on underground water resources of Long Island, New York, by A. C.
e é Geo Survey No. 48, 1908), g i ork, by Veatch and others (Prof. Paper
n part.

 

1.Op. cit., p. 35.
JAMECO GRAVEL. 91

Jameco gravel penetrated in wells of Long Island—Continued.

 

 

  
   

 

   

 

 

 

 

No. Locality. Owncr or place. | ee Character of the deposit.
Feet.

191 | Far Rockaway........ Queens County Water Co... 100 |} Beach sand.
195 | Aqueduct... - .| Shetucket pumping station... 146-154 | Coarse dark granitic gravels and clay.
197 | Springfield... .| Springfleld pumping station . 106-109 | Steel-gray sand with jasper pebbles.
199 | Jamana South. -| Oconee pumping station... . 185-192 | Coarse dark granitic gravel.
200 |....- veces --| Baisleys pumping station . . . 156-200 | Black sand and gravel.
201. |. sec do. -| Jameco Smeg Station.... 135-161 | Dark-brown granitic gravel and sand.
202 |..... do. -| Connell Creek.............-. 142-156 | Dark granitic gravel and sand.
203 |..... do... .-| Brooklyn test well No. 2..... 154-258 | Dark granitic gravels and sands.
204 | Springfield. .-| Brooklyn test well No. 3.... 201-277 Do.
205 j....- do... .-| Brooklyn test well No. 8.... 212-260 0.
206 |..... do. .-| Springfield pumping station . 170-183 | Reddish-yellow granitic gravel and sand.
212 | Jamaica. - .-| Brooklyn test well No. 11... 189-200 | Dark granitic gravel and sand.
213 |....- WO er rieeiacyse sence Pumping station, Jamaica 104-120 | Coarse sand and reddish gravel.

: Water Supply Co.
239 | Whitestone...........- Pumping station No. 1...... 45- 95 | Glacial sand and gravel.
241 |..... WO sissies --| Railroad wells...........--.- 85-120 | Coarse granitic gravel.
243 |... 2. DO sans wieiseem deceased: WW COl 0 ciate sera ane! 70- 96 | Medium coarse gravel.
261 | Lawrence.............. DD. Lord. cases cccnanicaincs 70-100 | Coarse sand, changing to gravel.
273 | Hewlett «aces vscascaes Queers County pumping 120-155 | Coarse sand and gravel with granitic pebbles.

station.
287 | Valley Stream......... Watt Pond pumping station. 118-130 | Sand and fine gravel.
290 | Springfield_........... ores Stream pumping sta- 105-115 | Water-bearing iron formation.
ion.
201 |..... DO erst Senses 38 Brooklyn test well No. 12... 98-138 | Dark dirty granitic sands.
292 | Rosedale...............] Brooklyn test well No. 13.... 70-102 | Reddish-yellow silty sand and gravel with granitic pebbles.
351 | Plandome Mills.....-.. Robt. Seizer........-..-.... 100-113 | Coarse sand.
469 | Dosoris Pond.......... ID.B, ;BuShescenesssaaadees 0 95- 97 | Light-colored ee gravel.
527 | Oyster Bay............ Charles Weeks.......-.----- 90-110 | Micaceous sand.
CO isis sairaeneSe ace Van Sise & Co..............- 53- 57 | Yellow sand and gravel.

£00 cons eceee sistance D. W. Smith........ 50- 65 | Fine yellow sand.

POOL wssic'sisipereriara cours E. K. Hutchinson.........-- 50- 83 | Sand.

SOD asin caren cinsiermei W.J.andA.8S. Hutchinson. . 185-190 | Yellow sand and gravel.

SOO ns sicesasins nezeis O« Day JONOS hs sro sreeviee seeene 135 | Coarse sand.

2G sts aversion cicis T. Underhill. .cc.6.52 02ee 5 80-107 | Fine gray and black sand.

MOO cise csrecen 2x aes Hamilton..........-.-..---- 80-130 | Sand.

Gris cede iaccizasscigse William Trotter..........--- 70- 90 | Gravel.

613 | Cold Spring Harhbor....| Eagle Dock................. 158-176 | Fine sand and gravel.
628 | West Neck.....-...-.. B. Ward.......--- 116-149 | Dark-brown ioe mixed with clay.
629 |..... GOs waz acceensatiete Mrs. M. H. Oats... 93- 97 | Brown gravelly sand.
633 | Lloyd Neck........-.-- O. L. Jones....... 105-122 | Fine to coarse yellow gravel.
652 | Halesite............... Light & Power Co. 71- 75 | Light-yellowish gravel.
654 | Centerport..........--- R.S. McCrary.... 175-185 | Granitic pebbles size of fist.
671 | Muncie Island.......-. E. H. Muncie 150 | Dark clay and sand.
897 | Bridgehampton........| Sanford & Son 105-115 | Yellow and Sree sand and gravel.
901 | Sag Barece es scars re ear Us Ki Morrisec ccc cncx secesce 143-145 | Sharp white sand with biotite.

 

 

Plum, Gull, and Fishers islands—On Plum Island the Jameco probably embraces the
material from 24 to 89 feet in the Army well. The Herod gravel member of the Manhasset
formation, the Jacob sand, and the Gardiners clay were evidently here cut out by the Mon-

tauk ice.
Record of United States Army well on Plum Island, New York.

Montauk till member of Manhasset formation: Feet.
WGA sit to cede bnkeSoe heae Me ceatihcemaaee ees Laees eA eeiokawe cet eded ye to oe seam 0 - 24
Sand! and late bowldérsss<.csa.364.5 Sat ediedinns oo Poee RAGE eeeee awa Saee Deed thea 24-20

Jameco gravel:

Mine sand. jsichare cece 2253420 Se Wah Petts esas) ansAagemawew seo Eeccagaehe 20 -31
Fine sand and pravell...c< 22sec 2. senenctemene hen eqdee soae hae eaue are een tea aS 31 +49
Coarse'sand and fine'gravel.... 2 0. <22as+wec2ssceaet22n525+4nnennsenesed SEee ees eee ee 49 -89

Gull Island is only just awash and nothing but till, which may be either Montauk or Wis-
consin, is exposed. The following record probably begins below the Gardiners clay, which,
if present, would occur at about sea level.

Record of United States Army well on Gull Island, New York.

Jameco gravel (mainly): Feet.
Lost and eandc cs swateee rea cee oieice casement ocas des Siew maamateees ieee sae 0- 30
Coarse sand. 21 2ecesececcee x tet can neinier seen eee a See eee ewes eee seSoEe 30- 40
Very coarse sand. .....--.- +--+ +--+ 2-2 e eee eee e rete ete teen teen eee 40- 46
Very coarse sand and gravel......--..------ +++ + +2222 eee e eee ee eee eee eee 46- 52
SFE 6 52- 57
Fine quicksand.......-..-+--+-- +--+ +22 reer e reece tree reese reese eee 57- 82
Sand iand Clayiicosexnasiene viesds reed peee eA 2s oe ss tine ek eas eeadya Sai 82-87
Gravel and sand. ..-....------ +--+ - eee c cece eter tee eee eee eee 87- 91
Coarse gravel and sand... ...---.---- 222-02 etree eres etree eee eee eee reese 91- 98

Cretaceous:

Wine Band 2 2 ess bs came es See ee pemAaasedals bts Se near eeeeeeemn 98-108
Light-colored clay... -..------ +++ 0-22-00 rset tere c ects tte tt sees e tee t eet ete eters 108-112

Dark-blue clay, rather oily; when exposed to the air became very hard...........-.... 112-291
92 GEOLOGY OF LONG ISLAND.
AGE.

The glacial or glaciofluviatile origin of the Jameco gravel is apparently shown by its
highly granitic character, and if, as is believed, the Mannetto gravel is of similar origin, the
Jameco was evidently deposited during a second glacial stage separated from the first by a long
interval of deglaciation. The period of erosion between the two stages is somewhat compar-
able, so far as the effects on the island are concerned, with the long Pliocene epoch. It was in all
probability at least as long as several of the later stages put together. This great length
suggests that several stages of glaciation might have intervened, but nowhere on Long Island
or on the New England coasts have evidences of glacial deposits that might be referred to such
stages been found, notwithstanding the numerous localities where the older Pleistocene deposits
have been brought up by folding and exposed in cliffs or have been penetrated by wells. A
possible clue to the age of the Jameco is afforded by its place in the glacial sequence of the
island, which is closely similar to the well-established succession of the Mississippi Valley.
This evidence as well as the weathering of the Jameco materials suggests its possible equivalence
with the Kansan stage of the interior of the country.

GARDINERS CLAY.

NAME,

The Gardiners clay derives its name from Gardiners Island, situated between the North
and South flukes at the east end of Long Island, on which several clay beds with included sands
are well exposed at a number of points. It is the exact equivalent of the Sankaty beds of
Veatch * but is not the equivalent of the Sankaty beds of J. B. Woodworth,? with which Veatch
mistakenly correlated it. The term Sankaty beds was proposed by Woodworth for a series of
marine sands and gravels with a few minor clayey layers, locally carrying a Pleistocene fauna,
which are involved in the folding that affected all the New England islands. The name is taken
from Sankaty Head, Nantucket, where the fossils were first observed. No true clay was exposed
at the type locality, except a fossiliferous bed only a few fect in thickness, although a series of
brownish clayey sands incorrectly designated clay were exposed to a depth of 20 feet at the
base of the cliff some 50 years ago.* The remaining parts of the bluff were made up mainly
of sands, gravels, and semi-till.

Later Veatch,‘ on the ground of similarity of fauna, applied the same name to the blue, gray,
or red Pleistocene clays of Long and Gardiners islands, which reach in the former island, according
to the evidence of wells, a maximum thickness of about 100 feet. The present writer was
originally inclined to the use of the term,’ but subsequent field work, during which the greater
part of the shores of Long, Gardiners, Plum, Fishers, and Block islands were traversed and the
bluff sections of Marthas Vineyard, Nantucket, and Cape Cod were visited, brought out the
fact that the true clays in each of the localities mentioned are stratigraphically below the lowest
of the deposits at Sankaty Head and hence should not be included under the same name. More-
over, the Sankaty beds of Woodworth are separable into two distinct units, the Jacob sand and
the Herod gravel member of the Manhasset formation (see pp. 106 and 121), each of which has
been traced by the writer from western Long Island to Nantucket. The true clays, to which
the term Gardiners clay is given, are interglacial deposits, but the Jacob sand and the Herod
gravel member of the Manhasset formation are of glacial origin. The term Sankaty as used
by Woodworth includes materials of unlike character but of glacial origin; as used by Veatch
it applies to interglacial deposits.

 

1 Op. cit., p. 36.

2 Glacial brick clays of Rhode Island and southeastern Massachusetts: Seventeenth Ann. Rept. U. S. Geol. Survey, pt. 1, 1896, p. 977.

3 Desor, E., and Cabot, E.C., On the Tertiary and more recent deposits in the island of Nantucket: Quart. Jour. Geol. Soe. London, vol. 5,
1849, pp. 340-344. :

‘Veatch, A. C., The diversity of the glacial period on Long Island: Jour. Geology, vol. 11, 1903, pp. 762-776.

5 Fuller, M. L., Probable pre-Kansan and Iowan deposits of Long Island, New York: Am. Geologist, vol. 32, 1903, p. 311.
GARDINERS CLAY. 93

CHARACTER,

On western Long Island, where the formation reaches its maximum development, the
Gardiners clay consists of irregular dark-colored beds alternating with layers or lenses of sand
and fine gravel and attaining near Brooklyn an aggregate thickness of 150 feet. In this region
the clays, unlike those in the localities farther cast, grade downward through glauconitic and
locally fossiliferous sand
into the Jameco gravel,
representing in fact
transitional deposits.
The clays themselves
consist of a very fine

silt, dark from the con- | __ AQ, wit SE SRL no

 

 

2S SSE
EE = EL= SF > as |
2

Se
a coLoreo_—__]

SONY,
<s

\

 
 
 

 
   
  

 

 

SS
32

AER S
THT ABR Ges

SAD .

RSQ DSA o® SS Xso0e

 

 

 

 

 

 

 

 

 

tamed. onganic matter — *2j0s sulH oF etomne cone, sai SC EROWNS POINT, PETTYS BIGHT, LONG ISLAND, NY.
and carrying more or

less lignitized wood.

The included sandy lay-

ers are commonly from

5 to 10 feet thick and jr WIE. » SN WY
oo oe oe

200 YDS. SOUTH OF BROWNS POINT, LONG ISLAND, N.Y,
Some of them are

thought to represent the
outwash from the adjacent land and others to be channel or shore-line deposits. The lignite
fragments that they yield are rounded as if waterworn.

Toward the east the clays gradually lose their dark lignitic color, bluish tints taking its
place, but, if well records are to be relied upon, they are still fossiliferous. Near the east end
of the island the bluish tint is replaced by reds and greens, although black clay is to be seen
locally on Gardiners Island. The red color is commonly of a brownish tinge and appears to be
due to the presence of material derived from the Triassic area of Connecticut, indicating the
probable existence of Connecticut River in its present position. In some places a more intense
red, similar to the
color of the bright
Mauch Chunk shale
of eastern Pennsyl-
vania, is to be seen.
The amount of red
material often ap-
pears to be in excess
== )200feet of what is actually
600 * present because of
small quantities

Horizontal scale ; —— -
[) eae i i Li that have been

Gardiners Jameco Cretaceous Bed rock

FIGURE 61.—Sections near Browns Point. By W. W. Mather.

Queens Co. Water Co. (273)

Jamaica (212, 213)
B.WW, No. 12 (291)
) Hewlett (274)

Barnum I.

   
  

   

St Citizens Water Co. (162)

 

é dela Siaieleniae THljwen washed down and
FIGURE 62,—Section from Wards Island to Barnum Island, showing fold at Rockaway Ridge (Hewlett) and the 3
relations of Gardiners clay, Jameco gravel, Cretaceous deposits, and bedrock. form a coating over

other deposits. In
this region the formation is not a lithologic unit but consists of several alternating beds of clay
and sand each from 5 to 10 feet or more in thickness. Probably the best illustration of this charac-
teristic is afforded by the section figured by Mather in his report on the first geological district
of New York.t. Mather’s illustration is reproduced here as figure 61. Similar complexity
is shown by many Gardiners Island sections. One of the features of this phase of the Gardiners
clay is the lack of persistence of the individual beds. A clay bed 10 feet in thickness may, for
instance, disappear within a space of a few hundred feet, whereas in other sections, as in most
of the exposures on the Massachusetts coast and islands, the formation is clayey throughout.

 

1Mather, W. W., Geology of New York, pt. 1, 1843, pl. 4, figs. 4-7.
94 GEOLOGY OF LONG ISLAND.

On Montauk Point the clay maintains a reddish tinge, although the color is nearer to
chocolate than to the bright red of Gardiners Island, and is more likely to be interlaminated
with fine sand. In fact, the material is intermediate between the deposits of Gardiners Island
and those of Port Washington. On Plum and Fishers islands the clay is similar to that at
Montauk, but on Block Island and Marthas Vineyard and at Truro it is blue-gray to nearly
black.

SOURCE OF MATERIAL.

Many difficulties are encountered in searching for an explanation of the derivation of the
materials composing the Gardiners clay. The presence of fossils bearing evidence of a moderate
climate and the occurrence of lignite point to accumulation in an interglacial stage, which, to
judge from the thickness of the clays, was of long duration. In western Long Island, where they
reach a thickness several times as great as near the east end, they may be conceived to have
been derived from the erosion of Cretaceous deposits. The Mannetto gravel, which originally
mantled the Cretaceous, had been almost entirely removed, and the Jameco gravel was below
sea level. The streams and the sea were, therefore, free to act on the Cretaceous clays, and
doubtless it was through their agency that a considerable part of the material for the Gardiners
clay, especially the interbedded sands and gravels, was obtained. Probably not all of the
material was thus derived, however, for farther east on the island there appears to have been little
or no Cretaceous above sea level. A clue to the source of the clay in this part of the island
may possibly be found in its color, which suggests its derivation from Triassic materials, prob-
ably brought into the ocean by Connecticut River, which, as previously pointed out, had appar-
ently already taken its present course. The amount of clayey sediment now carried by the New
England rivers is extremely slight, and the accumulation of 30 to 150 feet of clay over so wide
an area would, under the present conditions, require a time interval of great length. It is not
impossible that the land, although low in the vicinity of Long Island, may have been somewhat
elevated farther north, in which case erosion would be facilitated and relatively large amounts
of silt furnished. Of such an elevation at this time, however, the writer knows of no other
evidence, unless the cool climate is to be taken as indicating the existence of elevated areas in
the near vicinity—a not very reasonable supposition.

After the material was once brought to the sea its distribution would probably not be
difficult, for the region is one of strong and shifting currents, as attested by the many moving
shoals off Monomoy and Nantucket.

RELATION TO OLDER DEPOSITS.

The contact between the Gardiners clay and the top of the Jameco gravel is nowhere well
exposed on Long Island, but so far as can be determined it is everywhere conformable. The
line of demarcation, as brought out by well records on Long Island and especially by expo-
sures on Block Island, Marthas Vineyard, and Cape Cod (see p. 220) is usually sharp, gravels
of medium coarseness giving way abruptly to clay entirely free from sand or pebbles, as if
the supply had been cut off by the sudden retreat of the ice sheet, which had previously fur-
nished coarse materials in abundance. Sharp contacts such as occur in the New England
islands are presumably present in eastern Long Island. The clay extends for several feet before
coarser materials reappear as thin intercalated beds of sand or fine gravel, and no coarse gravels
were laid down until after the deposition of 50 to 200 feet of clay and fine sand forming the
Gardiners and Jacob formations. The only exception to the abruptness of contact seems to
be in western Long Island, where there appears to be a transition through glauconitic or fossil-
iferous sand into the Jameco gravel, as brought out in the well records.

The great body of the Gardiners clay rests upon the Jameco gravel, but along the borders
of the Jameco next to the Cretaceous land mass, especially along the edges of the great depres-
sion in the vicinity of Jamaica Bay, the clay laps up on the eroded surfaces of the Cretaceous
and Mannetto (fig. 57) or even upon the metamorphic rocks (fig. 62), with sharp erosion and
overlap unconformities.
GARDINERS CLAY. 95
CHARACTER OF THE UPPER CONTACT.

The Gardiners clay normally passes by gradual transition into the overlying Jacob sand,
the clay first becoming slightly more sandy, then alternating with thin lamine or layers of
sand, and finally giving place to the characteristic clayey sand of the Jacob (fig. 61, p. 93).
At many points, however, the normal conformable contact with the overlying beds is replaced
by an unconformity resulting from erosion by the ice sheet that subsequently deposited the
Montauk till member of the Manhasset formation. This powerful sheet not infrequently
scoured through the Herod gravel member of the Manhasset and the Jacob sand into the
Gardiners clay, so that the Montauk (fig. 63) or, in its absence, the still younger Hempstead
gravel member of the Manhasset may rest upon the clay. The erosion has given rise to differ-
ences of level of many feet in the surface of the Gardiners clay, according to whether the ice
removed only a few inches or took a considerable portion of its
bed, and the greatest differences may be found within a space
of a few yards. In many places the deposits were strongly
folded by the ice before the Montauk till member was deposited
over the up turned and eroded beds. Figur& 63.—Section near Eastern Plain Point,

The physical character of the contact with the Montauk — Gardiners Island, showing Montauk till mem-
till member differs with the nature of the till. Where a large Sac peers ee eae ee
amount of débris was carried by the ice, the clay in many places
gives way rather abruptly to a bowlder-clay till, in which the only suggestion of transition is
the unusual amount of clay and the strong red tinge imparted to the till by the material picked
up from the underlying Gardiners clay. At other points, where less material was being carried
by the basal part of the ice sheet, the demarcation between the two beds is less sharp, the
Gardiners clay gradually becoming less regular in lamination toward the top and finally giving
way to a structureless or irregularly laminated clay with a few foreign pebbles, indicating a
reworking by the ice. This slightly reworked layer is a somewhat characteristic feature of the
top of the Gardiners clay and is in places very difficult to distinguish from the undisturbed clay,
especially in eastern Long Island and on the New England islands and Cape Cod.

 

 

STRUCTURE.

At no point where the Gardiners clay is exposed at the surface is it found in an undis-
turbed condition. At some places it is warped into broad, low undulations (fig. 193, p. 156) and
at others it is compressed into sharp overturned folds (fig.
64), but it is nowhere horizontal for distances of more than
a few yards. Its striking character and sharp contrast
with the associated beds makes it an ideal key to the
structure, and it is, in fact, upon this bed that most of
the structural observations on the island have been based.
In general the disturbance is most marked on the north
side of Long Island and on the islands farther east, espe-

9 : oFect, cially where the land presents a steep front to the north,

FicurE 64.—Section near Jacob Hill, showing over- Jecoming less conspicuous in the interior and on the south

tured fold of Gardiners clay beneath Jacob sand. 4-4 In the former situations the clays are at many

points thrown into closely compressed, locally overturned isoclinal folds. In practically all

these folds the axes have approximately east-west directions. The anticlines have steeper
slopes to the south than to the north, and the overturning is always toward the south.

The folding is weakest at the west end of the island and becomes progressively greater
toward the east, reaching a maximum on Orient Point, Gardiners Island, and Montauk Point.
On the north coast of the western third of the island the Gardiners clay seems to have occupied
baylike reentrants in the Cretaceous coast line and to have been protected both by the projecting
Cretaceous headlands and by the thick overlying Herod gravel member of the Manhasset for-
mation, which took up the greater part of the disturbance resulting from the overriding ice

 

 
96 GEOLOGY OF LONG ISLAND.

sheet. Inthe Jamaica region the ice seems to have overridden an even surface that presented
few obstacles to its advance, and the disturbance appears to be limited to a few broad undula-
tions apparently due to warping under the influence of the load of ice.

Farther east the Cretaceous land was lower, and the Gardiners clay was deposited as a fringe
around its borders. The absence of protecting headlands of the older formation and the relative
thinness of the overlying gravels left the Gardiners clay with less protection than at points
farther west, and as a consequence the folding in it is much more pronounced. The details of
the folding are brought out below, where the distribution of the clay is described.

Besides being eroded and folded by the Montauk ice sheet, the Gardiners clay has been more
or less affected by a slight but somewhat widespread crustal warping. This warping seems to
be represented by a slight uplift of the eastern part of the island, as compared with the western
part, the clays being on the whole perhaps 25 feet nearer the surface at Montauk than at the
Brooklyn end of the island. It is in part to this cause that their more frequent appearance at
the surface in the eastern portion of the island is due, although the greater folding in this region
and the absence of the protecting masses of Cretaceous deposits such as occurred farther west
are perhaps the most important factors. It may be remarked that the uplift appears to have
been still greater in the New England islands and on Cape Cod.

DISTRIBUTION.

SURFACE EXPOSURES.

The Gardiners clay has been recognized in surface outcrops at many localities on Long Island,
from Manhasset Neck on the west to Orient and Montauk points on the east. It is also found
on Robins, Plum, Fishers, and Gardiners islands.

Hempstead Harbor.—Although, as indicated by exposures of the Jacob sand, into which the
Gardiners clay grades, the Gardiners is near the surface at Plum Point and vicinity and
near Port Washington
on Manhasset Bay, the
most westerly exposures

FiGuRE 65.—Section at Rocky Point, west of Cold Spring Harbor. a, Wisconsin till; b, Hempstead gravel are those found on the
ion; c, M' uk till ber of Manhasset; d, Herod gravel member of :
member of Manhasset formation; c, Monta ill member o anhasse erod grave embel east si de 0 f Hemps tea d

Manhasset; e, Jacob sand; f, Gardiners clay.

Harbor. Just south of
Red Spring Point about 5 feet of a gray sandy clay lying near beach level apparently represents
the top of the Gardiners, and a little farther south, about halfway between Red Spring Point
and Glen Cove Landing, another exposure showed a few feet of greenish clay with scattered
quartz pebbles from an eighth to a fourth of an inch in diameter, likewise representing the top
of the Gardiners clay. Still farther south, although the Jacob sand was exposed at several
points, the Gardiners clay was not seen, even where the Cretaceous is above sea level, being
covered, if it occurs at all, by talus of gravel from the higher parts of the bluff.

Rocky Roint, Cold Spring Harbor.—The next exposure of what appears to be Gardiners clay
is found at Rocky Point, on the west side of the entrance to Cold Spring Harbor. A low arch
at this point brings up about 5 feet of dark-gray clay containing the small scattered quartz
pebbles characteristic of the Gardiners clay (fig. 65). The upper part of the clay shows the
greenish-yellow tints due to weathering characteristic of the Gardiners clay. This clay should
not be confused with the clay outcropping on the beach below high-tide level, which is referred to
the Cretaceous (p. 70). Another exposure of the clay is reported west of Moses Point, at the
south end of ‘the island.”

Lloyd Neck.—At the foot of the bluff facing Cold suring Harbor, for a quarter of a mile or
more north of the base of the bar separating Cold Spring from Lloyd Harbor, there were to be
seen in 1903 a series of yellowish Pleistocene clays which possibly represent the top of the Gardi-
ners clay, although they may belong to the Mannetto. The following is a typical section:

 
GARDINERS CLAY. 97

Section of clays, etc., on Lloyd Neck.

Feet

Yellow clay interstratified with sand and containing cobbles up to 6 inches in diameter........ 2

Bright-vellow: Gla yisccccieaisg Saidiateinds od ainnisiediaSuido nos ec cdvawaanlealdee 2etenceaummmecanueiles os 1

Yellow clay with ferruginous sand and pebble layers........... 22.2.2 -2.0002-e-ecece cece eee ee 1

Yellow clay with clean quartz sand and pebbles... . 2.2.2.2... 2.00.0. 00 cece eee cee cee ee cee eee 1
Fine quartz gravel with manganese and iron stains and an occasional decayed granitic pebble,

extending to tide level... 22. 2... lee eee eee cece cece en eeeeses 5

The outcrops show gentle warping with dips of 5° to 10°. In places there are indications
of gray clay, probably Cretaceous, below tide level.

Eaton Neck.—In an amphitheater eroded back into the bluffs facing Huntington Bay, a
little north of the base of West Beach sand pit, 4 feet of chocolate-
colored clay of the Gardiners type lies unconformably upon a con-
siderable thickness of Mannetto gravel (fig. 66). The clay dips
toward the north and approaches the Cretaceous a little farther
along the bluffs. Although resembling the Gardiners clay in
character, this clay lies at an abnormal height above sea level and
may be a phase of the Montauk till member of the Manhasset
formation, such as is found near Montauk Point (p. 144). Half a
mile north of this exposure 6 feet of black micaceous clay over- preuax 66,—Section north of West Beach,
lain by 3 feet of brownish clayey sand and 20 feet of yellowish — Eaton Neck. u, Wisconsin till; , till
sand is exposed in the bluffs. This may be Gardiners clay, but the ition: o, Hood mavel mentee
freedom of the overlying sand from granitic or other northern — Manhasset formation and Jacob sand; d,
material and its general similarity to the Cretaceous sands indicate itn cratic towsonie? Gas oo
that the clay should probably be referred to the Cretaceous.

Woodhull Landing.—From Eaton Neck eastward for 20 miles no clays of the Gardiners type
are exposed at the surface, but at Woodhull Landing, northeast of Miller Place, there was in
1904 a poor exposure of mottled buff to gray clay con-
taining some sand and small scattered quartz pebbles.
The clay appears to have a thickness of 10 to 15 feet
or more and is traversed by joints with dendritic mark-
ings. Its characteristics are Gardiners rather than
2 \ ‘ Cretaceous.

500 FEET Rocky Point Landing.—Half a mile west of Rocky

Ficune 67,—Seotion halfa mile west uf Hooky Foint Lana. Point Landing the section shown in figure 67 was
ing, northeast of Miller Place. a, Buff sand (Herod gravel observed in 1903. The material along the fault is a
roar nunh eee eee ee tough brown clay free from sand or pebbles, and as it
resembles the unquestionable exposures of the Gar-

diners clay at other localities, it is referred to that formation. A quarter of a mile farther east
is another exposure having the relations shown in
figure 68. The material is a bright salmon-pink,
finely laminated, very plastic clay with mica part-
ings but without sand or pebbles; it seems to be
10 feet or more in thickness. The sand showing
beneath the clay is probably thin and under-
lain by the main body of the Gardiners, as the .
thickness exposed is but a small part of that FicuRE 68.—Section near Rocky Point Landing northeast of
usually characterizing the formation. Tale ete a, Bright salmon-colored clays with micaesous

Hallock Landing—Between Rocky Point and = 3h ae aa ee
Hallock landings the beach is wet and springy,
with occasional pools of fresh water, as if the clay were close beneath. The Jacob sand
appears at several points, affording further evidence of the presence of the Gardiners clay at no

1629°—14—_8

 

S
ve,
A

   

80 FEET

 

 

 
98

GEOLOGY OF LONG ISLAND,

great distance below the surface. A little clay, possibly Gardiners, was seen in a nearly vertical
-position (fig. 69) a little west of the landing, but its relations are somewhat obscure.

 

 

FIiGcurE 69.—Section west of Hallock Landing.
a, Gardiners clay; b, granitic gravels (proba-
bly Herod gravel member of Manhasset for-
mation).

clay was seen a quarter of a mile east of Roanoke Land-
ing, where the section represented in figure 70 was ex-

posed. This clay may be th

farther east another section, shown in figure 71, was seen.

Roanoke Point.—Kast of the last-named locality no Gardi-
ners clay was seen for 10 to 12 miles, although the indications
of the Jacob sand observed at a number of points suggest that
the clay is close to the -
surface. Thesprings and
pools of fresh water along
the base of the bluff in-
side the beach and the ,.

,

    
 

 

; Figure 70.—Section a quarter of a mile east of Roanoke
numerous landslips also —_ Landing. ‘a, Gardiners clay (?); 6, Herod gravel mem-
ber of Manhasset formation (?).

probably indicate the
presence of clay beneath
the surficial deposits. A

 

 

 

e Gardiners. Half a mile
FiGur£ 71.—Section three-quarters of a mile east of Roa-
noke Landing. uw, Bluff sand (Herod gravel member

- The clay was here strongly folded and overturned. of Manhasset formation (?); b, clay (Gardiners?); ¢,

Jacob Hill.—The first really good exposure of the

Jacob sand (?).

Gardiners clay is at Jacob Hill, 2 miles northeast of Northville, where several pinnacles of

contorted reddish or chocola

te-colored sandy clays stand out prominently just back of the

beach (fig. 72). The clay seems to be involved in an overturned. fold.
Brown Hills —No more exposures of undoubted Gardiners clay occur on the north shore for

 

FIGURE 72.—Section near Jacob Hill. a,
Reddish to chocolate-colored Gardiners
clay; b, buff clayey Jacob sand; c, gra-
nitic gravels lying beneath overturned
fold (Herod gravel member of Manhasset
formation?).

another 25 miles, the clays at the brickyards at Conkling Point,
southwest of Greenport, belonging to the Montauk till member of
the Manhasset formation, instead of to the Gardiners clay, repre-
senting, however, reworked and redeposited material derived from
the Gardiners. At Brown Hills, northeast of Orient village, many
indications of the presence of Gardiners clay were observed,
although none of the exposures were fresh at the time of the
writer’s visit. Figure 73 shows one of the best exposures. The
material is a tough, chocolate-colored clay dipping at angles as high
as 80°. At the beach about 15 feet of the clay is exposed, but the
base is not shown and probably the actual thickness is much
greater, especially in the hills far-
ther inland.

The conditions for observa-
tions are best after severe storms.
Mather, who examined the bluffs
after such astorm on October 11 and

12, 1836, found some remarkably good exposures, the most strik-
ing of which, illustrated in figure 61 (p. 93), shows a broad
anticline of Gardiners clay flanked with alternating sands and
clays of the Jacob formation. The whole deposit is beveled
off and is covered by a clayey stratified till (“clay with iron
crusts”), here referred to the Montauk member of the Manhasset
formation.

 

25 Feet

 

FIGURE 73.—Section at Brown Hills, near
Orient. a, Chocolate-colored clay (Gardi-
nersclay); b, gray sandy clay (Jacob sand).

Robins Island.—Several fine exposures of the Gardiners clay may be seen on Robins Island
between Great and Little Peconic bays. The best of these are near the north end of the bluff
on the west shore, where there is 10 feet or more of dark-gray, greenish, or purplish clay inter-
GARDINERS CLAY, 99

mingled with a little sand and carrying a few small quartz pebbles and more rarely a granitie
pebble. The beds are gently warped, in places rising 10 feet above the beach and in places
sinking below sea level. Farther south bluc and brown clays, with flat clay concretions, are
seen at several places (figs. 74
and 193, p. 156). Half a mile
south of these sections there
was in 1904 a sharp nose show-

ing buff and brown sandy clay, Figure 74.—Section on east side of Robins Island. a, Wisconsin till; b, buff contorted sand
(Jacob sand and Herod gravel member of Manhasset formation); c, dark clay (Gardinersclay).
somewhat contorted and stand-

ing at an angle of 60° to 70°. The relations are shown in figure 75. Springs along the beach
indicate the presence of clay near the surface at other points, but none was actually exposed.

South shore of Great Peconic Bay—One mile east of Red Cedar Point, near Southport, a
nearly black clay carrying the characteristic quartz pebbles of the Gardiners clay occurs near
beach level. It lies beneath the red banded Montauk till member of the Manhasset formation,
with which it is involved in vertical or overturned isoclinal folds at two or more points. A
third exposure was found in an abandoned clay pit a quarter of a mile east of Shinnecock Canal.
The bottom of the pit appears to be a dark-gray to black plastic clay of the Gardiners type,

, grading upward at about the level of the floor of the excavation
into a greenish-black clay full of pebbles representing reworked
Gardiners material (Montauk till member).

The next exposure is about 14 miles to the northeast, in the
bluff of Sebonac Neck, near the south end of which is seen
about 6 feet of a bright blue-gray clay weathering greenish and
carrying small quartz pebbles irregularly distributed through
the mass. It is interlaminated with a few thin streaks of red
sand or reddish-brown clay and seems to be true Gardiners clay.

Hog Neck.—Near the northwest point of Hog Neck several
feet. of folded greenish-blue fossiliferous clay was exposed in
FicurE 75.—Section on east side of Robins 1904. The fossil shells, however, were much broken and the clay

Island. 4, Buff to brown contorted sandy carries granitic pebbles, indicating that it was reworked by the

clay (Gardiners clay); 6, sand and clayey ‘ ; : :
sand (Jacob sand); ¢, buff sand (Herod Montauk ice, although undisturbed Gardiners clay is probably

gravel member of Manhasset formation). not far below.

Sag Harbor.—Red clay, apparently representing the Gardiners clay, was noted in the
moraine at several points southwest of Sag Harbor and has been worked on a small scale in
times past. One exposure was seen in 1903 on a road through the moraine a mile west of the
Sag Harbor and Bridgehampton road. Gray, red, and greenish clays were seen in an old pit on
a private road between the two highways mentioned. The clay lies 100 feet or more above sea
level and is everywhere disturbed. Its position is apparently due to folding or shove by one
of the ice sheets—presumably
the Montauk. Some pebbly
clays represent the parts re-
worked by the ice. EGA

Montauk.—Half a mile ~~ S a
west of False Point, Montauk, . ;
a good exposure of the dark

chocolate-colored type of the
Gardiners clay was seen. Its relations are brought out in figure 76. Another exposure of

clay, possibly Gardiners, having the relations shown in figure 87 (p. 107), was seen 1} miles
southwest of Montauk Light, and a third exposure, showing upturned clay, was found about
a mile farther west. The thickness exposed was nowhere more than 15 feet, but as the whole
of the formation was not seen the entire thickness may be much greater.

 

 

 

so

 

 

°

 

200 Feet
al

 

FIGURE 76.—Section half a mile west of False Point, Montauk.
100 GEOLOGY OF LONG ISLAND,

Gardiners Island.—Gardiners Island, lying between the North and South flukes, is the type
locality for the Gardiners clay. (See figs. 77 to 81.) On its western shore a few feet of contorted
reddish clays interlaminated with grayish-buff sand representing the top of the Gardiners clay
was seen in a low bluff about a mile north of Great Pond, but it was
not observed again until a point half a mile east of Cherry Hill Point
was reached. Here a succession of black, greenish (fossiliferous), and
red clays, merg-
ing upward, into
9 1s goreet Jacob sand and [-__---

y q °

Figure 77.—Section near Cherry dipping 45 OF INS

Hill Point, Gardiners Island. a, 50° N., was ex- IM
Black clay (Gardiners clay); b, : :

greenish fossiliferous clays (Gar- posed aE gullies

diners); c,red clay (Gardiners);¢, near the shore. jevnrz 78. —Section a ee of a mile east of northwest end of bluffs on
buff sand and clay (Jacob sand); The occurrence northeast coast of Gardiners Island. u, Herod gravel member of Manhasset
e, Wisconsin till. ho formation; b, fine gray Jacob sand; c, red Gardiners clay.

is illustrated in

figure 77, which is a north-south section. Figure 81, representing a section near the south
end of Bostwick Bay, shows the Gardiners clay banking against the Herod gravel member in
an overturned fold. Near the northwest end of the bluffs on the northeast side of the island a
broad anticline (fig. 100, p. 110) brings up
15 to 20 feet of red Gardiners clay, and a
little south is an overturned anticlme of
red clay. The relations are shown in
figure 78. Another exposure is shown in
figure 129 (p. 129). Complicated expo-
sures occur at short intervals as far as
Eastern Plain Point. One of these, show-
ing upturned Gardiners clay, is repre-
sented in figure 79 and Plate XVIII, A.
A still oe remarkable Sor eee is that FIGURE 79.—Section three-quartersof a mile east of northwest end of bluffs on
illustrated m figure 80, which represents northeast coast of Gardiners Island. a, Red Gardiners clay; b, gray clay and
a bluff section about 1,350 feet long show- ees (Jacob sand); c, buff sand (Herod gravel member of Manhasset forma-
ing six distinct. anticlines, several of them te

compressed and aan involving the Gardiners clay. The heights of several of these are
from 100 to 150 feet. The section figured by Veatch and shown here in figure 60 has been
discussed on page 90. Several instructive sections are afforded in the bluffs at the south end

(2)
1
\

 

 

   

 

 

 

 

 

se. ; FIGURE 81.—Section near south
° 200 400 600 Feet end of Bostwick Bay, Gardiners
* ae Island. a, Red clay, greenish
Figure 8).—Section near Whale Hill, Gardiners Island. u, Montauk till member of Manhasset forma- along contact (Gardiners clay);
tion; 6, Gardiners clay. b,sand and gravel (Herod gravel
member of Manhasset forma-

tion).

of Tobacco Lot Bay, in one of which fossils were found in a greenish-black phase of the
Gardiners clay similar to that at Cherry Hill Point.

Plum Island.—On Plum Island, just northeast of Orient Point, the same general features are
shown as on the neighboring parts of Long Island. On the north shore the Gardiners clay,
although nowhere exposed above sea level, is everywhere near the surface, as is indicated by
GARDINERS CLAY, 101

the numerous exposures of Jacob sand. On the south shore the clay is brought to the surface
at one or more points by folds. One of the best of these exposures was that seen near the
southwest end of the bluffs,
where 15 feet of the clay with
the relations indicated in fig-
ure 82 is brought up.

Fishers Island.—The best

SRPOSUTES of the Gard iene pares do arodleawiaontiatienr in Mand, u, Wisconsin till; b, folded and faulted beds of
clay on Fishers Island (see fig ‘ the Herod gravel member of Manhasset formation; c, brown to chocolate-colorcd clay with sand

83) are at the clay pit where = #™® (Gardiners clay).

the section shown in figure 84 was seen. The dip at the pit commonly averages 45° N., pointing
to a fold of considerable magnitude, much greater than was supposed by Ries, who reported
that the disturbance extended only to a depth of 20 to 30 feet. That the folding is essentially

 

 

 

° 50 100 150 Feet

 

 

 

   
 
  

 
 
     

72°00" 71°65"
Pee
ore
ete
oT
cosse ~yoRs s0UND
a pANnP East
Pl s js Pt
— pbk
” g North Dumpling pis
°
” South Flat Hammock
¢* Dumpling? q Clay Pt
Sm
-
~~
North Hf Ronen /
3 08
StlverEe
Pong

 

 

 

a s 15
“Race Pt p 1 ve ° 1 Mile

 

 

 

 

 

 

72°00" 71°85"

 

 

 

FiGure 83.—Index map to localities on Fishers Island. Contour interval 20 fcet.

superficial is likewise believed by the present writer (see fig. 85), but, as indicated by figures 84,
87 (p. 107), and 134 (p. 130), which are drawn to scale, it is certainly much greater than was
stated by Ries. The clay pit was started in a
valley where the clay showed at the surface, but
it has been worked back until now 10 to 30 feet
of till or gravel has to be stripped off. The outer
or upper part of the material worked at the pit
is a brownish sandy clay interlaminated with sand,
perhaps 40 feet thick. The remainder is a dark
grayish blue to nearly black plastic clay, with a

So Feat slight brownish tinge. No pebbles could be found

FicurE 84.—North-south section at Clay Point, Fishers Island by the writer except in the lowest part of the

(June, 1904). @, Wisconsin till; 6, Herod gravel member of Man. clay exposed, where a lens of granitic gravel was
hasset formation; c, interlaminated sand and clay (Jacob sand); : . :
@, dark-gray to brownish-black plastic Gardiners clay. seen, possibly due to the incorporation of some

of the underlying Jameco materials. No fossil

shells or leaves are reported. Some rounded clay concretions occur, and dendritic markings are
found between some of the lamine.

Besides the main folding there are many minor contortions which appear to be due to

movements of the clay layers over one another. The only point besides the clay pit at which

 

 

 
102 GEOLOGY OF LONG ISLAND.

the Gardiners clay is well exposed is at Isabella Beach, where the sections represented in figures
86 and 106 (p.112.) are to be seen. In thesection shown in figure 106 the clay is 12 feet thick,
and consists of alternating layers of gray and chocolate-colored silts, weathering to a somewhat
darker color and dipping about 45° N. At the locality of figure 86 the clays are exposed to a
thickness of more than 20
feet, and occur in a broad
trough coincident with a
surface valley. Clay is
said to have once out-
cropped near Clay Point
on the north shore of the

Ficurn 85.—Generalized section of Fishers Island. a, Wisconsin till; b, Montauk till member of Man- island, but ther oe Re
hasset formation; c, Herod gravel member of Manhasset formation; d, Jacob sand; e, Gardiners clay; noth ing but Wisconsm
f, Jameco gravel; g, Mannetto gravel (?); h, Cretaceous clay; i, light-gray granite. The separation of : :

Jameco and Mannetto is hypothetical. tall to be seen In the low

 

 

PARE ISIS

soo feet

bluffs in that vicinity.
In the base of the bluff forming the headland three-quarters of a mile northeast of the north
end of Isabella Beach there is a few feet of greenish-gray clay, free from pebbles and similar
to parts of the Gardiners clay, but its relations could not be determined. (See fig. 135, p.
130.) At no other point was the clay seen, the hills apparently being composed mainly of sand
and fine gravel. Any storm, however, is likely
to alter the bluffs materially, and if the clay is
above sea level it may be exposed at any time.

DEPOSITS PENETRATED BY WELLS.

 

 

The details of the distribution of the Gar-
diners clay as shown by wells are summarized  Ficure 86.—Northeast-southwest section along Isabella Beach, Fish
in the following table, based on the records Tada...
obtained in connection with the water investiga-
tions. The correlations in general are the same as in the report on the underground waters,!
but in a few records, as in Nos. 71, 188, 258, 262, and 539, the writer from his study of the
surface outcrops is inclined to make slightly different interpretations. Several exposures of
clays that have been reported considerably above sea level on the necks of the north shore and
correlated with the Gardiners (Sankaty of Veatch) have been omitted from the table as more
likely belonging to the Cretaceous. In many of the records the material classed as clay probably
includes the Jacob sand, which can be differentiated only with difficulty in wells.

Gardiners clay penetrated in wells of Long Island.

 

 

 

 

  
  

 
   
 
 

  
    

 

 

 

 

 

No. Locality. Owner or place. Fea Character of the deposits. ee caota: used
Feet.
Rapid Transit Co.......--.-..---.---- (3-189) || Clavie ctions octnaciekiaine coveccce Sankaty.
.| Forest Street and Evergreen Avenue.. 105- BIWG ClO eaccevecterueaereesecs Sankaty or Cretaceous.
Bartlett Street and Flushing Avenue. 87-127 ae or brownish sand and | Sankaty.
ue clay.
62 |...-- Ones aos Seaeeshotis Ten Eyck Street...........-..--2--+-- 75-100 | Blueclay.._..-.........2...-. Sankaty?
65 1.0... dO iecveruas 268 ..| Porter and Maspeth Avenues......... ABET OO  |eeccrass, AAO ic, sichevard d-crasanrapaeioweastacoae Do.
136 | Aqueduct........-.--- Brooklyn test well No. 17............. 95-106 | Dark-gray clay (swamp de- | Sankaty.
osit).
141 | East New York..-..... Brooklyn test well No. 5.............. 216-281 aay Silty Clays oso ices.c cacteniose Do.
176 | North Beach. . ..| Bowery Bay Building Association 32- 36 | Blue and gray clay. ns Do.
187 | Far Rockaway James Caffery AQ 66 | CLAY: arn vecewiceareaeonen Do.
188 |..-.- do.. B. L. Carroll. 45- 65 | Blueclay, without pebb Do.
188 |..-.- WO oapscmeicinnint ne cine esis On ceceee 20- 90 | Blueclay and quicksand Sankaty and Jamecc.
190 Nexus do.....-. Queens County Wa 60-100 | Blueclay............ Sankaty.
193 | Threemile M T.R.Chapman..............--- a 140-202 | Dark clay, some ver, Do.
195 | Aqueduct..... -| Shetucket pumping station 135-146 | Gray clay...-.-...- Do.
199 | Jamaica South........| Oconee pumping Station........ ay 115-145 | Fine gray clay........-. Do.
200 |.-..- Gd Olen a eo eeraa ne Baisley pumping station.............. 106-156 | Blue clay and quicksand... .. Do.

a Numbers refer to well records in report on underground water resources of Long Island, New York, by A. C. Veatch and others (Prof. Paper
U.S. Geol. Survey No. 44, 1906).

 

i Veatch, A. C., Underground water resources of Long Island, New York: Prof. Paper U.S. Geol. Survey No. 44, 1906, pp. 168-337.
GAPDINERS CLAY. 1038

Gardiners clay penetrated in wells of Long Island,.—Coutinued.

 

No. ity. 5 Depth of ones a eibaaducic tind Correlation, with name used
Locality Owner or place. formation. Character of the deposits. in original record.

 

 

     

   
  
 
     
   
  
  

      
   
    
     

 

Feet,
Jameco pumping station. ............. 78-144 | Dark-gray clay, inclosing bed | Sankaty.
iu of yellowish sand.
Brooklyn test well No. 1........---..- 804142 | Gray CIAY 22.42.23 esacsneea canes Do.
-| Brooklyn test woll No, 2...........-.. 83-154 | Dark-gray clay or silty sand... Do.
-| Brooklyn test well No. 3......-.....-. 86-201 | Fine gray silty sand and clay. Do.
-| Brooklyn test well No. 4...........-.- 72-212 | Gray clay.........---2.--.--+- Do.
-| Springfield pumping station.....-.... 65-170 | Gray clay, with included bed Do.
of yellowish-gray sand.
---| Brooklyn test well No. 11............- 95-189 | Gray clay............2..------ Do.
3 Pumping station Jamaica Water Sup- 60-104 | Blue clay............2...----- Do.
ply
+} Pumping station No, Le..s.1 +.» werese D5 4B |e acs Oi is sien ak Shsteeeecedas toe Do.
-| Railroad wells 60- 85 | Clay............. 3 Do.
W. W.Cole.... 16- 70 | Clay and quicksand. . -| Sankaty?
-| G. B. Wilson 65- Blue clay........ -| Not correlated.
-| Bathing Association. ...........--.... 25- 55 | Clay.......-- Sankaty
John Lawrence 40-100 | Sand and clay eee Do.
D. D. Lord.... 35- 70 | Clay, fine gravel, and she = De.
a Ma Woe Bart sriscsocerstumisnccsincicisrcteanian 5 40- 76 | Gray. clay and’ white sand | Sankaty and Jameco.
; . with shells.
Queens County pumping station...... 54-115 | Blue clay, ree sand, and Do.
uartz san
285 | Valley Stream -| Brooklyn test well No. 19...... as 72- 95 | Yellowish-gray clay........-.- Sankaty?
295 | Springland... -| Brooklyn test well No. 10. . dy 80- 94 | Gray lignitic sand and blue | Transition and Sankaty?
ela:
351 | Plandome Mills -| Robert Seizer 50-100 Mud and SAN 2 21652 -| Sankaty?
374 | Barnum Island Poorhouse . 75-113 | Dark clay and lignite Sankaty.
469 | Dosoris...... -| D. F. Bush. . 85- 95 | Reddish sand, gravel, and Do.

ee Bay.. -| Chas. Weeks. -| Sankaty?

  

 

 
    
 

Do
Do.
Do.
Do.
Wisconsin and Tisbury.
Sankaty?
Sankaty.
: i eee .-| Sankaty?
=| William: Trotler <0: s2<22deccee0+3 7 Do.
613 God sp ring Harbor...| Eagle Tete: arceneinssaines Sankaty.
628 | West Neck 2) Bis WARG s ssteaicaanciotas aoe senmytisasas en Sankaty?
629 |..... Olsete erase =) Mrs, M. Hi Clots sicosecscccccauineecies Sankaty.
671 | Muncie Island. =| Bie He Muniz seccesies cregwnccewrdes Sankaty?
691 | Bayshore...... -| Great South Bay Water Co. Do.
801 | Port Jefferson. . Jadu: Darling Sounajsieiaisis gee emanate cre ee Cretaceous?
877 | New Suffolk. . . all RIG Well s.. ss scos.0503 He cedeeneatiesee 1s ¥ Sankaty?
880 | Hampton Park ....... Mrs. S. t MCDOnald . ...i.2e:- etn oe hae 34- 80 Clay (part probably Montauk Do.
till member).
881 |..... O'S eta eedrialdasaveiers E.G. Whittaker..............----.--- 2- 82 | Very thin ey (part probably - Do.
Montauk till member). |
885 | Shelter Island......-.. Jc Ny Stearnes sananectsteeduontateied 27- 35 | Red and blue clay and white | Sankaty.
and red sands.
888 jo... GO 'eieie widteicistergisionts sl Aw O. Ryder. sccaseasyoecntesamesie 344 60- Shel Se iawersresarese in ae waned, 3 Do.
889 |owexc do... .| Shelter Island Heights Association. -.. 60- Red claysccscuicmesd poReeeee se : Do.
892 | Greenport. .| Waterworks 100-150 | Brown clay..................- Do.
901 | Sag Harbor... . All Dic Bes MOPBIS cio2 actors cepciseqmiemisa se 100-132 | Gray or yellow clay......-...- ' Sankaty?
907 Shelter Than sss: Dr. Benjamin: jo 2c.23 cesses eens 45- 60 | Sand, with fossil shells........ ' Sankaty.

 

 

 

 

 

The table brings out the distribution of the Gardiners clay throughout Long Island, except
over the higher Cretaceous areas, which were land masses during its accumulation. In fact,
indications of the clay are found in nearly all the carefully kept records of the deeper wells
outside the Cretaceous areas mentioned, except near Springfield (No. 197), where the overlying
transitional Jacob sand is represented. It is not impossible that in some places, as at Port
Jefferson, certain of the clays reported in the records may be Gardiners instead of Cretaceous.

At the west end of the island, in Brooklyn and vicmity, the formation, which there con-
sists of bluish clay with a few layers of yellowish sand or quicksand, is persistent with a thick-
ness usually of 25 to 50 feet, although in places, as at Porter and Maspeth avenues (No. 65),
much greater thicknesses of clayey material are reported. It is not improbable that the thick-
ness of 142 feet given in this well record includes the Jacob sand and a part of the Manhasset
formation and possibly a part of the Jameco and the Cretaceous. The character of the Gardi-
ners clay in this region is well brought out by the section of the well at Bartlett Street near
Flushing Avenue, which has been given on page 86.

The formation in the region north of Jamaica Bay is described as a gray to almost black
clay, in some places (No. 136) mixed with vegetable matter, suggesting salt-marsh deposits,
and elsewhere (Nos. 295 and 374) carrying more or less lignite, much of it in the form of rounded
fragments, as if derived from the reworking of the Cretaceous. Some greensand (glauconite)
104 GEOLOGY OF LONG ISLAND.

occurs mixed with the green clay near Hewlett and at Rockaway Ridge (No. 2738) and fossils are
found near Lawrence. A typical section of the ordinary nonlignitic type of the Gardiners clay
in the Jamaica Bay region is afforded by the record of the Brooklyn test well No. 3, Brooklyn
Aqueduct and New York Avenue (No. 204), given in the discussion of the Jameco gravel on
page 87.

The tripartite arrangement of the formation—a sand included between two clays—which
is characteristic of the Gardiners clay on the island, is well brought out by this record. Its
thickness in the region under discussion ranges from 11 feet near Aqueduct (Nos. 136 and 195)
to 140 feet near Springfield (No. 205). The changes in thickness are very abrupt, as shown
by a well (No. 197) half a mile east of No. 205, which shows no clay whatever. The difference
is due to a Cretaceous outlier at this point, which, though now buried by later glacial deposits,
stood above the plane of deposition of the Gardiners clay. At Far Rockaway, one of two
adjoining wells (No. 188) showed clay at 45 to 65 feet, and in the other it was reported at 20
to 90 feet. Similar differences occur elsewhere in the region, part being due to causes like the
one above described, part to differences in the amount of deposition, and part possibly to erosion
by the Montauk ice or to stream or wave erosion in later times.

On the north shore 14 feet of blue clay is reported at North Beach, west of Flushing Bay,
20 to 54 feet near Whitestone, 5 to 60 feet near Oyster Bay, and 8 to 58 feet on West Neck.
In composition the clay is somewhat variable. Near Whitestone it is a blue clay associated
with quicksand; at Dosoris a reddish-brown gravel and sand mixed with clay; at Oyster Bay
a greenish clay with some sand; and at West Neck a blue clay. The Dosoris section, which
is somewhat unusual as to materials shown but normal as to its tripartite arrangement, is given
below from Veatch’s report, with the writer’s correlations.

469, Record of D. F. Bush’s well near Dosoris Pond.

Recent: Feet.
Mellowish-browii sand. 2.2.46. ac2ccasnqaccasdeanunied te dod d GeeseniNe els Batata ceeepeed 0-4
Marsh deposits: 12022226 orcemanngntetentcdsdi ee ied ean baat coweaees Sb SUS Ais 4-7

Montauk till member of Manhasset formation: Blue clay with pebbles (‘‘hardpan”)....-.-..- 7 -15

Herod gravel member of Manhasset formation: Quicksand......... ein tnickes nhatate sears 15 -85

Gardiners clay:

Reddish gravel and cla ys.c-veess ven vasdeadedeme yee eee sede taetawbeshe nes pede 85 -88
Very red sandie sev ses es evs as Seseceeiecanwe se veri scden cd eteee@ecuebe yes eetee yt ees 88 -88}
Reddish gravel and clays. 225i. .eiceeecedgd.ees set ea beet eeiecekeed oy tes bee eee 884-95

Jameco gravel: Light-colored gravel with a considerable percentage of glacial material; fur-

nishes artesian water............-.--22-2-----2222-0--0-- esa rola fayaeakaneiaameiset 2 Bimoee a Saayaes 95 -97

The wells of the north shore have in general yielded no fossils from the Gardiners clay.
A ‘‘black marl” containing oyster shells identified by W. H. Dall as Ostrea virginica was reported
at a depth of 18 feet, or about 80 feet above sea level, in a well on Manhasset Neck (No. 364),
northeast of Port Washington, but from the information afforded by adjacent wells and exposures
in. the bluff along the harbor it seems altogether improbable that the Gardiners clay is present
at this elevation. It is more likely that the fossils belong to an old drift, probably the Montauk
till member of the Manhasset, and are of secondary rather than primary origin.

Toward the east end of the island the clays encountered in the wells are more reddish
and are more commonly fossiliferous. Red clays are reported from Shelter Island (Nos. 885
and 889) and Greenport (No. 892). Pleistocene fossils are found at Quogue (No. 859), at
Shelter Island (Nos. 888 and 907), and at Bridgehampton (No. 897). Clays are encountered at
New Suffolk (No. 877), at Hampton Park (Nos. 880 and 881), and near Sag Harbor (No. 901).
In thickness the clay ranges from a few feet on Shelter Island to 50 feet at Greenport, 84 feet
at New Suffolk, and 80 feet at Hampton Park.

AGE,

Two lines of evidence bearing on the age of the Gardiners clay are available, the first being
their fossil content and the second the character of the immediately overlying and underlying
beds.
GARDINERS CLAY. 105

The fossils of glacial formations are either primary—those whose position and condition
are such as to indicate growth in place; secondary—those that have been picked up and rede-
posited by the ice; or tertiary—those that were taken up first by the ice and later by water
before being redeposited. All three kinds are represented on Long Island and great care is
needed in discriminating them. Fortunately, those found in the Gardiners clay in most local-
ities show features that indicate unquestionably their primary character.

Shells of ‘‘clams, oysters, razor fish,” ete., have been repeatedly reported from wells on
Rockaway Ridge and elsewhere on western Long Island in materials associated with the clay,
generally in a sand stained black by organic matter found at the base of the clay. As they
have been found in wells, their occurrence can not be actually observed, but their presence in a
sand carrying lignite and greensand and thoroughly stained with organic matter, in short
possessing the characteristics of sandy marine flats, points strongly to their occurrence in place.

At Fort Hamilton, facing the Narrows at the entrance of New York Bay, Nassa obsoleta,
Crepidula fornicata, Mytilus edulis, Anomia ephippwum, Mya arenaria, and Solen ensis were
reported as being obtained from the Gardiners clay (Sankaty of Veatch) in a well sunk at this
point.

At Bedford, according to Redfield ? and Desor,? were obtained Ostrea, Venus mercenaria,
Purpura lapillus, and Baccium obsoletum.

A specimen of Ostrea virginica was obtained from a well on Manhasset Neck at an elevation
of 80 to 100 feet above sea level, but it is evidently of secondary origin, unless the clay has been
brought to an entirely abnormal and unusual height by the ice shove, which is regarded as
improbable. The clam and oyster shells obtained near the bottom of a 40-foot layer of blue
clay, at a depth of 60 feet below sea level, in a well near the end of the point (No. 368), were
probably in place.

A ‘‘marl bed containing oyster shells” is reported as occurring in a well on Main Street,
Oyster Bay, at a depth of 45 feet, or 35 feet below sea level.‘

Many writers, including Samuel L. Mitchill in 1800, 1813, 1814, and 1818, Timothy Dwight
in 1821, John Finch in 1824, W. W. Mather in 1837 to 1843, Gabriel Farnum in 1875, Elias
Lewis in 1877, Warren Upham in 1879, and F. J. H. Merrill in 1886, have recorded fossil shells
from wells and other sources mainly in the western part of the island at horizons corresponding
to that of the Gardiners clay. (See bibliographic review, pp. 4-22.) Of these writers, Lewis
alone notes the occurrence of shells in wells, the fossils observed by the other writers being in
drift of shallow and possibly post-Wisconsin deposits. The wells noted by Lewis were at Flat-
bush, Prospect Park, Bath, East New York, Farmingdale, and Amagansett. In the field work
for the present report shells of Pecten were reported in two wells at Hampton Park (Nos. 880
and 881

The best exposures of fossiliferous strata are found on Gardiners Island, two localities yield-
ing shells in place. One of these localities is just east of Cherry Hill Point, the western extremity
of the island. A diagram of the beds at this place is shown in figure 7 7 (p. 100). The thick-
ness of the strata from top downward are as follows:

Section of fossiliferous series near Cherry Hill Point.

Wisconsin: Till resting conformably across edge of following bed...........--..----.........-- 2
Jacob sand: Sand and sandy clay in alternating layers.........---.--.-----2--2--..-02200------ 5
Gardiners clay:
Red clay with a little lignite...........-------- piesa Sa ShSraWhe dose NN ois Canale Wists ala etdatate ee 15
Greenish clay with Pleistocene fauna in place......--...---.---++-- 22+ - 502-20 eee eee ee eee 10
Black clay with organic matter, exposed.......--.-.---- +++ ++- 022222 eee ee ere ee eee eee eee 3

 

1 Veatch, A. C., op. cit., p. 168.
2 Am. Jour. Agr. and Sci., vol. 6, 1847, pp. 213-219; Am. Jour. Sci., 2d ser. , Vol. 5, 1848, pp. 110-111; Proc. Boston Soc. Nat. Hist., vol. 4, 1854,
181.
a 3 Proc. Boston Soc. Nat. Hist., vol. 2, 1848, p. 247; vol. 4, 1854, pp. 180-181.
4 Woodworth, J. B., Bull. New York State Mus. No. 48, 1901, p. 661.
106 GEOLOGY OF LONG ISLAND,

The fossils collected by Veatch at this point were identified by Dall as Arca crenella,
Modiola sp., and Cyprina islandica Gmelin. Considerable numbers of each of the forms occur.

On Shelter Island shells were reported in great variety at a depth of 60 feet in the well
of A.O. Ryder. At Quogue, on the south side of Long Island, fragments of shells brought up
from a depth of 135 feet in the well of A. B. Hallock (No. 859) were examined by Dall, who
states that the material contained ‘‘fragments of Mulina, Astarte, an unidentifiable bivalve,
a specimen of Nassa trivittata Say, and fragments of an echinoderm. This is probably
Pleistocene.’ Pieces of shells embedded in greenish clay (the usual character of the fossil-
iferous part of the Gardiners clay) were brought up from a depth of 100 feet in the well of
Sanford & Son at Bridgehampton (No. 897).

Broken shells of species now existing were found about one-fourth of a mile south of the
north end of the bluffs on the west side of Hog Neck, 3 miles northwest of Sag Harbor. They
. occurred in a greenish-blue clay, which, however, contains a few erratic pebbles, indicating
that it has been reworked by the Montauk ice. Although strictly speaking they are in till,
there is practically no’doubt that they were derived from the Gardiners clay of the immediate
vicinity. Small fragments of broken shells were seen in the Hempstead gravel member of the
Manhasset formation at one or more points but are apparently of secondary or tertiary
origin.

From the distribution of the fossils it will be seen that they constitute a persistent feature
of the Gardiners clay, occurring at all levels {rom the transitional basal sands, as at the Rock-
away Ridge locality, to the middle, as at Gardiners Island. They also occur in the sands
above the clays on Gardiners and Robins islands and Nantucket, a fact which would seem
to indicate that the conditions were very similar throughout the period of accumulation, being
in fact not very different from those existing on the southern coasts of New England
to-day.

Besides the fossil shells, lignite and other forms of organic matter are of common occur-
rence in the Gardiners clay, especially near the west end of the island, and are found in small
amounts as far east as Gardiners Island. In some places the black muck brought up from
wells so closely resembles the muck of the present bavs in color, texture, and odor that the
two are practically indistinguishable. Some of the lignite is rounded as if rolled about by the
waves, indicating an origin at sea level. It is thus seen that parts of the deposits have a close
resemblance to salt-marsh or shallow-lagoon deposits.

Lignite and other woody materials were reported by many of the early investigators as
occurring in the wells of western Long Island at horizons not far from that of the Gardiners
clay. Probably some of these materials, especially the true lignites, are from the Gardiners
clay, but it seems likely that many of the fresher fragments described as wood, tree trunks,
branching trees, etc., are younger, probably representing soil zones of the Vineyard inter-
glacial stage.

The Gardiners clay, as indicated by its fossils and its wood and lignitic content, muck, etc.,
must undoubtedly be regarded as an interglacial deposit. Below it lies the Jameco gravel,
which, as has been stated, is probably of glacial origin, and above it is the great Manhasset
formation (preceded by the transitional Jacob sand), consisting of unfossiliferous gravels with
a thick intercalated till member (Montauk), all of which are likewise thought to be of glacial
derivation. If the tentative correlation of these glacial formations with the Kansan and
Tllinoian glacial stages should prove correct, it would fix the time of the Gardiners clay as cor-
responding to the stage known in the interior of the country as the Yarmouth interglacial stage.

JACOB SAND.
NAME.

The Gardiners clay grades upward through interlaminated clays and sands into fine silty
sands. When wet many of these sands are somewhat plastic and show a pinkish tinge due to
their clay content, which gives them a certain resemblance to the Gardiners clay. Although
their deposition followed without a break that of the Gardiners clay, they nevertheless show
sufficient lithologic difference from that formation to permit their recognition throughout
JACOB SAND, 107

Long Island and the islands farther east. Their lithologic characteristics, marking a distinct and
persistent change in the conditions of deposition, entitle the beds to recognition as a separate
formation.

To this formation the name Jacob sand has been applied, from Jacob Hill, a high point on
the north shore of Long Island, 8 miles northeast of Riverhead, near which the formation is
well exposed.

CHARACTER.

In its most characteristic form the Jacob sand consists of exceedingly fine sands, mainly
quartz flour, but with many grains of white mica and some of dark-colored minerals. In color
the sands commonly range from a very light gray to yellowish and buff tints, but where laminz
of true clay are present they may be stained reddish externally. They are everywhere clearly
stratified, although individual beds several feet thick and appearing structureless to the eye are
encountered. When wet most of them are somewhat plastic but lack the toughness of true
clay; all are decidedly gritty to the teeth and most of them to the touch. Interbedded with the
fine varieties of the Jacob deposits are some more distinctly sandy beds, usually buff or yellow-
ish, and several feet thick, in which particles of fairly fresh granitic minerals can be recognized.

SOURCE OF MATERIAL.

Whether the gradual change from plastic clays to the exceedingly fine, claylike quartz sands
of the Jacob formation was due to a change in level, to a change in direction and strength of the
currents, to the advent in the region of the finer materials from the outwash of an advancing
ice sheet, or to a combination of all these factors, can not be stated definitely.

Perhaps the best clue to the source of the material is afforded by the general sequence of the
deposits. Following the fine plastic Gardiners clay, whose character indicates, in all probability,
a very slow accumulation under conditions of scanty supply, the Jacob sand affords indica-
tions of increased supply and more rapid accumulation, and the succeeding Herod gravel
member of the Manhasset formation affords evidence of stil more rapid deposition and the
near approach of the ice sheet associated with the Montauk till member of the Manhasset. In
other words, the Jacob sand seems to mark the first influx of new material on the advance of
the ice sheet, bringing to a close the interglacial stage characterized by the Gardiners clay.

RELATION TO OLDER DEPOSITS,

As previously noted, the Jacob sand in many places merges by insensible gradations into the
Gardiners clay, although elsewhere the sand gives way to the clay more abruptly. It has not
been seen in contact with beds older than the Gardiners, but it must overlap the Mannetto or
Cretaceous at many points below sea level.

CHARACTER OF THE UPPER CONTACT.

Toward the top of the formation the beds grade upward into medium and then into coarse
sands, which in turn give way to the Herod gravel member of the Manhasset. These upper
sands are buff in color and in places reach a thickness of 15 to 30 feet. It is possibly in a sandy
layer of this type that the fossils found
in the bluffs on the shores of Great
Peconic Bay, 2 miles west of the Shin-
necock Canal, occurred. (See fig. 117,
p. 126.)

Owing to local nondeposition of 5 190 ee

 

 

the Herod gr avel member, or more FIGURE 87.—Section 13 miles southwest of Montauk Light. a, Banded Montauk
commonly to erosion by the Montauk till member of Manhasset formation; b, Herod gravel member of the Manhasset;

ice, the Montauk till member of tho ;,qgit! say Jesh rdf toett hy itm
Manhasset formation in places rests

directly upon the Jacob sand. Generally the bedding of the sand and till is conformable, but in
a few places the Montauk rests on upturned or folded Jacob beds, which have locally been more or
less eroded. This is brought out in figure 59 (p. 89) and especially in figure 87, which shows the
108 GEOLOGY OF LONG ISLAND.

Montauk member resting on the disturbed or eroded Jacob sand. Both the folding and the
erosion, to judge from the contour of the resulting surface, seem to have been due to ice, pre-
sumably to the same sheet that later deposited the overlying Montauk till member. The uncon-
formity due to erosion in many places amounts to many feet and differs from place to place.
At some points the work of the Montauk ice sheet was wholly erosional, there being no deposi-
tion of drift, and at such places the overlying Hempstead gravel member of the Manhasset may
rest directly upon the Jacob sand. Where the Montauk rests upon the sand considerable
quantities of the sand have been incorporated in it, giving it a noticeably silty texture, which
has been a potent cause of the characteristic cementation of the till. As in the Gardiners clay,
there are all gradations between the undisturbed deposits through reworked Jacob sand into

silty till.
STRUCTURE.
What has already been said as to the structure of the Gardiners clay applies with equal
force to the Jacob sand. Though classed as sand, its texture was so fine and it contained so
much silt that it behaved like clay under the action of the overriding ice, being bent, folded,
crumpled, and overturned instead of crumbling and disintegrating as the coarser sands and
gravels commonly did. Lying stratigraphically higher, and hence nearer the surface, it was
more subject to disturbance than the Gardiners clay and has been exposed at more places along
the coast. The Jacob sand, like the clay, is most disturbed along the north coast, especially
near the east end of the island, exhibiting more gentle folds in the southern part. Most of the
folds trend approximately east and west, although on the sides of the bays the lateral thrust
has in places, as at Port Washington, produced folds with north-south axes. Details of the
folding are given in the section on distribution below.

DISTRIBUTION.

SURFACE EXPOSURES.

The distribution of the Jacob sand on Long Island is in general the same as that of the
Gardiners clay, although from its position above the clay it is more exposed..

College Point.—The most westerly outcrop noted was at the base of the bluff between College
Point and Tallman Island, where several feet of fine light-gray micaceous sand was exposed in
1904 near tide level in a nearly horizontal position.

Port Washington.—The next locality toward the east at which the Jacob sand was seen is
near Plum Point, on the east side of Manhasset Bay, 14 miles northwest of the town of Port

Washington. At many points near and at the

SERS Rae 0 Ne 2.2 — bottom of the immense abandoned gravel pit at

oe ZnS the base of Plum Point the Jacob sand was for-

2 be GEN a oe ee merly to. be seen, limiting the depth to which

(HEX gravel and sand (Herod member) could be taken

FiaurE 88.—Section northof Weeks Point, Hempstead Harbor. a,Wis- Out. The exposures in this pit at the time of the

Ce aaa till member of Manhasset formation; c, contorted writer's visits, in 1903 and 1904, did not admit of

a determination of the structure of the forma-

tion, but in a similar pit near the shore about a quarter of a mile southeast a fine pinnacle of light-
gray, highly contorted clayey sand was seen.

Hempstead Harbor.—The Jacob sand is exposed at many points on the east side of Hemp-
stead Harbor. A little north of Weeks Point, about 14 miles northwest of Glen Cove, a sharp
fold of Jacob sand rising 20 feet above the beach and having a breadth of about 40 feet was seen
(fig. 88). Between Red Spring Point and Glen Cove Landing the sand was observed at several
places, and still farther south, near Glenwood Landing, a pinnacle of light-gray Jacob sand
rising about 10 feet above the floor of a large gravel pit (Herod gravel member) was seen.

Oyster Bay.—The Jacob sand was exposed in 1904 at the top of the bluff at Rocky Point,
2 miles north of the town of Oyster Bay. The bed was very thin and in places had been entirely
removed by the Montauk ice (fig. 65, p. 96). An exposure of Jacob materials is also reported
at the extreme southwest point of Center Island, and the sand of the same formation was again
seen in the beach below high-tide level near the west end of Coopers Bluff, northeast of the town.

 

 

 

 
JACOB SAND. 109

Lloyd and Eaton necks.—On Lloyd and Eaton necks the Jacob sand appears to be either below
sea level or to have been removed by ice erosion (Montauk), the drift of this sheet generally

 

9 50 Feet

 

FiGurE 89.—Section a quarter of
a mile west of Hallock Land-
ing. a, Herod gravel member
of Manhasset formation (struc-
ture not shown); b, contorted
grayclayey sands(Jacob sand).

resting directly
upon the Creta-
ceous.

Northport to
Port J efferson.—
Throughout the
stretch of nearly
15 miles east
from Northport
the Jacob sand
appears to he  Fieure 90.—Sectionnear Woodville Landing. a, Upturned sand and gravel (Herod
below sea, level. are member of Manhasset formation); b, contorted and folded Jacob sand;
At the only place
where the lower beds are seen, which is on the coast 3 miles northeast of

 

 

° 50 Feet

 

Northport and about a mile north of the village of Fort Salonga, the Jacob and associated beds
appeared to be absent, the Montauk till member

resting immediately upon the Cretaceous clays.

 

FicurE 91.—Section at landing west of s
Jacob Point. a, Banded clayey till of Hallock Landing (fig 2

Port Jefferson to
Wading River.—Be-
yond Miller Place expo-
sures are fairly com-
mon. The first good
outcrop seen was a
quarter of a mile west 6 100 200 Feet”

 

 

FIGURE 92.—Section near Jacob Hill. uw, Till; 6, Herod gravel

(Montauk till member of Manhasset 89) ) where the clayey member of Manhasset formation; c, upturned and contorted
formation); b, pink till, gray clay, sands are upturned at pinkish to buff clayey Jacob sand; d, former extension of bluff.

and sand (Jacob sand).

Relations to sand not shown.

a high angle because of

both folding andfaulting. Two miles farther (about half a mile east of Woodville Landing) highly

 

disturbed sands of the Jacob type are again seen (fig. 90).

Wading River to Orient Point.—For the next 10
miles the Jacob sand is not exposed, being below sea
level along the bluffs. It first reappears in upturned
and contorted masses a little east of Roanoke Landing,
north of Centerville (fig. 71, p. 98). Two miles east, at
the landing west of Jacob Point, the Jacob sand is
nearly on end in a small ravine (fig. 91) and at several
points along the
beach for three-
fourths of a mile
or more, beyond
which it again
sinks below sea
level. It was
next seen 24

 

 

 

 

: o 100 Feet
ae |
° soFeet miles farther
ace enna ieacieresll i 4.—Secti : wats
e ast, in the bluft FIGURE 9. ection at Brown Hills,near Orient. a, Gray

FIGURE 93.—Section at Jacob Hill. a, Dune sand; b, band-

to buff sands (relations to clay not clear, but proba-

ed Montauk till member of Manhasset formation; e, at J acob Hill, bly the same as in fig. 97); b, dark clay (Jacol sand);
brown clayey Jacob sand; d, buff clayey Jacob sand wh ere gr eat pin- c, yellowish upthrust sands (Herod gravel member of

(poorly exposed).

Manhasset formation).
nacles composed

of Gardiners clay and Jacob sand stand out from the bluff (fig. 92). Still better expo-
sures, however, were found a quarter of a mile farther on, where some 60 feet or more of
110 GEOLOGY OF LONG ISLAND.

brown and buff clayey sand or sandy clay of the Jacob type is exposed (fig. 93). In the 20 miles
or more of coast between this locality and Orient Point the Jacob sand is exposed at only one
place—in the bluffs of Brown Hills, northeast of Orient village.
Here the exposures are much the same as at the point last
described, the sands be-
ing highly disturbed,
folded, and contorted.
Something of the present
character of the outcrops
and the unconformable
relation of the overlying

 

 

 

 

 

 

 

FIGuRE 95.—Section at Brown Hills, near Orient. a, Dune

a 7 + 30 Feet
sand; b, Wisconsin till; c, sand and gravel (Herod gravel sand is shown in figures a
member of Manhasset formation); d, very fine disturbed 94, 9 5, 96, and 97. FIGURE 96.—Section at Brown Hills, near
elayey sands (Jacob sand) standing out in detached Orient. a, Till (Montauk till member of
masses. Relations probably the same as in figure 97. Robins and Shelter Manhasset formation); b, gray clayey sands.

islands.—South of the

North Fluke the Jacob sand is well exposed on Robins Island, where it occurs on the west
side, about 500 yards south of the north end of the cliffs, both in broad open folds and in
highly upturned masses, like those shown in figure
74 (p. 99). Fossils occur in the bed shown in figure
98. The Jacob sand appears to be penetrated by
wells on Shelter Island but is not clearly developed
above sea level.

  

 

 

 

 

oO 50 100 Feet
t 2 : FiGurRE 98.—Section on west side of RobinsIsland. a, Till; b,
Figure 97.—Section at Brown Hills, near Orient. a, Till; b, folded buff sand (Herod gravel member of Manhasset forma-
Herod gravel member of Manhasset formation; c, disturbed tion); c, thin layer of cemented gravel; d, gray clayey Jacob
clayey Jacob sand. sand, with fossils at e.

Gardiners Island.—On Gardiners Island the Jacob sand is abundant, occurring in many
places and reaching thicknesses of 20, 30, and perhaps 50 feet. Evidence of local and temporary
returns to conditions favoring the deposition of clay
is afforded by thin clays alternating with beds of Jacob
sand.

The Jacob formation, consisting of alternating
Figur 99.—Section half a mile north of Cherry Hin Point, Clay and fine sand, was seen above the red clay at the

Gardiners Island. a, Herod gravel member of Manhasset fossil locality east of Cherry Hill Point (fig. 77, p. 100).

AORN Si aR EPy ele eR PCIe Half a mile north of the point the Jacob in the form
of finely stratified gray sand with ripples (a common phase on

Gardiners Island) was seen in nearly horizontal beds (fig. 99). 38‘

Near the north end of the cliffs on the northeast shore it is

Oe Se involved in both Z

Ss open (fig. 100) .
and overturned Figure 100.—Section near west end of bluffs on

SS
folds (fig. 78, p- northeast shore of Gardiners Island. a, Red
fo} ay Fe 100) ; A quarter Gardinersclay; b, gray clayey Jacob sand.

FIGURE 101.—Sections half a mile east of west end of bluffs on north- : Bas os a <
east coast of Gardiners Island, showing fine gray folded Jacob of a mile southeast it is again seen in overturned

sand overlain by till. folds (fig. 101 a, 6), and 350 paces farther in the
same direction it is involved in the highly contorted mass shown in figure 79 (p. 100)
and Plate XVIII, A, the bedding being practically vertical. Other exposures are shown in
figures 129 and 130 (p. ——). The Jacob sand continues in constant association with the

 

 

 

 

If

 

/

 

 

 

 

 

 
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 8&2 PLATE XVIII

 

 

 

 

 

-l UPTURNED GARDINERS CLAY AND JACOB SAND ON EAST COAST OF
GARDINERS ISLAND.

 

 

 

 

 

OVERTURNED FOLD OF JACOB SAND LYING ON HEROD GRAVEL MEMBER
OF MANHASSET FORMATION, EAST COAST OF GARDINERS ISLAND.

So
JACOB SAND. 111

Gardiners clay in the 1,350-foot section represented in figure 80 (p. 100), near the end of
the bluffs toward Eastern Plain Point. The details of one of the overturned and recum-
bent folds in this section are shown in Plate XVIII, B. The Jacob sand occurs here and
there in the bluffs bordering Tobacco Lot Bay, but the beds are so contorted, faulted, and

otherwise broken up that they

   

I

300 Feet
FicuRE 103.—Section along middle of south side of Plum Island. a, Till (Wisconsin ?); b, greenish clayey sand (Montauk till member of Manhasset formation?); c, talus,

 

 

 

 

Montauk type; d, Herod gravel member of Manhasset formation; ¢, gray clayey sand, in places brown or pinkish (Jacob sand).

form a confused
jumble, the rela-
tions of which it
would take weeks :
to work out in de- Oo 100 Feet
tail. Fossils occur

 

x FiGuRE 102.—Section half a mile west of landing, Plum Island. a, Till; 6, Herod gravel
in the Jacob at one member of Manhasset formation; c, fine micaceous contorted Jacob sand.

point.

South Fluke-——The Jacob sand is commonly absent on the South Fluke,
owing to erosion by the Montauk ice. It occurs, however, at several points on
Montauk peninsula. A mile west of Rocky Point, on Napeague Bay, contorted
sand, possibly the Jacob, is present near the top of the bluff (fig. 126, p. 128).
Half a mile west of False Point, northwest of Montauk Light, sands and gravels
are seen between the Gardiners clay and the Montauk till member of the
Manhasset
formation,
probably
representing
the com- oO 50 100 Feet
bined Jacob :

FIGuRE 104.—Section east of Fort Terry, south side of Plum Island. a, Montauk till member of
sand and Manhasset formation: b, Herod gravel member of Manhasset formation; c, brown to reddish clay
Herod gravel interlaminated with sand (Jacob sand).
member of the Manhasset (fig. 76, p. 99). Two miles east of Ditch Plain life saving
station beds of fine sand interlaminated with chocolate-colored clay are seen rest-
ing on a series of greenish-gray sands and fine yellowish gravels, the whole being
much eroded and overlain in turn by the Montauk till member (fig. 59, p. 89).
This might be either an overturned and recumbent fold of Jacob sand upon the
Herod gravel member or a sandy phase of the Gardiners clay resting on Jameco
gravel. The former is regarded as the more probable. A mile and a half south-
west of Montauk Light there is some highly disturbed and folded Jacob sand
having the relations shown in figure 87 (p. 107).

Plum Island.—The Jacob sand is seen below the Herod gravel member in
a broad,
low anti-
cline half
a mile
west of
the Plum
Island

landing o
102) FIGURE 105.—Section east of Fort Terry, south side of Plum Island, showing part of overturned fold in
(fig. clayey sands (Jacob sand ?).

 

 

 

 

20’

 

 

 

 

and at in- ;
tervals from this point to the lighthouse. It is everywhere disturbed, the bed-
ding standing in places at an angle of 50°, and it probably occurs in a succession

of folds similar to that illustrated. On the south of the island it is seen involved in broad, low
folds from the west end of the bluffs to Fort Terry (fig. 103). About half a mile east of the fort
it appears to be involved in several overturned and recumbent folds, having the relations shown
in figures 104 and 105.
112 GEOLOGY OF LONG ISLAND,

Fishers Island —The best exposures of the Jacob sand on Fishers Island are to be seen in
the clay pit and in thesections at Isabella Beach. In the pit (fig. 84, p.101) there is 40 feet of
brownish sandy clay interlaminated with sands and overlying the darker and more plastic
Gardiners clay into which it grades. At one of the Isabella Beach localities the Jacob sand
is represented by 15 feet of fine gray clayey sand (fig. 86, p. 102). At the other about 35 feet
of the Jacob appears with the top unexposed (fig. 106); the
lower 15 feet is of the usual gray-green clayey-sand type, but the
upper 20 feet approaches a gray sandy clay in character. In
an artificial cut near the steamboat wharf on the west side of West
Harbor a considerable amount of grayish clayey sand of the
Jacob type is exposed, as shown in figure 173 (p.147). The rela-
tions shown in the right-hand half of the figure, particularly the
upturning and unconformity, are especially characteristic of the

- ae conditions at the Jacob stage in Long Island and farther east;

ee STON HTT MN AL ee but nowhere else, save at Sankaty Head, Nantucket, has a gravel

Fishers Island. u, Wisconsin till; b, gray been seen interbedded with the sands, as shown in the left-

ae ees Foe hand part of the figure. There is also somewhat less of the old

ing to Jacob sand; ¢, gray sand belonging to look characteristic of most exposures of the drift of this stage,

Jacob sand; /, chocolate-colored and gray Jyyt this may be due to the freshness of the artificial exposure.
clay (Gardiners clay). 5 aks : 4

The topography, moreover, has a distinctly pre-Wisconsin

aspect, and the overlying till resembles the Montauk member rather than the Wisconsin. For

these reasons it seems probable that the clayey sands are to be referred to the Jacob sand.

Along the base of the bluff on the south side of the high hill south of West Harbor a thick-
ness of 10 feet of pinkish and brown sandy clay alternating with lamine of sand is exposed in a
low anticline about 100 feet across and a few feet high. This belongs without doubt to the
Jacob sand.

   

?
7)
yy

   

WP
Oi

 

DEPOSITS PENETRATED BY WELLS.

Because of the extreme fineness of the sand and the admixture of more or less clay it is very
difficult to differentiate the Jacob sand from the Gardiners clay in drilled or driven wells, or
those sunk by the jet process, and although surface exposures prove that the formation is
fairly persistent throughout the whole of Long Island, it appears to have beer. recognized as a
distinct bed in only a few wells. In most of the well records it is doubtless included in the
Gardiners clay. Some of the records, with correlations of the writer, are given below.

Probably the best record is that of a well near Hewlett Point, at the west side of the entrance
to Manhasset Bay.

258. Record of G. B. Wilson’s well, near Hewlett Pojynt.

Recent: Feet.
Dug well (iresh water, slightly hard)-..........2..-..0.0.02020.0.00.000-0 020 cee eee eee ee eee 0-14
Beate Gam dies. ek S ae sats saa alta tc bela areata ok oo cedeShdveiauiysysl bby oa claw Sayama aees 14-20

Montauk till member of Manhasset formation:

Light-colored clay with stone....... 2.2.2... 2.222000 e eee eee eee eee 20-30
Quicksand .s.:iciS25 2255262 eahatoaseewans Sos Soe Ree eeamG imo ee uw aceMee Meee eeens 30-32
DtODY Clays ences seine ee wipes Santee Se ieletajslg ed a paige oma ne eee ee ued Cle ok 32-36

Herod gravel member of Manhasset formation: Coarse gray sand containing salt water at 46

feet and brackish water at 59 feet.-...... 22.22.0222 cece cence eee eee eens eee 36-59

Jacob sand:

Alternate layers of sand and clay.....-.-. 2.2 2.2.000 0022022 c cence eee eee eee ee 59-63
WellOwishisantd ceeds 855: 2558 ac ataeaada beans c oo RamEcunnna Osos Mataaanmine ee ad aes 63-65

Gardiners Clay® BIMG-Clay..tcsneiecemd-s nape censceys posi sal denials ee by ea Geene eee os ece 65-

Jameco gravel:

Fine yellow and grayish pand -..0.3 sce. seek oes ege says geawen esas ene wahowuauecoeees —103
lard patlccscs vane? sealed 52 guels hades UA Suc ee Uae Qeubuuitial ARS Bidaae A ORON Lames 103-105

Yellow gravel with fresh water. ........2..2000002200 0200 c cece cee eee eee cece eceeee 105-108
JACOB SAND. 113

The record of a well on the Dodge estate, near Port Washington, is of interest as showing the
tendency to identify the Jacob as a clay. There is little reason to doubt that the dry yellow
clay of the record represents the Jacob sand, for the Gardiners clay, so far as known, is nowhere
yellow, whereas the Jacob sand is in many places buff or iron stained.

$66. Record of well of Dodge estate, near Port Washington.

Feet
Wisconsin: Yellow stony loaMens: 24: scaieseseeee eve e5b4 S548 Soules Vy ooee4 oo: hedee eee oes 0-6
Hempstead gravel member of Manhasset formation: Fine dry sand...................-2-.-.-. 6-16
Montauk till member of Manhasset formation: Rough stratum of cobbles with scarcely any
Sand DELWECT 22 senduc anaes 24.122. cetda Oaeeeneade se aas anne aek deren SNAG in hana 16-22
Herod gravel member of Manhasset. formation:
White building sind; very compat ..< c.s..sc. ss eas gaa ceaddeeees says seeces yeesengaus sas. DVM
White loosevdrarsand wuses nese ceed euiceeeee se os 22 ai BESSA EEE BELO 2be NE 4 nenwehadke ed aescs 10-50
Jacob sand? Wellow:day: Clayies. zacuss 4 cyvuewara vce ssacers 2oeSekS vege ies nse e Qoece ns ases oa DORAL
Gardiners clay: Blue clay, containing some water..........2..2-2-.-2-000 00000022 e eee eee eee 71-91
The record of a well on West Neck also suggests the Jacob:
629. Record of Mrs. M. H. Clots’s well, West Neck.
Feet
Wisconsin: Surtacé loamt.cos meas seacais eye ese cendanewtionins ag Peewee Aede eee sive cas 0-10
Montauk till member of Manhasset formation: Hardpan with gravel..........2.............. 10-25
Herod gravel member of Manhasset formation and Jacob sand: Fine brown sand; a little clay... 25-85
Gardimers: lay BIM@uClay - fo cicitrieced on ee oneeae cra huaei es a DLSs a5 hed semua eee aueins 85-93
Jameco(?) gravel: Brown gravelly sand; water bearing...............2-.2..2..22-22--2-2... 93-97
AGE.

The Jacob sand is a transitional deposit between the Gardiners clay (here considered as
representing the Yarmouth interglacial stage) and the Herod gravel member of the Manhasset
formation (considered as representing a part of the Illinoian glacial stage), but is regarded as
belonging to the Illinoian stage. There is reason to believe that the change in deposition, as
was pointed out in the discussion of the source of material (p. 107), was caused by the advent
of glacial silts brought down from the north during the advance of the Montauk ice, but long
before it invaded the region under discussion. The character of its fossils seems to indicate
that the climate at the time of its deposition did not materially differ from that existing during
the accumulation of the Gardiners clay.

The best locality for fossils is near the south end of the cliffs on the east side of Gardiners
Island and south of the point at the south end of Tobacco Lot Bay. Fossils from a 4-foot bed
of sand and fine gravel (Jacob) at this point were described as early as 1867 by Sanderson
Smith,! who gave a list of 25 species, all of which except one or two inhabit the waters south of
Cape Cod at the present time. The shells, however, had a more northern aspect than those of
the species now inhabiting these waters. The species are as follows:

Small coral. Arca transversa Say.
Tornatella punctostriata Adams. Arca pexata Say?

Bulla canaliculata Gould. Ostrea borealis Lam.
Fusus decemcostatus Say. Pecten islandicus Chemn.
Purpura lapillus Lam. Pecten magellanicus Lam.
Nassa trivittata Say. Cardita borealis Conrad.
Nassa vibex Say. Astarte sulcata Fleming.
Columbella lunata Sowerby. Lucina radula Gould?
Chemnitzia interrupta Stimpson. Venus mercenaria Linn.
Crepidula unguiformis Lam. Mactra laterales Say.
Crepidula fornicata Lam. Mya arenaria Linn.
Natica duplicata Say. Balanus fragment.

Natica heros or triseriata?

 

1 Annals New York Lyceum Nat. Hist., vol. 4, 1867, pp. 140-151.
1629°—14—_9
114 GEOLOGY OF LONG ISLAND.

A collection made by Veatch from sandy clays and sands at the same point and examined
by Dall afforded the following species:

Chrypodomus pygmzeus Gould. Astarte elliptica Brown.
Chrypodomus decemcostatus Say. Thracia conradi Couthuoy.
Natica (Lunatia) heros Say. Cyprina islandica Gmelin.

Pecten magellanicus Gmelin.

Fossil fragments have also been found in the Jacob sand on Robins Island. (See fig.
98, p. 110.)

The views of Sanderson Smith as to the northern aspect of the forms were corroborated
by Dall, who says: ‘‘The material appears to be practically identical from both localities [on
Gardiners Island] and to represent the fauna now existing in the Gulf of Maine or on the coast
north of Cape Cod, a little colder water being indicated than is now found south of the cape.”

The extensive fauna from the same horizon at Sankaty Head, Nantucket, likewise points
to temperatures no colder than those of northern New England.t As the accumulation of ice
for the next invasion had begun, however, the beds must be classed with the Illinoian rather
than with the Yarmouth stage.

MANHASSET FORMATION.

NAME.

Although the body of the deposits succeeding the Jacob sand may be subdivided into three
distinct units, there are places, even in the best of cliff exposures, where the middle division is
absent and the upper and lower beds, consisting of gravels of similar characteristics, unite to
form a single unit. The combined beds give rise to the broad plateau stretching between the
northern moraine and the north coast and projecting through the outwash plain here and there
south of the outer moraine. Because the middle bed is locally absent, and because the deposits
constitute a topographic unit and in the absence of cliff and other sections it is in places diffi-
cult to recognize the component members, it is necessary for their proper discussion to have a
general term for the deposits as a whole. The term Manhasset is here used as a collective name
for the beds referred to, beng taken from Manhasset Neck, along the shores of which, in the
immense gravel pits on the Hempstead Harbor side, are to be seen exposures of these beds more
than 100 feet in height. The name was first applied by J. B. Woodworth,? who described and
mapped in detail the deposits in a part of the west end of the island.

Veatch, in his report on water resources, substituted the term Tisbury for Manhasset, on
the supposition that the beds were the equivalent of Woodworth’s Tisbury beds of Marthas
Vineyard,’ which consist of stratified clays and clayey sands with some bowlders suggesting till
outcropping along the north shore. The horizontality of these beds on Marthas Vineyard is
emphasized by Woodworth, who says: ‘Their marked horizontality is strongly contrasted with
the dislocated attitude of the beds in the outcrops of the older folded series which appear at in-
tervals along the shore.” Horizontality was in fact, according to information furnished to the
writer by Prof. Woodworth, the principal criterion of recognition. Inasmuch as the beds of the
lower part of the Manhasset formation on Long Island, as well as the corresponding beds on
Marthas Vineyard (included by Woodworth in his Sankaty), are strongly folded (see Pl. XIX,
A), it isevident that the term Tisbury as originally used was intended to cover only the undis-
turbed beds laid down subsequent to the epoch of folding due to the Montauk ice. In other
words, it was probably used for the beds here described as the Hempstead gravel member of
the Manhasset formation, although this correlation is only approximate. For these reasons it
seems best to adopt the term (Manhasset) originally applied to the beds on Long Island rather
than use the Marthas Vineyard term in a way apparently not intended by the geologist who pro-
posed it. The relations of the Marthas Vineyard and Long Island terms are approximately as
follows:

 

1 Desor, E., and Cabot, i. C., Quart. Jour. Geol. Soc. London, vol. 5, 1849, pp. 340-344. Verrill, A. E., Am. Jour. Sci., 3d ser., vol. 10, 1875,
pp. 364-375. Cushman, J. A., Am. Geologist, vol. 34, 1904, pp. 106-109.

2 Bull. New York State Mus. Nat. Hist. No. 48, 1901, map.

3 Seventeenth Ann. Rept. U.S. Geol. Survey, pt. 1, 1896, p. 977.
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 82 PLATE XIX

 

 

 

 

 

A. FOLDED BEDS OF MANHASSET FORMATION NEAR TOM POINT,
PORT WASHINGTON.

 

 

 

 

 

 

BR BANDED MONTAUK TILL MEMBER OF MANHASSET FORMATION
NEAR FRIARS HEAD.
MANHASSET FORMATION. 115

 

 

 

 

 

 

 

Long Island (this report). Marthas Na enentin

§ Hempstead gravel member. Tisbury beds.
ei a (eee lak ‘
a2 Montauk till member. Gay ead.
4 - .
g Ilerod gravel member.

Sankaty beds.
Jacob sand.
Gardiners clay. Not exposed.

 

 

 

SUBDIVISIONS,

The Manhasset formation may be described as a series of glacial sands and gravels, 150 to
250 feet thick, having a middle member in which the sands and gravels are locally replaced by
till. Where the middle member is well developed it is represented by a bed of till 40 to 60 feet
or more thick, the overlying and underlying beds being reduced to thicknesses of 50 to 75 feet
each. The central till is not everywhere well developed, however, being in places, as in the
gravel pits on the west side of Hempstead Harbor, reduced to a bowlder bed only a few feet
thick. In a few places it disappears entirely, grading laterally into coarse stratified gravels,
and in such places the entire formation consists of sands and gravels, marked, however, by
slightly coarser materials at the till horizon.

Although the till is locally absent, it is on the whole a persistent and easily recognized
member throughout Long Island and in fact along the New England coast as far north as
Maine, separating the two gravels into a lower bed here called Herod gravel member and an
upper bed for which the name Hempstead gravel member is here introduced. The till itself
is here called the Montauk till member.

GENERAL DISTRIBUTION.

The character, relations, and distribution of the three subdivisions of the Manhasset forma-
tion are considered in detail under their separate heads, only the distribution of the formation
as a whole being here discussed.

The Manhasset formation constitutes by far the larger part of the beds found above sea level
on Long Island, forming most of the drift hills at the west end of the island and the plateau
that borders the north shore from East River to Port Jefferson and extends southward beneath
the moraines toward the south shore, along which it rises above the outwash plains at numer-
ous points. East of Port Jefferson the Manhasset forms the base on which the moraines rest,
as well as the plateaus of Robins, Shelter, Plum, Fishers, and Gardiners islands and of the South
Fluke.

OCCURRENCE NORTH OF THE HARBOR HILL MORAINE.

Western Long Island —West of Little Neck Bay, which lies just east of Flushing, the
Manhasset formation is not seen in any considerable amount, what there is of it being buried
beneath the general till sheet, the Wisconsin moraines, and the later Wisconsin stratified gravels.
These deposits have so obscured the Manhasset topography that the plateau character, which
is very pronounced farther east, is not conspicuous.

Great and Manhasset necks, North Hempstead —On Great Neck, east of Little Neck Bay,
the plateau character is notably pronounced, large stretches of nearly level flats standing
between 100 and 120 feet above sea level from the railroad northward (Pl. IV, p. 30). Man-
hasset Neck shows the plateau character still better, the upper surface being here about 180
feet above sea level from the moraine northward to a point beyond Port Washington village,
where it slopes rather abruptly down to the 100-foot level, at which there is another extensive
plateau stretching toward Prospect Point.
116 GEOLOGY OF LONG ISLAND.

Hempstead Harbor to Oyster Bay.—The Manhasset formation is best developed in the
region between Hempstead Harbor and Oyster Bay, where it forms a belt nearly 7 miles wide
between Harbor Hill moraine and the coast. The surface seems to have a normal elevation of
180 to 200 feet, although rising somewhat higher near the moraine. South of Glenwood Land-
ing, on Hempstead Harbor, is a local terrace of gravel at the 100-foot elevation, separated as
usual by a fairly abrupt slope from the higher Manhasset level (PI. IV). The equivalent of this
terrace is traceable around the coast from the vicinity of Red Spring Point to Oyster Bay
(figs. 7 and 8, pp. 30 and 31).

Oyster Bay to Miller Place —From Oyster Bay to Northport the continuity of the Manhasset
formation is broken by numerous bays and harbors and by deep pre-Wisconsin stream valleys,
and the differentiation of the high and low deposits is more difficult, the one class grading
almost insensibly into the other. Lloyd, West, and Eaton necks, however, belong in the main
to the lower or 100-foot terrace, and Great and Little necks and the deposits stretching south-
ward to the moraine belong to the 160 to 200 foot level. East of Northport to the point where
the Manhasset disappears beneath the moraine near Miller Place, a strip a mile or two in width
along the shore belongs to the 100-foot level, and the rest, extending back to the moraine,
belongs to the higher Manhasset.

OCCURRENCE BETWEEN THE HARBOR HILL AND RONKONKOMA MORAINES.

Roslyn reqion.—Between the Harbor Hill moraine at Roslyn and the Ronkonkoma moraine
south of Albertson station is a stretch of country of puzzling contour. On the map it appears
as a fairly level plain suggesting an outwash accumulation, but on the ground there are many
irregularities. Here and there over the plain hills and ridges rise 10 to 15 feet or more above
the general level, their tops generally being flat and standing at accordant levels. Such a
topography might arise from deposition around ice blocks or might represent projecting masses
of the Manhasset formation, but in the absence of adequate sections it is impossible to determine
which origin is more probable. In favor of the second suggestion, however, it may be said
that the Manhasset undoubtedly extends beneath the moraines and is likely to come to the
surface at almost any point. The altitude of the flat-topped elevations is accordant with that
of the Manhasset level north of the moraine.

Huntington region.—In the region south of Huntington station (Fairground on the map)
are many well-developed kettle valleys, the result of the melting of ice masses lving in the
valleys of an older and now buried topography. The Manhasset formation, although not
exposed, can not be far beneath the surface.

Smithtown region.—A glance at the topographic map (PI. IT, in pocket) shows the well-
developed branching drainage system of Nissequogue River. An esker three-fourths of a
mile northeast of Smithtown extending to the bottom of the present valley indicates the Vine-
yard age of the erosion features, and an examination of the materials exposed in the several
valleys shows nothing but deposits of the Manhasset type. It seems clear that at this particular
point practically all the deposits between the moraines are Manhasset.

Port Jefferson region —In going southward from Port Jefferson station one passes over an
exceedingly flat plain of outwash from Wisconsin ice, which continues with hardly a percepti-
ble irregularity for 2 miles or more. At this distance, however, irregularities begin to appear.
Kettle depressions pit the surface and low swells rise above it, as near Terryville. <A little
farther on the depressions take the form of broad, shallow, well-defined yet streamless valleys
with branches on either side, the intervening ridges constituting the elevations. In fact, the
topography has undergone a change from one «ue to deposition to one due largely to erosion.
The valleys lead southward toward the sea but are cut off by the southern moraine, which rises
above the plains, completely blocking the channels. The erosion is clearly assignable to the
Vineyard interval and there is every reason to regard the deposits as Manhasset.
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 62 PLATE X%%

 

 

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LIUS BIEN CO.N.Y

TOPOGRAPHIC FEATURES NEAR MIDDLE ISLAND, LONG ISLAND, NY.

si Seale @3500
1 2 oO al 2 Miles
Seeemass,

a

 

Contour mterval 20 feet.
Datum is mean sea level,
1913

 
MANHASSET FORMATION. 117

Rocky Point region.—In the region east of Port Jefferson conditions seem to be similar to
those in the vicinity of Huntington. Just south of Rocky Point village are unusually good
examples of branching kettles resulting from the melting of ice masses in the valleys of the
underlying Manhasset surface. Plate XX shows one of these kettles as represented on the
topographic map. A mile or two farther south the valleys, like those south of Port Jefferson,
are evidently cut in the Manhasset formation.

Wading River region.—The conditions in the vicinity of Wading River are much the same
as at Rocky Point village, except that the branching kettles and surface valleys in the Man-
hasset are still more conspicuous. Although the Manhasset controls the topography every-
where except within a short distance of the moraine, there is nevertheless here as elsewhere
more or less Wisconsin drift, which locally complicates and even obliterates the Manhasset
surface.

Middle Island region.—On the geologic map (Pl. I, in pocket) a considerable region,
extending from Coram on the west to the headwaters of Peconic River on the east and from
the vicinity of Long Pond on the north to the Ronkonkoma moraine on the south, is represented
as till. Throughout this region the topography is characteristic of erosion. Several deep and
fairly sharp valleys with branching and rebranching tributaries, all manifestly cut in a pre-
Wisconsin surface, lead southward toward the sea. Plate XX shows what is probably the best
example of a kettle valley on Long Island, the depression being nearly 4 miles in total length
and having not less than five major branches (one of these rebranching) as well as many minor
ones not shown on the map. Though mantled with a thin coating of later drift, the body of
the deposit of this region belongs to the Manhasset formation.

Fresh Pond Landing region._The moraine is very weakly developed near Fresh Pond
Landing, the Manhasset capped by thin outwash stretching inward from the coast. It is cut
by the northward-leading channel shown in Plate IX, B (p. 42), the continuation of which can be
traced several miles toward the south by depression channels and kettles.

Riverhead region.—The region between Riverhead and the moraine on the north seems to
consist mainly of the Manhasset formation, which was deeply dissected by stream erosion and
later covered by a thin mantle of outwash along the moraine and by thinner and more irregular
outwash deposits elsewhere. The old drainage topography is marked by the original channels,
by kettle valleys, or by chains of isolated kettles. The region between Riverhead and Baiting
Hollow probably affords the best illustration on the island of the last-named feature (Pl. LX, ().
Some of the old valleys are almost as well and as definitely marked by the succession of kettles
as if the channels were continuous.

Mattituck region —The region about Mattituck presents another example of deeply dis-
sected Manhasset deposits overlain by a superficial coating of late drift. This feature is best
brought out by Mattituck Inlet (Pl. XI, C, p. 52), which represents an almost unaltered drainage
system of the Manhasset. This channel originally led southward, but is now obstructed by
Wisconsin drift and forced to empty northward into Long Island Sound through what was
originally one of its headwater channels.

North shore from Mattituck Inlet to Orient Point.—Kssentially the same conditions as at the
localities farther west exist east of Mattituck Inlet. The Manhasset, here as elsewhere char-
acterized by Vineyard erosion valleys, constitutes the main part of the deposits, the outwash
from the Wisconsin ice being weakly developed and confined mainly to the vicinity of the
moraine.

Peninsulas of the North Fluke and Shelter Island.—South of the line along which the Man-
hasset of the North Fluke proper and its mantle of outwash sinks beneath the sea lie a series
of islands and peninsulas, the latter almost disconnected from the mainland, which rise abruptly
from sea level to heights of 60 to 160 feet. From west to east these are Robins Island, Nassau
Point, Great Hog Neck, and Shelter Island, the whole forming a belt exactly parallel with the
North Fluke. Each of the peninsulas shows clear evidence of pre-Wisconsin erosion and equally
118 GEOLOGY OF LONG ISLAND,

clear evidence of, in the main, post-Gardiners deposition, and although the deposits are not a
unit with those underlying the North Fluke proper, they must be considered as belonging to
the same general series—the Manhasset formation.

Peninsulas of the South Fluke.—Stretching northward from the axis of the South Fluke,
well north of the outer moraine, are a number of peninsulas similar to the peninsulas and islands
associated with the North Fluke and likewise falling into a well-marked east-west alignment.
Their exposures show them to be composed of Manhasset material, except for the Gardiners
clay near sea level. Unlike the peninsulas of the North Fluke, however, they do not seem to
belong to a series distinct from that of the fluke proper, but rather to represent remnants of a
plateau or terrace similar to the north-shore plateau west of Port Jefferson.

OCCURRENCE SOUTH OF THE RONKONKOMA MORAINE.

Hempstead region.—East of Jamaica and continuing across the town of Hempstead to the
Oyster Bay line, the broad plains that stretch southward from the Ronkonkoma moraine,
although in their broader aspects having the appearance of outwash deposits from Wisconsin
ice, present many minor features suggesting that an older topography may project here and there
through the superficial mantle of outwash. Except at Rockaway Ridge, however, the topog-
raphy is not sufficiently definite nor the exposures of the older beds sufficiently clear to identify
them with certainty, but there is little doubt that the Manhasset constitutes the greater bulk
of the deposits beneath the Wisconsin gravels that form the surface of the outwash plain. The
development of the Manhassct deposits immediately north of the moraine and their observed
occurrence beneath the northernmost of the morainal ridges would make it almost certain,
even if there was no other evidence, that the Manhasset formation extends southward beyond
the moraines in strongly developed form.

Rockaway Ridge (see Pl. IT, in pocket) affords a good example of the extramorainal Man-
hasset material, standing many feet above the surrounding outwash plains from the Wisconsin
ice and exhibiting an erosion surface evidently antedating the deposition of the surrounding
gravels. The character and relations of these deposits are considered in more detail on page 127.

Bethpage region and Half Hollow Hills —Two well-developed terraces of gravels of the
Manhasset type occur just south of the West or Mannetto Hills (Pl. III, p. 28), and a single but
higher and more extensive terrace is present in the Half Hollow Hills. These terraces are cor-
related with the Manhasset formation.

Wyandanch to Central Islip —From Wyandanch, near the south end of the Half Hollow
Hills, eastward along the railroad to Brentwood there is very little evidence by which to differ-
entiate the Manhasset from the outwash, but from Brentwood to Central Islip station features
suggesting an older surface are more numerous, making it clear that the Manhasset is at or near
the surface and is beginning to exert a decided influence upon the topography.

Central Islip to Yaphank.—The Manhasset becomes an important factor in the topography
immediately east of Central Islip but is soon mterrupted by the broad outwash channel leading
south from the Smithtown region north of the outer (Ronkonkoma) moraine. Near Ronkon-
koma its control of the topography again becomes apparent, and similar conditions continue
eastward to the second great valley at Yaphank. Along the base of the moraine and stretching
southward to the railroad the Manhasset is recognized by irregularities in the shape of clevations
rising above the outwash or by dendritic drainage channels, now streamless, quite different from
the channels of the outwash proper. Throughout this stretch, also, the Manhasset is an impor-
tant factor of the topography, especially near the coast, the outwash, except near the moraine,
having only a subordinate influence. However, the relief of the old surface was so slight, the
materials are so similar in composition, and the general slope is so near that of the Wisconsin
deposits that, although it is possible to say that two surfaces of widely different ages are present,
it is impracticable to differentiate between them with sufficient accuracy for mapping.

Yaphank to Shinnecock Canal.—Conditions similar to those just described exist in the
region between Yaphank and Shinnecock Canal, the Manhasset apparently being even better
represented. Along the coast, and especially on the peninsulas, much of the topography is
PROFESSIONAL PAPER 82 PLATE XxX!

U.S GEOLOGICAL SURVEY

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B. MANHASSET AND OUTWASH TOPOGRAPHY ~~

NEAR AMAGANSETT LONG ISLAND, NEW YORK

OUTWASH TOPOGRAPHY NEAR SOUTHAMPTON.

A.

1
62500

 

cale

1

=

 

Contour mterval 20 feet.

Datum is mean sea level

1913
MANHASSET FORMATION. 119

clearly of a type characteristic of erosion rather than of deposition and belongs to the Manhasset
rather than to the Wisconsin outwash. The necks southwest of the canal and southwest of
Moriches are examples of accumulations that are apparently almost entirely of Manhasset age.

Bridgehampton region.—Eastward from Shinnecock Bay to Mecox Bay the Manhasset is
not definitely recognized, although indications are not entirely lacking that the deposits are in
places near the surface. Between Mecox Bay and Bridgehampton the Manhasset again con-
trols the topography, although locally covered with a considerable thickness of outwash which
has entirely obscured the older drainage. In several places, however, the older drainage lines
are now indicated by kettle channels or chains similar to those occurring at many points between
the moraines near Huntington, Rocky Point, Middle Island, Wading River, Riverhead, and
elsewhere. One of these channels is shown in Plate IX, A (p. 42).

Amagansett region.—Kast of Bridgehampton the Manhasset is again absent from the surface
as far as Easthampton, but from Easthampton eastward through Amagansett as far as Promised
Land it shows at many points. The topography in this region is very irregular, almost no out-
wash being present. This is well brought out by Plate XXI, B, in which the extramorainal
topography is in notable contrast to the more purcly outwash topography shown in A of the

same plate.
DEPOSITS PENETRATED BY WELLS.

The Manhasset is encountered in probably more than three-fourths of the wells on Long
Island and is clearly represented in a large number of well records. In many records it is even
possible to recognize the three subdivisions, as brought out in the tables and records given in
the separate discussions of the Herod, Montauk, and Hempstead members. Data regarding a
number of additional wells, in which the subdivisions have not been differentiated, are given in
the following table:

Undifferentiated Manhasset formation in the wells of Long Island.

 

 

 

    

 

 

 
  

 

 

 

 

 

; Depth of Correlation with name used
No.@ Locality. Owner or place. aiaterial, Character of materials. in original records.
Feet.
35 | Brooklyn.....----.--- Horest Street and Evergreen 23-105 | Yellow gravel and sand................. Wisconsin and Tisbury.
venue.
38 DOscesas 2 esses. Bartlett Street and Flushing b645 | Sand and gravel...........-------......- Do.
venue.
135 | East New York....... New Lots Road and Foun- 4-93 | Yellowish sand, granitic gravel, and thin Do.
tain Avenue. gray clays.

187 | Far Rockaway....-- James Caffery.........-.---- 0-42 | Yellowish gravel..........-.-2.2--....-- Tisbury.

188 DO vcinseseeds cael! Be TAR AITO ce. ciass ince ysoisiciees 0-45 | Fine to coarse sand and gravel.......... Do.

191 DO sccassice .-| Queens County Water Co... 0-60 | Light-yellowish sand and gravel......... Do.

193 | Threemile Mill 2| DFR, Chapmani...cecrecw cians >0-140 | Sand, quicksand, and clay....-..... .-| Wisconsin and Tisbury.
195 | Aqueduct....- Shetucket pumping station. . 90-135 | Fine to coarse gray to brownish sand -| Tisbury.
199 | Jamaica South Oconee pumping station. . ’9-56 | Reddish-yellow sand....-.-..... Wisconsin and Tisbury.
201 DO semsecias Jameco pumping station. . 18-86 | Yellow to gray sand with pebbles -| Tisbury.
202 Do Brooklyn test well No. 1.. 54-89 | Gray to yellow sand and gravel. . Do.
203 Do. .-| Brooklyn test well No. 2.... 19-83 | Yellowish to gray sand and gravel. 38 Do.
204 Springfield uci, -| Brooklyn test well No. 3... 45-86 | Fine yellowish sand.............--.....- Do.
205{  Do.......... ..| Brooklyn test well No. 4...-. 27-72 | Brownish-yellow and gray sand.-........ Do.
206 De eeemmeeeie -| Spriny apnea pumping station. 20-65 |..... 0 ais paraiso cis creiesasste wit cesses a seasects Do.
212 | Jamaica......-.. .-| Brooklyn test well No. 11.. 20-95 |..... GG 32% (ces Do.
241 | Whitestone... .- .| Railroad wells.........-.--- 15-60 | White sand Do.
285 | Valley Stream. -| Brooklyn test well No. 19... 18-72 | Gray to yellowish sands and gravel...... Do.
287 D0 scenascas= .| Brooklyn test well No. 25..-. 15-62 | Fine yellowish sand...................-- Do.
291 | Springfield. - .| Brooklyn test well No. 12.... 30-98 | Yellow, gray, and reddish sands......... Do.
295 DOs cancers .| Brooklyn test well No. 10. ... 40-80 | Yellow and Bray SANS. seis os Aiesiceccterss Do.
374 | Long Beach.....-... POOPHOUSE s.:2-ccw ston anaes 0-75 | Yellow to gray, sometimes clayey sands. . Do.

a Numbers refer to well records in Prof. Paper U. 8. Geol. Survey No. 44. b In part.

SPECIAL FEATURES OF

THE DISTRIBUTION OF THE MANHASSET FORMATION.

The Manhasset formation as a whole displays three belts of more prominent development,
which may be called the north-shore belt, the Middle Island belt, and the South Fluke belt.

North-shore belt.—Of the three belts the north-shore belt alone is continuous throughout
the island, being represented by the broad Manhasset terraces from New York to Port Jefferson

and by the bluff deposits from Port Jefferson east to Orient Point.

The accumulations are

thickest at the Sound shore and become rapidly thinner toward the south, being at a distinctly
lower level south of the Harbor Hill moraine.

The slope is well shown in the region east of
120 GEOLOGY OF LONG ISLAND.

Wading River (fig. 107), where the outwash is relatively thin, the Manhasset surface declining
from an altitude of about 120 feet along the coast nearly to sea level along Peconic River, which
appears to occupy a fosse between the plain and the northern face of the Middle Island belt of

the Manhasset. Just east

 

       
   
  
 

~ % 3 z of Riverhead the beds slope
8 8 8 8 from an elevation of about
2 & > & 80 feet on the Sound to sea
Wig eo} level on the shore of Peconic
hy Sus a8 Bay, 4 miles to the south.
i? Be. <2 Still farther east both the
ti 37) BI Io thickness of the Manhasset
al > a} |e along the north coast and
5 2] /€ its extent toward the south

1D} | . .
ao decrease until near Orient

Point the formation has a
maximum elevation of only

    
 
  
   
 

£ about 30 feet and a width

5 “i of less than a mile.

s 2 Middle Island belt.—The
S2\ 2 Middle Island belt is most
a distinct at its east end,
ae where it is represented on

Shelter Island. To the west
it is represented by Great
Hog Neck, Nassau Point,
and Robins Island, by the
thick deposits bordering Pe-
conic River on the south
from Riverhead to South
Manor, and by the high
deposits between the mo-
raines at and near Middle
Island. West of this region
the continuation of the Mid-
dle Island belt is obscured
for many miles, but there
are topographic indications
pointing to a Manhasset
scarp similar to that of the
north-shore belt but mainly

SECTION IN SHELTER ISLAND REGION

  

MANHASSET

  
  

Ronkonkoma
moraine

SECTION WEST OF RIVERHEAD

SECTION THROUGH MANNETTO HILLS

Ronkonkoma
moraine
Shelter Island
MANHASSET
Figure 107.—Cross sections showing structure of Long Island.

Ronkonkoma ,
moraine

HarborHill
moraine

CRETACEOUS
‘SECTION THROUGH HARBOR HILL AND ROCKAWAY RIDGE

   
    
 

; = 2 buried, extending westward
; =) 3 along the line of the Ron-
f 8 i i z . konkoma moraine to the
(2 SEN ele . 2 Half Hollow Hills, which be-
': . ace zy $= long to this belt. The next
a3 | 38 ous representatives of the belt
a3 \ ge EE appear to be the Bethpage

  

terraces, lying southwest of
these hills and possibly indi-
cating a swing of the belt
in that direction. Rockaway Ridge, the last Manhasset remnant in this belt, agrees in trend
with the southwesterly bearing assumed between the Half Hollow Hills and the Bethpage ter-
races. Possibly Gardiners Island, at the opposite end of Long Island, represents the easterly
continuation of the same belt.

 

 

 

 

 

 

 
MANHASSET FORMATION, 121

The Middle Island belt shows, where not obscured by later deposits, the same northward-
facing scarp as the north-shore belt, but the southward slope is not so conspicuous. The drainage,
however, seems to have commonly flowed toward the south, indicating a general slope in that
direction. The formation maintains its thickness on the whole more persistently than in the
north-shore belt, although showing great local variations. At Rockaway Ridge the upper
surface stands about 30 feet above sea level; at Bethpage, 180 feet; in the Half Hollow Hills,
240 feet; at Middle Island, 140 feet; south of Peconic River, 100 feet; on Robins Island, 60 feet;
on Nassau Point, 60 feet; on Great Hog Neck, 40 feet, and on Shelter Island, 100 feet or more.
The subaerial erosion is fully as far advanced as in the north-shore belt, and the features due
to marine erosion are even more conspicuous, although the erosive action was probably less.

South Fluke belt—The South Fluke belt of the Manhasset formation is most readily traced
by beginning at the east. The great mass of the deposits beneath the thin coating of late till
on the Montauk Peninsula are Manhasset and constitute the east end of the belt. Interrupted
by the connecting beach and dunes at Promised Land, the belt is continued toward the west
by the broad Manhasset areas of the two great necks east of the town of Sag arbor, by Hog
Neck north of this town, and by the high hills between Noyack, Little Peconic, and Great Peconic
bays and the moraine, as well as by the Manhasset remnants seen south of the moraine. The
South Fluke belt seems to join the Middle Island belt in the vicinity of Riverhead. The maxi-
mum elevation of the Manhasset at Montauk is about 150 feet; in the region between Prom-
ised Land and Sag Harbor and on the shores of Little Peconic and Great Peconic bays it is 120
feet. From these altitudes the Manhasset appears to slope southward, passing beneath the
moraine and a part of the outwash, and seems to have originally reached sea level a little south
of the present coasts, which are now commonly lined with bluffs rising a few feet above tide
level.

In figure 107 a number of profile sections bring out the relations of the Manhasset forma-
tion in the three belts described above.

HEROD GRAVEL MEMBER.

NAME.

The term Herod gravel member is applied tov the sand and gravel beds constituting the
lower third of the Manhasset formation, or that part lying below the middle or Montauk till
member. The name is taken from Herod Point, near Wading River, on the north shore of Long
Island, where the gravel is well exposed.

CHARACTER.

The Herod gravel member varies greatly from point to point, in some places being pre-
vailingly sandy and in others consisting largely of gravel. The change in character is abrupt
in many places, both vertically and horizontally, sand beds giving place to gravel or gravel to
sand within a distance of a few yards. In general sand is more likely to prevail near the con-
tact with the underlying Jacob sand, and gravel is more likely to become abundant as the
horizon of the overlying Montauk till member is approached. In places beds of sand 10, 20, or
even 30 feet thick, containing scarcely a pebble, are to be seen, but in its more normal phases the
deposit consists of an alternation of thin layers of sand and gravel, the whole having a gravelly
aspect. The pebbles are commonly small, those half an inch to 2 inches in size predominating,
but in the upper part of the member they are considerably larger, 3 to 4 and even 6 inch
pebbles being common. The character of the pebbles differs greatly in the different parts of
the island.

Western Long Island.—Near the west end of the island a large percentage of quartz peb-
bles is present, this material in fact predominating over the granites. The greater part of the
quartz pebbles are stained yellow by oxide of iron, giving rise to the term ‘“‘yellow gravels,” by
which they were formerly known and on the basis of which they have been by some writers
correlated with the ‘“‘yellow gravels” of New Jersey. The ‘“‘yellow gravels” of New Jersey
are in reality a much older deposit, corresponding with the Mannetto or still older beds. In
122 GEOLOGY OF LONG ISLAND,

them the basic granite pebbles are gone, those of the acidic type are deeply rotted, and even the
cherts and some of the quartz pebbles have been weathered and weakened. In the Herod
gravel member, on the other hand, the granites are as a rule not deeply weathered and the
quartz and chert pebbles are quite fresh.

Next to the quartz the granite or gneissic pebbles are most abundant, both basic and
acidic types being represented. Many of the basic or biotitic pebbles are more or less weathered
and rotten, although perfectly fresh specimens are not uncommon. It is believed that fresh-
ness is the normal condition, the alteration of the weathered pebbles having been well advanced
before they were incorporated in the deposit. The acidic muscovite-orthoclase varieties seem
to be but little weathered.

In addition to the quartz and granite pebbles there are numerous concretionary frag-
ments consisting mainly of quartz grains cemented by reddish (hematitic) oxide of iron and
ranging from a fraction of an inch to a foot in length. Limonite concretions occur here and
there in place. Silicified fossils and cherts, although forming quantitatively a very unimpor-
tant part of the deposits, are nevertheless sufficiently common to be found by careful search in -
almost any exposure in this part of the island. It is interesting to note that on the whole the
quartz pebbles are rounded as much as, if not more than, those of the granite.

The staining of the gravels is in part primary and in part secondary. Many of the stained
quartzes, for instance, occur in beds in which the surrounding pebbles are entirely unstained,
showing conclusively that their staining antedated their deposition in their present situation.

On the other hand, the beds in many places have been discolored

 

SSRN SN since their deposition. locally the discoloration is limited to a
XS ANN NN _ * é
SSA SSRN RN small bunch of pebbles, perhaps not more than 6 inches in

°.
=)

 

diameter in the aggregate, the staining material clearly coming
from an iron-bearing pebble in the center. In some places the
streaks extend directly downward from the source of the staining
solutions, which may be either a pebble or a lamina of sand rich
in iron-bearing minerals. An interesting feature is shown in
figure 108, which illustrates what at first sight appeared to bea
most puzzlmg case of vertical bedding. The vertical banding
appeared to be as regular and perfect as in any normal bedding, and only close examination
revealed it to be due simply to discoloration.

The greatest amount of oxidation appears to have occurred where some finer sand or clay
served to collect the downward-percolating waters, which have stained and even partly cemented
the immediately overlying beds. In places, as in the gravel pits beneath the moraine on the
east side of Roslyn, there appears to be a general staining of the section as a whole, the material
being of the characteristic buff color.

The bedding of the gravelly phases of the Herod member is normally horizontal, as shown
in the sections in the big gravel pits on Hempstead Harbor, but cross-bedding is not rare, espe-
cially in the upper part of the member. It is, however, generally of local occurrence and of
no great magnitude. The bedding in the sandy phases of the member is nearly everywhere
horizontal, except where disturbed by subsequent folding, and much of the lamination is
distinct and delicate. Ripple marks are present here and there. Internal unconformities
due to contemporaneous erosion and deposition are not uncommon, although in the member as
a whole they can not be said to be numerous.

A noticeable feature of the member as exposed near Far Rockaway, on the south shore, is
the presence of numerous pebbles showing faceting by the wind. A large part of these lie at
some distance below the surface and beneath other gravels, but they appear from the absence
of subsequent rounding to be substantially in place. No faceting was observed on the pebbles
in the Herod member of the north shore.

Central and eastern Long Island.—EKast of Hempstead the character of the Herod member
undergoes a gradual change. Quariz and concretionary fragments become less common and

ney

nit
ii

ET TE
HE

     

iittala lit

1
‘

 

 

Vee

   
      

     

 

 

   

  

      

Figure 108.—Diagram of vertical pseudo-
bedding in Herod gravel member.
MANHASSET FORMATION—-HEROD GRAVEL MEMBER. 123

are seen at relatively few points beyond the Cretaceous and Mannetto remnants on Lloyd and
Eaton necks, on the north coast, or east of the Mannetto and Half Hollow hills of Huntington
Township, in the interior of the island. Cherts and silicified fossils appear to be absent. Struc-
turally there seem to be more irregularities as one goes eastward, cross-bedding being much more
common and bowlder pockets not rare. The stained appearance is largely lost, the beds in
general having a very fresh aspect. Acidic granites become relatively common, but basic
granites are comparatively rare, although some trap fragments occur. In the relative amounts
of sand and gravel there is no marked change, although there appears to be a tendency toward
greater fineness of material. Although it is difficult to make an accurate comparison of the
Herod member with the outwash gravels of the Wisconsin stage, because of the absence of
good exposures of the latter, it is probably safe to say that in general they resemble one another
very closely both in composition and structure, and that in exposures where the relations are
not shown it would be impossible to distinguish the two, a fact that adds much difficulty to the
differentiation of the deposits south of the moraine.

SOURCE OF MATERIAL.

Western Long Island.—From the west end of Long Island castward to the last exposure of
Cretaceous and Mannetto at Eaton Neck and Northport there is, as has been pointed out, a
predominance of quartz in the Herod member as a whole, but beyond the limits of the extensive
older beds the quartzose character disappears. It seems clear, therefore, that it is to the beds
of these older deposits, either on the island itself or in adjacent parts of Long Island Sound,
that one must look for the source of the materials. If any considerable quantities were brought
from the Sound itself, it would be expected that characteristic materials would be found east
of the Cretaceous and Mannetto land masses. No notable quantities of such materials, how-
ever, have been found.

In the clayey parts of the Cretaceous the pebbles are usually white and entirely unstained,
but in the sandy and gravelly phases staining is very common. The staining in the Mannetto
appears to be universal. The stained pebbles of the Herod member may therefore be referred
with some confidence either to the Cretaceous or to the Mannetto gravel, and the white pebbles
would be referred either to the clayey Cretaceous deposits or to young drift brought in from the
north. The only clue to indicate which source afforded the white quartzes is the extent to which
they are rounded, the Cretaceous pebbles being in general considerably more rounded than
those from the Pleistocene. From this indication the Cretaceous seems to have been the
principal source. The so-called concretionary fragments appear to represont both actual con-
cretions and thin cemented layers from the Cretaceous sands. Such layers are very numerous
and in places highly irregular, simulating true concretions. Some may come from the Mannetto
gravel, but none have been observed in place in this formation.

The granite pebbles appear to have been transported in the main from the Connecticut
shore, the freshness of most of the material indicating derivation directly from the ledges.
Some of the granites, however, seem to have been derived from ledges or from pebbles from
older deposits in which weathering was already well advanced at the time of removal, although
they were still sufficiently firm to permit their handling by ice or water. The relative scarcity
of granite pebbles in the Herod member south of the moraine is attributed to the greater dis-
tance the materials were transported and the greater erosion they have undergone, whereby
the smaller and more weathered pebbles were broken up and dissipated. The cherts and silici-
fied fossils are evidently from the metamorphic limestones on the mainland to the northwest.

Central and eastern Long Island.—Although granitic pebbles are nearly everywhere abundant
in the Herod member, itis on the whole moresandy than most glacial gravels. As has been shown,
the Mannetto gravel was once a thick and extensive formation, stretching some distance into
the region of the Sound, if not to the Connecticut shore. Notwithstanding the great erosion to
which this formation has been subjected, it is not improbable that there were remnants of it
beneath the Sound at the time of the Herod deposition, and these may have furnished some of
124 GEOLOGY OF LONG ISLAND.

the materials, although stained pebbles such as are found farther west are commonly lacking.
Extensive areas of the Sound were also doubtless underlain by the Jameco gravel, which pre-
sumably furnished a large amount of material. To its derivation from these formations the
Herod member probably owes its prevailing sandy character. The granite pebbles probably
represent in part the reworked Jameco and in part fresh material brought in from the mainland.

RELATION TO OTHER DEPOSITS.

At the base, as elsewhere mentioned, the Herod gravel member merges by gradual tran-
sition into alternating layers of coarse and fine sands and finally into the clayey Jacob sand
(figs. 67, p. 97; 75 and 76, p. 99; and 98, p. 110), the only unconformities being those of over-
lap where the gravel reaches beyond the Jacob sand and abuts upon the Mannetto gravel or
the Cretaceous deposits.

In many small exposures the Herod member appears to be overlain conformably by the
Montauk till member (figs. 109; and 167, p. 146), but in larger exposures, where several rods of
the contact may be seen, an unconformity is almost invariably found. The unconformities range
from shallow, almost unnoticeable depressions in the Herod surface to deep and perhaps sharp
troughs, many of which cut entirely through the Herod into the underlying Jacob sand or
Gardiners clay.

The nature of the contact between the Herod member and the Montauk member is far
from uniform. Where the overlying deposit is a true till the contact is in many places sharp
and distinct and it may be of the so-called knife-edge type, the transition from one member to
the other taking place within less than a quarter of an inch. This is probably to be regarded
as the characteristic contact. In places, however, there is a somewhat gradual transition from
the gravel into the till, as if the former had been reworked and incorporated with the latter.
Where the Montauk is represented by its
gravelly phase there is no true contact,
the finer gravel of the Herod member
grading upward, although in places some-
what abruptly, into the coarser gravel of
FiGuRE 109.—Section near Quince Tree Landing, Montauk, showing till of the Montauk member. Here and there

Montauk type resting on arched Herod gravel member. e
the Montauk member is too poorly de-
veloped to be recognized and the Herod merges with the similar gravel of the Hempstead
member to form a single thick gravel formation.

At afew places the Montauk ice seems to have planed and eroded the Herod member without
leaving the usual deposit of till, and the Herod member is separated from the Hempstead member
by an unconformity. One of these places is shown in figures 116 (p. 126) and 180 (p. 153).
The ice in passing over broke up the stratification in the upper part of the lower sand and in
connection with a subsequent oxidation or staining produced local phases strongly resembling
soul zones.

 

 

oO 100 200 Feet
an ten ten tenenanced

STRUCTURE.

In common with the underlying beds the Herod gravel member was affected by the dis-
turbance produced by the overriding Montauk ice. There are, however, certain points of
difference. Because of its loose, friable character the Herod tended to crumble and disinte-
grate rather than to resist and become warped under the ice pressure. Folding is therefore
less common in the gravel than in the more resistant Gardiners clay and Jacob sand, and where
it has occurred the folds are generally broad and open, as if the material had been lifted by
deformation of the underlying clay. This deformation may have been due to pressure trans-
mitted laterally or to unequal settling under the weight of the ice sheet. In places, however,
either because it contained a higher percentage of clay or because it was frozen at the time, the
gravel appears to have afforded more resistance to the ice than usual and was folded in much
the same way as the underlying beds, although never forming the sharp pinnacle-like folds nor
showing the minute crumpling exhibited in many places by the clays. The character of the
folding is brought out in more detail in the following discussion of the distribution of the
gravel,
MANHASSET FORMATION—-HEROD GRAVEL MEMBER, 125

DISTRIBUTION.

East River to Little Neck Bay.—Along the north shore west of Little Neck Bay the Montauk
till member reaches down nearly or quite to sea level, the Herod gravel member where present
lying mostly below that level. It is possible that the Herod member is not as thick here as
farther east, owing either to the earlier advance of the ice in the west and the consequent
early replacement of the Herod by the Montauk, or possibly to greater reduction by erosion.

Great and Manhasset necks, North Hempstead.—The most western locality at which the
Herod gravel member appears in considerable amounts is on Great Neck, where it forms the
lower part of many of the bluff sections and extends below sea level. On Manhasset Neck the
gravel is seen on the west and north shores (fig. 137, p. 135) but is best developed on the west
side. A line of immense gravel pits cutting into the hills extends along the harbor, giving
clear-cut sections of the Herod member from its contact with the Montauk till member at an
altitude of 75 to 100 feet down to the Jacob sand or the Cretaceous
clay near sea level. The material here consists of a fairly regular
alternation of sand and fine gravel throughout the whole of the section.

Hempstead Harbor to Oyster Bay.—The Herod member is well cx-
posed in the gravel pits near Glenwood Landing, on the east side of
Hempstead Harbor, where 40 to 50 feet of rather fine cross-bedded  preure110.—Sectionon thecoast
gravel was seen. It seems to form a considerable part of the lower por- north of Fort Salonga. Mon-

i tauk till member (@) banked
tion of the bluffs from Roslyn to the mouth of the harbor. From against Herod gravel member
Hempstead Harbor to Oyster Bay the member is seen at few places ” overlain Py, vseonsin
along the shore, owing apparently to the extensive erosion by the Mon- ;
tauk ice, but it unquestionably occurs beneath the plateau stretching inland from the coast,
probably embracing most of the materials from sea level to a height of 50 or 75 feet. At
Rocky Point, 2 miles north of Oyster Bay, it is seen between the Gardiners clay and the Mon-
tauk till member but is here of slight thickness (fig. 65, p. 96). On both the west and east
shores of Oyster Bay Harbor and at Coopers Bluff it appears to constitute the lower parts
of the bluffs.

Lloyd Neck to Northport—As is usual where the Cretaceous is present above sea level,
very little of the Herod member is to be seen at Lloyd Neck, whatever Herod material may have
been deposited around the Cretaceous masses having been removed by the Montauk ice or so
disturbed as to be rendered unrecognizable. On West Neck, just south of Lloyd Neck, con-
siderable Herod material is present and may be seen lying upon the Cretaceous clays (the
Gardiners clay being absent) at one or more points along the shore of Cold Spring Harbor.
From Halesite to Centerport on Great Neck the conditions are similar to those on Lloyd Neck,
no good exposures of the Herod member being seen. On the west side of Little Neck a short
distance south of Little Neck Point folded sands
of the Herod type were seen underlying what
appears to be the Montauk till member. On
Eaton Neck, to the north, the conditions also
Figure 111.—Section half a mile east of Woodhull Landing, showing resemble those on Lloyd Neck. In one eee

strongly arched beds of Herod gravel member. 5 tion, however, folded beds of the Herod gravel

member were observed between the Gardiners

clay and the Montauk till member (fig. 66, p.97). Fairly good exposures of the gravel, consist-

ing of rather fine, even-bedded sand with wavy ripples, were found in the lower part of the bluffs
on the east side of Northport Harbor, north of the town.

Northport to Port Jefferson.—Gravels of the Herod member, 25 or 30 feet thick, were
exposed in 1904 for some distance in the bluffs along the beach northeast of Fort Salonga, 3 or
4 miles northeast of Northport. Here the gravels are commonly horizontal, although some
sections show a slight disturbance due to the Montauk ice, also unconformable contacts with the
Montauk till member (fig. 110). Eastward from this point the Montauk member descends
gradually to sea level, cutting out the Herod member. The Herod is seen again, however, on
Nissequogue Neck between Nissequogue River and Stony Brook Harbor (figs. 139 and 140,
p. 137) and in the vicinity of Stony Brook station (fig. 141, p. 137). Some of the contacts are
unusually complicated (fig. 140), and much gravel is incorporated in the till.

 

 

 

 

 
126 GEOLOGY OF LONG ISLAND.

Port Jefferson to Orient Pownt—The first good exposure of the Herod gravel member east
of Port Jefferson is found half a mile east of Woodhull Landing, where a great thickness of
gently folded sand and gravel is seen (fig. 111). A quarter of a mile west of Hallock Landing the
Herod member occurs in both horizontal and upturned and faulted
masses, as shown in figure
112. The gravels under-
lying the upthrust Jacob
sand near Hallock Land-
ing doubtless represent
the Herod member, as do
also the horizontal grav-

: sore cls underlying the Mon-
; tauk till member near
FicurE 112.—Section a quarter of

; 00 Feet
a mile west of Hallock Landing, Herod Point (fig. 113), es if 290 Fee
showing faulted beds of Herod 4 7 FicuRE 113.—Section west of Herod Point. «, Dune sand; b, banded
gravel member (a). Paine Landing (fig 1 14), till (Montauk till member); c, Herod gravel member.
Hulse, Fresh Pond, and

Jericho landings, and other points. The Herod member is exposed also as slightly warped
beds beneath the Montauk till member near Friars Head (figs. 115; and 179, p. 153) and near
Roanoke Landing and Point (fig. 144, p. 189), and it
probably forms a considerable part of the material in
the bluffs from Roanoke Point to the vicmity of Luce

  

 

 

 

 

 

 

 

Qo too Feet

 

Fiaure 114.—Section near Paine Landing. a, Till (Montauk ° 20 40Feet
till member); b, thin clay layer belonging to Montauk mem-

F Se . ;
ber; c, Herod gravel member. IGURE 115.—Section near Friars Head, showing Herod

gravel member beneath banded Montauk till member.

Landing and Jacob Hill, where it is again definitely recognized. In one section near Jacob Hill
the Herod member is entirely cut out by the pre-Montauk unconformity (fig. 93, p. 109), although
present in adjacent exposures (figs. 92, p. 109; 157, p. 143). The Herod member was seen
between Luce Landing and Jacob Hill (figs. 145, 146,

   

p- 140), also a mile southwest of Duck Pond Point (fig. 116), ae ar
but at many points from this place eastward to the ter- ens
mination of the North yy <2"
Fluke at Orient Point

 

 

the gravel is absent,
the interval being rep- 9” 20 Feet

resented by an erosion FIGURE 117.—Section northwest of Shinnecock Ca-
J J f if 4 nal, showing folding and faulting in gray clay be-
Figure 116.—Section 1 mile southwest of Duck Pond uncon ormity extend- longing io the Jacob sand and in the Herod gravel
ee hare sae b, Se till; c, Montauk ing downward into member of the Manhasset formation. Fossils
ill member; d, Herod gravel member. (probably secondary) at f.

the Jacob sand (fig. ee

96, p. 110). Figure 97 (p. 110), however, shows the Herod in its normal relations.

Bethpage terrace —The altitude and thickness of the Herod member north of the moraine
indicate strongly that it must be represented to a greater or less extent south of the moraine,
but no exposures admitting of definite recognition are found between the moraine and the
vicinity of the West or Mannetto Hills. Near the clay pits at Bethpage, at the south end of these
hills, and immediately west of Farmingdale, a mile farther south (see Pl. III, p. 28) are two

 

 
MANHASSET FORMATION—-HEROD GRAVEL MEMBER. 127

well-marked terraces nearly 2 miles long and half a mile to a mile or more wide, composed of
granitic gravels. The fact that what appears to be the Montauk till member occurs at the top
of the Half Hollow Hills, just east of this locality, at an elevation of 240 feet, seems to show
that the terraces at Bethpage and Farmingdale are to be correlated with the Herod member.
The deposits in general are rather coarse, especially at the Bethpage locality, where they contain
a large number of pebbles and seem to represent the beginning of the transition into the Mon-
tauk till member.

Eastern Long Island—As indicated on the geologic map (PI. I, m pocket), the Manhasset
formation occurs beneath thin coatings of outwash or in many places probably rises above the
outwash material, south of the outer (Ronkonkoma) moraine from the Half Hollow Hills
eastward to Great Peconic Bay, but the exposures do not permit the identification of the par-
ticular member of the Manhasset to which

 

 

they belong. It seems probable, however, | _--45))
that the Herod member is mainly below sea Gravel 7
level in this area.
Rockaway Ridge—The ridge extending 9 “ia ~ gaiont

 

from Far Rockaway northeastward to Lyn-  mMevre 118—section northwest of Shinnecock Canal, showing folding
brook rises distinctly above the Wisconsin out- PEE Ee COR Seren

wash and has a much older topography. The gravel of the ridge differs from that of the normal
Herod member in several particulars. The first of these is the unusual amount of quartz
contained in it; in fact, at first sight quartz appears to be the only material present, a fact
which led Woodworth! to place the deposits in the Tertiary. More careful search, however,
has developed the presence of many granites, and wells sunk along the ridge penetrate the
Gardiners clay after passing through the gravels. The latter are therefore younger than the
former and older than the outwash; hence they must be placed in the Manhasset formation.
Their position and the absence of any record of till or other deposits that could be correlated
with the Montauk point to their being the southern representative of the Herod gravel member
of the north shore.

The granite pebbles observed were all of the acidic type and were waterworn and rounded.
Most of them were deeply
weathered, thereby differing
noticeably from the similar
pebbles on the north shore—a
feature resulting from their
greater exposure to the weather.
Many of the quartz pebbles
were from 4 to 6 inches in di-

0 ameter, and a large number of

FicuRE 119.—Section east of Cedar Point, northeast of Sag Harbor, showing disturbed beds of them exhibited a very marke d
Herod gravel member beneath Montauk tillmember. By D. W. Johnson. “

 

 

 

and perfect faceting similar to
that on the pebbles of Nantucket and Cape Cod, which the writer’s work shows to have come
from the same horizon.

South Fluke.—The Herod gravel member doubtless occurs at a large number of points on
the South Fluke, but as the sections are covered with talus and as the key beds (Gardiners clay
and Montauk till member of Manhasset) are absent at many places, it can be identified only
with difficulty at those points. Good sections were observed in 1904, however, west of Shinne-
cock Canal, about midway between the canal and Red Cedar Point, where the beds were folded
and faulted in a marked degree (figs. 117 and 118). Broken Pleistocene shells of secondary
origin were found in the upper part of the member. On Jessup Neck, about 4 miles west of Sag
Harbor, several exposures of disturbed gravels, possibly belonging to the Herod member, were
seen, and on the west side of Hog Neck, about 3 miles northwest of Sag Harbor, there are several
good exposures of the Herod, the relations being as shown in figures 151 and 152 (p. 142). Near
Cedar Point the section shown in figure 119 was noted. Between Cedar Point and Sammys

 

1 Bull. New York State Mus. No. 48, 1901, map.
128 GEOLOGY OF LONG ISLAND.

Beach, 4 miles northeast of Sag Harbor, are many exposures of folded and faulted gravels,
some of which appear to be overlain by the Montauk till member and hence are to be referred

 

 

 

 

 

Figure 120.—Section between Cedar Point and Sammys Beach,
northeast of Sag Harbor, showing folded gravels (Herod gravel FIGURE 121.—Section east of Cedar Point, northeast of Sag Harbor. a, Hemp-
member?) with cobble (a) and clayey (b) layers probably repre- steal gravel member; 6, Montauk till member; c, folded and faulted gravels
senting Montauk horizon. (Herod gravel member).

to the Herod member (fig. 120). The disturbed gravels shown in figures 121 and 122 are also
probably Herod, as are the gravels and sands below the unconformity in figure 123. One of

60 5

 

 

 

  

 

 

°
0
Figure 122.—Section east of Cedar Point, northeast of Sag Figure 123.—Section west of Sammys Beach, showing
Harbor, showing disturbed beds of Herod gravel member probable unconformity separating Herod gravel mem-
overlain by till (Wisconsin?). ber and Hempstead gravel member.

the exposures in the Montauk region is represented in figure 109 (p. 124), which shows a broad,
low fold of the Herod member as it appears in a cliff section between the Napeague and Hither

 

 

  

 

 

Oo 50 100 Feet
Lt ° 100 200 300 Feet
FIGurE 124.—Section near Culloden Point, Montauk. a, Dune sand; 6,
Wisconsin till; c, folded gravel (Herod gravel member?); d, banded FIGURE 125.—Section 1 mile north of Quince Tree Landing,
Montauk till member. Montauk, showing folded beds of Herod gravel member.

Plain life-saving stations. On the north shore disturbed or overturned gravels, apparently
belonging to the Herod member, are seen near Culloden Point (fig. 124). Other but more obscure
exposures are found along the shore between the point and the landing
near the railroad station. West of Rocky Point many exposures of
folded gravels, possibly of the Herod member (fig. 125), were noted,
but in general their relations were not disclosed. Near Quince Tree
Landing, on Napeague Bay, however, the gravel is clearly seen to
underlie the Montauk till member in one section, and in another it is
banked against Jacob sand in an upturned mass (fig. 126).
Robins Island—The Herod gravel member is exposed in broad,
0 ~ asreet open folds at many points in the bluffs on the west side of Robins
wreunn 126--Hection ty mutes sland (figs. 98, p. 110; 193, p. 156). At one point there appears to be
northof Quince Tree Landing, a strong erosion unconformity due to the action of the Montauk ice,
peisel ond pi ie which, however, left no deposits (fig. 194, p. 157). A little farther along
ber (a) resting against clayey an important overthrust fault was seen, the upper part of the Herod
sina member being shoved bodily over the lower part toward the south
and the beds of the lower part being distinctly upturned and crumpled by the drag (fig. 127).
On the other side of the island the exposures are poorer, but there are long stretches of
upturned and disturbed sands, overlain in places by the Montauk till member, which are
apparently to be referred to the Herod member (fig. 128). At one point the gravel beds exhibited

 
MANHASSET FORMATION—-HEROD GRAVEL MEMBER. 129

a distinct contortion in addition to the broader undulations (fig. 74, p. 99). An upturned mass
is shown in figure 75 (p. 9).

Shelter Island.—Owing to the fact that wave cutting is relatively less active on Shelter
Island than on the north shore of Long Island, more of the clill sections here are covered with
talus. Traces of foldedsands and gravels,
however, were noted at many points along
the lower parts of the bluffs on the north
side of the island. This material seems
to belong to the Herod member, for it is
stratigraphically below the heavy till
correlated with the Montauk member,
which is well developed on the island.

Gardiners Island.—The complexity
of the folding and the covering of talus
on most of the more gravelly bluffs of
Gardiners Island make the tracing of the Herod gravel member very difficult. As no gravel
beneath the Gardiners clay is here known, and as profound folding appears to be distinctive of
the Montauk invasion, it is fair to presume that the great masses of the strongly folded glacial
gravels of the island belong to the Herod member. The conditions can be best shown by the
illustrations. Figure 167 (p. 146) shows the
gravel in open folds beneath the Montauk
till member at a point half a mile north of
_ Cherry Hill Point, and figure 99 (p. 110)
Figure 128.—Section on east side of Robins Island, showing disturbed beds shows the Jacob sand and Herod member in

EE RETR thick and but slightly disturbed beds alittle
beyond. The contact is stained black and is more or less oxidized, suggesting a soil zone. A
few hundred feet farther east horizontal Herod material was seen beneath an overturned fold
of Gardiners clay (fig. 81, p. 100). On the northeast side of the island, near the west end of the
bluffs and not far from the base of the sand spit, the relations
illustrated in figure 78 (p. 100) were observed. At 980 paces from
the end of the bluff the Herod member was again seen in a gentle
fold (fig. 129), and beginning 14 miles from the end of the bluff an
almost continuous section of folded beds of the Herod gravel
member was to be seen in 1904 for a distance of 1,350 feet (fig.
80, p. 100), beyond which folded beds of the Herod were seen

 

 

 

 

° 100 Feet

 

FicurE 127.—Section on west side of Robins Island, showing thrust fault in
Herod gravel member.

507

 

 

oO

 

 

: : 3 . 7 FIGURE 129.—Section half a mile south
intermittently to Eastern Plain Point, a mile farther on. On the © ot west end of bluffon northeast coast

shores of Tobacco Lot Bay the Herod member appears to have tore oo. a ie oe
: - . TO! ai sset formation; b, gray
suffered more from the Montauk ice erosion andislessseen. The Jacob sand; ¢, dark-gray to black clay

accompanying section (fig. 130) shows the appearance of the best alternating with laminw of fine sand

(Gardiners clay).

exposure near the point at the south end of the bay. South of
the point there are fine exposures of buff hori-
zontally stratified sands and gravels, which prob-
ably belong to the Herod member.

Plum Island.—West of the steamboat landing
on Plum Island the first good exposure of the Herod
gravel member seen along the shore in 1904 was
FicureE 130.—Section near point at south end of Tobacco Lot found about half a mile from the wharf in an open

Bay. u, Till (partly Montauk till member); b, Herod gravel fold (fig. 102, p- 111). The next quarter of a mile
Remnbeth 6, DIOS cle WeeiEHNE Eeone MADER showed @ suceession of similar folds, though not so
well exposed at the time of the writer’s visit. At the west end of the island, near the
lighthouse, a thrust fault with the upper layers bent upward was seen. The fault plane
makes an angle of about 45° with the horizon. The thrust is toward the south (fig. 131).

1629°—14-—_10

 

 

 
130 GEOLOGY OF LONG ISLAND,

On the south side of the island the Herod member was seen in considerable thickness a
quarter of a mile east of the west end of the bluffs, where it has the relations shown in figure
170 (p. 146). Ahundred paces farther east it was again well exposed and showed a great number
of parallel faults (figs. 82, p. 101, and 132), and afew hundred yards
beyond it appeared in a highly folded mass. From this point to
_ Fort Terry, although the expo-

~ sures are not so good, the member

ma ELIS is seen at short intervals (fig. 103,

ae p. 111). About half a mile east of
Pitas 2 ee eta 10 Feet the fort several fine exposures

at west end of Plum Island, show- FIGURE 132.—Details of faulting in Herod gravel Show highly disturbed and eroded
ing folds passing into faults in Herod member near west end of bluffs on south side beds of the Herod member (fig.

Coa poate 104, p. 111), and a little farther on
a good exposure of the Herod has till backed up against it. From this point to the east end
of the island and westward along the north coast to the wharf the cliffs have been covered
artificially and no exposures are now visible.

Fishers Island.—On Fishers Island the Herod member is best exposed in the clay pit,
where the sandy phase is strongly developed in the big anticline. The relations and structure
at this point are well shown in figure 84 (p.101). Figure 133 shows additional details of the
structure, although owing
to the talus present the
relations are not entirely
revealed.

At Isabella Beach and
at the bluff three-fourths
of a mile northeast the
Herod member is arched
in broad open folds (figs. 86, p. 102; 134, 135). The conditions at the West Harbor locality
(fig. 173, p. 147) are similar to those at Isabella Beach, except that the materials are moderately
coarse gravels with pebbles the size of ahen’s egg. The greater part of the high hill on the south

shore south of West Harbor appears to be com-
~ posed of the Herod member, which seems to be
gS, ena, ee cross-bedded on an extensive scale, and which,
: to judge from the outcrop of the Jacob sand on
which the beds rest, is folded into broad arches
only a few feet high.

Except at the localities described, where the

gravels rest on the Jacob sand, the Herod mem-

FIGURE 134.—Section vanntigh hill three-quarters of a mile northeast b . t be recognized with absolute cer-

of east end of Isabella Beach, Fishers Island. er can No ecognize

tainty, although there is every reason to believe

that the yellow and buff sands and gravels seen at a great number of points beneath the thin
coating of Wisconsin till, forming, in fact, by far the greater part of the island, belong to this
member. They proba-
bly reach their greatest
development either in
the high hills south of

Ww. Tak Trond Fiaure 135.—Section parallel with beach at headland three-quarters of a mile northeast of east end
est arbor, already of Isabella Beach, Fishers Island. a, Till; b, gray sand belonging to Herod gravel memher; ¢, clayey
mentioned, or in the sim- gravel be:onging to Herod member; d, greenish-gray clay (Gardiners clay).

ilar hill southeast of Chocomount Cove, which rises more than 120 feet above sea level and is
probably composed mainly of the Herod member.

Deposits penetrated by wells—The tripartite division of the Manhasset formation (the Tis-
bury of Veatch) was not fully established in the first season’s work and is not mentioned in

 

 

 

 

 

FIGURE 133.—East-west section in clay pit on Fishers Island, showing disturbed beds of Herod gravel
member of Manhasset formation overlying Gardiners clay.

Ma eas See,

  
        

ports

  

Perriese et EES 2%

50 Feet

 

 
MANHASSET FORMATION—-HEROD GRAVEL MEMBER. 131

the report on water resources. The subdivisions can be recognized, however, in many of the
well records, and from these the accompanying table has been drawn up. The table includes
only those wells in which the gravel is found below the Montauk till member. The Herod
gravel member, however, is recognized in the beds overlying the Gardiners clay and the Jacob
sand in many other wells, practically all ot those listed under these two formations indicating
also the presence of the Herod gravel member of the Manhasset formation.

Herod gravel member of Manhasset formation in wells of Long Island.

 

. Depth of for- és Correlation with name used
No,a Locality. Owner or place. mation: Character of materials. in original records.

 

Feet.
Bartlett Street and Flush- 73-81 | Coarse glacial sand..............-..2---. .| Wisconsin and Tisbury.
ing Avenue,
Ten Eyck Street............ 52-75 | Coarse yellow sand and gravel............- Tisbury.

.| Railroad test boring... b 57-76 | Sand (not quartz gravel)... .| Pleistocene.

  
  
     
    
    
 

 
    
   
 
   
 
  

 

    

  

  

  
    
 

--| Baisley pumping stati 97-106 | Yellowish sand and gravel .| Tisbury.
--| Brooklyn test well No. 7 69-98 | Grayish and yellow sand. Do.
.-| H. B. Gilbert........- a 56-114 | Fine sand to coarse gravel te Do.
258 | Hewlett Point....| G. B. Wilson... a 36-59 | Coarse gray SANG... cere .-| Not correlated.
357 | Port Washington..| T. Valentine..... dash 60-123 | White and yellow sand...................- Tisbury.
366 |..--- GO asciceniceme Dodge estate....... oe 22-50: |, White Sand... -.cjccic-0 sci wsinisicceciineinsiels tee Do.
421 | Nuneola --| Commission test well........ 30-55 | Yellowish sand and gravel.......-......-- Do.
422 | Albertson Sialleae iss WO ieerecieiereirciee te siete 23-37 |..... WO .2..4 decsnanmeniersasiee pa kesed ets ted Not correlated.
436 | Roslyn....-. .-| Mrs. T. Vowman. 53290 |) Pine. Sand sccm acwewivineenececesne sens dasien Tisbury.
446 | Glenhead --| A. A. Knowles... 75-136 | Sand..........-..- asciginiste tiacieenaitts 358 Do.
457 | Glen Cove.. ..| F. E. Willets..... 44-70 | Light-colored sand......-.........2..----- Do.
465 | Dosoris.. .| W.M. Valentine. 70-125 | Brownish sand and gravel...-.---..----.-. Do.
481 | Lattingto L. C. Wier... 63-92 | White and orange-colored sai .| Tisbury and Mannetto.
483, do E. Latting. 63-73 | White sand and gravel .| Tisbury.

 

64- White sand._..... a} Tisbury and Mannetto.

 

 

 

 

 

 

 

485 |.....di 38-100 | Sand and gravel. .| Tisbury.
629 | West Nec: b 25-85 | Fine brown sand... Do.
a Numbers refer to wel! records in Prof. Paper U. 8S. Geol. Survey No, 44. b In part.

The persistency of the Herod member is not only indicated by its outcrops but is also brought
out and emphasized by the well records. Its character seems to be very uniform, the member
being usually described as a white, light-gray, yellow, or brownish sand with gravel indicated
in about half of the records. Although ranging from fine to coarse in texture, it appears in its
most common phase to be medium grained. In development it shows the same differences in
wells as it does in outcrops, the recorded thickness ranging from 10 to 60 feet. Some of the
apparent differences are probably explained by imperfections in the records, but the greater
part of them are doubtless due to erosion by the Montauk ice, as in the surface exposures.

Among the well records showing the character of the Herod member is that of the railroad
test boring on Tallman Island, near College Point. The section as shown by a sketch by C. M.
Jacobs, consulting engineer, in the museum of the Long Island Historical Society, with the
correlation of the writer, is as follows:

Record of railroad test boring on Tallman Island, New York.

Feet

Recent: Sand and trap bowlders; old sea beach.........-.-.-----2-2-2265-0-0-22005-- Oe 2
Hempstead gravel member of Manhasset formation: Yellow quartz sand....-........--- 7.3- 30
Montauk till member of Manhasset formation:

Quartz gravel and bowlders.......-.------- +++ 2+ e+e eee ee eee eee cere eee eee eee 30 ~ 31.5

Yellow quartz sand, medium fine........----..-----+-+ 2-2-2 eee ee eee eee eee eee 31.5- 50

Trap bowlders, quartz sand, and gravel; regular glacial drift..........--.-.+-++---- 50 — 57
Herod gravel member of Manhasset formation:

GAT. gc scan ceceeee 2 ae eee RS ommend hes aie a eertn ate LO Skee See anes 57 63

Quartz gravels ccs... 2c.tedeekie ee diciees se laws sss etetacdetist nwt aah oe ee ee tet 63 - 66

Gravel aiid 6d 3 ccccd ns one ds wcnsoacae Beeeees sees paresesadee see ye ewes ey estes 66 73.3

Quarizoravelscasqseeacete ened moaes Ves eke Creek solcee ees 82488 Sta tees 73. 3- 76.8
Cretaceous (?):

Soft Clay veces kceee vest oe eee deere sceasies ines seeeataneeae ees eee oe EEE 1634 79.3

Lignite intermixed with clay bands.........-.---..--2+-+2+-+2 2-00 eee eee eee eee 97.3- 91.7

Streaked red and white clay; hard, bored out as a solid core.......-...--.---..--- 91. 7-110. 4

Fordham gneiss: Soft white micaceous ‘‘sandstone”.-......--..--------+2+e2e--ee eee 110. 4-159
132 GEOLOGY OF LONG ISLAND.

The Herod member is also indicated in the record of a well (No. 366) on the Dodge estate
near Port Washington, given in the discussion of the Jacob sand on page 113; in the well of
the Commission on Additional Water Supply for New York City near East Williston (No. 421),
given in the discussion of the Montauk till member on page 149; and in the Commission well
near Albertson (No. 422). In the well of F. E. Willets, near Glen Cove (No. 457), the following

section was recorded:
Record of F. E. Willets’s well near Glen Cove.

Wisconsin drift and Hempstead gravel member of Manhasset formation: Feet.
Brown loam.....---.-------- Eh 5 dpe eaucti ici ehabateel S& Loc Soy 28 (2 Bees cac ten ae oN Se ea eee 0- 9
Brownish gravel and sand..............2.2-0-0- 22222022 reece eee eee eee 9- 29

Montauk till member of Manhasset formation: ‘‘Hardpan”; clay with bowlders...-.......- 29- 44

Herod gravel member of Manhasset formation:

Light-colored sand............... 22-2222 2 222 eee eee eee eee cee teres 44-7
Brownish Clayiwo.022 24 <cheaseisuceceoned sy Sooo. tend pase eR eee es eee ee cece 70- 83
Sand, growing whiter as the depth increases. .....-----.---.------ 222-2 errr eter trees 85-158

Cretaceous (?):

Clay, with enough grit to make it hard (‘‘hardpan”).....-.---.-----+-++++++++++++--- 158-164

White gravel (no water).......-..---- 2-02-22 + 02 eee eee eee eee teeter eee 164-182

White coarse sand, with an abundant supply of water.......-.--------------+--+-+-++-- 182-186
AGE.

As already noted in the discussion of the age of the Gardiners clay and the Jacob sand,
the Herod gravel member of the Manhasset seems to represent water-laid deposits marking
the nearer approach of a great ice sheet, the first effect of which was the influx of sandy mate-
rial of the Jacob formation, bringing the Gardiners stage of clay deposition to a close. This
ice sheet eventually invaded the region, producing the erosion features which are everywhere
pronounced and leaving the thick Montauk till member. The deposition of the gravel was
merely an incident of the invasion and belongs to the same glacial stage, which is considered
to have been the equivalent of the Illinoian stage of the central United States.

MONTAUK TILL MEMBER.

NAME,

The term Montauk till member is applied to the middle of the three subdivisions of the
Manhasset formation. It is at the horizon of the deposits described by J. B. Woodworth? as
the bowlder clay bed of the Columbia (Manhasset of his geologic map), occurring in the gravel
pits of Hempstead Harbor and vicinity. More detailed study has shown it to be present through-
out the island and to reach an especially strong development on the south side of Montauk
Point, from which it takes its name. The Manhasset bowlder bed of A. C. Veatch is the thin
western representative of this member,’ but the name Manhasset can not be applied to it
because that name is preoccupied for the formation as a whole.

CHARACTER.

General composition.—The Montauk member in the western third of the island appears
at first sight to consist of coarse, roughly laminated sands, in which many pebbles and bow!l-
ders are irregularly embedded. A closer examination, however, shows that the spaces between
the visible sand grains are practically everywhere filled by a clay or quartz flour. At the west
end of the island, west of Hempstead Harbor, the member abounds in bowlders and is often
spoken of as a bowlder bed. The pebbles and bowlders consist mainly of biotitic granite or
gneiss and although many are much weathered they show signs of glaciation. Quartz pebbles,
which are very common in the gravel beds above and below it, are scarce in the Montauk member.

Near the center of the island the bowlders form a less conspicuous part of the member,
which here consists mainly of faintly laminated sands with an irregular sprinkling of pebbles
and of bowlders 3 to 6 inches in diameter. The amount of clay present averages more than

 

1 Bull. New York State Mus. No. 48, 1901, pp. 627-630. 2 Prof. Paper U. S. Geol. Survey No. 44, 1906, Pl. VII and elsewhere.
MANHASSET FORMATION—-MONTAUK TILL MEMBER. 133

farther west, especially near the top of the member, where a pebbly clay is not uncommon.
Bowlders, though not conspicuous in the exposed sections, are nevertheless present in con-
siderable numbers, being thickly strewn along the beaches and over the floors of the erosion
amphitheaters, Most of the pebbles and bowlders consist of acidic types of granites and
gneisses,

In the Riverhead district and farther east the till is much more clayey, clay constituting in
some sections, especially on the South Fluke, a large part of the member. Through it, how-
ever, are scattered many pebbles and bowlders, here largely of Triassic trap and sandstone.
On the two flukes the till ranges from the faintly banded clay, sand, and bowlder type, like
that noted as occurring in the center of the island, to the clay type of the Riverhead district,
the latter phase being especially common at the top of the member. Cretaceous fossils are
found in the till at Montauk.

Till and gravel phases—Although in its typical development the Montauk member may
be defined as a laminated till, it exhibits many variations in character. The lamination is
likely to be found anywhere strongly marked, and the clay and sand to be assorted into lamine
and layers, giving the whole mass a definitely stratified character. The gravelly phase is gen-
erally coarser and more irregularly stratified and carries both more clay and more granitic
material than either the underlying Herod gravel member or the overlying Hempstead gravel
member. Transitional phases are commonly not difficult to recognize, but the pure gravel
type, unless it carries berg-dropped bowlders or bowlder pockets, can seldom be identified
with certainty. The gravelly phase is most common in the western part of the island, and
the till phase is perhaps most persistent in the central part. Near the east end gravelly phases
are also common, but here, instead of the whole bed giving way laterally to gravel, it is more
common for only a part of the bed to undergo this change, gravels and sands being interbedded
with till layers.

Lamination.—The lamination mentioned is very characteristic of the Montauk member,
probably being visible in fully 95 per cent of the exposures, and from the fact that it is
exceedingly rare in the Wisconsin drift it affords one of the best means of identifying the Mon-
tauk member. It might be called incipient stratification. It is usually inconspicuous when
seen close at hand, especially in unweathered exposures, but it generally appears sharp when
seen a few feet away. The appearance of lamination seems to be produced in some places by
an alignment of scattered pebbles, but it is more commonly due to differences in texture, which
although indistinct in fresh exposures are brought out clearly by differential weathering. The
layers giving rise to the laminated aspect are more like bands than definite strata and are not
distinctly separated from the adjoming mass.

Cementation.—The cementation of the Montauk materials is, next to the lamination,
the most characteristic feature of the till phase, beg observable in more than 75 per cent
of the exposures of that phase. The material is cemented into a mass difficult to penetrate
with a pick and impossible with a shovel. Such material may weather like soft rock, giving
rise to the knife-edge ridges and needle-like pinnacles that are very characteristic of what
is commonly known as “‘badland topography.’’ The cementation, however, is not confined
to the till but is present in the gravel phase of the Montauk member at many points. The
best illustration of this feature is afforded by the gravels of Lloyd Neck, which, though not
forming pinnacles like the till, nevertheless show a sharpness of noses and gullies not seen in
any other gravel on the island.

Color.—The normal till of the Montauk member has a dull bluish or gray color, due in
part to the high percentage of erratic fragments present and in part to the gray color of the
quartz-flour matrix. Probably 75 per cent of the till exposures show this color. Of the
remainder perhaps 5 per cent are of a dull gray-buff color, in part resulting from the smaller
proportion of granites present and in part from a slight staining of the quartz.

In the Riverhead region some of the till is discolored by the fragments of Triassic sand-
stone that it contains, and some has a superficial staiming due to wash. On the South Fluke
and to a less extent elsewhere much of the body of the till is colored greenish, dark gray, or
134 GEOLOGY OF LONG ISLAND.

red by the Gardiners clay worked into it. At one or two points on the north shore quartz
pebbles derived from the Cretaceous, the Mannetto gravel, or the Jameco gravel give the Mon-
tauk member an abnormally light color. Chalky grayish-white shades are also conspicuous
beneath kettles containing peat, where the till is locally bleached.

Ovidation.—As indicated above, the Montauk is normally of a grayish color and, except
where exposed at the surface, presents to the eye little evidence of oxidation. In some
of the more sandy and porous phases, however, recognized by their buff color, incipient oxida-
tion is observed. Where it rests in its normal position beneath the Hempstead gravel mem-
ber there is no special weathering of its upper surface, hence its unconformable contact is doubt-
less the result of ice action rather than of subaerial erosion. Where the till was at the sur-
face before the advance of the Wisconsin ice it appears to have been somewhat deeply weathered,
but most of the weathered part was reworked and incorporated in the Wisconsin drift. Deep
weathering is to be seen in some of the thick till of Montauk, Plum Island, and other localities.

SOURCE OF MATERIALS.

The materials of the Montauk till member are evidently of glacial origin, a large percentage
of the fragments showing clear signs of glaciation, and the method of their accumulation indi-
cating association with or at least close proximity to an ice sheet. The coarser materials,
including the bowlders throughout the larger part of the member, are clearly derived from
the area of crystalline rocks in Connecticut. The Triassic material so abundant in the district
near Riverhead is likewise derived from Connecticut outcrops. Of the finer material, a part
was probably derived from the deposits of Long Island Sound, but the greater portion seems
more likely to have come from the Herod gravel member, the Jacob sand, and the Gardiners
clay, which, as has been indicated, were all deeply eroded by the Montauk ice. The part that
the Gardiners clay has contributed in places is clearly shown by the large quantities of colored
clays reworked into the till on the South Fluke from Riverhead eastward.

RELATION TO OTHER DEPOSITS.

As is brought out in detail in the sections relating to the distribution of the Gardiners
clay, the Jacob sand, and the Herod gravel member of the Manhasset formation, there is con-
siderable variety in the relation of the Montauk till member to the underlying beds. The drift
in some places rests conformably on the Herod gravel member (fig. 113, p. 126), but in others,
where the erosion by the Montauk glacier was severe, it rests on the Jacob sand (fig. 93, p. 109)
or even upon the Gardiners clay (fig. 62, p. 93). The underlying beds are almost invariably
disturbed and in many places are highly folded and faulted.

In eastern Long Island, as stated in more detail on pages 201, 207, and 208, there were
several advances of the Montauk ice, the last of which folded, crumpled, and faulted the
underlying strata, including the earlier beds of the Montauk member, but deposited little or
no till. As a result, the Montauk member in places has an unconformable upper contact (fig.
178, p. 153), even though the normal sequence was not interrupted, thus supplying an exam-
ple of what may be called contemporaneous erosion.

In the greater part of eastern Long Island the ice seems to have lingered until the closing
stages of the Manhasset accumulation, the Hempstead gravel member, which farther west
marks the final stage, being commonly absent, and either the original or the ice-eroded Montauk
surface being left practically uncovered until the mantle of Wisconsin till was spread over it.
Owing to the reworking of the surface by the ice sheet that deposited the later drift, it has been
impossible to determine the extent of the weathering.

STRUCTURE.

The Montauk till member is commonly less disturbed than the underlying deposits, mainly
because the latter received the brunt of the first vigorous advance of the glaciers, before the ice
became overloaded with drift and began to deposit. In fact, throughout the western two-
thirds of the island the Montauk deposits are but little disturbed, for the ice apparently never
MANHASSET FORMATION—MONTAUK TILL MEMBER. 135

regained sufficient vigor to produce either erosion or folding. In the eastern third of the
island, however, and on the adjacent islands, the period of deposition appears to have been
followed by a resumption of ice activity, bringing on a period of scouring, folding, and faulting
even more vigorous than the first.

DISTRIBUTION.

West of Little Neck Bay.—An cxamination of the cliff sections west of Little Neck Bay
seems to reveal the presence of two sheets of till separated in some places simply by an erosion
unconformity and in others by the unconformity and a gravel bed. This region taken by itself
affords few ecrtain data for differentiating the deposits, all of which might belong to the Wis-
consin. The lower till, however, shows the tendency to make abrupt transitions and to break
up into irregularly stratified gravels which is characteristic of the Montauk member but which
is rarely if ever scen in the Wisconsin of Long Island. Moreover, although the exposures are
much interrupted, the till when followed step by step toward the east, appears to become more
definite and to pass into the bowlder-bed phase of Hemp-
stead Harbor. It therefore seems probable that the lower
tul of the region west of Little Neck Bay belongs to the
Montauk member. The best section was that scen in the
bluff one-third of a mile east of College Point, where the
relations were as shown in figure 136.

_ Great and Manhasset necks, North Hempstead.—On  ¢'
Great Neck, North Hempstead, where the cliffs are not ob-  Ficure 136.—Section one-third of a mile east of Col-
scured by talus nor artificially covered, traces of the Mon- ye, yoneutead Gavel menber
tauk till member were observed here and there between

the Herod and Hempstead gravel members, but only on Manhasset Neck were clear-cut ex-
posures seen. Among the best of the cliff sections was that at Barker Point, on the east side of
the entrance to Manhasset Bay. The section as observed by J. B. Woodworth! is shown in
figure 137. The section as exposed when seen by the writer in 1904 showed the same succession
but with more marked disturbance of the beds.

East of Barker Point, around the north end of Manhasset Neck, the exposures, although
poor, show traces of the Montauk till member at many points. The till is best exposed, however,
in the gravel pits facing Hempstead Harbor, south of Bar Beach. In these pits the Montauk
member is represented by a relatively thin bed, usually ranging from 3 to 15 feet in thick-
ness, which is remarkably persistent, being exposed in the same position in pit after pit. The
bed here consists of a plastic or sandy bluish micaceous clay
matrix in which are thickly embedded pebbles and glaciated
bowlders of various sizes, some of them several feet in diameter.
At this point there is no noticeable disturbance or erosion at the
contact with the underlying beds. The large bowlders are here
a characteristic feature of the formation, a feature which becomes
still more marked in eastern Long Island and southeastern Mas-
er os eae eae sachusetts. So numerous are the bowlders along Hempstead

Manhasset Neck. u, Wisconsin til; 6, arbor that the bed may be traced, where not otherwise exposed,
en ee sen by the talus of large rocks trailing down the hillsides. Com-
After J. B. Woodworth. * pared with those of the Montauk member, the Wisconsin bowlders
are few and small. Heaps of Montauk bowlders in the gravel
pits represent the unusable residue of the bed. Although in some respects among the best
exposures on the island, the Manhasset Neck pits show the Montauk member in one of its
weakest developments, the bed being not only thinner and less characteristic than at many
other points but also lacking the usual accompaniment of folding and erosion.

Hempstead Harbor to Oyster Bay.—Traces of the Montauk member were seen in some
temporary exposures near Roslyn and at intervals to Glen Cove Landing. Just north of Weeks
Point a very good exposure showing 20 feet or more of Montauk of the characteristic compact

,

2057

 

 

 

 

 

 

1 Bull. New York State Mus. No. 48, 1901, p. 629.
136 GEOLOGY OF LONG ISLAND.

banded type was seen in 1904 (fig. 8S, p. 108). A short distance to the north the till gives way
to an equal thickness of the highly irregular gravelly phase of the Montauk. From this place
to Rocky Point, 2 miles north of Ovster Bay, the bluffs are either obscured by talus or artificially
covered. At Rocky Point, however, there are several fine exposures of the characteristic
banded till of the Montauk member merging into semistratified gravels resting unconformably
on the Gardiners clay and the Herod gravel member of the Manhasset formation (fig. 65, p. 96).
At Coopers Bluff, on Cove Neck, the gravel phase seems to be strongly developed, although
obscured at the time of the writer's visit.

Lloyd Nech.—Near the west end of the bluffs three-fourths of a mile southeast of Lloyd
Point there is 50 feet or more of gravel of a very unusual type (Pl. XXII, B). It rests in appar-
ent conformity on the Cretaceous, which is well exposed in the vicinity. It consists of irregu-
larly bedded sand and gravel, the Jatter predominating. The pebbles are commonly from 1
to 3 inches in diameter, but there are many layers of coarse gravel in which not a few of the
pebbles are from +4 to 6 inches in diameter. Quartz is, relatively speaking, sparsely represented.
The great mass of the coarser material is granitic, giving the.cliff a rather dark color compared
with most of the cliffs of the island. At several points the pebbles were found to be much
weathered, even the larger ones falling to picces under the hammer and some of them crumbling
in the fingers. Elsewhere the material appeared to be relatively fresh andfirm. One of the most
noticeable features of the gravel is its semi-induration, brought out in Plate XXII, B, which,
although a face view, shows the noses and erosion channels very distinctly. These features
appear still more sharp when seen in profile and afford a strong contrast to the outcrops of other
gravels.

In its weathering the bed resembles to a certain extent the Mannetto gravel, but it differs
from that formation in that the decay is not universal, that relatively little quartz is present
though granites abound, that it averages much coarser in texture
than any known Mannetto, and that its pebbles are unstained.
The highly granitic character suggests some of the descriptions of
the Jameco gravel as found in certain wells, but this gravel
belongs below sea level, and in the absence of any cvidence of fold-
ing on a scale to bring it up over a broad area there seems to be
no possibility of correlating it with the Jameco. In its texture

_ and in its cementation it differs widely from the Herod gravel
pees geared acco member, but on comparing it with the gravelly phase of the Mon-
tauk till member; c, Cretaceous. tauk till member we find more resemblances. As has been
pointed out, this member, while normally a banded till, in some places grades into irregularly
stratified gravels, which, though nowhere exposed on so large a scale as the gravels on Lloyd
Neck, in small outcrops present the same appearance. In their cementation especially these
gravels resemble those of the Montauk member, the only geologic division on the island above the
Mannetto gravel that exhibits this feature. In fact their cementation, together with their
peculiar stratification, affords an almost certain means of identification. The gravels at this
point are therefore regarded as a local phase of the Montauk till member. The exceptional
weathermg of a part of the gravels is regarded as due to the incorporation of portions of ledges
or of older deposits in which decay was already in progress but had not yet reached the stage
of disintegration. The correlation is made more certain by the presence of the Montauk mem-
ber in its normal phase resting against the opposite or east side of the Cretaceous knob, the
relations at this point bemg as shown in figure 138. The Montauk member appears to sink
below sea level where the beach curves toward the north half a mile farther cast (fig. 175, p. 152),
but it is seen again at several places for half a mile northwest from East Fort Point (fig. 176,
p- 152). The Montauk member at this point is a fine-grained, clayey, compact, semi-indurated
till, whereas the overlying Wisconsin is a loose, w anthonnd, aed not at all indurated till, with
many large cobbles and small bowlders. The difference in color of the two deposits was
striking and could be perceived readily by the cyc at a distance of a mile. Actinically, how-
ever, the difference was not so great and the photograph reproduced as Plate XXII, A, does
not show the contrast.

 

50 Feet
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 82 PLATE XXII

 

¢

ial ORE

 

 

 

-l. CONTACT OF WISCONSIN TILL WITH MONTAUK TILL MEMBER AT LLOYD
NECK.

 

 

Sqr A iy

 

 

 

mats prem ie

 

B. GRAVELS (MONTAUK MEMBER OF MANHASSET FORMATION?) ON LLOYD NECK.
Showing composition and erosion. Photograph by G.N Knapp.
MANHASSET FORMATION—MONTAUK TILL MEMBER, 137

West Neck.—In the large abandoned clay pits near the south end of Lloyd Beach, on
Cold Spring Harbor, a considerable thickness of semistratified till of the Montauk type is seen
above the Cretaceous clay. The sections differ greatly but show a gencral resemblance to
those on the north shore of Lloyd Neck. The thickness in the northerly pits is more than 30
feet, but in those farther south it ranges from 20 to 25 feet.

Lattle Neck, Huntington.—Half a mile south of Little Neck Point a bed of till about 20
feet thick containing many quartz pebbles was seen above the Cretaceous clay. Its relations
were not shown, but from its thickness, which would be
very abnormal for the Wisconsin at this point, it is believed
to be Montauk. A little farther north a till resembling this
bed was seen above highly folded and overturned glacial
gravels (Herod member?). The same till still farther north
grades into stratified beds of the type characteristic of the
gravelly phase of the Montauk member.

Eaton Neck and vicinity Although evidences of Mon-
tauk erosion are pronounced on Eaton Neck, few exposures -
of the drift are seen. Figure 66 (p. 97) shows a few feet of 30 Feet
the banded Montauk, as exposed near the base of the: West 5 cos 10,—Section miaway betwean Nissoqugeus
Beach sand spit, on the west side of the neck. Other expo- _ Riverand Stony Brook Harbor. a, Wisconsin till;
sures were seen about four-fifths of a mile to the north, near ey ae ee SDE ae
Eaton Point and a quarter of a milesouth of Eaton Neck light.

A quarter of a mile east of East Beach, which connects Eaton Neck with the mainland, the
Montauk member was seen in the bluffs, and just west of the broad salt marsh the bluffs exhibited
in 1904 a considerable thickness of the Montauk,
separated by a sharp contact from the overlying
brown loamy Wisconsin till.

Fort Salonga.—In the bluffs east of the road
leading to the beach from Fort Salonga, 3 miles
northeast of Northport, are several fine exposures
of the Montauk member. At the first of these,
half a mile east of the road, 25 feet of gravel of
the grayish semi-indurated and semistratified
Figure, 140.—Section showing details of the Montauk-Herod con- drift was seen beneath a few feet of structureless

ee parce en oti: yellow Wiseonsin till, A few hundred feet to the

west the till graded laterally into gravel. The

marked unconformity and disturbance between the Herod gravel member and the Montauk

till member shown in figure 110 (p. 125) was near this point. A short distance farther east a

fine section of indurated Montauk was noted. The Montauk was also seen above the Cretaceous
clays west of the road to the beach.

Smithtown Bay region.—On the neck between Nissequogue Bay and Stony Brook Harbor
the bluffs were commonly covered with talus, but a number of sections showing the Montauk
till member resting upon
disturbed beds of the Herod
gravel member were noted,
the contact being in places

: : Figure 141.—Roadside section near Stony Brook station, showing contact of banded Montauk till
highly irregular (figs. 139 member with Herod gravel member. By D. W. Johnson.

and 140). A similar expo-
sure was seen in a roadside cut near the Stony Brook station (fig. 141).

Crane Neck and Oldfield points—The exposures of the Montauk south of Crane Neck
Point rank among the best on the island, although its relations to the other beds are not well
shown. From 30 to 40 feet of till is here shown, the lower 20 feet consisting of massive material
with only feeble indications of banding. The upper part gradually becomes banded and then
laminated and finally gives way at the top to gravel. One of the features of the exposure is
an immense bowlder over 20 feet in diameter, occurring in the middle part of the till, On

 

 

 

 

 

 
138 GEOLOGY OF LONG ISLAND,

the north side of the point the bluffs are mainly talus-covered, but the Montauk till member
appears to continue for half a mile. On Oldfield Point, 2 miles east, the exposures are poor,
but the bluff appears to consist largely if not entirely of till, the greater part of which appears
to be Montauk.

Port Jefferson to Wading River —On the east side of Port Jefferson Harbor the exposures
are poor, but the talus seems to indicate that the Montauk till member occurs low down, pos-
sibly extending below sea level. It probably rises inland, but it is not recognized in the big
gravel pit south of Port Jefferson. East of Mount Misery Point, along West Beach, 20 feet
of till was seen in places. This contains a bed of bowlders as much as 1 or 14 feet in diameter,
having an aggregate thickness of 4 or 5 feet. The till grades into gravel laterally and probably
represents the Montauk member.

From this point eastward to Wading River nothing that could be definitely correlated
with the Montauk member was noted. The bluffs in the interval show folded and in places
faulted sands and gravels, the disturbance being of a magnitude comparable with that pro-
duced by the Montauk ice rather than by the Wisconsin. This feature would indicate that
the Montauk, if present, occurs at a higher level than any exposures shown in the bluff, an
assumption which is borne out by the fact that the next exposure of the Montauk—at Wading
River—is at the top of the bluffs.

Wading River to Fresh Pond Landing.—Between East Landing and Herod Point, northeast
of Wading River, the Montauk member reappears as a semi-indurated banded till at the top
of the bluff, having a thickness of more than 20 feet (fig. 113, p. 126), but it soon disappears
again. That its position is above the bluff sections is indicated by the disturbed character
of the gravels. Near Paine Landing, three-fourths of a mile farther east, a thick bed of till
of the Montauk type caps the bluffs and covers the slopes with its talus. The underlying
layers are somewhat warped and eroded (fig. 114, p. 126). Just west of Hulse Landing the
following section was measured in a gully:

Section west of Hulse Landing.

Recent: Dune: sand wish ivose ath oat wile oaeiaae a eta ee ld Bok iagt Adeees isan selec ewe ea sOsee Saat s 3
Montauk till member of Manhasset formation:
Trregularly banded sands and gravels with bowlders..............2.-...-22-5-2022222222--+-- ald
Pinkish sandy clay with pebbles.................2.-.-02220-020 20200000002 c eee eee eee eee 1
Gray banded till, semicemented...............22.020.22202-0 202000022 c eee eee eee 5
Herod gravel member of Manhasset formation: Horizontal sands and vravels-.........--..-...- 40

A similar section was seen in 1904 about 100 paces east of Hulse Landing at a point where
the upper bowlder-bearing gravel was 20 feet thick and the lower till 10 feet thick, the inter-
vening clay having disappeared. ‘The till in this vicinity carries many large bowlders, hundreds
of which lie upon the beach and extend out into the water, marking the former extent of the
deposit. Some of them measure over 20 feet in diameter. A quarter of a mile to the east
the Montauk member appears to reach a thickness of 50 to 60 feet but is of a grayish gravelly
type rather than the usual compact partly cemented drift. From this point for half a mile
eastward the till continues along the top of the bluff above 75 to 90 feet of the Herod gravel
member.

Friars Head.—The most typical exposure of the Montauk till member on Long Island
was seen in the vicinity of Friars Head, about a mile north of Baiting Hollow and 6 miles
northwest of Riverhead. Nowhere else are the cementation, banding, and characteristic ero-
sion so well shown. The drift is about 30 feet thick and consists of a mixture of sand,
pebbles, and bowlders with some clay, which, with the help of percolating waters, has bound
the whole mass into a firm, compact body that resists a hammer almost like a soft sand-
stone. The material seems, however, to loosen under the influence of water and has been
eroded into sharp knife-edge ridges and needle-like pinnacles resembling the typical badland
topography. ‘This characteristic is well shown in Plate XIX, B, in which a thin layer of loose
MANHASSET FORMATION—-MONTAUK TILL MEMBER. 139

Wisconsin till appears on top at the left. The view shows only small erratics, but bowlders
6 or 8 feet in diameter are seen at many places. Many of the fragments consist of trap and
appear to have come from the Triassic areas of Connecticut. Some of
them are weathered and rotten. So tenacious is the matrix that the
bowlders stick to the almost vertical faces of the bluffs until it is almost
entirely removed from around them (fig. 142).

The banding of the Montauk member, which is faintly seen in a near
view, is much more apparent from a distance, as brought out in Plate
XIX, B(p. 114). The banding does not depart much from the horizontal,
although it is here and there warped into broad undulations, as shown in
figure 143. A near-by exposure shows the Herod gravel member beneath
the till (ig. 115, p. 126), and a short distance to the east the Montauk is
overlain by the Hempstead gravel member and Wisconsin till. Fiaure 142.—Section of pin-

Roanoke Landing to Orient Point.—East of Friars Head the Montauk — ce o/Montann ae lhe
member is seen at short intervals for a distance of 2 miles, to a point _ trating tenacity of matrix
nearly north of Riverhead, being in places represented by till and else- 3S How" PY Projecting
where by gravel phases (fig. 179, p. 153). A good exposure of the gravel
was seen in a ravine a little west of. Roanoke Landing, although near by the till phase was
well developed. The following section shows the conditions near the landing:

 

4

Section near Roanoke Landing.
Feet.

Recent) Dine said a: toca goss eo Seo Ged PRS ES ee aes 10

Hempstead gravel member of Manhasset formation: Buff, irregularly stratified sand and gravel. 20

Montauk till member of Manhasset formation: Banded till with bowlders (possibly includes some
Herod gravel - member’ at. base) ecco: vcs sedee eye es sss sa vetenteeadges see ies sees vesseene eee za. (80

The Montauk member is reduced in thickness toward Roanoke Point,
where it is represented by a 15 to 20 foot bed about two-thirds of the way up
the bluff. It is in places clayey and here and there is tinged red by the wash
from sandstone fragments, which with many
trap bowlders have been brought from the
Triassic area of Connecticut. Some of these
bowlders reach 15 feet in diameter. The
beds under the Montauk are in places strongly
folded. Near Roanoke Point the Montauk is
Giant ee tea eetes «an Oe top of the bluffs and merges with

ing character of erosion and undulations of the Wisconsin til, but farther east it is seen

eee in a lower position persisting as a reddish bed "SURE M4~ Columnar
15 fect thick at 80 to 100 feet above the beach (fig. 144). It has afforded Landing. «, Hemp-
large bowlders at several points. Dee a ae.

A poor exposure of the Montauk member banked against upturned Jacob ber; ¢, Herod gravel
sand was seen at the landing west of Jacob Point (fig. 91, p. 109), but this ane
member was not again observed between this landing and a point half a mile beyond Luce
Landing, where the following section showing doubtful Montauk occurs:

 

 

  

Section east of Luce Landing.

Feet
‘Recents Dine sanGannen4d.naheeeumiisis ce aeee Soe ye RSA eee seg ia a dee 5
Wisconsin: Buff till merging downward into gray till ..-....-----------+-+--+ +222. eee eee eee \ ss
Montauk till member of Manhasset formation (?): Gray till......-.------.-2---2--0 6.2022 eee |
Herod gravel member of Manhasset formation: Irregularly bedded sand and gravel...........-- 60

A section just beyond is shown in figure 145, and another a quarter of a mile farther east in
figure 146. In neither place is it absolutely certain that the till is Montauk. The till continues
with similar relations for another quarter of a mile and then disappears from the bluff sections,
although it is probably present higher up in the hills, as the lower beds are strongly folded. The
140 GEOLOGY OF LONG ISLAND,

sections shown in figures 98 (p. 109) and 182 (p. 154) were observed in 1904 near Jacob Hill.
The till was of the normal banded, semicemented type.

The next exposure suggesting the Montauk member was seen about half a mile east of the
west end of the Oregon Hills, where a bowlder
bed of granites and Triassic traps and sand-
stones appears in the middle of the bluffs (fig.
147). The mass was stained reddish by wash
from the sandstone fragments and in places
graded into a sand. <A quarter of a mile
farther east a 10-foot bed of gray till overlain

 

9 50 Feet ‘
Se by cross-bedded ferruginous cemented sands

FigurReE 145.—Section half a mile east of Luce Landing. a, Dune sand;
b, till (mainly Montauk till member); c, Herod gravel member.

and gravel (the gravelly phase of the Montauk %)
was exposed. A mile southwest of Duck Pond
Point occurs the section shown in figure 116 (p. 126). Near this point several pockets of
bowlders were observed at the horizon of the Montauk and probably represent that member
(fig. 148). Farther east a persistent bed of cobbles was followed for several hundred feet.

A mile and a half east of Duck Pond Point the following section was measured:

Section 14 miles east of Duck Pond Point.

Feet.

Recent: Duis sands suse secre avoree chee ac uusaials ison See Saat uadeaelaaes aoe os nan EeeS 3

Wisconsin: Bowlder tills o> sacs ress cise dd ayn oaeeeeeos 22.23.5423 eenounekesedeuee. ca dneadadsedts 3
Montauk till member of Manhasset formation: Banded, semicemented sands with pebbles irregu-

larly distributed through the mass.............2.2.-2-.2220 2220-02020 - 2c e cence eee eee 10

Herod gravel member of Manhasset formation: Gravel and sand..........-.-...------+---+-- 12

Between the locality last mentioned and a point a quarter of a mile south of Inlet Point,
northwest of Greenport, large quantities of till were seen, much of it crowded with bowlders.
The washing :
away of the
finer parts of
the till has left

 

 

 

 

 

a thick fringe of
atts bowlders along
ep $0 Feet the beach, in s Ae Peek
Ficure 146.—Section three-quarters of amile sgqme Pp laces SS

east of Luce Landing. «a, Dune sand; 3, fine 2 3

banded till (Wisconsin or Montauk); c, Mon- piled Mm gr eat

tauk till member; d, Herod gravel member. he aps The ex-
posures do not in general permit the differentiation of the Montauk member from the Wiscon-

sin, but it is thought that a considerable part of the material may belong to the Montauk.

FIGURE 147.—Section at Oregon Hills, showing layer of cobbles and
bowlders, presumably representing the Montauk till member.

 

 

 

 

Figure 148.—Section near Duck Pond Point,
showing fault and bowlder pocket (Montauk till Figure 149.—Section a quarter of a mile south of Inlet Point, showing relation of
member) in gravels of Manhasset formation. Wisconsin till to Montauk till member.

The accompanying section (fig. 149) shows the relation of the Wisconsin and Montauk at a
point a quarter of a mile south of Inlet Point. In general the Montauk appears to be a pebbly
rather than a bowlder till.

From Inlet Point to Orient Point much the same conditions prevail. The Montauk member
for the most part can not be separated from the Wisconsin till with certainty, al though the thick-
MANHASSET FORMATION—-MONTAUK TILL MEMBER. 141

ness of the mass at many points and the extent to which the underlying beds have been folded
seem to prove that the Montauk is represented (fig.96,p.110). A bowlder pocket similar to those
formed at Oregon Hills and vicinity was noted three-fourths of a mile south of Rocky Point
(north of Greenport), resting in a depression in the Montauk. This pocket deposit was of a type
transitional between the till and ordinary gravel, consisting of interlaminated sand and clay
with pebbles and small bowlders scattered through it.

East Williston.—Near the village of East Williston, about 3 miles south of the head of
Hempstead Harbor and about a mile south of Ronkonkoma moraine, a clay pit in a shallow
depression of the outwash surface exhibits the following section:

Section in clay pit at East Williston)

Feet.
DOlladarssace kenga PE lateacd Ta earn ape epi ee 0 ae nego ta dn AeA ee Be SmI ELAN fe LS
Sand, gravelly, with quartz and granitic pebbles, locally reddened. ............-.....22-..--
Clay, sandy, swith quart? pebbles. cecusccccaescc coe ce cnc d dee cee Goa Fe See LL 8
Clay;-sand y) ansvellowbasids.c4 2c. sanaanwudint aris scm e aactadeasalatuiacs oearones ealtaaboaiens =
Clay, blue, finely laminated, rarely with quartz pebbles; exposed..........----..+.--22------- 3

In addition to the quartz pebbles the writer found in the pit many small pebbles of rotten
granite and in a near-by well a greenish biotitic sand such as would be expected to result from
a decomposed bowlder. Heinrich Ries? reports unidentifiable stems and leaves. The bed is
of small extent, wells a mile away generally failing to encounter it.

The age and origin of this clay present a rather puzzling problem. Ries and Crosby seem
to refer it to the Tertiary, but recent observations show that it not only contains glacial pebbles
throughout but is also underlain by glacial gravels. In all probability it is to be referred to
the Montauk member of the Manhasset or to the Wisconsin till, representing reworked Cretaceous
materials, Gardiners clay, or deposits of the Vineyard interval. In favor of the Montauk origin
may be mentioned the clayey character of the material and the advanced decay of the granites,
although these might represent older deposits reworked into the Wisconsin. Against the
Montauk origin is the altitude of the bed (150 feet), which is somewhat greater than the normal
elevation of the Montauk member in this region. On the other hand, the altitude is what
might be expected of an extramorainal deposit of Wisconsin till, but against the Wisconsin origin
may be urged the thickness of the deposit, its extent (apparently half a mile or more), and its
clayey character, all of which are abnormal for lenses of the later drift. On the whole the
writer feels that the deposits will most likely prove to be Montauk.

Half Hollow Hills—An examination of the materials forming the terrace-like top of the
Half Hollow Hills discloses irregularly bedded gravels considerably coarser than the gravel
members of the Manhasset and containing scattered bowlders, now seen on the terrace surface
and on the slopes and at the foot of the hills. The largest bowlders were noted on the road lead-
ing into the hills 14 miles northeast of Wyandanch. The materials of the hills most nearly
resemble the Montauk member, with which they are provisionally correlated.

Middle Island region —The surface of the region between Coram and the headwaters of
Peconic River is characterized by many bowlders and some patches of material resembling
till. Inasmuch as there is considerable Wisconsin drift in the region, as indicated by the
superficial morainal topography and the obstruction of the Manhasset valleys, it is difficult
to differentiate the surface material, but it is thought that a part of the bowlders and till may
represent the Montauk member.

Red Cedar Point.—On the South Fluke, which is here assumed as starting at Riverhead,
the first recognizable exposure of the Montauk member to the east appears about a mile east
of Red Cedar Point and about 6 miles east of Riverhead. The till appears to begin almost at
the west end of the bluffs but is not well exposed for some distance. About a quarter of a
mile from the beginning of the cliffs, however, a fine exposure of highly folded and overturned

 

1 Woodworth, J. B., Bull. New York State Mus. No. 48, 1901, p. 645. 2 Trans. New York Acad. Sci., vol. 12, 1893, pp. 40-47.
142 GEOLOGY OF LONG ISLAND.

Montauk and other beds was seen (fig. 150). The Montauk at this point is -very clayey,
consisting of alternating bands of gray and red clayey sand in which are embedded large num-
bers of bowlders of Triassic trap and red sandstones with some granite. The clayey character
is believed to be due to the reworking of the underlying Gardiners clay and Jacob sand into
the till. The mass is superficially stained a distinct red by wash from the weathered Triassic
fragments, but internally it is of a buff or gray color. The beach in front of the exposure is
paved with trap bowlders.

Shinnecock Hills and vicinity —About half a mile east of Shinnecock Canal, in an old clay
pit, on the shore of Great Peconic Bay, is an exposure of a pebbly clay type of Montauk till
overlying and plain-
ly derived from the
Gardiners clay. In
the hill north of Cold
Spring Pond, 14 miles
. farther northeast, the
° soFeet usual compact band- (0 Feet
FIGURE 150.—Section 2 miles northwest of Shinnecock ed type of Montauk FIGURE GL elon pn reek BIAS ct Hog Neck,

Geof, seat Lever ier dll wea noted atear  unitiae Bey g Comma

and pebble till (belongs to Montauk till member); eral points. The full worked Gardiners clay and belonging to the Mon-

d, bowlder pocket. thickness was not ex- tauk till member; b, Herod gravel member.
posed, but it is known to exceed 30 feet (fig. 183, p. 154). Bowlders of the Triassic formations
continue to be conspicuous.

Jessup Neck.—On the west side of Jessup Neck, near the north end of the exposures,
the section shown in figure 184 (p. 154) was seen. The material is a brownish till-like mass
of bands of red and gray clay, in which pebbles and cobbles with some Triassic bowlders are
irregularly embedded. The Montauk ice after depositing this mass seems to have become
more vigorous and to have both folded and eroded the material it had laid down, so that the
overlying Hempstead gravel member lies unconformably across the
top. The surface of the exposure is stained red by the wash from
the red clay and Triassic material.

Hog Neck.—A quarter of a mile south of the north end of the
bluffs on the west side of Hog Neck, 3 miles northwest of Sag Har-
bor, several fect of greenish-blue clayey till containing both erratic
pebbles and broken fossils
was seen, the whole result-

ing from a reworking of

Paume wa setin on vets the underlying Gardiners
bor. a, Till; 8, overtumed fold of clay with a certain admix-
contorted sandy clay with erratic ture of foreign material
pebbles representing reworked Gar- oo ‘

diners clay and belonging to the The bed is much folded  Frevre 153.—Section near Hog Creek Point, on South Fluke,
i : : showing Hempstead 1 bi ti Montauk till
Montauk till member; c, Herod and contorted, standing wing Pp! gravel member resting on Montauk ti!

gravel member, 4 : member.
out in the cliffs with the
relations shown in figures 151 and 152. A quarter of a mile to the south a gray to bluish-gray
till (Montauk 2) is seen below an upper rusty yellowish to buff till representing the Wisconsin,
the two being separated by a very sharp contact.

Cedar Point.—About two-thirds of the way between Cedar Point and Sammys Beach,
some 5 miles northeast of Sag Harbor, typical banded till of the Montauk member was seen
associated with highly folded and faulted gravels, the relations being as indicated in figures
119 (p. 127) and 121 (p. 128).

Hog Creek Point.—The bluffs between Sammys Beach and Hog Creek Point were generally
covered with talus, but the greater part of the material appeared to be till, with some banded
or even well-stratified layers, which, however, merge into true till. At the head of the point,
near Lion Head Rock, till of the Montauk type was scen in broad low folds, the relations being

 

 

 

 

 

 

-

° 2 25Feet

 

 
MANHASSET FORMATION—MONTAUK TILL MEMBER. 148

as shown in figure 153. Similar relations appear to continuc, though less satisfactorily exposed,
at intervals to the end of the bluffs near Fire Place. Above the till at several points is a series
of sands involved with the till in broad open folds (fig. 154). Their character and position
are typical of the Hempstead gravel member, but the folds have been beveled off at the top
in a manner exactly analogous to the erosion produced by the final readvance of the Montauk
ice, and the gravels may be simply a phase of the Montauk member.

 

 

 

0 20Feet
ee
FiGgurRE 155.—Section 1 mile west of Rocky Point, Mon-

Figure 154.—Section near Hog Creek Point, on South Fluke, showing Hemp- tauk, showing bed of banded Montauk till member
stead gravel member resting on Montauk till member. beneath layer of granitic gravel and cobbles and gra-
nitic sand and gravel (Hempstead gravel member).

Montauk peninsula—Between Fresh Pond and Quince Tree Landing, at the east end of
the bluffs on Napeague Bay, the Montauk member was seen poorly exposed in the upper part
of the bluffs. It is at least 15 feet thick and may be considerably thicker, as there are indica-
tions that it may in places extend down to the beach. Just south
of the landing an exposure showing the Montauk member in a broad

 

 

  

Qo 100 200 Feet
Figure 156.—Section 1 mile west of ee TN Neo
Rocky Point, Montauk, showing inter- FiGuRE 157.—Section half a mile south of Culloden Point, Montauk, showing intercalated
ealated bed of gravel in Montauk till sand and clays in Montauk till member. a, Montauk till member; b, clayey sand; c, clay;
member. d, gravel; ¢, sand; f, Wisconsin till.

fold was seen (fig. 109, p. 124). Figure 155 shows folded beds of the Montauk member, as

seen half a mile west of Rocky Point. A near-by section (fig. 156) showed a layer of gravel

interbedded with till of the Montauk member. Strong talus slopes of till character are seen
at Rocky Point and vicinity.

Faults? From Fort Pond to Culloden Point the
bluffs are largely covered by talus, but till, pre-
sumably of the Montauk member, seems to be
SG or ie y the predominating material. There are indica-

Horizontal scale | ay » Vertical scale oe tions that thin strata of both clay and sand
———— ee are interbedded with the till (fig. 157). Near
Provns 1 Setionessto Monta igh atowingenrseaid Culloden Point the Montauk member is ex-
Hempstead member; b, sand, with greenish clayey lamin, belonging posed for some distance at the base of the bluff.

to Hempstead member; c, sand and fine gravel belonging to Hemp- 7 . é is 2
stead member; d, iron-stained bowlders and ferruginous conglomerate Its upper surface is very irregular, but w hether

layer at top of Montauk till member; e, sands and gravels (downfaulted the irregularity is due to erosion or to folding

pele Heontnd ne (hued banded ts ofMowank ooo not be determined (Bg 187, p. 158), An

exposure showing what appears to be Montauk

till member banked against folded beds of the Herod gravel member is shown in figure 124
(p. 128).

At Shagwong Point and at the headland just east of Oyster Pond 10 fect or more of
indistinctly banded Montauk till member was seen in the lower part of the bluffs beneath
reddish clay, apparently a local phase of the Montauk, from the wash of which it is stained
red in places on its exposed surfaces. A quarter of a mile east of the second headland a con-
siderable thickness of the Montauk was observed resting above a dark chocolate-colored clay

 

 
144 GEOLOGY OF LONG ISLAND,

assumed to be the Gardiners clay. The drift consists of an upper banded till of the type
characteristic of the Montauk and a lower more gravelly phase grading laterally into gravel,
as shown in figure 76 (p. 99).

The Montauk till member appears again a little southeast of False Point in folded masses
with dips as high as 30° in places. Some of the exposures were very clear and sharp in 1904.
Toward the southeast the till
sinks below the beach, but it
rises again near the lighthouse
(fig. 174, p.151). The till at
this point contains many large
fragments and is somewhat
9 50 190 Feet. banded but is not much ce-

FiguRE 159.—Section southeast of Montauk Light. a, Till phase of Montauk till member; 3, mmented. It grades upward
bowlder pocket; c, sand and clay phase of Montauk member; d, clayey sand phase of Hemp-_- : . :
stead grave] member; e, normal sandy phase of Hempstead gravel member. into a banded clayey till with

many erratics.

In the immediate vicinity of the Montauk lighthouse the Montauk member is seen in a
thick bed at the base of the bluff, where it has the characteristic banded development. The
profile of the extreme point, look-
ing east, was in 1904 as shown in
figure 189 (p. 155). Figure 158
(p. 143) illustrates the complexity
of the exposures just north and fig-

 

 

 

 

ure 159shows the conditions imme- * ane reat
. . Lene eae cite el
diately south of the lighthouse.
. FIGURE 160.—Section 14 miles southwest of Montauk Light, showing red clays interca-
Fr om Montauk Point south- lated in till of Montauk till member. a, Hempstead gravel member (2).

westward to the point marking the

abrupt change in the direction of the coast line to a more westerly bearing the exposures of
the Montauk member are almost continuous. Among the features of interest in this stretch
is a thick bed of dark-brown to red clay interbedded
and folded with the till of the Montauk member at a
point about 14 miles from the lighthouse and half a
mile from the southerly point mentioned. Its rela-

FiuRE 161—Section 13 miles southwest of Montauk Light, tons are shown in figure 160.
showing gradation (from left to right) of banded and massive West of the bend in the coast just mentioned

oS UE mess }er aud Nereis 1a Me GrolyMe ie he Montauk ia alinest continuously exposed for
nearly amile (fig. 192, p. 156). In places nothing
but till is observed in the bluffs, although it is here divided into an upper loose buff to brown
till, probably Wisconsin, and a much thicker banded mass belonging to the Montauk. The
section is represented in figure
161, which shows the two tills
and the gradation of banded . ¢['-’
into massive Montauk till. Half  ¢
a mile farther east the Montauk
shows a thick lens of sand and
gravel, not unlike the Herod or
Hempstead members, between -
two beds of drift (fig. 162). The
lens is practically undisturbed, the stratification still retaining its horizontal position. A
feature of the Montauk in this region is its whitish color beneath kettle holes containing peat.
Though ordinarily of a buff color, it is here bleached to a chalky white, the difference in color

  

   

 

100 Feet
FIGURE 162.—Section 2 miles southwest of Montauk Light, showing lens of stratified gravel in
Montauk till member. a, Wisconsin till.
MANHASSET FORMATION—-MONTAUK TILL MEMBER. 145

between adjacent masses being noticeable even from a distance. Figure 59 (p. 89), shows the
Montauk resting on upturned and eroded sands, gravels, and clays.

Between Ditch and Fort plains there appears to be another almost continuous exposure of
the banded till of the Montauk member, but the outcrops are more obscured than farther east
(fig. 191, p. 156). The upper part seems to be a thin coating of Wisconsin till, which at one
place thickens to 25 feet, comprising nearly half of the bluff. Toward the west end of the
bluffs the Montauk is seen in con-
tact with the underlying gravel.

West of Fort Pond the bluffs
of the south coast seem to be a
duplication of those near Montauk
Point, except that the gravelly
phase of the Montauk is more com-
monly present. There is generally
a sharp demarcation between the Montauk and the overlying Wisconsin (fig. 163). The
Montauk till is not uncommonly interbedded with stratified clay, sand, and gravel (fig. 164),
some of the beds of which reach in places a considerable thickness.

The strong development of the
Montauk member on Montauk Point,
the profiles of the bluffs now cut in the
south coast, and the offshore rocks and
bars all point to a former extension
of the Montauk member considerably
farther south. It is not improbable

 

 

50Feet

FiGurE 163.—Section on south side of Montauk peninsula between Napeague and Hither
Plain life-saving stations. a, Dune sand; b, Wisconsin till; c, Montauk till member.

 

 

eee : that the Montauk ice sheet extended

FIGURE 164.—Section on south side of Montauk peninsula between Napeagueand gome distance into the sea, and in that
Hither Plain life-saving stations, showing intercalated clays, sands, and gravels in case more or less Montauk till, not

Montauk till member.
eroded by the late Manhasset ice or in
the Wisconsin stage, would naturally be found south of the moraine or even beneath the sea.
The only known evidence of such extension is the uncovering of bowlders and other glacial
material by the waves along the coast in the vicinity of Easthampton, noted by Mather.!

      

 

 

 

oe ation ~ : oO Oo Ole: 2.9 O:ONS n
FicurE 165.—Section on east side of Robins Island. a, Hempstead gravel FIGuRE 166.—Section on east side of Robins Island. a, Mon-
member; 6, Montauk till member; c, Herod gravel member (?). tauk till member; b, Herod gravel member.

Robins Island—There does not seem to be any strong development of Montauk on the
west side of Robins Island, for although the beds are folded and faulted as if by Montauk ice,
only a thin layer of till, which might be either Montauk or Wisconsin, is seen at the top. Some
of the gravels contain considerable quantities of clay intermingled with the grains in the sands
and show more cementation than elsewhere occurs in the Herod gravel member. The same is
true to an even greater extent of some of the gravels of the east shore and it is not unlikely
that both may represent the gravelly phase of the Montauk. Near the north end of the bluffs
on the east side the banded-till phase of the Montauk is locally well developed, although the
complexity of the disturbance makes its relations uncertain. Figures 165 and 166 represent
the conditions of the exposures in 1904.

Shelter Island.—Bluff exposures showing the Montauk in section are not known on Shelter
Island, although it seems probable that the Montauk occurs under the talus in the lower part
of some of the bluffs. If so, it is likely to be exposed in any storm. The surface till of the

 

 

1Mather, W. W., Geology of New York, pt. 1, 1843, p. 165.
1629°—14——11
146 GEOLOGY OF LONG ISLAND,

southern half of the island, especially in the low till plains of the east and south coasts, is
regarded as probably Montauk, as its thickness is much greater than it seems possible to ascribe
to the Wisconsin, which is thin elsewhere.
Gardiners Island.—Traces of banded till re-
! °F sembling the Montauk were visible at many points
ae 66 Sop teat on the southwest coast of Gardiners Island, but
wig ag i didlos af agedivend of Bests Bay, Gardiners 10 clear-cut exposures were observed. On the
Island. a, Wisconsin till; 8, banded till of Montauk till member; northwest coast between Cherry Hill Point and
cin ner of on ky (Moin): dstd=nd ET! Bostwick Bay a very good exposure of the strongly
folded and leveled Montauk member was seen, its
relations being as indicated in figure 167. The contact between the till and the overlying gravel
phase is marked by a layer of dark-green to black clay from 3 to 5 feet thick, resembling in occur-
rence that at Shagwong Point,

 

 

 

 

P

on Montauk. In fact, the Mon- i oN

tauk member of Gardimers Island Nos
presents many strong resem- | oa
blances to that on Montauk

peninsula. ‘5
Figure 168.—Section near north end of bluffs on northeast shore of Gardiners Island, showing
On the northeast coast the folding of bed of banded till of Montauk till member with the intercalated clay.

 

 

° 100 200 Feet
ee |

Montauk member is commonly
absent, although its horizon is in places marked by erosion unconformities or by bowlder pockets
or layers and near the north end a thick bed is involved in a large fold (fig. 168). Near Whale
Hill it again attains a considerable thickness and is infolded
with the other beds, as shown in figure 80 (p. 100). At
one point a stratum of red clay several feet thick is inter-
bedded with the till (fig. 169), again suggesting conditions
= 2 similar to those shown in figure 160 (p. 144), at Montauk.
° : = Near Eastern Plain Point the Montauk forms in places the
eal Ses tr A arp ae te Sao greater part of the exposures and contains two persistent
Montanie ail nies her. beds of red clayey sand about two-thirds of the way up
the bluff. These clayey beds tend to confuse the sec-
tion because of their resemblance to the :
Gardiners clay. Folded Montauk mate- 40
rial is again exposed near the south end
of Tobacco Lot Bay.

Plum Island——The north shore of
Plum Island does not afford any good
exposures of till, although there are indi- °
cations that not less than 20 feet of this FIGURE 170.—Section near west end of bluffs on south side of Plum Island. a,
material is present in places, the greater Piers a a Aaetae Basan dle ag EE REET RERY Yy, PaBOR
part of it probably being Montauk. The .

southwest corner of the island consists of a broad bowlder-
strewn plain, which rises toward the east, exhibiting till
of the Montauk type in the bluff sections. It is overlain
by a greenish clay containing pebbles similar to those in
some of the exposures on Gardiners Island-and on Montauk.
The whole plain, except perhaps a thin superficial coating
eee ern are Tree Te of Wisconsin material, is regarded as belonging to the Mon-
Island. u, Wisconsin bowlders; }, Hempstead taukmember. On the east the drift abuts against an eroded
cg omens ll member) . surface of the Herod gravel member, as shown in figure 170.
From this point east to Fort Terry no good exposures of the

Montauk were seen, but a quarter of a mile east of the fort it reappears with the relations
shown in figure 171. The bowlders on top of the section are probably Wisconsin. East of

 

 

 

 

 

 

 

 

 
MANHASSET FORMATION—MONTAUK TILL MEMBER. 147

this exposure the Montauk appears resting across the eroded edges of the Herod gravel
member and the Jacob sand, as is shown in figure 104 (p. 111). One exposure showed a large
Montauk bowlder stranded in process of plowing its way through the underlying gravel (fig. 172).
The rest of the bluffs on the east end of the island are artificially covered.

Fishers Island.—On Fishers Island the Montauk member is of somewhat unusual character,
although the exposures are typical of certain well-defined phases near the type locality. The
member has been recognized above sea level at only two points—at
the West Harbor exposures and in the bluff three-quarters of a mile '/—
northeast of the north end of Isabella Beach. The ‘‘bowlders” Bs
reported in the Ferguson well probably belong to this member. pha

At the West Harbor exposure (fig. 173) the Montauk is probably eS
represented by the heavy bed of till resting unconformably on the
upturned and eroded edges of the Jacob sand and the Herod gravel
member.

 

 

 

 

°

 

5 ; 7 FiGureE 172.—Section east of Fort Ter-
At the second locality mentioned the exposures show a series of ry, Plum Island, showing bowlder

beds of clayey sand alternating with beds of pebbles about the size of, Montauk fill membor arrested
s a 7 plowing along the surface of

of a hen’s egg occurring in a matrix of clay or clayey sand. Both Herod gravel member.

sand and gravel show the peculiar mixture of coarse grains or pebbles

with fine silts that is characteristic of rapidly formed and only partly assorted deposits such as

accumulate at the margin of glaciers. The deposit unquestionably belongs to the Montauk sub-

stage, representing certain of the more aqueous phases of deposition. A little farther north,

although the contact is not

seen, the semistratified de-

posits appear to be replaced

~ by till.

8b: eece Deposits penetrated by

wells —Although the Mon-

FieurE 173.—Artificial section near the steamboat landing on west side of West Harbor, Fishers tauk was not re ize
Island (1904). @, Till (Montauk till member?); b, gravel (Herod gravel member); c, gray clayey ees cogn d ge
sand (Jacob sand?); d, gravel (probably lens in Jacob sand). a distinct member during

the first season’s field work,
it was well known that there was a bowlder bed in the middle of the Manhasset formation at
many places, and it was looked for in the well records. The compactness of the member, the
presence of bowlders in it, the large number of granitic pebbles that it contains, and its clayey
constitution are all helpful in its recognition, and the writer feels that he can identify it in
many records in which its presence was not originally suspected. Its occurrence in wells is
summarized in the table on the next page, compiled from the records in Veatch’s report on
the water resources of the island.

 

 

 

 
148

GEOLOGY OF LONG ISLAND.

Montauk till member of Manhasset formation in the wells of Long Island.

 

: y N fa Ti
No.a Locality. Owner or place. en Character of materials. ame, eee
Feet. . ene oa
23 | Brooklyn.......-....- Fifth Avenue and Hight- 35- 45 | Reddish-brown bowlder clay......-.-- Wisconsin and Tisbury.
eenth Street.
29) |nsoza 0}! sstecewmcreyaeies Dean Street and Vanderbilt 56- 81 | Brown sand and bowlders........ Do.
Avenue.
Bartlett Street and Harrison 65-150 | Red clay with large bowlders. . -| Sankaty.
Avenue. : 7
Bartlett Street and Flushing 31- 73 | Sand and granitic clayey gravel . -| Wisconsin and Tisbury (?).
Avenue. s ,
.| Ten Eyck Street........---- b 0- 52 | Clay, sand, and bowlders... -| Wisconsin.
99 North Eleventh Street... 50-100 | Blue clay, gravel, and bowld -| Sankaty (?)and Jameco(?).
-| Grove Street....-.----.----- 33- 58 | Hard, cemented hardpan and re Wisconsin or Tisbury.
brown sand and gravel. :
New Lots Road and Foun- 93-118 | Reddish-brown sand and gray grav- | Tisbury (?) and Sankaty.
tain Avenue. elly clay. :
WF lee. a Gus coskawseseteses Brooklyn test well No. 4. ... 97-141 Dita eee and gravel and gray | Tisbury and Sankaty.
pebbly clay. i
141 |..... Ooh eiardietcje2zciteje Brooklyn test well No. 5.... 192-216 | Gray clay and granitic silty sand... -... Sankaty
151 | Flushing..... .| Citizens’? Water Supply Co-. 90- Blue stony clay...-.--------.-+--+---- _ Do. (?).
176 | North Beach Bowery Bay Building Asso- 20- 32 | Compact mixture of sand and gravel..| Wisconsin to Tisbury (?).
ciation. z
186 | Tallman Island....... Railroad test boring.......-- 30- 57 | Till, with interbedded sand.....-..... Pleistocene.
199 | Jamaica South........| Oconee pumping station... . 56-115 | Grayish to dark-reddish brown sand...) Tisbury.
200 |-..-- do........---------| Baisley pumping station. ... 58- 97 | Gray sand and gravel ---| Do.
220 | Hollis. ......-...- i Brooklyn test well No. 7.... 15- 69 ) Granitic sands and gravel. . ---| Wisconsin and Tisbury.
223 | Dunton.......-.-..... Montauk Water Co : 8- 64 | Blue clay and gray sand and gravel... 0.
236 | Bayside........------- Commission test well........ 17- 55 | Black clayey sand and reddish-brown Do.
sand and gravel. i
DBF" |ordcie OO) 22 csemeseeceaney| cece Os <2. seevicecean eases 0- 65 | Light to dark sandy clays, sands, and | Wisconsin.
granitic gravel.
246 | Elm Point..........-- H. B. Gilbert............... 0- 56 ‘alow ree bowlders, gray sand, | Wisconsin and Tisbury.
and gravel.
258 | Hewlett Point......-- G. B. Wilson............-..- 20- 36 | Stony clay.......- peeteteeseceseetetee Not correlated.
273 | Hewlett -| Queens County pumping 33- 54 | Gravelly clay and dirty sand and gravel.| Sankaty (?)
station.
357 .| T. Valentine. PB 53- 60 | Bowlder till..............-...-------+- Manhasset bowlder bed.
364 C. H. Mason......-...--.--- 18- 52 | Black marl, loam, with pebbles and | Not correlated.
oyster shells (probably reworked
Gardiners clay).
366 Dod ge estate. ..+.e.ccwssee0u 16- 22 | Bowlder till........-. an dGine minis na es Manhasset bowlder bed.
373 -| Long Beach Association... -. 76- 82 | Quartz gravel, with pieces of blue clay | Sankaty.
containing sand and gravel.
378 | Rockville Center...... Commission test well......-- 48- 52 | Sand and gravel, with bowlders....... Wisconsin and Tisbury.
do 2- 3) Tough, sandy clay, with bowlders (?).. 0.
10- 11 | Gray sand and glacial débris (?)......- Wisconsin.
3- Dark silt to cobbles (?)........--.-..-- Do.
7- 26 | Yellow clay, sand, and gravel, with Do.
bowlders.
3- 21 |..-.- GO: winesicitiac.n cen rereeechareeeas Not correlated.
Roslyn..... 50- 53 | Sand, with thin layer of bowlders..... Manhasset bowlder bed.
446 | Glen Head... 60- 75 | Sand and clay..........-..--.--------- Do.
Locust Valley... 80- 87 | Brown clay...--...-.-- 4 Do.
<a 29- 44 | Hardpan, with bowlders. Do.
-| W.M. Valentine............ (6= 79)| Dard pan ...ssivsvcocsescea cease ‘ Do.
| D; Fe Bushs sesoseseerecizee 7- 15 | Blue clay, with pebbles, hardpan. ., Wisconsin.
-| L. C. Wier... 60- 63 | Red clay and gravel, hardpan... -| Manhasset bowlder bed.
.| E. Latting... 60- 63 | Red clay and gravel........ Do.
-| W. D. Gutherie.. 60- 64 |...-. De sweetersaieexs Do.
duzees OD sicicarteccreiniere 38- Large bowlders..... & Do.
-| Mrs. M. H. Clats... 10- 25 | Hardpan with gravel... -| Wisconsin and Tisbury.
.| Commission test well. 45- 50 | Coarse gravels, highly granitic. Do.
William Ralston... 22- 25 | Black hardpan with pebbles. : Do.
-| J. Weber.....-. 38- Clay without bowlders.....-. .| Pleistocene.
-| John Morrissey 17- 45 | Coarse sand and large cobbles. - -| Wisconsin and Tisbury.
.| Irving Overton..... 46 52 | Stony gravel.......-.-....--- : 0.
.| Commission test well 6- 45 | Dirty gray sand and gravel .| Not correlated.
.| Father Ducy-...... 0- 60 | Hardpan and bowlders...... -| Wisconsin.
.| Jerome Saxe. 0-160 | Stony gravel and clay, hardpan... -| Pleistocene.
biactaeiaie,s Q- 30 | Coarse gravel........--.-..---- -.| Not correlated.
&- 70 | Gray sand and granitic gravel. .| Wisconsin and Tisbury.
satan O- 60 | Hardpan and gravel........... : 0. 2
10- 50 | Gravel with streaks of hardpan .| Not correlated.
aif staraiarcreystahawiaiecserie O- 40 | Hardpan...............-.--- ae Do.
786 | Farmingville.. -| August Fuch....... 58- 62 | Hard stony yellow hardpan. ..| Tisbury.
797 | Echo.......- -| Commission test well 50- 60 | Dirty-gray granitic gravel... .-| Not correlated.
848 | Huke Landing .| J. H. Darlington... 35- 60 | Dark-red clay and black sand. .-| Sankaty.
854 | Baiting Hollow.......| C. H. Wells........ 50- 51 | Cemented clay and gravel... .| Wisconsin and Tisbury.
861 | Quogue..... -) Quantuck Water Co. 3- 5 | Sand, clays, and bowlders. 25a Do.
875 | North Bea... -| C. W. Payne....- 8- 10 | Hardpan.................... .| Not correlated.
883 | Shelter Island. Ulmer....... 14- 20 |..... GOws feos see goaecensiensectecennee Wisconsin and Tisbury.
885 |.-..- do..... J. N. Stearns.. 15- 27 | Hard mixture of clay, sand, and gravel.; Wisconsin.
890 |..-.. do... -| Manhasset Hotel . 8- 20 | Hardpan, with sand bed.............. Wisconsin and Tisbury.
895 | East Marion...........) W. F. Fursts.........-....-- 18- 22 Hard-packed sand and gravel......... Wisconsin.

 

 

 

 

 

 

 

 

 

 

 

  
   
 
    
 
 
 
   
 
 
  

 
 
  

    
 
 
 
 
 
  
  
 
 
 
  
     
  
  

 

 

 

  
  
 

 

 

 

    
   
     
    
  
    
   

 

 

 

a Numbers refer to well records in Prof. Paper U. 8. Geol. Survey No. 44. b In part.

The differences between the correlations of Veatch and those of the writer, as brought out in
the last column of the table, seem to be due to the fact that the existence of the member, further
than the bowlder bed mentioned, was unrecognized at the time of the preparation of the report
on the water resources, many of the beds being included by Veatch with his Sankaty (Gardi-
ners clay) because of their clay content, no other clayey member then being known. The
MANHASSET FORMATION—MONTAUK TILL MEMBER. 149

absence of any information as to the great unconformity and the consequent abrupt changes
in level of the beds also tended to make the recognition of the member very difficult.

Among the well records in which the Montauk till member is recognized the following are
of especial interest: Well at Bartlett Street and Flushing Avenue, Brooklyn (No. 38), given
under Jameco gravel on page 86; railroad test boring at Tallman Island near College Point
(No. 186), given under Herod gravel member, on page 131; the G. B. Wilson well, near Hewlett
Point, at the west side of the entrance to Manhasset Bay (No. 258), given under Jacob sand
on page 112; and a well on the Dodge estate near Port Washington (No. 366), given under
Jacob sand on page 113.

The following is a record of a well near Bayside:

287. Record of commission's test well near Bayside. 1

Wisconsin drift, or Hempstead gravel member of Manhasse! formation: Feet.
Mellow-sdind y° clays cmcpescehee. sanunasote wind pods 54.5.8 ¢ aileron aa aa nade RENE + 0- 2
Yellow clayey sand with some pebbles.................2....0.0022e 2c ce cece cece eeeee 3- 5.5

Montauk till member of Manhasset formation:

Dark Cla yey SANG ws cccdyen Se cia qrasisarssnicnesie Gis aioe eid Adee ke Mow ews ex ee axe a LES 10-18
Mottled sand and gravel (pronouncedly glacial)..............00 2.2.0.0 cece eee eee eee 20-29. 5
Multicolored sand and gravel similar to that found below the blue clay on the south shore. 35-36
Dark-yellowish clayey sand (glacial)..............2.020 000202 e cence eee eee eee 40-46
Dark, multicolored fine to coarse sand (glacial).............2202.000 0-0 cece cece cece cease 49-65

Herod gravel member of Manhasset formation:

Fine to coarsesyellow sand with very little glacial material..............2.2.0.2....-- 65-66
Yellow sand and small gravel with many fragments of ferruginous concretions.......... 70-71

The records of the wells penetrating the somewhat doubtful materials at East Williston
and vicinity may also be inserted at this point:

421. Record of commission’s test well near East Williston. !

Wisconsin: Feet.
Very dark brown surface loam..._..... 2222.22.02. c cee cc nce e ee ene eeenee 0 -0.8
Reddish-brown loamy sand.............-. 2.2... 20 02 eee e ce cece eee 2.7- 2.9

Montauk till member of Manhasset formation (?):

Yellow clayand bowlderé\ cscccncucas soos se Coens pees se ceeaecee dees 7. 5-13. 2
Light yellowish-white sand and gravel............. 2.02.2 2.22 022 cece eee eee eee eee 17. 5-18. 5
Reddish-yellow silty sand ........c.e022¢2¢ +o de¥uewestesas dic eeseeseeesee ccemseceen 22. 5-23. 5
Very black sand, full of mica, looks like ground-up bowlder........................- 25 -26.5
Herod gravel member of Manhasset formation (?):
Fine to medium yellowish-white sand...............2. 2.020222. 0 002020222 e eee eee 30 -36
Fine yellowish-white sand to medium gravel.....................02.2002020220-2--5-- 40 -41
Small light-colored gravel (considerable percentage of glacial material)............... 41 —42
Fine to medium yellowish-white sand..................2-2.20 2222000222222 c eee ee 45 —51
Small light-colored gravel with glacial material...................2.2.2-22222...... 54-55
422. Record of commission’s test well near Albertson. } és
eet.
Recent black loamy Clayeeccc.ccnee cco soses casey eo te eetaise eso osha Anobaneeaan 1.7- 2.3

Montauk till member of Manhasset formation (?):
Brownish-yellow clay with a few pebbles very similar to the clay at East Williston. .. 3 - 3.5

Brown and yellow clay with reddish-brown sand and gravel (glacial).................. 8 -9.5
Dark-grayish sand with much fresh biotite; evidently débris from a glacial bowlder.. 10. 5-11.5
Yellow clay, sand, and gravel (‘‘bowlder clay”).........--.-.2-2.22-22-2.2-02.2-002- 15-21
Herod gravel member of Manhasset formation (?):
Sand and coarse gravel (glacial)..........-..---20.-022 00222. 23-24
Fine yellow sand with a noticeable percentage of glacial material.................... 27° -37
AGE.

The Montauk till member was clearly deposited, as its character indicates, either beneath
or at the margin of an ice sheet. Although in certain parts of Long Island, especially near the
east end, there are indications of several advances and recessions of the ice, there is no evidence

 

1 Numbers refer to Veatch’s report. Correlations by M. L. Fuller.
150 GEOLOGY OF LONG ISLAND.

such as soil zones or features due to subaerial erosion to indicate any great lapse of time between
them, and the period of deposition of the Montauk member is therefore to be regarded as a unit.

The Montauk is the third great drift deposit on the island, the two older sheets from their
position, thickness, material, weathering, and erosion, being referred to the pre-Kansan and the
Kansan. If the identification of these earlier drifts, especially the Kansan, is correct there is
little doubt that the Montauk should be referred to the Illinoian, as the series of deposits is un-
broken from the Kansan or Jameco through the Yarmouth or Gardiners to the Illinoian as
represented by the Jacob sand and the Herod and Montauk members of the Manhasset
formation.

Beyond Long Island the Montauk member continues through the New England islands
into Massachusetts, where it is represented by a typical structureless till, being here a land rather
than a glaciomarine deposit. The Montauk and the equivalent till of the mainland constitute
the principal drift of New England, and in comparison with this body of till all other drift
deposits are insignificant. In the interior of the United States a great drift sheet emerges from
beneath the Wisconsin in western Pennsylvania and stretches westward to and beyond the
Mississippi, reaching a thickness of hundreds of feet in places and, like its Montauk equivalent
in New England, greatly surpasses in development the other drifts. In other words, in the
Mississippi-Ohio valley, in New England, and on Long Island the third drift is by far the most
important of the glacial deposits, and it is not unfair to assume that in each region it belongs to
the same glacial stage, the Illinoian. The correlation of the Montauk with the Illinoian is
rendered more probable by the recent investigations in Europe, which appear to show a close
agreement of glacial stages with those of the Mississippi Valley and Long Island, as if the
succession had been not only similar but simultaneous.

To attack the problem of age from another standpoint, it may be noted that the period of
erosion between the Wisconsin and the Manhasset (the latter including the Montauk), was of
great length, being many times greater than that reported between the Wisconsin and the Iowan
drifts. If not of Illinoian age, the drift must be referred to another ice sheet unknown either in
the Mississippi Valley orin Europe. That the most powerful sheet and the thickest drift in Long
Island and New England should belong to an invasion not elsewhere represented is improbable
if not impossible. If the grave doubts that have recently arisen as to the existence of the Iowan
in the central portion of the country are justified the number of invasions in the eastern and
central regions is the same and the correlation of one with the other is made more certain.

HEMPSTEAD GRAVEL MEMBER.

NAME,

After the Montauk invasion and its attendant erosion, deposition, and folding, the ice
retreated from Long Island and a series of gravels were laid down, doubtless derived from the ice
which appears to have lingered in the vicinity. For these gravels, which represent the upper-
most of the three subdivisions of the Manhasset formation, the name Hempstead gravel member
is here introduced, from Hempstead Harbor, along the west side of which the gravel is finely
exposed in the upper parts of many large gravel pits.

CHARACTER.

The Hempstead gravel member is very similar to the Herod gravel member, showing the
same variations in different parts of the island. In fact, there is nothing in its lithologic
character by which it can be distinguished from the Herod member and the description of the
Herod given on page 121 applies almost equally well to the Hempstead. If there is any differ-
ence it is in the more sandy character of the younger member. Because of their resemblance
the beds can not be differentiated from one another except where they are associated with key
Ha such as the Gardiners clay, the Jacob sand, or the Montauk till member of the Manhasset
ormation.
MANHASSET FORMATION—-HEMPSTEAD GRAVEL MEMBER. 151
SOURCE OF MATERIAL.

What has been said of the source of material of the Herod gravel member is almost equally
applicable to the Hempstead gravel member. The only difference to be expected is a smaller
percentage of material derived from the Cretaceous and Mannetto deposits and a greater per-
centage from Connecticut sources. In general, however, the difference is not well marked, the
Hempstead member of western Long Island showing practically as much of the Cretaceous and
Mannetto material as the Herod member.

RELATIONS TO OLDER DEPOSITS.

The normal contact between the Hempstead member and the underlying Montauk member
is conformable, but, as elsewhere indicated, the final event of the Montauk invasion in the eastern
part of the island was a vigorous advance
of the ice, as a result of which both the
earlier Montauk and the underlying beds
were folded, faulted, and eroded. As little
or no deposition attended this last ice ad-
vance, the Hempstead, where occurring

 

 

above the Montauk in this part of the 100 Feet teow enero jj

island, is likely to rest on an eroded or frevunre 174.—Section east of Montauk Light. a, Hempstead gravel member;
?

folded surfac e (fig 17 4) b, clay with glacial pebbles and bowlders belonging to the Montauk till

member; c, banded till belonging to Montauk member.

The contact between the Hempstead
and the Montauk, even where conformable, is usually sharp and abrupt, but in places a
transitional phase from a few inches to a few feet thick is observed. Where the contact is
unconformable it is almost universally abrupt.

STRUCTURE.

The Hempstead gravel member is much less disturbed than the underlying deposits, the
overriding Wisconsin ice apparently having been either thinner, less active, or of shorter duration
than the preceding ice sheets. The folding is in general rather superficial, affecting but a few
feet of the gravel as brought out in figure 202 (p. 210) and Plate XIX, A (p. 114), although
there are indications that it was of considerable magnitude in some places where the ice
pressed against bluffs or other steep slopes.

DISTRIBUTION.

Relation of Hempstead gravel member and Montauk till member.—In western Long Island the
Montauk member occurs as a thick zone showing abrupt lateral transitions from till to gravel
or vice versa, so that not uncommonly one exposure shows a thick bed of till at a horizon at
which an adjacent exposure shows nothing but coarser gravel. Between the extremes are many
gradations, the till being thin or absent and the gravels relatively thick or the till thick and the
gravel phase absent. The member, however, appears to be a unit and to represent a single event
in geologic history. The overlying beds are in general undisturbed.

Farther east, in the middle portion of the island, the till phase becomes more common and
persistent than in the west. It still retains its unity, however, and is still overlain by essentially
undisturbed beds.

In the part of the island near Riverhead a marked change appears to have taken place.
West of this point the period of Manhasset accumulation seems to have comprised, first a stage
of aqueous deposition (Herod gravel member), next an ice invasion with the deposition of till
(Montauk till member), and last a return to aqueous deposition (Hempstead gravel member).
East of Riverhead the opening stage of aqueous deposition was much the same as at points farther
west, but the epoch of ice invasion appears to have lasted much longer, continuing well toward
the close of the Manhasset deposition. The invasion was not, however, confined to a single
152 GEOLOGY OF LONG ISLAND.

advance, as in the central and western parts of the island, and the deposits are not a unit.
Instead the ice appears to have advanced and retreated several times, giving rise to the alter-
; nations of till with stratified clays, sands, and gravels
noted on Gardiners Island, at Montauk, and elsewhere.
Throughout the whole of the North and
South flukes and on the adjacent islands
exposures that can be certainly correlated
Figure 175.—Section 1 mile northwestof East Fort Point, With the Hempstead member are lacking,
Lloyd Neck, showing disturbed and faulted gravels ap- for although gravels and sands are found
parently overlying the Montauk till member. hare at a thare above Un Montauk mets
ber they appear, even where best developed, as on the Montauk peninsula, to
have been overridden by a readvance of the ice and strongly folded or faulted.
That this disturbance is very old, probably Montauk, is indicated by the deep
subaerial erosion to which the beds were subjected between the time of disturbance
and the advance of the Wisconsin ice. Unfortunately, however, the evidences of
subaerial erosion are not everywhere conspicuous, and it is consequently impossible
to say whether the folding is Montauk, the gravels being Montauk or younger, or
Wisconsin, the gravels being perhaps as young as the Hempstead’member. For
this reason it has usually been impossible to differentiate the beds with certainty
in eastern Long Island. When differentiation is impracticable the beds above the
Montauk till member will be spoken of as the gravels of the upper Manhasset.

It is noted that the Hempstead gravel member, although generally absent
from eastern Long Island, reappears on Block Island and at places farther east.

West of Inttle Neck Bay.—On the north shore near the west end of Long
Island a bed of sand or gravel in places separates the Wisconsin till at the surface
from the Montauk till member. This bed occupies the normal position of the
Hempstead gravel member, with which it is probably to be correlated. Among
the exposures best showing the relations of this gravel is that one-third of a mile
east of College Point, represented in figure 136 (p. 135).

Great and Manhasset necks, North Hempstead.—Traces of the Hempstead
gravel member between the Montauk member and the Wisconsin drift are seen
here and there on Great Neck, North Hempstead, but the first clear-cut exposure
showing the relations was seen at Barker Point, 2 miles northwest of Port Wash-
ington village, on Manhasset Neck, where the section shown in figure 137 (p. 135)
wasfound. On the north and northeast shores of Manhasset Neck the exposures
are poor, but south of Bar Beach on Hempstead Harbor the Hempstead member
was observed in many gravel pits. Only the lower part, however, was seen,
the upper part being eroded previous to the Wisconsin ice invasion and later
covered with a thin coating of Wisconsin till.

Oyster Bay.—The Hempstead gravel member is nowhere well exposed along
the coast between Hempstead Harbor and Oyster Bay, although unquestion-
ably occurring beneath the relatively thin Wisconsin till in the highlands back
from the shore. At Rocky Point, 24 miles north of Oyster Bay village, an ex-
posure about 15 feet thick was seen in a trough of the Montauk member (fig. 65,
p. 96), and the Hempstead member appears to form the upper part of the bluff at
Mill Neck, northwest of the village, and at Coopers Bluff, 2 miles northeast.

Lloyd Neck.—The Hempstead gravel member appears to form the upper
part of the hills on Lloyd Neck beneath the mantle of Wisconsin outwash and till
but is seen in few bluff sections. There is an exposure near the northward curve
of the beach, half a mile east of the Cretaceous outcrop and 1} miles southeast
of Lloyd Point, where folded and faulted gravel of the upper part of the Manhas-
set formation is exposed. The character of the exposure is brought out in figure 175 and
Plate XXIII, B. A mile farther east and continuing to East Fort Point a fine to clayey sand,

 

 

 

 

 

FIGurE 176.—Section northwest of East Fort Point, Lloyd Neck, showing Wisconsin till in unconformable contact with Hempstead gravel member and Montauk till member.

 

 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 82 PLATE XXIII

 

 

 

 

 

A. UNCONFORMABLE CONTACT BETWEEN HEMP-
STEAD (?) GRAVEL MEMBER OF MANHASSET
FORMATION AND CRETACEOUS DEPOSITS ON
LITTLE NECK, HUNTINGTON.

 

 

 

 

 

B. MANHASSET GRAVEL FOLDED BY OVERRIDING ICE.
MANHASSET FORMATION—-HEMPSTEAD GRAVEL MEMBER, 153

probably the Hempstead member, was exposed above the Montauk member almost continuously,
although here and there cut out by erosion during the Vineyard stage, especially near the cast
end of the section (fig. 176).

Little Neck, Huntington.—In the large clay pit on the east side of Little Neck, Huntington,
a little south of Little Neck Point, finely stratified sands and gravel are seen resting against the
Cretaceous clay with the relations shown in figure 177. The pebbles in the gravel are fresh
and at the base there are a number of moderate-sized and perfectly fresh granite bowlders.
Thé freshness of the gran-  ,/__
ite seems to preclude its ett
being Mannetto, and the
large and fresh bowlders
could, so far as is known,
have been brought in only ki
by the Montauk ice or of
floating bergs from its Ficure 178.—Section near Friars Head, showing

: Hempstead gravel member resting unconform-
margin, hence the gravels ably against the Montauk till member.
are apparently to be cor-
related with the Hempstead member. The unconformity, which is one of the sharpest observed
on the island, is shown in Plate XXIII, A.

Smithtown Bay region.—The Hempstead member is definitely recognized at few places
around Smithtown Bay, but an outcrop on the coast between Nissequogue River and Stony
Brook Harbor (fig. 139, p. 137) shows a somewhat well developed bed above the Montauk till
member.

The gravel at the top of the bluffs on Crane Neck Point east of Smithtown Bay grades
downward into the Montauk till member and may probably be regarded as the Hemp-
stead gravel member, or at least as a transition between the Montauk and Hempstead members.

Port Jefferson to Wading River.—The gravels in the upper part of the
bluffs bordering the east side of Port Jefferson Harbor are
distinctly above the Montauk till member and are there- 100"
fore apparently to be referred to the Hempstead member. :
In the big gravel pit south of the town of Port Jefferson
the gravels are thought to be the Hempstead, at least in
the upper part, although in the absence of information as
to the position of the Montauk member, which is the key
bed, it is impossible to determine the horizon of the gravel ele
with absolute certainty. The Hempstead member appears é
to include the greater part of the deposits shown in the bluffs
along West Beach north of the town. From this point :
to Wading River there appear to be no unquestionable use

 

  

 

 

Figure 177.—Section in clay pit near end of Little
Neck, opposite Northport. a, Slightly weathered
gravel (Hempstead gravel member ?); b, bowlder
bed (Montauk till member ?); c, greenish weathered
surface of Cretaceous clays (d).

 

 

 

 

 

 

oO

Figure 179.—Columnar
section between Friars
Head and Roanoke
Landing. a, Dune
sand; b, Wisconsin till;

  

 

 

 

FicguRE 180.—Columnar

c, Hempstead gravel
member; d, unconform-
ity; e, Montauk till
member; f/, Herod
grave] member.

exposures of the Hempstead member, the folded and
faulted character of the gravel and the altitude of the
Montauk member indicating that the gravels are perhaps
to be referred to the Herod member, although the Hemp-

section near Roanoke
Landing. a, Dune sand;
b, Hempstead gravel
member; c, Montauk
till member.

stead member probably occurs in the higher lands back from the coast.

Friars Head—From Wading River to Friars Head the Hempstead member is nowhere
exposed, the Montauk being at the tops of the bluffs. A little east of Friars Head, however,
the Hempstead lies lower, nearly 40 feet of buff sand and gravel having the relations indicated
by figures 178 and 179 being exposed. The Hempstead rises a little farther on and is absent
from the bluffs to a point near Roanoke Landing, where the gravels at the top of the bluff,
above the gravelly phase of the Montauk member in the center of the section, represent the

Hempstead member.
154 GEOLOGY OF LONG ISLAND.

Roanoke Landing and Jacob Hill—Near Roanoke Landing about 20 feet of the Hemp-
stead member was seen above the Montauk till member, with the relations shown in figure
180 (p. 153), and a little east of the landing the section shown in figure 144 (p. 139) was measured.
Near Jacob Hill a considerable thickness of gravel belonging to the upper part of the Manhasset
formation was seen above the Montauk till member at
several points (figs. 181 and 182).

 

  

 

 

° 20 Feet Oo

50 Feet
FIGURE 181.—Section west of Jacob Hill, showing irregular contact be- FIGURE 182.—Section west of Jacob Hill. uv, Hemp-
tween Hempstead gravel member and Montauk till member (struc- stead gravel member; b, Montauk till member;
ture poorly exposed). ce, Herod gravel member.

Oregon Hills and vicinity-—Uf the bowlder beds and pockets noted near Oregon Hills and
Duck Pond Point (fig. 147, p. 140) represent the Montauk member, as there is reason to believe,
the gravels above them must be referred to the Hempstead member.

Rocky Point.—Because of the height at which the Hempstead member occurs, very little
of the gravel is seen between the Oregon Hills and Orient Point. About three-fourths of a
mile south of Rocky Point, north of Greenport, however, several sections show sand and gravel
over the Montauk till member. The following is a section at this locality:

Section three-fourths of a mile south of Rocky Point.

Wisconsing: Til loncs. qugcsesae dad datitinmay ssa cuisine aydlastediabiniG. <iee Se es Selddteee cease Seid 10
Hempstead gravel member or Montauk till member:
Sand and fine gravel vcossveuicteteee vee ne cet aes Bese eeaecede See sy org seeiewebeee ee Se sdeae Be 5
@oarseipra vel aii. ccc en etensbcaies ye 625074 Leeda cae en tes td ese Yee 6 eee 5
Montauk till member:
Bowldér pockétj:<ssiis.sndiedawan- cases orcas eeeeeieieee haste gt eee cueedsdekal ae ioe eggs 1-3
Senlistratihed: tills. ccscihysceaisise es ye 2S a a6 Maaemebeast wide FA aae Suaehsate Rides y 202d neha 20

Riverhead to Sag Harbor—No good exposure of the Hempstead gravel member was seen
between Riverhead and Shinnecock Canal, although traces were seen here and there (fig. 183).
Half a mile or so east of the canal and in the bluffs north of Cold Spring Pond, 14 miles to the
northeast, gravel, perhaps the Hempstead member, was
seen at several points above the Montauk till member.

 

 

 

 

 

° 25 Feet

 

oO 250 Feet
FIGURE 184.—Section on Jessup Neck, west of Sag Harbor.
FIGuRE 183.—Section northwest of Shinnecock Canal. a, Hemp- a, Dune sand; 6, Wisconsin till; c, Hempstead gravel
stead gravel member; b, Montauk till member (very clayey). member; d, unconformity; e, Montauk till member.

On Jessup Neck there are many exposures of gravel, most of them only slightly disturbed.
In only one place, however, near the north end of the bluffs on the west side, are the relations
of the deposit clearly seen. At this point the gravel is a well-developed horizontal bed rest-
ing unconformably upon the Montauk member with the relations shown in figure 184. Another
exposure near the same point was of interest in showing an early stage of a flexure such as has

given rise to many faults on the island (fig. 185). From Jessup Neck to Sag Harbor there are
no good exposures.
MANHASSET FORMATION—HEMPSTEAD GRAVEL MEMBER. 155

Hog Creek Point.—South of Lion Head Rock, near Hog Creek Point, gravels belonging
to the upper part of the Manhasset formation were seen in strong development above the
Montauk till member (figs. 153 and 154, pp. 142 and 143), and just north of Fireplace an
exposure showed a marked unconformity in the
gravels, seemingly the result of Montauk erosion. 40"
No drift of this stage is present, but it is probable
that the gravels represent the Herod and Ilemp-
stead members (fig. 186). Gravels of the upper
part of the Manhasset were also seen above the
Montauk till member near Cedar Point, a few _°

t FiGure 185.—Section on Jessup Neck, west of Sag Harbor, show-
miles west (fig. 121, p. 128) and above the uncon- ing fold changing downward into fault.
formity shown in figure 123 (p. 128).

Montauk peninsula—Farther east the next point at which the gravels were seen was half
a mile west of Rocky Point, on Fort Pond Bay, where the conditions shown in figure 155 (p. 143)
were observed. The gravels here (upper part of Manhasset formation) are strongly folded. At
Culloden Point, sands be-
longing to the upper part
of the Manhasset forma-
tion, were seen resting upon
and apparently infolded
with the Montauk till mem-
ber, as brought out in figure
187. Near Shagwong Point
FIGURE 186.—Section near Fireplace, South Fluke, showing unconformity in gravels, presumably the gection of gravels (be-

Hempstead and Herod gravel members. loncinte to the doser Beanz

ging pp
hasset), shown in figure 188, was exposed. A persistent bed of chocolate-brown clay (upper
Manhasset?), 3 to 4 feet thick, was also seen near this locality above 10 feet of the Montauk till

member and 1 to 3 feet of later drift.

 

 

 

 

 

oO 50 roo Feet

 

Just north of Montauk Light
occur several fine exposures of
folded and overturned sands and
gravels. They clearly lie above
the Montauk till member, which
rises from beneath them near the

FIGURE 187.—Section near Culloden Point, Montauk. a, 4. we :
Wisconsin till; b, sand with reddish clay lamin (either lighthouse, but it is possible that

Hempstead gravel member or gravel phase of Montauk they represent the gravelly phase

till member); c, Montauk till member. of the Montauk member. The
conditions are illustrated in figure 174 (p. 151).

Opposite the lighthouse and at the point a considerable thickness

of sands and gravels which unquestionably belong to the Hempstead

member lies above the

Montauk member,  FiGvRE 189.—Section south of
Montauk Light. a, Mon-

Figure 158 (p. 143) tauk till member; b, cross-

shows the occurrence bedded sands belonging to
Hempstead gravel member;

of possible Hempstead c, alternating sand and clayey
i j sands belonging to H

Figure 188—Section 1 mile west of False Point, Montauk. a, Till (Mon. Material in the bluffs a sei a

tauk till member); b, cemented ferruginous sand and gravel with some and at the same time sand and gravel of aerial

bowlders (Montauk till member?); ce, sand belonging to Hempstead -; : : Hempstead mem!
gravel member; d, gravel belonging to Hempstead gravel member. indicates the puzzling , me
complexity of the ex-

posures. The section between the small bay south of the lighthouse and the point is shown
in figure 159 (p. 144). Figure 189 shows the profile at the extreme point.

In the 2-mile stretch of beach southwest of Montauk Point no good exposures of the gravel
were observed. Just north of the bend of the shore from southwest to west, however, gravels

 

 

  

 

oO “20 Feet
an ed

 

 
156 GEOLOGY OF LONG ISLAND.

belonging to the upper part of the Manhasset formation were seen above the Montauk till
member for a distance of nearly a quarter of a mile. The general attitude of the beds is hori-
zontal, but they are
2 ; — locally disturbed and
g ge folded (fig. 190). In
the bluffs half a mile
east of Ditch Plain
gravels were noted rest-
ing on the Montauk
member and apparently
cut by an extensive thrust fault. The conditions are represented in-figure 191. Near the
beginning of the bluff west of Ditch
Plain the somewhat complicated occur-
rence of gravel represented in figure
192 was observed.

In the bluffs of the south shore
west of Fort Pond traces of the
Hempstead gravel member are seen
here and there near the top. One of
the best sections measured was at a point about a mile from the west end of the bluffs. It is
as follows:

 
     

REGO Ne SY wie,
° < - 0 2 :9 .
Ficure 190.—Section 25 miles east of Ditch Plain, Montauk, showing Hempstead gravel member over-
; lying Montauk till member.

 

 

 

 

 

 

Figure 191.—Section half a mile east of Ditch Plain, Montauk, showing folded
and faulted gravels overlying Montauk till member.

Bluff section near ‘‘ First House,’’ Montauk.

Feet.

Recent? Dune: sande caccnnadacccaganesadd oc 2-259.4-a2d andes SOS has eee eeunGee Soe aa 5

Wisconsin: Gray to buff bowlder till...........-.. 0-22.20. 2. eee eee 3
Hempstead gravel member or Montauk till member: Buff sand and gravel with basal layers

CEMENT. DY ALON tie os aise erase als tt ORME Nain ates ale eco Itch aber eek latent Ate NN co ee 25

Montauk till member:
Sand phase (irregularly stratified sand alternating with thin clay lamine).................- 20
Till phase (banded drift and talus).........-.--..-- 220-22. 2 eee eee eee eee 30

Adjacent islands.—The conditions on the smaller islands adjacent to Long Island at the
east end are very similar to those on the North and South flukes. Thin beds of sand or gravel
are seen in places above the Montauk member on Plum Island (6, fig. 171, p. 146) and on Gardi-
ners Island (, fig. 167, p. 146), but except on Robins Island no noteworthy developments of
the gravel were observed.
On Robins Island, how-
ever, a considerable body of
the Hempstead gravelmem-

z os ae ber was noted above the
GURE 192.—Section west of Ditc ain, Montauk, showing apparent unconformity between : .
cross-hedded grave] (Hempstead gravel member) and underlying banded till (Montauk till tall. Figure 165 (p. 145)

member). shows disturbed Hemp-
stead gravel resting upon an irregular surface of the Montauk member on the east side of the
island; figure 193 shows a slight thickness of presumably Hempstead gravel member above an

unconformity on the west side of the island; and figure 194 shows a greater thickness in uncon-
formable contact with

older gravels supposed
to belong to the Herod Z
gravel member. ° 100 Feet

. Vs
Deposits penetrated Figure 193.—Section on west side of Robins Island. @, Hempstead gravel member; b, unconformity

by wells.—The Hemp- marked by layer of ferruginous cemented gravel; c, sand, gravel, and clay (Jacob sand); d, dark-gray,
; green, and purplish clay (Gardiners clay).
stead gravel member is

penetrated by a large number of wells in the western and central parts of Long Island, prac-
tically every well that has entered the Montauk till member (see table, p. 148) having first passed

 

 

9 100 200Feet

 

 

 
VINEYARD FORMATION. 157

through the Hempstead. In wells it is usually very difficult if not impossible to distinguish the
member from the overlying Wisconsin drift, and this differentiation has not in general been
attempted in the following table, which gives a few of the more definite occurrences:

Hempstead gravel member of Manhasset formation in wells of Long Island.

 

Depth of for- Name used in original

No.a Locality. Owner or plaice. Character of materials.

 

  
 
  

 
  

 

 

 

 

 

 

 

mation. reports.
Feet.
23 | Brooklyn............. Eighth Avenue and Eight- 15-35 | Silty to clean sand and gravel......... Wisconsin.
eenth Street.
Bartlett Street and Harri- 60-65 | Coarse sand.........2..22.22-2-2.2000- Tisbury .
son Avenue.
Brooklyn test well No. 5.... b 16-192 | Reddish-brown granitic gravel........ Wisconsin.
-.| Baisley pumping station... 21-58 | Fine to coarse yellow sand ..| Wisconsin and Tisbury.
T. Valentine. 15-53 | Cobbles and yellow sand Transition and Tisbury.
.-| Dodge estate - . ‘ 6-16 | Fine sand...............- -| Tisbury. |
.| Long Beach A 40-76 | Gray to yellow sand and g: .| Tisbury and Sankaty.
a Numbers refer to well records in Prof. Paper U.S. Geol. Survey No. 44. bIn part.

Of the wells included in the table complete records are given of No. 366 on page 113 and
No. 373 on page 73.

AGE.

The Hempstead gravel member is a retreatal deposit of the ice sheet which at its farthest
advance laid down the Montauk till member. As has been indicated elsewhere, the ice
lingered in the eastern part of the island
to the close of Manhasset deposition, the
last important incident of its occupa-
tion being a vigorous readvance which
scoured and disturbed the older beds at
a time when it had withdrawn from the
west end of the island, permitting the
accumulation of the outwash deposits
represented by the Hempstead member,
which is thus contemporaneous with the last part of the Manhasset invasion and is to be placed
in the Ilinoian.

 

 

 

° 100 Feet
eee

FIGURE 194.—Section on west side of Rohins Island. u, Hempstead gravel mem-
ber; b, brownish loamy zone along unconformity; c, Herod gravel member.

VINEYARD FORMATION.

Between the base of the Recent beach deposits, which probably do not extend more than
20 or 25 feet below sea level, and the horizon at which the Gardiners or the Jacob fauna is to
be expected, peat, marsh muck, wood, stumps, and tree trunks, also quahog, clam, scallop,
and oyster shells have been found. The finding of so many of these remains in deposits that
seem to be above the Gardiners clay and the Jacob sand and below the Wisconsin and Recent
accumulations seems to point to an intervening formation of intermediate age. As it is unlikely
that they belong to the glacial Manhasset formation it seems probable that they should be
referred to the Vineyard ' interglacial stage, representing marsh, soil, and beach deposits formed
at a time when the land stood considerably above its present position with reference to sea level.

In the following table is presented a list of occurrences of shells, wood, peat, etc., which
seem likely to have come from this formation. The occurrences are largely taken from the
reports of A. C. Veatch? and F. J. H. Merrill,* but the present writer alone is responsible for
the interpretations.

1 Woodworth, J. B., Seventeenth Ann. Rept. U. 8. Geol. Survey, pt. 1, 1896, p. 979,

2 Prof. Paper U.S. Geol. Survey No. 44, 1906, well records.
3 Annals New York Acad. Sci., vol. 3, 1886, p. 357.
158 GEOLOGY OF LONG ISLAND.

 

 

 
  

 

  

Wells reporting possible occurrences of the Vineyard formation. =
No. of
Location. well Depth. Material.
(Veatch).
Feet.
Fort Greene (1814)............|/..-------- 70 | Clam shells.
Fort Lafayette..........-...-- 2 23-40 | Gravel and sand with broken shells (possibly Wisconsin drift with secondary fossils).
2 40-53 | Compact silts with many shells including Nassa obsoleta, Anomia ephippium, Mya arenaria,
Crepidula fornicata, Mytilus edulis.
Governors Island. ...........- 10 70 | Dark gravel with shells (under till). _
Brooklyn, 556 Kent Avenue... 55 129 | Oyster shells (these occur below a thick clay and may belong to the Gardiners clay).
Long Island City, 408 Ninth 118 50-57 | Quicksand with marine shells (under till).
venue.
Brooklyn test well No.3...... 204 72 | Peat (in yellow sand above Gardiners clay).
Brooklyn test well No. ae 205 59-72 | Water-rolled twigs (in gray sand above Gardiners clay).
New Utrecht.-...---.- zl wsdewentee 43-67 | Pyrula, clam, oyster.
Flatbush Almshouse.........-|.--..----- 40-50 | Clams and oysters.
Belson Brooklyn and Flat- |.......... 60 | Exogyra costata.
ands.
Bushwick i fslS acon eeaik 40 | Log of wood.
East New York... crallyieter on 80 | Clam shells.
Hicksville. ..._. 3 502 15-22 | Black silts, etc., resembling soil zone (beneath outwash). 3
Quogue.___....... ee 859 135 | Mulinia, Astarte, Nassa trivittata, and fragments of echinoderms (horizon doubtful).
Bridgehampton...-.........-- 897 100 | Shell fragments in sand and gravel.

 

 

 

 

WISCONSIN DRIFT.

The term Wisconsin is applied to the deposits laid down during the last glacial advance as
a mantle over the older deposits of Long Island, the application of the term to this region being
based on the tracing of the deposits by T. C. Chamberlin,! G. F. Wright,’ and others across New
Jersey, Pennsylvania, New York, Ohio, Indiana, and Illinois, into the type area in Wisconsin,
from which the name was derived. As it is a surface formation, much more is known of its
character, distribution, and manner of accumulation than of the features of the older drifts,
and its deposits may with advantage be differentiated into a number of component parts,
the most important of which on Long Island are (1) the till sheet or ground moraine, (2) the
outer or Ronkonkoma moraine, (8) the outwash from ice along the Ronkonkoma moraine,
(4) the later (inner) or Harbor Hill moraine, (5) the outwash from ice along the Harbor Hill
moraine, and (6) the retreatal deposits.

THE TILL SHEET.

CHARACTER.

The till sheet or ground moraine includes the deposits laid down beneath the glacier when
the débris contained in the base of the ice sheet or dragged along beneath it was set free, either
through melting of the ice or by friction with the overridden surface. It is composed of unas-
sorted mixtures of clay, sand, and bowlders, the nature of which differs greatly in different parts
of the island. In western Long Island granitic material commonly constitutes 5 to 10 per
cent of the pebbles, though in some localities nearly half of the pebbles are granitic. In other
places, however, quartz pebbles predominate, it being in fact almost impossible to find granitic
materials in some of the outcrops. Toward the central part of the island, beyond the Cretaceous
and Mannetto remnants of Eaton Neck, the percentage of quartz rapidly decreases and that of
granitic pebbles and bowlders increases. In the eastern portion of the island pebbles and
bowlders of the granite type usually predominate in the till. In general it may be said that
the till varies in composition with the character of the underlying materials over which the ice
had recently passed. This explains the quartzose character of the till in the vicinity of the
Cretaceous deposits and the Mannetto gravel, the gravelly or sandy character over the Herod
gravel member of the Manhasset formation, and the more clayey character and local red colora-
tion that it has where resting upon portions of the Montauk till member of the Manhasset forma-
tion containmg Triassic material. At several points, especially on Jessup Neck west of Sag
Harbor and on Montauk Point, the till appears to have been formed locally of reworked sand
dunes, and it is not improbable that many of the sandy phases of the north shore are of similar
origin.

 

1 Third Ann. Rept. U. 8. Geol. Survey, 1883, pp. 291-402. 2 Bull. U.S. Geol. Survey No. 58, 1890, pp. 39-110.
WISCONSIN DRIFT. 159

The till has yielded fossils at a considerable number of points. The greater number
evidently represent material reworked from the Gardiners clay, the Jacob sand, or the Vine-
yard formation, but many silicified fossils from the limestones of the mainland occur, and here
and there a Triassic sandstone with leaf impressions is found.!

In color the till, where unoxidized, is usually a dull gray, with a slight tinge of buff or brown
due to the oxidized materials incorporated in the mass. In western Long Island, however, it
commonly exhibits a distinct reddish tinge, due to the presence of Triassic material. This
coloration is noted in only a few places east of Little Neck Bay, Flushing, although traces are
observed where the Wisconsin overlies the reddish phase of the Montauk till member of the
Manhasset.

The thickness of the Wisconsin till is greatest in western Long Island, where it is commonly
10 to 15 feet thick, and in some places, where it is represented largely or entirely by slightly
shoved or reworked portions of the underlying gravel, much thicker. It seems to become
thinner toward the east, the bluff sections of the central part of the island commonly showing
not more than 5 to 10 feet, and those of the extreme eastern parts usually less than 5 feet.

In structure the till is usually rather loose, its materials showing a general lack of coherency.
For this reason exposures do not stand well as a rule and soon become covered with talus.
Relatively little clay is present in the till. In this respect it differs very noticeably from the
Montauk till member, which is not only associated with clayey beds in many places, but carries a
sufficient amount of clay throughout its mass to act as a binder, thus making possible the cemen-
tation observed in it.

In texture the Wisconsin till is very diverse, all grades of coarseness from sand to bowlders
being known. On the whole, however, it tends to be somewhat coarse, resembling the surface
till of New England rather than the more compact till of the Montauk member. Bowlders are
not very conspicuous in western Long Island, being in few places as large or as closely packed
as in some areas of the Montauk till member, such as the bowlder bed of Hempstead Harbor.
In fact large bowlders are of comparatively uncommon occurrence in the general till sheet
mantling the Manhasset terrace, though they are abundant in the moraine to the south.

In general there are no indications of banding in the Wisconsin till, but a few exposures
were seen in which a lamination similar to that of the Montauk member was noted. All such
exposures were of very small extent and were clearly the result of local rather than of general
conditions. They are confined mainly to the sandy phases of the till, being almost nowhere
present in the coarser varieties (Pl. XXIV, B).

Where the Wisconsin till is less than 4 feet thick, it has commonly been oxidized from top
to bottom and exhibits brownish or yellowish colors such as characterize the drifts of New
York and New England. Where the till is thicker, the oxidation may fail to reach the bottom,
the lower part being of a lighter and more grayish color. In most places where the till is 10
feet or more thick, however, it has a slight buff tinge throughout, due to the fact that a con-
siderable portion of its material was oxidized before being incorporated into the glacier that
later deposited it. Presumably if the invasion had been longer continued, the later till derived
from less-weathered‘materials would have been as dark and unoxidized as that of the Montauk
till member.

SOURCE OF MATERIAL.

The materials of the Wisconsin till are derived from the formations over which the ice
passed, the larger portion of the deposits coming from the older unconsolidated gravels, sands,
and clays of the immediate vicinity. This is especially true of the region from, Flushing to
Port Jefferson, where not only the great abundance of loose material but also the character of
the topography favored the absorption of large amounts of material by the ice. Farther cast
the percentage of material derived from near-by deposits seems to have been less, the Sound
affording. unfavorable conditions for absorption. A considerable quantity of the coarser
material, including the bowlders, is derived almost entirely from the mainland, as are the granite

 

1Newberry, J. S., Proc. New York Lyceum Nat. Hist., Ist ser., 1871, pp. 149-150.
160 GEOLOGY OF LONG ISLAND.

pebbles except those derived from the Manhasset formation or older gravels. It is noticeable
that Triassic fragments, which are common in the Montauk member, are relatively rare in the
Wisconsin, except at the extreme west end of the island, apparently indicating that the Wis-
consin invasion was weaker or less prolonged than the earlier Montauk invasion.

RELATIONS AND STRUCTURE.

The relation of the Wisconsin till to the older deposits is very simple. It is a superficial
mantle resting upon the eroded surface of the older deposits and following closely the contour
of the erosion surface, rising in the hills and sinking in the valleys. Where the surfaces on
which it was laid down were even its thickness was commonly only a few feet, but in the
valleys it was not infrequently deposited to a greater depth. Over one large area, including
the greater part of the Nissequogue drainage system, the drift is so thin as to be unrecognizable.

The Wisconsin till in general does not itself show any indications of disturbance other
than by landslides along the present bluffs. Folding and faulting, such as characterize the
older formations, are generally absent, apparently indicating a very weak ice sheet compared
to the Montauk.

The base is in many places sharply defined, especially where the Wisconsin till rests upon
the Montauk till member, knife-edge contacts being common (Pl. XXII, A, p. 136). In other
places, however, there is more or less transition between the underlying gravel and the till, as
if parts of the gravel had been dragged along, reworked, and incorporated into the till. There
are also many local examples of contortion and folding on a small scale (Pl. XIX, A, p. 114),
although nothing comparable with the folding during the Montauk substage was observed.

DISTRIBUTION.

Greater New Y ork.—West of the eastern limit of Greater New York, near Little Neck Bay,
the Wisconsin till is relatively thick, covering the greater part of the surface with a mantle
effectually hiding the underlying Manhasset formation. Exposures showing 15 or 20 feet of
till are not uncommon, and even thicker sections are found at many points in the vicinity of
Brooklyn and Long Island City. In fact, the general till sheet seems in this region to grade
almost insensibly into the thick till of the moraine. The material is a rather tough bowlder
clay apparently consisting largely of Triassic ingredients brought from the New Jersey side of
the Hudson, 5 miles to the northwest. Both the composition and the unusual thickness are
largely explained by the proximity to the outcrops at this point. The Ronkonkoma ridge,
now crossed by the Harbor Hill moraine just south of the head of Manhasset Bay, originally
extended across this region but was overridden and reworked at a later stage by the ice, and
much of its material was incorporated in the Wisconsin till sheet.

A detailed investigation of the geology of this part of the island, which it did not appear
desirable to duplicate in the field work for the present report, had been made by R. D. Salisbury
and others ! several years before, at a time when the Montauk till member had not been recog-
nized as a separate division and all till was included in the Wisconsin. The writer had no
opportunity for reexamining the region in detail, but from what he has seen he is inclined to
regard the Wisconsin till, although undoubtedly of considerable thickness, as forming only a
part of the till exposed, the lower and probably thicker portions seemingly belonging to the
Montauk till member of the Manhasset, correlated with the Illinoian. The fact that the Iinoian
is the principal till wherever found in New England and in the Ohio and Mississippi valleys, the
Wisconsin being almost everywhere relatively thin, makes it seem improbable that the condi-
tions at the point under discussion are exactly reversed, especially as the Wisconsin constitutes
hardly more than a mantle in adjacent regions. The depth of oxidation, which is in not a
few places 10 to 15 feet or more, is perhaps the most satisfactory of the direct evidences of the
presence of older drift, being much in excess of the 5 feet commonly reached by the Wisconsin
weathering.

 

1 New York City folio (No. 83), Geol. Atlas U. S., U. S. Geol. Survey, 1902.
WISCONSIN DRIFT. 161

In the vicinity of Astoria and between Little Neck and Flushing bays, according to R. D.
Salisbury ‘—

The hillocks of ground moraine [till sheet of this report] occasionally assume an elliptical form, about twice as long
as broad, the longer axes being parallel to the direction of ice movement. Such hills of ground moraine are called
drumlins. One of the best examples of a drumlin in this region is the hill at Lawrence Point. Other examples of
drumlins, or of drumloid hills, occur three-fourths of a mile farther south, half a mile northwest of Steinway, and north

of College Point, where Tallman Island appears to be a drumlin. The elongate hill just southwest of Tallman Island
also has something of the drumloid form.

Little Neck Bay to Oyster Bay.—Between Little Neck and Oyster bays, where the Wiscon-
sin drift is seen in its most characteristic development, the till is gravelly, including large amounts
of stained and white quartz pebbles from the underlying Cretaceous beds and the Mannetto
gravel. It overlies the eroded Manhasset surface as a mantle or veneer, having a maximum
thickness of about 15 feet but averaging considerably less. Even shallow roadside sections
may cut entirely through the covering into the Manhasset below. Although the surface as a
whole maintains the flatness characteristic of the Manhasset terrace, it shows in many places
a subdued morainal aspect, due in part to the unequal deposition of the till and in part to a
disturbance of the gravel of the Manhasset formation by ice drag or shove. As would natu-
rally be expected, all gradations between slightly disturbed Manhasset material and thoroughly
reworked gravels are found. Bowlders are not, as a rule, either numerous or large in the till
sheet of this region, although blocks of considerable size are seen here and there. The till
sheet follows the contour of the Manhasset surface rather closely, but its thickness is more
variable in the valleys than on the terrace surface. In many of the smaller valleys the till
- filling is considerable, but in the large depres-
sions now occupied by the harbors and bays of
the north shore the amount of till is ordinarily
rather slight, apparently because of a concen-
tration of ice activity causing a tendency to
erode rather than deposit at those localities.

Oyster Bay to Port Jefferson.—The distribu-
tion and character of the Wisconsin till between
FIGuRE 195.—Section showing till ridge at head of valleys opening to Oyster Bay and Port Jefferson is very similar

the north. . 6 : : :

to that in the district immediately west. Its
thickness, however, is somewhat less, and it is in general somewhat more gravelly and carries
fewer bowlders. One very large bowlder, however, measuring nearly 40 feet on its longest
diameter, was seen on the road between Port Jefferson village and the railroad depot. Because
of the occurrence of the Montauk till member at the surface at many points it is difficult, at
some places where the exposures are poor, to tell whether the till is Montauk or Wisconsin,
but where the exposures are good there is usually little difficulty. The contact, where the
older and younger tills come together, is usually very sharp.

A notable feature in this region is the thickening of the drift into a sort of miniature moraine
at the head of a number of the north-south valleys, as indicated in figure 195, apparently caused
by the shove or drag of the ice masses passing up the valleys.

Cold Spring Harbor region.—The Wisconsin till sheet undoubtedly extends beneath the
Harbor Hill moraine and the outwash associated with it, reaching at least as far south as the
Ronkonkoma moraine, but because of the thickness of the overlying deposits it is rarely seen.
Here and there, however, where a pre-Wisconsin valley of considerable extent stretched back
above the inner moraine, as south of Cold Spring Harbor, residual ice seems to have prevented
the covering of the region by outwash, and a coating of Wisconsin till was left at the surface
on the sides of the old valley. This is made manifest largely by bowlders, although outcrops
of the till are not wanting. It is probable, however, that some of the bowlders came from
the Montauk member of the Manhasset formation, which presumably outcrops around the
border of the valley.

 

 

 

 

1 Op. cit., p. 14.
1629°—14—_12
162 GEOLOGY OF LONG ISLAND.

Dix Hills-—The Wisconsin till is best seen where outliers of older formations rise above
the outwash, as in the region north of the Dix Hills, where not only bowlders but also good
exposures of till are seen overlying the older deposits. Plate XXIV, B (p. 162), shows an out-
crop of banded Wisconsin till resting upon an older and somewhat disturbed gravel, apparently
the Mannetto gravel.

Smithtown “driftless area.”—The Smithtown ‘‘driftless area,” which is driftless only in
lacking conspicuous Wisconsin deposits, is one of the most remarkable regions of the island.
A line extending along the south base of the Harbor Hill moraine from Nissequogue River west-
ward to Kings Park, thence southward to the Ronkonkoma moraine, thence eastward within
a mile or two of Hauppauge, and finally northward through Smithtown to the point of beginning,
would inclose an area of nearly 15 square miles, comprising the western part of the drainage
basin of Nissequogue River (Pl. X, p. 46), in which no recognizable Wisconsin till occurs.
At first sight its absence might seem to be due to post-Wisconsin erosion, but that such
a drainage system, the most advanced of all on the island, could have been developed
here while practically nothing was being accomplished in post-Wisconsin time in other situa-
tions equally favorable to erosion is manifestly unlikely. The discovery of a Wisconsin esker
three-fourths of a mile below Smithtown, extending to the very bottom of the present valley,
fully established the pre-Wisconsin origin of the drainage system. That the ice passed over
the region is conclusively shown by the presence of the well-developed moraine on the south
rising from 40 to 100 feet or more above the Manhasset level. How, then, is the absence of
drift to be explained? To the writer the most probable assumption seems to be that the dis-
trict was covered with a thick mantle of snow or snow ice previous to the advance of the gla-
cier, which on invading the region overrode the surface deposits without coming into contact
with them. This would explain the absence of disturbance by shove, the lack of gravelly till
accumulations such as are usually very conspicuous where the Manhasset formation has been
overridden by the Wisconsin ice, and the almost perfect preservation of even the minor drain-
age features. Under this assumption the only drift to be looked for would be the englacial
material set free on the final melting and retreat of the ice. The absence of bowlders in the
region indicates that if present the englacial material must have been scanty and very fine
grained. That such material may indeed have been set free is not improbable, but because of
its similarity to the Manhasset deposits it has not been recognized. No coarse materials or
in fact anything clearly identifiable as Wisconsin drift was seen anywhere in the western half
of this drainage system.

Middle Island region.—Stretching from Coram northeastward to Long Pond, about 2
miles south of Wading River station, and thence southward to the Ronkonkoma moraine is a
broad terrace-like tract of high land (apparently Manhasset formation), which stands above the
outwash level and is more or less cut by pre-Wisconsin drainage lines (Pl. XX, p. 116), the
whole clearly resembling the Manhasset terraces near Hempstead Harbor and elsewhere along
the north shore. The surface is likewise characterized by a subdued morainal topography,
apparently due to the drag or shove of the loose gravels by the Wisconsin ice, and is covered
with more or less scattered bowlders, mostly small, and with patches of Wisconsin till. This is
the largest single area of conspicuous intermorainal Wisconsin drift on the island.

Peconic Rwer region.—The region along Peconic River between the two moraines (PI. IX,
C, p. 42) shows a fair number of bowlders and here and there a small mass of Wisconsin till,
but the greater part of the region is made up of an undifferentiated mixture of Wisconsin out-
wash and gravel of the Manhasset formation. It is on the projecting Manhasset surfaces that
the bowlders and patches of till are most likely to be found. .

Riverhead to Orient Point.—The till south of the Harbor Hill moraine on the North Fluke
is very thin, and through considerable stretches it is impossible to recognize the drift in sec-
tions. Its presence is made manifest, however, by a bowlder here and there and by irregulari-
ties of the surface due to ice shove.

Adjacent islands and the South Fluke-—The conditions on the adjacent islands—Robins,
Shelter, and Gardiners—are not notably different from those on the North Fluke, although their
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 82 PLATE XXIV

 

   

 
 

. TYPICAL BOWLDER BEACH ON NORTH FLUKE.

 

 

 

 

 

   

 

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3B. BANDED WISCONSIN TILL ON OLD GRAVELS (MANNETTO?), DIX HILLS.
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WISCONSIN DRIFT. 1638

more rugged topography seems to have encouraged a more extensive reworking of the deposits
by the Wisconsin ice and a greater deposition of till.

On the north side of the South Fluke essentially the same conditions prevail as on the islands.
The till is mostly local and carries relatively few bowlders. On Jessup Neck and at places on
Montauk the till seems to be composed largely of reworked pre-Wisconsin sand dunes.

South of the Ronkonkoma moraine.—There is no decisive evidence that the Wisconsin ice
ever passed south of the line of the Ronkonkoma moraine in western Long Island. A number
of granite fragments, the largest a foot in diameter, were noted over the surface of the Half
Hollow Hills and a few still larger bowlders were seen in some of the hollows, but they are
believed to belong to the Montauk till member of the Manhasset formation rather than to the
Wisconsin. No unquestionable till was observed nor were any irregularities due to ice drag
or shove, such as characterize the Manhasset surfaces north of the moraine, seen in this region,
the disturbed condition of the Cretaceous beds of the clay pits being ascribed to creep. If the
ice ever covered the region, its presence was but temporary, and it receded without leaving any
lasting traces. The only clear evidence of till beneath the outwash on the South Fluke is in the
vicinity of Easthampton, where in times past bowlders have been washed out from beneath the
sands by the waves. This material is thought to be Montauk rather than Wisconsin, but it is
not impossible that an extensive though very attenuated sheet of Wisconsin drift may exist
beneath the outwash east of the Shinnecock Hills. The occurrence of numerous kettles in the
outwash ! (see p. 168) probably indicates the presence of ice south of the moraine, but whether
these hollows represent ice blocks left after an invasion of the Wisconsin glacier or simply extra-
glacial snow or snow-ice accumulations is not known.

RONKONKOMA MORAINE.

NAME.

To the outer moraine, which extends from the point where it emerges from beneath the
later Harbor Hill moraine, near Lake Success, south of the head of Manhasset Bay, eastward to
Montauk Point, the name Ronkonkoma is epplicd, from Lake Ronkonkoma, not far from the
center of the island, and one of its best-known features.

CHARACTER OF MATERIAL.

The Ronkonkoma moraine exhibits marked variations in character in its different parts,
ranging from almost pure till to fine sands. In a given area, however, its character is fairly
uniform. The till phase is most largely developed in western Long Island, where certain sec-
tions reveal many feet of this material. Even here, however, the till is likely to alternate with
gravels, indicating water action. In the western part of the island the gravels are commonly
very coarse, with only faint traces of banding, and resemble the tumultuous esker deposits of
New England and elsewhere. Finer sands and gravels, some of them distinctly stratified, are
present in places.

Farther east, in the region of the West or Mannetto Hills, the gravelly phase becomes more
pronounced. The greater part of the deposits observed are of coarse, almost structureless
gravels, but till or similar impervious material appears to be present in considerable amounts,
as indicated by the numerous springs, kettle lakes, and similar features. The stratified gravels
occur in increased quantities.

East of the Dix Hills the material is finer, gravel and sand being here the predominant
constituents of the moraine. Indeed, in places the moraine seems to consist almost entirely
of sand, especially in the region near New Village and Selden, south of Port Jefferson, and at
points between Manorville and Riverhead.

Bowlders are much less numerous and decidedly smaller in the Ronkonkoma moraine than
in the inner moraine. Few are more than 5 feet in diameter and those exceeding 10 feet are
exceptional. Notwithstanding this, one of the largest bowlders on the island, said to have
measured originally 125 feet in circumference, was found in this moraine, at Rock Hill, 2 miles

north of Eastport.’

 

1 Mather, W. W., Geology of New York, Fe 1, 1843, p. 165.
2 Bryson, John, “Rock in Long Island, N. ¥.: Am. Geologist, vol. 16, 1895, pp. 228-233.

Hiab ‘

og PR ART DEPAKIE
164 GEOLOGY OF LONG ISLAND.

The weathering is mainly superficial, like that of the till sheet, and is rare, except on the
included pebbles derived from older deposits. The only cementation occurs in the neighborhood
of basic pebbles or similar sources of iron,

‘SOURCE OF MATERIAL.

In composition the moraine partakes less of the character of the local material over which
the ice passed than the till sheet, owing apparently to the fact that much of the moraine was
formed from material that lay high up in the ice, whereas the till sheet was built up from basal
materials. During the time required for materials to work upward to a considerable height
within the ice the glacier travels far, hence the morainal material was probably derived from a.
more remote point than that of the till sheet.

The granites, which abound in the moraines, are clearly derived from the New York or
Connecticut mainland, although possibly in part reworked from the underlying drifts. The
fact that the proportion of granitic pebbles and bowlders is greater in the moraine than in the
drifts mentioned would seem to indicate that they were derived to a large extent directly from
the mainland. There is, however, in the moraine of western Long Island a notable percentage of
stained quartz pebbles which must have been derived largely from the Mannetto gravel of adja-

-cent regions, and it is probable that in the sandy districts farther east a still larger part of the
morainal material was obtained from adjacent beds of the Manhasset formation over which the
ice passed. Very little Triassic material occurs in the Ronkonkoma moraine although, as pre-
viously seen, it is a large constituent of the older drifts.

RELATIONS TO OLDER DEPOSITS.

The base of the Ronkonkoma moraine rests upon the eroded surface of several older forma-
tions. In western Long Island it lies largely upon the Manhasset terrace, in the hills near
Westbury upon the Mannetto gravel, in the Mannetto and Dix hills upon Cretaceous and Man-
netto, and in the region east from these hills to Montauk Point upon the Manhasset. Inasmuch
as the Manhasset rises to 200 or 240 feet above sea level and the Cretaceous in West Hill probably.
to 350 feet, it is clear that in western Long Island but a fraction of the total height of the mo-
raine, whose maximum is about 410 feet, represents true morainal accumulations. Farther
east, in the Riverhead region, the thickness of the morainal deposits is greater, only about 100
feet of a total of 400 feet being represented by the Manhasset. On Montauk the morainal
deposits are again of subordinate importance, forming but a relatively small part of the 150
feet which measures their altitude.

DISTRIBUTION.

From Lake Success, south of Manhasset Bay, where the ridge emerges from beneath the
Harbor Hill moraine, to Syosset, the moraine is composed mainly of kamelike accumulations
of stratified drift and till. It is here relatively inconspicuous, being at many points cut by deep
gaps and at others partly buried by the outwash deposits of streams issuing from the ice front
during the accumulation of the later Harbor Hill moraine. From Syosset to High Hill the topog-
raphy of the ridge is distinctly morainic, being marked by conspicuous and very irregular ket-
tles and knolls. The high percentage of quartz in the deposits, topographic indications, and
the evidence of well records all point to the moderate thickness of the morainal material, the
Mannetto gravel reaching at some places within 20 feet of the surface.

At High Hill the moraine reaches its highest elevation east of the mountains of New
Jersey and Pennsylvania, culminating in a sharp knob rising 410 feet above sea level, although
the body of the moraine reaches only about 350 feet. The percentage of quartz pebbles in
the knob strongly suggests Cretaceous or Mannetto material, but there is an admixture of
granites to the very crest, indicating that the knob is a part of the moraine, at least superficially.
In the lower part of the moraine at the same locality granites are very abundant, and quartz
is present only i small amounts. The Cretaceous and Mannetto apparently rise to not less
than 340 feet at this point, judging from the terrace on the south. Just east of High Hill, at
WISCONSIN DRIFT. 165

distances of 1 and 14 miles, there are two gaps occupied by outwash of the later stage, and
another broad gap is found south of Commack. In the intervening areas the moraine is rather
high, standing 100 to 200 feet above the outwash, or 250 to 350 feet above the sea.

From the Commack Channel to the big channel now occupied by Connetquot Brook, a
distance of 7 miles, the moraine is, in the main, a well-developed and fairly continuous ridge,
reaching an altitude of 220 feet, or 100 to 140 feet above the outwash. About 2 miles south-
west of Hauppauge, however, at the headwaters of Nissequogue River, the moraine subsides
locally to or below the level of the outwash plain, forming the most westerly example of what
may be termed a ‘‘depressed moraine.’ Similar conditions exist in the vicinity of Lake
Ronkonkoma, where great outwash plains take the place of the ordinary ridge of till or gravel.
The moraine, however, is in most places represented by low till accumulations reaching slightly
above the surrounding level, but more especially by the immense kettle plain formed by the
deposition of an outwash sheet over great blocks and masses of ice, which, on melting, gave
rise to the very pronounced kettle topography of the region. Lake Ronkonkoma itself repre-
sents a large kettle formed in this manner.

Southeast of Selden the morainal ridge becomes once more very pronounced, continuing
with a height of 300 feet or so to Coram Hil. In this region very little but fine sand can be
seen in crossing the moraine, and in places the vegetation is very thin and the sand still shifts
shightly under the action of the wind. Superficially the material is largely dune sand, but
whether this is simply a mantle over a moraine of the normal type or whether the moraine is
unusually sandy and free from gravel at this point is not definitely known. The latter suppo-
sition, however, is thought to be probable.

Near Yaphank the moraine is interrupted by the deep channel now occupied by Carmans
River, but from this channel to Shinnecock Canal the ridge is in general strongly developed,
reaching a height of over 300 feet in places, as at Bald Hill, southwest of Riverhead. The
moraine is not without breaks, however, there being several points in the region south of
Manorville, southeast of Riverhead, and near Good Ground where gaps of considerable width
occur.

Although some of the breaks in the moraine east of Coram Hill are due to erosion by the
later outwash streams, more of them have resulted from the nondeposition of morainal materials,
as in the vicinity of Lake Ronkonkoma. Jn such places the deposition by the outwash streams
was usually much in excess of the morainal accumulation, with the consequence that the outwash
deposits reach a much greater height than the morainal deposits, the moraine being of the
depressed type.

At Rock, 2 miles north of Eastport, remnants of a bowlder said to have originally measured
over 125 feet in circumference are to be found. The bowlder, which has been quarried inter-
mittently by the people of the vicinity since the settlement of the island, and is now much
reduced, is said to be still an imposing obelisk-like object 50 feet in circumference.!

At Shinnecock Canal there is a break in the moraine extending practically to sea level,
but the Shinnecock Hills east of the canal, though largely composed, as shown by the bluff
sections, of gravel of the Manhasset formation, nevertheless have a strong superficial morainal
topography due largely to the disturbance and reworking of the underlying gravel by the
Montauk ice and rendered especially conspicuous by the entire absence of trees such as else-
where usually obscure the contours of the moraine. The irregular hills and steep intervening
troughs, basins, and kettles are all well shown. It should be noted, however, that less than a
century ago these hills were covered by drifting dunes, to which a part of the surface irregularities
are due.

The moraine in this region, as in that south of Riverhead, is made up of confluent units and
is not a.simple ridge, the tendency being toward the accumulation of large, high hills, such as
that north of Hampton Park, Southampton, or sharp knobs such as Bald Hill, southwest of
Riverhead, and the high cone 3 miles southeast of Manorville, nearly 300 feet in altitude. A
noticeable feature of these hills is that although the morainal topography is highly developed

 

. 1 Bryson, John, Rock Hill, Long Island, N. Y.: Am. Geologist, vol. 16, 1895, pp. 228-233.
166 GEOLOGY OF LONG ISLAND.

and is characterized by numerous knobs and kettles, there are in addition many radiating
trenches apparently due in part to the action of running water. “The forms are thought to be
the result of the accumulation of steep detrital cones by overloaded waters issuing high up in
the ice, 200 to 350 feet above sea level, if one may judge by the altitude of the deposits. The
radiating channels mainly mark the position of the rivulets in the closing stages, although pos-
sibly they are to a subordinate extent due to subsequent erosion before the land became covered
with vegetation. Many of the channels have flat bottoms, many have steep slopes on the
outside of the swings, and in some the late erosion is distinguished from the older by a notching
of the bottom.

From Shinnecock eastward to Promised Land the moraine is again strongly developed,
being represented by a ridge rising to an altitude of more than 280 feet, or about 200 feet above
the outwash plain. There are, however, a number of breaks similar in character and origin
to those between Yaphank and Shinnecock farther west.

At Promised Land occurs the most important break in the moraine found on the island.
The ridge is here interrupted for more than 4 miles, the intervening space being occupied by a
sea beach covered with recent dunes. On Montauk the conditions are similar to those in the
Shinnecock Hills, the morainal features being especially conspicuous because of the absence
of trees. The morainal development, which seems to be more the result of disturbance and
remodeling of the old Manhasset topography than of deposition or other accumulation, is on a
larger scale than in the Shinnecock Hills. Probably not more than 50 of the 150 feet of the ele-
vation, however, is to be referred to the moraines, and it is almost certain that on the outer
point the thickness of Wisconsin deposits is very much less.

The Ronkonkoma moraine is supposed to be represented farther east by the morainal
accumulations of Block Island, Marthas Vineyard, and Nantucket, but the correlation with
these deposits is not absolutely certain, for the reason that the continuation of the Ronkonkoma
moraine eastward is below sea level, and the evidence of connection afforded by the submarine
bars is not conclusive.

OUTWASH FROM ICE ALONG RONKONKOMA MORAINE.

OCCURRENCE.

The outwash from the Ronkonkoma moraine includes the great sloping plains lying south
of the moraine and extending continuously, except for the short breaks at the Shinnecock
Hills, from the west end of the island to the vicinity of Amagansett. It is well developed around
Lake Ronkonkoma, a large kettle lake surrounded by moraine and outwash in the central part
of the island.

CHARACTER OF MATERIAL.

The material of the outwash plain ranges from the moderately coarse gravel with pebbles
as much as 2 inches in diameter found along the margin of the moraine to find sand at the
south shore. The relative percentage of quartz and granite pebbles varies greatly, all grada-
tions being found from a pure quartz gravel not much different from portions of the Cretaceous
and Mannetto, except that the staining is less conspicuous, to granitic gravels in which quartz
pebbles form a very small part. In general, as in the older formations, the amount of quartz
varies with ‘the proximity to Cretaceous or Mannetto masses. West of the Dix Hills the per-
centage of quartz is especially high and in some places a granitic pebble can be found only with
difficulty.

Because of the flatness of the deposits sections are extremely rare, but from the few shallow
excavations it appears that all gradations from nearly horizontal stratification to a highly
complicated flow and plunge structure exist. The materials are in few places weathered or
stained and are not known to be cemented either by iron oxide or otherwise, even locally.

Certain parts of the outwash plain have a thin superficial coating of dark-brownish loam,
consisting in some places largely of sand, but in others of pebbles intermixed with a certain
amount of finer silt. It is this finer material, which is oxidized, that gives the color to the
WISCONSIN DRIFT. 167

deposits. The depth is in some places only a few inches and was nowhere seen to exceed 14
feet. No trace of lamination was noted in the deposits seen by the writer. The contact with
the underlying material is usually sharp, and the material has the aspect of being a separate
formation, apparently not greatly different from the so-called “Jamesburg loam” of New Jersey.
The material is well developed in the Hempstead Plains and is seen near the moraine at points
north of East Moriches and southeast of Sag Harbor.

SOURCE OF MATERIAL.

This outwash was, in general, fed by streams issuing at the base of the ice or at least at
lower points than those forming the Ronkonkoma moraine. The materials, being derived
from portions of the ice near the base, are of more local origin than the higher morainal deposits,
a fact which would explain the greater percentage of quartz, etc., derived from the adjacent
areas of Cretaceous and Mannetto. This is especially true of the outwash issuing through
gaps in the moraine. The material from higher portions of the ice, as in the higher outwash
fans along the base of the moraine, which were evidently supplied from the same sources as the
moraine itself, is likely to have had a more remote origin, as was explained in the discussion of
the source of the morainal materials. The diversity in the relative amounts of quartz and
granite pebbles is very great and depends mainly on original differences in supply due to the
character of the material over which the ice passed and possibly also to the presence of deposits
of the Manhasset formation or other gravels in the path of the outflowing streams. Such
deposits are known to have been present in the path of the streams that laid down the later
outwash from the ice along the Harbor Hill moraine below the Mannetto and Half Hollow
hills, where the gravels of the Manhasset formation approached the surface or projected through
the outwash at many points.

RELATIONS TO OLDER DEPOSITS.

The outwash from the ice along the Ronkonkoma moraine rests upon an old and exten-
sively eroded surface of gravels belonging to the Manhasset formation. This old surface had a
southward slope similar to that of the present outwash, although somewhat more gradual.
Under the action of long-continued stream work, however, it became trenched by many well-
defined and fairly deep southward-leading valleys, its edges were indented by marine estuaries,
and its borders were locally cut by low marine cliffs. Near the moraine, where the outwash de-
posits were most abundant, and especially where the deposition was effected by small rivulets
rather than by large streams occupying well-defined channels, the older topography has been
obscured, but farther south the outwash becomes attenuated and the Manhasset shows at the
surface. In some places, where glacial streams of considerable size led through gaps in the mo-
raine, the work was at first one of erosion rather than of deposition and channels were cut either
in the earlier outwash or in the underlying Manhasset. Such channels may be seen extending
southward across the Manhasset outwash at many points, although they are much smaller than

‘those formed at the subsequent Harbor Hill substage. Some of the material brought down
in these channels was deposited in the lower parts of their courses and in the estuaries of the
Manhasset coast, but most of it was swept beyond the present coast line. In general, there-
fore, where the outwash is thick it overlies the Manhasset plain and valley alike, but where
it is thin it rests largely in the valleys or other depressions of the Manhasset surface.

DISTRIBUTION.

West of Manhasset Bay, near the head of which the Ronkonkoma ridge disappears beneath
the later Harbor Hill moraine, no outwash from ice along the Ronkonkoma moraine is recog-
nizable, the deposits being entirely covered by the later drift.

From Jamaica to the vicinity of the Mannetto Hills stretches a great outwash deposit,
constituting what has been called the Hempstead plains. The deposit is evidently made up
of outwash material, part associated with the Ronkonkoma and part with the Harbor Hill
moraine, but it has been impossible to differentiate these parts in the region as a whole, owing
168 GEOLOGY OF LONG ISLAND.

to the similarity of material and the absence of distinct topographic features. From the later
Harbor Hill moraine several distinct channels pass through the Ronkonkoma moraine and
lead southward across the outwash. The incision of these Harbor Hill channels shows that
near the Ronkonkoma moraine at least the outwash from ice along the Ronkonkoma moraine
is the principal surface deposit, reaching a height of 120 feet. Farther south many of the
channels are less marked and indications of a spreading out of the later outwash in fans over
the earlier outwash are observed.

In and around the west side of the Mannetto Hills is a local area of outwash from ice along
the Ronkonkoma moraine without any apparent admixture of later drift, reaching a maximum
elevation along the base of the moraine of about 200 feet. A similar area, now standing as a
terrace 30 feet above the later outwash, or about 180 feet above sea level, is seen on the west
side of the Dix and Half Hollow hills, and a smaller area is found on the southwest flanks of
the group of hills between the Dix and Mannetto groups. The greater part of the area between
the groups of hills and between the hills and the coast, however, seems to be outwash from ice
along the Harbor Hill moraine.

From the Half Hollow Hills to Brentwood is a broad stretch of outwash from ice along the
Ronkonkoma moraine rising to the height of 150 feet or more and having a typical contour.
East of Brentwood, however, the outwash, though still present in considerable amounts, becomes

thinner and the gravels of the Manhasset

5 is a formation project through it atintervals.

as oe) & é :

aes a Its maximum elevation is about 160 feet.
xs AS . . *

eae 4 * AtConnetquot River the composite plain

s
Carmans River
20ft

100" Bs is interrupted by a broad outwash chan-
PN teen tees | nel of the Harbor Hill substage, while
eh south of Yaphank it is cut by a still

Sea devel broader channel of outwash from ice
along the Ronkonkoma moraine un-
mixed with Manhasset material and ap-
parently deposited in a broad valley or estuary in the Manhasset formation. The profile along
the railroad near Yaphank station shows the relations of the outwash from ice along the Ron-
konkoma moraine to the Manhasset formation and the notching due to Vineyard erosion
(fig. 196).

From Yaphank to Shinnecock Canal the same intermixture of outwash and Manhasset
forms that was noted west of Yaphank is observed (elevation along moraine 80 to 140 feet),
but between Shinnecock and Mecox bays the outwash, although much lower, predominates.
From Mecox Bay to and beyond Bridgehampton the topography is again composite, the Man-
hasset rising above the outwash at many points and even where below the outwash manifesting
its presence by kettle channels and other similar features. The marked kettle channel at
Scuttle Hole has been described (p. 43) and illustrated (Pl. IX, A, p. 42). Outwash deposits
rise to 150 feet at this point. From Bridgehampton to Easthampton the outwash again con-
trols the topography (Pl. XXI, A, p. 118), although considerable influence is exerted locally by
the Manhasset and the surface is extensively modified by the formation of dunes west of Georgica
Pond. From Easthampton to Promised Land the topography is of the mixed type (Pl. XXI, B).
No outwash from ice along the Ronkonkoma moraine is found on Montauk.

 

 

 

FicurRE 196.—Profile of Carmans River outwash channel near Yaphank.

HARBOR HILL MORAINE.

NAME.

After the upbuilding of the Ronkonkoma moraine and the associated outwash plains the
ice retreated northward to or above the line marked by the northern or inner moraine and,
perhaps after some fluctuation, finally halted on this line. The northern moraine, which extends
from New York Harbor on the west to Orient Point and beyond on the east, has been desig-
nated the Harbor Hill moraine, from the hill of that name near Roslyn, at the head of Hemp-
stead Harbor, this being the highest point of the moraine on Long Island (384 feet).
WISCONSIN DRIFT. 169
CHARACTER AND SOURCE OF MATERIAL,

Till is much more abundant in the Harbor Hill moraine as a whole than in the earlier
Ronkonkoma moraine. This is especially true in the region west of the point where the Harbor
Hill moraine crosses the Ronkonkoma moraine. From this point stratified materials rapidly
decrease in amount, and till becomes more conspicuous, and from Jamaica westward nothing
but till is seen in most of the exposures, even where these are 25 to 30 feet or more in depth.
The moraine in this part of the island is, in fact, composed practically of till, consisting largely
of Triassic material brought from the northwest across Hudson River. Bowlders abound in
this region (PI. V, B, p. 32).

East of the point where it crosses the older ridge the Harbor Hill moraine becomes more
gravelly, stratified materials being observed practically to the top of Harbor Hill. In this
region the moraine contains rmauch stained quartz from the Mannetto gravel and some white
quartz from the Cretaceous. Tull is not at all uncommon and bowlders are fairly numerous,
though generally small. From the vicinity of Oyster Bay eastward to Port Jefferson both till
and gravel are largely represented in the moraine, but sandy phases, such as occur in the outer
moraine, are not common.

East of Port Jefferson the moraine, although containing abundant stratified material,
carries more unstratified drift, especially bowlders, which in places line the beach or even form
bowlder pavements and heaps extending for considerable distances. The bowlders considerably
exceed in number those in the outer moraine and their average size is much larger. Several
from 30 to 50 feet in diameter have been seen.

In general the source of the material is similar to that of the material in the Wisconsin till
sheet, for it likewise varies in character according to the nature of the material over which the
ice passed. Granitic pebbles and bowlders are more common in the inner than in the outer
moraine, indicating a greater percentage of materials, at least of the coarser sizes, from the
mainland.

RELATIONS TO OLDER DEPOSITS.

The Harbor Hill moraine, like the Ronkonkoma, rests upon the eroded surfaces of several
older formations. West of Hempstead Harbor it lies upon gravels of the Manhasset formation,
* the surface of which descends westward from about 180 feet above sea level near Roslyn to
sea level or below at the Narrows of New York Harbor. For several miles east of Roslyn the
moraine seems to be underlain by Mannetto remnants reaching a height of considerably more
than 200 feet. To judge from the topography of the deposits of this character south of Wheatley,
the buried Mannetto surface must be very irregular (Pl. VI, D, p. 32). From this point east-
ward to the end of the North Fluke the relations of the moraine to older deposits, though irreg-
ular, are very simple, the moraine resting almost solely upon the Manhasset surface, stretching
across its flat terraces, descending its slopes, and crossing its deep valleys. The elevation of
the base of the moraine ranges from a little below sea level to the level of the Manhasset Plateau.
This plateau gradually declines from an altitude of 200 feet near Huntington to 160 feet in the
vicinity of Port Jefferson, 80 feet north of Riverhead, and scarcely 20 feet at Orient Point.

DISTRIBUTION.

The Harbor Hill moraine shows a distinctly lobate form, the lobes being, however, on a
smaller scale than those of the Ronkonkoma ridge and apparently being due to the influence of
the bottom of the Sound or of the form of the north shore upon the movement of the ice. The
lobes are not, however, marked by any distinctive characteristics of composition, structure, or
form.

The part of the moraine west of Manhasset Bay differs from that in any other portion of
the island both in composition and topography. The material is here practically all till, the
moraine possessing a more subdued topography, the steep hills, small cones, irregular gravel heaps,
and steep-sided kettles characteristic of the stratified moraine being replaced by larger, more
170 GEOLOGY OF LONG ISLAND.

regular hills with relatively gentle slopes and less irregular, shallower, and less abrupt depres-
sions. The moraine in this region rises to a height ranging from 100 feet in the vicinity of the
Narrows to nearly 260 feet southwest of Manhasset Bay, or from 80 to 100 feet above the Man-
hasset formation, upon which it rests. A feature of the ridge in this part of the island is the
distinct erosion scarp along its south side from the vicinity of its junction with the older moraine
south of Manhasset Bay westward to Brooklyn (Pl. XI, D, p. 52). This, however, is a sub-
sequent feature and not a normal phase of morainal development.

East of Manhasset Bay there are no important gaps in the continuity of the moraine, the
ridge being unusually persistent and uniform. At the heads of Manhasset Bay and Hempstead
Harbor, however, the moraine is cut by sharp and deep channels leading southward across the
outwash plain. Each of these gaps or passes has an altitude of about 180 feet, or very nearly
that of the Manhasset surface. The moraine rises to a height of 384 feet in Harbor Hill, or 200
feet above the Manhasset level. Exposures in large gravel pits in the valley beneath the moraine
near Roslyn show horizontal Manhasset deposits, establishing the superficial character of the
morainal accumulations.

East of this point for about 7 miles the ridge is practically continuous, although gradually
declining in elevation until near Cold Spring Harbor it hardly rises above the Manhasset out-
wash levels. The valley at this point, although the slopes are more or less covered with till,
seems to have been occupied by residual ice during the upbuilding of the morainal and outwash
deposits, and to this fact 1t owes its freedom from Wisconsin filling.

From Cold Spring Valley to a point near the bend of the railroad east of Greenlawn the
moraine is again fairly continuous, although a break of some importance is found 2 miles
southwest of Huntington. Near the bend of the railroad mentioned there is a still more impor-
tant break marking the passage of an outwash channel, which can be distinctly traced to
Babylon, on the south shore. Other breaks occur between Larkfield and Kings Park stations,
at Nissequogue River, and at Port Jefferson. At the last-named point a large gravel pit
gave (in 1903) an almost complete section of the Manhasset formation up to the base of the
overlying moraine, conclusively showing the superior stratigraphic position of the morainal
ridge.

The rolling topography of the Harbor Hill moraine is exhibited east of Port Jefferson,
where, although the cliff is generally covered with talus, enough can be seen to show that the
morainal till is a superficial deposit resting on horizontal gravels of the Manhasset formation,
which make up three-fourths of the bluff. The moraine in this interval, although still having
the nature of a ridge, in places rises less than 50 feet above the Manhasset terrace on which
it rests. It is marked, however, by kettles that are more conspicuous than any found west
of this point, some of them 40 to 60 feet in depth and having unusually steep slopes.

East of Port Jefferson station the moraine is essentially of the ‘‘depressed’’ type for 24
miles (Pl. VII, B, p. 34), there being practically no ridge. Instead, the outwash plain breaks
off sharply into a belt of immense kettles (fig. 12, p. 34), the bottoms of which lie as low as
100 to 120 feet above sea level, or 60 to 80 feet below the surrounding plain.

Near Miller Place the moraine again takes the form of a ridge, which persists without
notable breaks for more than 10 miles. It reaches an elevation of 220 feet southeast of Miller
Place, 260 feet near Rocky Point village, 246 feet northeast of Wardencliffe, and 230 feet
northeast of Wading River. As the Manhasset rises but little over 100 feet above the sea in
this region, the Harbor Hill moraine is thicker here than in most other places on the island.
The bowlders in it rapidly mcrease in number and size east of Port Jefferson, although they
are not so numerous on the beach as at points farther west, because the waves have not cut
so far into the moraine. Among the largest of the inland bowlders is one found half a mile
northwest of Wading River village near the marsh. It is a sharp pyramid of granite having
a height of 20 feet, a base measuring 18 by 15 feet, and a cubic content of about 4,000 feet.
About it lay several other large fragments, apparently originally parts of the same bowlder
One of these was over 10 feet in diameter and contained 1,000 cubic feet or more. A still
WISCONSIN DRIFT. 171

more massive bowlder was seen just north of the highway from Wading River as it turns to go
up the valley toward Wardencliffe, a little over a mile west of Wading River. Although partly
buried this block probably measures 20 by 20 by 16 feet and contains about 6,400 cubic fect.

Between Wading River and Fresh Pond Landing the morainal development rapidly
weakens, the crest declining from a height of over 220 feet, or 120 feet above the Manhasset,
at a point southwest of Paines Landing to 150 feet, or only 50 feet above the Manhasset, near
Fresh Pond Landing. In fact, this point marks the end of the moraine as a prominent ridge,
a considerable part and in places even the whole of the ridge farther east, although generally
regarded as a moraine, consisting in reality of sand dunes. It is, however, very difficult to
separate the two in the absence of sections, for a coating of sand a few feet thick may cover
and obscure morainal accumulations of great importance and give the ridge the appearance of
bemg composed of dunes when it is in reality largely morainal. For this reason it has been
thought best, except where the dunes are known to predominate, to map the ridge as moraine.

In general, the moraine east of Fresh Pond Landing may be described as ranging from a
low disconnected ridge to isolated patches of morainal drift, the whole covered in many places
with a thick coating of dune sand. Here and there, as northwest of Centerville, the morainal
deposits reach an altitude of 240 feet, or 140 feet above the Manhasset, but in general 170 feet
is the maximum elevation and 80 feet the height above the Manhasset. The moraine is here
usually a narrow ridge, which in places retains but a fraction ol its original width, the remainder
having been cut away by the sea, as shown by the bowlders upon the beach and in the water
as well as by the topography. The seaward side of the moraine is generally a steep bluff more
or less covered with talus, and the inner side is a more gentle depositional slope.

The pseudomorainal character of the ridge where it consists predominantly of sand has
been mentioned. It is well brought out by Plate VIII, B (p. 34), which shows a ridge 20 feet
or more in height and exhibiting a topography that would ordinarily be regarded as unques-
tionably morainal, but the section shows it to consist entirely of dune sand. The morainal
accumulations are here represented only by the till less than 5 feet thick underlying the sand.
Plate VIII, A, is a distant view of a much larger hill, probably not less than 50 feet high, which
likewise appears to consist largely of dune sand.

The region east of Riverhead, more especially that east of Greenport, presents many
opportunities for determining beyond all question the relations of the moraine to the Man-
hasset formation, many sections both m the bluffs and in the amphitheaters and ravines
showing the thick till of the moraine resting upon horizontal Manhasset beds. In 1903 the
best sections seen were half a mile northeast of Inlet Pomt, north of Greenport, and near
Rocky Point, east of Marion. Any storm, however, is likely to change materially the char-
acter of the sections. Those seen in 1903 were no longer conspicuous in 1904, but probably
others equally good have been exposed since. Care should be taken not to mistake the Mon-
tauk till member of the Manhasset formation, which occurs in considerable thickness at the
top of the bluff at several points, for the Wisconsin morainal deposits.

The immense number and large size of the bowlders on the north coast from Greenport
eastward constitute a striking feature. Not only is much of the beach covered with an
unbroken pavement, but the bowlders are in places piled upon one another in great masses.
Plate XXIV, A, shows the appearance of the beach where a moderate number of bowlders are
present. A list of a number of the largest of those that have been measured or estimated is
given below. It should be noted, however, that many of these bowlders lie in front of cliffs
in which both Wisconsin and Montauk materials are exposed and that a portion unquestionably
belong to the older deposit (Montauk).
172 GEOLOGY OF LONG ISLAND.

Large bowlders on Long Island.

 

 

    

 

Location. Situation or reference. Size.

Near Whitestone Point.................... Reported by R. D. Salisbury 2 20-foot bowlder.

Near Eden Point....... Reported by R. D. Salisbury ........... Do.

Southeast of Manhasset. Reported by Warren Upham > 54 by 40 by 16 feet.

North Hempstead .............2.-2-2--..-- Reported by Samuel L. Mitchill ¢ 40 or long, 20 to 40 feet wide, 10 to 17 feet

igh.

$ mile southeast of Lloyd Point........... On beach; probably from Wisconsin till..........-...--.- 17 by 14 by 9 feet.

4 mile south of Halesite................... In till in Manhasset Valley......-......22-22--2202-022 008 Diameter 20 feet.

4 mile south of Crane Neck Point.... --| In Montauk till member of Manhasset formation........-. Diameter 30 feet.

% mile south of Port Jefferson........ .-| In till in Manhasset Valley....-..-...2.----2---020- eee eee 35 by 20 by 5 feet.

4 mile west of Woodville Landing. .-| On beach in front of moraine...............2----+---+--+-- 25 by 10 feet.

1} miles west of Wading River...... .-| Near highway through valley in moraine, ete........--... 20 by 20 by 16 feet.

2 mile northwest of Wading River Slope of moraine near edge of marsh...............--.----- Ey, base 20 by 18 feet, height 15

leet.

East Landing, Wading River............. On beach in front of moraine..........-..--.2--.---2--+----- 25 by 20 by 6 feet.

Near Hulse Landing......-.....-...------ On beach and in water. Both Montauk till member of | Hundreds from 10 to 20 feet in diameter.
Manhasset formation and Wisconsin drift present in
bluff.

-| 30 by 15 by 8 feet.

38 by 20 by 11 feet.

Diameter 15 feet.

-| Base 23 by 20 feet; height 10 to 18 feet.
-| Diameter 25 feet.

 
    
 
 
 
 
 

Middle of Oregon Hills... -
} mile west of Duck Pond :
1} miles east of Horton Point. .

3 mile east of Inlet Point............ 8 -— 0. :

3 mile east of Inlet Point........-... i .--| Many over 10 feet in diameter.
4 mile southwest of Inlet Point... . mis d Do

ioe southwest of Rocky Point. . a .--| 25 by 25 by 30 feet.

ast of Rocky Point...........-..-.-.---. Several bowlders 20 to 25 feet in diameter.
Probably 30 to 40 feet before.

Jennings Point, Shelter Island............ Reported by F. J. H. Merrill d__..........-...-.---2..----- 9,000 cubic feet.

2 miles north of Hastports .ci ees sien career In moraine. Reported by John Bryson ¢_..............-. 50 feet in circumference, 20 feet high

(originally 125 feet in circumference).

 

 

 

aNew York City folio (No. 83), Geol. Atlas U. 8., U. S. Geol. Survey, 1902, p. 14.
b Am. Jour. Sci., 3d ser., vol. 18, 1879, p. 201.

e Med. Repository, vol. 3, 1800, p. 330.

d Annals New York Acad. Sci., vol. 3, 1886, pp. 341-364.

eAm. Geologist, vol. 16, 1895, pp. 228-233.

Owing to the covering of dune sand, it is not always possible to recognize small breaks in
the moraine. The first break in the region east of Fresh Pond Landing is northwest of Baiting
Hollow, where the outwash, except for a thin coating of dunes, reaches the edges of the bluffs
bordering the north shore. At Mattituck Inlet is a more important break, the gap here being
more than a mile wide and extending to sea level. A small break with a southward-leading
channel intersects the Oregon Hills. Other important breaks occur at Hashamomuck Pond
and a mile northeast of that place, both the moraine and the Manhasset formation being cut
to or below sea level. This shows that before their connection by sand bars and marshes what
is now the North Fluke consisted of a number a detached semimorainal islands, such as Plum
Island is to-day. The most easterly break is at Truman Beach, near Orient, this likewise
marking a former channel between islands.

OUTWASH FROM ICE ALONG HARBOR HILL MORAINE.
GENERAL CHARACTERISTICS.

The deposition of the Harbor Hill ridge, like that of the earlier moraine, was accompanied
by the formation of a more or less extensive outwash deposit. In composition this deposit shows
no material difference from the outwash from the ice along the earlier (Ronkonkoma) moraine
already described (p. 166), varying in the same manner from point to point according to the nature
of the materials over which the ice passed. The sources of the materials of the two outwash
deposits are practically identical, and so far as can be seen, the mode of deposition and character
of the bedding (flow and plunge structure, etc.) are likewise the same. The brownish sandy
or pebbly loam and clayey sand (comparable with the so-called Jamesburg loam of New Jersey),
described as locally forming superficial coatings over the outwash from ice along the Ronkon-
koma moraine, are likewise present in places on the outwash from ice along the Harbor Hill
moraine, the most conspicuous developments being (1) in the easterly of two outwash channels
northeast of High Hill, (2) in the region southeast of Elwood and northeast of the Dix Hills,
(3) in the district north of Coram, (4) at points between Wardencliffe and Ridge, and (5) in
the region south of Manorville. It is also found locally near Jamaica. Like the outwash
from ice along the Ronkonkoma moraine, the outwash from ice along the Harbor Hill moraine
WISCONSIN DRIFT. 1738

rests upon the eroded surface of gravels of the Manhasset formation, and being, as a rule, rela-
tively thin, in many places fails to hide the Manhasset topography, which is made apparent to
the eye by the numerous kettle valleys or by elevations rising above the outwash level. The
topography of the outwash differs in no essential way from that of outwash along the Ron-
konkoma moraine.

DISTRIBUTION,

Narrows to Jamaica.—The plains in the stretch of more than 15 miles between the Narrows
and Jamaica are low and flat, and exhibit a lobate fan-shaped outline with radiating drainage
creases converging toward the base of the moraine at three distinct points—near Prospect Park,
in Brooklyn, at East New York, and near Dunton, southwest of Jamaica. The surface is locally
covered by a foot or more of brownish loam resembling the ‘‘Jamesburg loam’’ of New Jersey
(p. 172).

Roslyn-Hempstead region.—The deposit in the area between the moraines south of Roslyn
has been described under Manhasset formation (p. 116). It may be regarded either as a kettle
plain over a Manhasset surface or as a thin outwash among higher Manhasset hills, but more
probably it is a combination of the two. South of the outer moraine the kettles disappear
and the later and earlier outwash deposits merge into the broad Hempstead plains, in which
they could not be differentiated.

Wheatley-Cold Spring region.—From the Wheatley Hills to the valley at Cold Spring
station the outwash from ice along the Harbor Hill moraine is represented by a narrow strip,
in few places more than 2 miles wide, of what may be called a kettle plain, the ordinarily smooth
outwash surface being broken at many points by kettles, some steep-sided and of considerable
depth, which evidently mark the former positions of melting ice masses in the valleys of the
Manhasset formation, which is here not far below the outwash surface.

Huntington-Babylon region.—Stretching southward from the Harbor Hill moraine between
Cold Spring Valley and Greenlawn is one of the most strongly developed outwash deposits
from ice along the Harbor Hill moraine. In detail it consists of two broad level outwash chan-
nels from half a mile to 14 miles in breadth, one leading southeast from the morainal ridge
near Cold Spring and passing between High Hill and the hills south of the Huntington fair
ground, the other leading southwest from the base of the ridge near Greenlawn and passing
between the Dix Hulls and the hills before mentioned, the two uniting near Melville between the
Mannetto and Half Hollow hills. Between the two channels, in the vicinity of the fair ground,
is an extensive area of outwash of the kettle-plain type. Many of the kettles are more than a
quarter of a mile long, two more than half a mile, and one more than a mile. Several kettles,
especially the largest, have a branching form such as would characterize kettles resulting from
the melting of ice masses in old Manhasset valleys, and this, in fact, is probably their origin.
Some of the ice blocks evidently rose distinctly above the outwash surface, for ridges, apparently
of materials set free from the melting of the ice masses, are found on the kettle rims along the
fair-ground road and elsewhere.

The deposits of the united outwash channels pass southward as a belt more than 2 miles
in breadth between the Mannetto and Half Hollow hills, beyond which they spread out in a
broad fan stretching along the coast from Massapequa to Babylon.

The greater part of the outwash, including most of that south of the Mannetto and Half
Hollow hills, appears to have been deposited during the earlier stages of the Harbor Hill ice
halt and before the melting of the ice blocks in the intermorainic district. It is probable that
at this time the entire area between the moraines was of the kettle-plain type. In the later
stages of the ice halt less material was set free, the waters coming mainly from two points, one
at each end of the area. By this time the ice blocks seem to have largely melted and the kettles
along the two outwash streams became filled. No further materials, however, appear to have
been deposited in the Fairground area between these streams. So slight was the amount of
detritus carried by the streams that it appears to have been deposited before Melville was
reached, the waters at this point gathering into definite channels, one on each side of the valley,
174 GEOLOGY OF LONG ISLAND,

leading southward toward the coast. Of these channels the one on the cast side continues
sharp and distinct to the point where it empties into Great South Bay, near Babylon, but the
more westerly stream was apparently weaker and its channel is somewhat indefinite in the
lower part of its course. ;

Smithtown region.—East of Greenlawn thick outwash is found only in a belt a mile or two
in width along the base of the moraine, beyond which the Manhasset approaches the surface
and exerts a decided influence on the topography. East of a line from Kings Park to Commack
the outwash entirely disappears, leaving the broad drainage basin of Nissequogue River (Pl. X,
p. 46) as destitute of outwash as it is of till. (Gee p. 162.) This is the so-called Smithtown
‘‘driftless’’ area.

Port Jefferson region.—At Smithtown Branch and St. James the outwash is again recog-
nized along the moraine, but it decreases in thickness toward the south, Manhasset drainage
lines being recognizable within 2 or 3 miles of the moraine. The southerly part of the belt
is dotted by kettles, many of them occupied by ponds, the largest and most beautiful of whichis
the well-known Lake Ronkonkoma. Several of the depressions are of the kettle-valley type.

South of Port Jefferson the outwash plain is well developed for 2 miles or more south of the
moraine, but irregularities in the form of kettles appear near Terryville, and a little farther
south low but distinct ridges and valleys, such as everywhere characterize the Manhasset surface,
are seen. It is evident that the outwash is very thin and probably is confined largely to the
valleys. The surface of a considerable area near the outer moraine has been reworked by winds
and a coating of dune sand spread over it, in places completely hiding the underlying materials.

Rocky Point and Riverhead area.—East of Port Jefferson the outwash becomes still thinner,
and kettle valleys and even unfilled Manhasset drainage channels are seen close to the moraine at
numerous points, as near Rocky Point,
at Wading River, south of Fresh Pond
Landing, and northwest of Riverhead.
The kettle valleys in this region (see
Pls. IX, B, p. 42; XX, p. 116) are
among the most conspicuous on the
island, individual kettles reaching a depth of 60 to 80 feet and having a length of several miles.
Northwest of Riverhead chains of kettles, instead of single elongated hollows, mark the Man-
hasset valleys (PI. IX, C). One of these is 4 or 5 miles long. Some of the kettles are marked
by raised rims, apparently consisting of material set free from the ice blocks, which must there-
fore have risen above the surrounding surface.

The true outwash from ice along the Harbor Hill moraine does not extend south of Peconic
River, the Wisconsin materials there consisting of kame and local outwash deposits resting on
an irregular Manhasset surface, the whole having a distinct morainal aspect. The deposits are,
nevertheless, in the main sharply separated from the Ronkonkoma morainal ridge and are
better mapped as outwash than as moraine.

North Fluke——On the North Fluke the outwash plain becomes narrower toward the east,
being about 4 miles wide at Riverhead and absent at Orient Point. It becomes progressively
thinner and the Manhasset controls more and more of the topography. There are, however,
fewer kettles and kettle valleys, presumably because the Manhasset surface, on which the out-
wash rests, was more level than at points farther west owing to its slight elevation and conse-
quently less-marked erosion. Kettles are nevertheless not uncommon, especially between
Riverhead and Mattituck, and open Manhasset or kettle valleys nearly or quite cut through
this fluke at Mattituck and at Hashamomuck and Truman beaches. Some of these kettles
show, in addition to the usual bowlders, marginal ridges of drift set free by the melting of the
ice blocks. One of the best examples of these, found about 1} miles northeast of Mattituck
on the road to Cutchogue, is shown in figure 197, the rims being raised about 20 feet above
the surrounding plain. A pair of kettles near the second road leading northwest from the
Cutchogue-Southold highway, about 14 miles northeast of Cutchogue, showed a sharp connect-
ing crease as if cut by water flowing from one into the other.

 

 

 

Figure 197.—Kettle rim of till near highway between Mattituck and Cutchogue.
WISCONSIN DRIFT. 175

OUTWASH CHANNELS.

In the later part, or at the end of the Harbor Hill substage of outwash deposition, the out-
flowing glacial waters were no longer overloaded with débris, and hence ceased to deposit and
began to erode. As a result numerous well-defined and some large channels leading southward
toward the sea were cut in the surface of the outwash. The greater number of these channels
start at or near the Harbor Hill moraine and cross the island to the south coast, but some
start at the moraine and become indistinct before reaching the sea and others begin several
miles south of the moraine.

Roslyn channel.—The most western channel of importance is that starting at the gap in
the moraine at Roslyn. This is a sharp, well-defined channel several hundred feet wide, about
15 feet deep and in places, as at the road half a mile south of Roslyn station, characterized
by a low terrace between the bottom and the outwash level. Its course is shown by the geologic
map (Pl. I, in pocket).

Melville channels.—The next important channels are those leading southward from Melville
between the Mannetto and Half Hollow hills. The character and significance of these channels
have been discussed in another place (p. 49).

Centerport-Babylon channel.—One of the most persistent of the smaller channels is that east
of the Dix Hills. Starting at the moraine near the head of Northport Harbor, it extends across
the steep outwash fans to Elwood, across the combined outwash and Manhasset to Commack,
through the Ronkonkoma moraine at the east end of the Dix Hills, and across the outwash
from ice along the Ronkonkoma moraine to the south shore at Babylon, 16 miles from its point
of beginning.

Connetquot channel.—The broad Connetquot channel, which measures from a mile to a
mile and a half in width, starts near Smithtown and runs first eastward and then southward,
emptying into Great South Bay between Islip and Sayville. In many respects it is unique
among the Long Island channels. It neither heads in the moraine nor develops in an outwash
plain. Instead, it starts high above drainage level on the east side of the Smithtown ‘‘driftless’’
area (Pl. X, p. 46) and makes a broad bend to the northwest and then another to the south
before finally passing through the outer moraine. The northerly and easterly side of the channel
is marked by a sharp and distinct scarp, 20 to 30 feet or more above the floor of the channel,
and intersected at short intervals by drainage creases, now streamless. The same scarp is found
at the gap in the moraine and on both sides of the channel for some distance to the south, but
it gradually becomes less conspicuous and is bounded by gentler slopes. Many of the tributary
drainage creases are well developed and branching, being far more advanced than any other
post-Wisconsin channels on the island. A similar drainage system is found a short distance
to the east, converging toward the gap in the moraine through which the main channel passes.

The advanced stage of development of the Nissequogue drainage system on the west side
of the river suggests that a similar stage may have existed at some time on the east. This
the writer believes to have been the case, the headwaters being represented by the larger branch-
ing channels entering the Connetquot channel between Smithtown Branch and the moraine.
Another drainage system with its principal headwaters northwest of Lake Ronkonkoma,
but with another branch heading somewhere east of Hauppauge, is thought to have led south-
ward along the present course of Connetquot River. Before the advance of the main Wisconsin
ice sheet the western half of the Nissequogue drainage basin appears to have been covered
with snow or snow ice, so that the glacier passed over to the moraine beyond without either
disturbing the surface or covering it with drift. In the eastern part of the basin, however,
the conditions were different, at least in the later part of the invasion, and sufficient drift,
mainly stratified, was deposited to cover and obliterate the drainage topography. The ice
over the western half of the drainage system persisted after the retreat of the ice from the
Ronkonkoma moraine, but in the eastern half only a few buried masses remained. Over this
eastern area, it is thought, there swept large quantities of water, the current following the
outside of the curve marking the easterly boundary of the Connetquot channel from Smith-
town Branch to the moraine, cutting the sharp terrace which lies just east of the highway
176 GEOLOGY OF LONG ISLAND,

between the points mentioned, crossing the old divide east of Hauppauge, and flowing down
a pre-Wisconsin channel of a tributary to the stream heading in the district northwest of Lake
Ronkonkoma. After the cessation of the outflow the ice masses underlying the outwash
deposits melted, leaving the rolling surface now seen, and the erosion of the minor notches in
the cliffs began. The history outlined is somewhat complicated, but it seems to fit the facts
better than any other explanation yet proposed.

Carmans River channel_—The only other channel of importance is that along Carmans River
in the vicinity of Yaphank. Most of that part lying south of the moraine belongs to the Ron-
konkoma substage, but a narrow channel along the present stream seems to belong to a later
stage. The channel is believed to mark an intermediate outwash deposit laid down later than
the Ronkonkoma moraine but earlier than the Harbor Hill moraine and the outwash from ice
along it. (See fig. 196, p. 168.)

RETREATAL DEPOSITS.

The final retreat of the ice from its position upon the surface of the gravels of the Manhasset
formation appears to have been accompanied by no considerable outwash, the deposits that
were left on the surface during the retreat being composed of till rather than gravel. In some
of the cliff sections a few feet of gravel rests on the till and it is believed to represent outwash
deposits of the final retreat. Such deposits, however, are more commonly absent than present.
Some of the swells breaking the regularity of the plateau-like Manhasset surfaces may represent
low, flat outwash fans of this stage, but the number of bowlders lying upon most of the surface
seems to indicate that the top deposits are mainly of till. Channels cut by streams issuing
from the ice sheet during its retreat persist at several points.

R. D. Salisbury! and his associates mapped considerable areas on the north side of the
island from East River to Flushing Bay as stratified drift of the last retreat, and as there was
no opportunity for a reexamination of the area, this mapping has been followed in the present
report. The fact that the surface gravel overlies the main drift of the region does not, however,
necessarily indicate that it is Wisconsin. On the contrary it may be the Hempstead gravel
member of the Manhasset formation resting upon the Montauk till member of the Manhasset,
as was found to be true of the College Point ‘‘kames,” the Wisconsin till in many places being
almost unnoticeable.

The most satisfactory exposure of retreatal material is found on Manhasset Neck northwest
of Port Washington (Pl. IV, p. 30), where a broad delta exhibiting characteristic foresets and
topsets was formerly to be seen but has been now largely removed for the sand and gravel it
contained. According to J. B. Woodworth,’ who studied the delta in detail, it was formed in
a local glacial lake during the ice retreat, the water standing about 80 feet above the present
level of the sea.

A thin retreatal outwash deposit resembling that between the Harbor Hill and Ronkon-
koma moraines south of Huntington mantles the surface of Lloyd Neck. At the time of its
accumulation ice masses still rested in its valleys and on their subsequent melting gave rise to
the numerous kettles and kettle valleys. These are well shown by the topographic map (Pl.
II, in pocket).

RECENT SERIES.

EXTENT.

The Recent deposits, although not extensive compared to the glacial and older materials,
are nevertheless of considerable importance. A stretch of nearly 100 miles of beach, probably
averaging a quarter of a mile in width, has been constructed, making an addition of 25 square
miles to the area of the island. The largest addition, however, has been made through the
growth of the salt marshes, which have extended the area of the island by at least 100 square
miles. The fresh-water marshes probably have an aggregate area of 15 square miles or more,
and dune sands cover about 25 square miles of inland territory in addition to that along the

1 New York City folio (No. 83), Geol. Atlas U. S., U. S. Geol. Survey, 1902. ? Bull. New York State Mus. No. 48, 1901, p. 653.
RECENT SERIES, 177

beaches. In all probably more than 125 square miles of the present area of the island is due
to accumulation in Recent time. This, however, is probably more than counterbalanced by the
land lost by erosion and by subsidence.

STREAM DEPOSITS.

Deposits in stream channels —Although Long Island abounds with stream-cut valleys and
channels, there are few stream deposits that can be referred to postglacial accumulation.
On the plateau of the north shore the valleys are older than the last ice invasion, withthe
deposits of which their sides are locally mantled. The action of streams in Recent time is usually
limited to a shallow notching of the valley bottoms or to slight washes of sand and gravels from
their sides.

Most of the channels in the plains of the southern half of the island are not occupied by streams
at the present time, evidently having been cut under conditions quite different from those now
existing. Some of these channels proceed from the outer or Ronkonkoma moraine, others rise
back of it, and still others even start from notches in the inner ridge, indicating that the source
of the water was in the ice. Many of the minor channels, however, are cut only a mile or two
back from the sea, and these, it seems likely, were cut, in part at least, by postglacial stream
action before the protecting mantle of vegetation obtained a foothold. In the latter channels, if
not in some ot the former, the surface materials have probably been more or less shifted in post-
glacial time and hence are to be included with the Recent deposits. The same is true of many
of the notchlike channels at points on the flanks of the moraines.

Alluvial fans.—At the base of each moraine there are many more or less fanlike accumula-
tions of sand and gravel brought down as local wash, largely before the surface was covered
with vegetation, but in part by wash or creep in Recent time. These deposits are best seen
where the moraine is high and the materials are sandy, as in the region between the Dix Hills and
Coram and at a number of points farther east, but are commonly too small to be indicated by
the contours of the topographic map. Many small but well-developed fans also occur at the
mouths of the ravines of the Mannetto and Half Hollow hills south of the moraine, and typical
talus cones and fans occur at the base of the bluffs and at mouths of ravines along the north
shore of the island.

Deltas.—Because of the slight amount of postglacial erosion that has taken place, deltas
are, as would naturally be expected, practically absent at the mouths of the valleys. Small
deltas from 50 to 100 feet in diameter are often formed during heavy rains from materials washed
from the ravines of the north shore, but these are usually destroyed by the currents or waves
in ashort time. The harbors of the north shore and the great bays of the south shore are more
or less filled with sands shifted about under the action of the tide, but these deposits appear to
bear no relation to the streams emptying into the sea in the vicinity. Here and there deltas
are formed by tidal currents both inside and outside of the inlets through the beaches, but most
of them are small. The shoal lying off the mouth of Nissequogue River is the only one of any
consequence resembling a delta indicated by the charts.

MARINE DEPOSITS.

BEACHES AND SPITS.

A long stretch of beach extends with a few interruptions from Coney Island to Southampton,
a distance of nearly 90 miles, and separates from the ocean several partly or completely inclosed
bays, such as Jamaica, Great South, Moriches, and Shinnecock. The longest stretch of unbroken
beach is that extending westward from Southampton to Fire Island Inlet-—a distance of 45 miles.
This beach, which is almost a straight line throughout its length, is rarely more than half a mile
and generally less than a quarter of a mile wide. The part south of Shinnecock Bay is known
as Hampton Beach, but most of the remainder is designated Fire Island Beach. Waves occa-
sionally cut through it in time of storm, although the openings are commonly soon closed again.

1629°—14——_13

.
178 GEOLOGY OF LONG ISLAND,

Shinnecock Bay, just west of Southampton, 9 miles long and 3 miles wide, has at present no
direct connection with the ocean, but a canal leads northward into Great Peconic Bay and
another westward into Moriches Bay. An artificial cut made to the ocean was soon closed by
the waves. Moriches Bay is connected through a narrow natural channel with Great South Bay,
which in turn connects with the ocean through Fire Island Inlet.

The beach is composed mainly of quartz sand, although some garnetiferous and magnetic
materials are seen. Pebbles are generally scarce, but some are seen where the beaches connect
with the main island, as near Southampton and Westhampton. The surface above high-water
mark is generally covered with dunes from 5 to 20 or even 30 feet in height, among which are
scattered many small fresh marshes. The movement of materials by the waves is plainly west-
ward, the chief source being between Southampton and Montauk, where the coast, as has been
seen, has suffered considerable erosion. It is possible, also, that a part of the material has been
thrown up from the shallow sea bottom of the vicinity by the action of waves. Practically no
sand is contributed by the streams of the island at the present time.

West of Fire Island is the beach known as Oak Island Beach in the eastern part and Jones
Beach in the western part. This beach begins about a mile north and a little more than a mile
east of the west end of Fire Island Beach. It seems to have never been connected with the
main island and appears to be older than Fire Island Beach, which is now being built outside
and overlapping it. Itis therefore a pure barrier beach, whereas Fire Island Beach partakes
of the nature of a spit.

Just west of Jones Beach and separated from it by the narrow Zachs Inlet is Short Beach,
about 2 miles in length. Beyond is Jones Inlet, followed by Long Beach, about 8 miles in length,
and Far Rockaway and Rockaway beaches, which are continuous and together about 11 miles
long. Manhattan and Brighton beaches, lying west of Rockaway Inlet on Coney Island, which
are together about 5 miles in length, complete the list. All these beaches are without natural
connection with the main island and have derived no material directly from it, being essentially
barriers. They show some diversity in direction, with a tendency to overlap, seen where the
Rockaway approaches the Manhattan Beach.

North of Long, Jones, and Oak Island beaches there are a number of small sandy islands
in a line parallel to the beaches, with which their longer diameters are also parallel.
These appear to represent the earliest bars formed by the waves and currents in the shallow
waters off the south coast. Later the longer, higher, and more connected barriers, such as Oak
Island, Jones, Long, and Rockaway beaches, were built up outside of the earlier bars from mate-
rials derived from the sea bottom. At the same time a spit was being projected westward from
Southampton (Hampton Beach), composed of material derived from erosion of the shore farther
east rather than directly from the sea bottom. Later, partly with material from the same
source and partly with sands from the sea bottom, the spit was extended westward to Fire
Island Inlet, shghtly overlapping the earlier Oak Island Beach.

The process of formation of the beaches is not continuous. Many feet may be added in a
single storm; again, the waters of the ocean may break through, leaving wide gaps in the pre-
viously continuous beach. There is also at many points a tendency to periodic changes from
deposition to erosion. Thus for a long time Fire Island Beach has been building outward, but
at the time of the present field work the waves were cutting it away, leaving everywhere at
high-tide line a low scarp 4 or 5 feet high, giving a section through the original beach and its

capping of dunes.
CONNECTING BEACHES.

When the ice of the last glacial advance retreated from the region there were many dis-
connected islets adjoining the main island. In most places the intervening waters were shallow,
and waves and shore currents rapidly extended hooks and spits from the projecting points and
later united many of them into connecting beaches, joining the previously independent islets
and completing Long Island as it now appears. Marshes have also served as a connecting
agency. Beginning at the west on the north shore, the first islet that has been joined to the
main island is Hunters Point; next an unnamed island on the Sound in the northeastern part
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BECENT SERIES. 179

of Long Island City; then Tallman Island naar College Point; and Prospect Point on Manhasset
Neck. All these are connected with the body of the island by marshes. East of Hempstead
Harbor Dosoris and East islands are connected by beaches; farther along Oak Neck and Center
Island by beaches and marshes; and Lloyd and Eaton necks, including Duck and one other
small island, by beaches. There are no further indications of former islands between this point
and Southold. Between Southold and Greenport breaks exist at Hashamomuck Pond and at
Pipe Cove, and there was a channel at each end of Truman Beach, near Orient.

In the bays between the flukes Ram Island, Mashomuck Point, and another smaller island
were connected with Shelter Island by beaches, and Little Hog Neck was in like manner joined
to the North Fluke. On the South Fluke the Montauk peninsula was connected with the main
island by Napeague Beach, nearly 5 miles in length. Near Sag Harbor, Hog and Jessup necks
and two smaller islands were connected by beaches or marshes, as were Cow Neck and a small
island on the south side of Great Peconic Bay. There does not, however, seem to have been
any natural channel at Canoe Place, west of the Shinnecock Hills, although the land at this
point is only a few feet above sea level and but a few hundred feet in width. The canal banks
show glacial deposits rather than beach sands. A former connection of the waters of Peconic
and Shinnecock bays would have necessitated a sinking of 10 or 15 feet below the present level
of the land, a submergence of which there is no evidence.

SMALL SPITS AND HOOKS.

Among the minor shore features of Long Island are hundreds of small spits and hooks.
Many of them are very typically developed. They are naturally most common along the irregu-
lar part of the north coast west of Port Jefferson and on the shores of the bays between the
North and South flukes. Many smaller ones are found on the shores of Great South Bay and
other bays of the south shore.

Currents sweeping along any stretch of coast tend to move in straight or gently curving
lines just outside of the headlands, rather than on lines conforming to the minor irregularities
and indentations of the shore. The material that they transport is deposited, owing to the
slackening of their progress, when deeper water is reached, forming bars more or less com-
pletely connecting the headlands and at many points inclosing areas of relatively deep water.
The beach between Horton and Duck Pond points, Southold, was formed in this way, and a
second bar is in process of formation. In places, as near Peacock Point, between Oyster Bay
and Hempstead Harbor, as much as 600 feet of beach may be built out in a few years.!. Where
the currents are feeble or conflicting, or the supply of material is not abundant, small straight
or curved bars are formed rather than the longer ones described. In either case the bars generally
continue to receive additions of material and are finally built up so that they come within the
range of influence of the waves, which serve to pile up the materials still further, until they are
brought above the level of the sea to form connecting beaches, spits, and hooks. Of the spits
the more prominent are Lloyd Point and East Beach, on Lloyd Neck; Eaton Point and West
Beach, on Eaton Neck; the spit at the entrance to Smithtown Harbor or Nissequogue River
(Pl. XXV); West Meadow and the opposite beach at Stony Brook; Setauket and Mount Misery
beaches on Port Jefferson Harbor; East beach, near Miller Place; Long Beach, near Orient
Point; the spits at the north and south ends of Gardiners Island; Goff and Lazy points and
Hicks Island, on the Montauk peninsula; and Cedar Point, Sammys and Acabonack beaches,
between Sag Harbor and Napeague Beach. (See Pl. I,im pocket.) Of these, Lloyd Point, West
Beach, and the beaches at Mount Misery, Lazy, and Goff points, Hicks Island, and Cedar Point
are of interest as being curved, hooked, or otherwise complex spits. Many of the smaller un
named beaches, such as those partly cutting Hempstead and Cold Spring harbors, are of equal

interest. MAGNETIC AND GARNETIFEROUS SANDS,

Among the most striking features of the material of the wave and current formed beaches
of Long Island are the magnetic and garnetiferous sands, which are seen at many points along

1 Mather, W. W., Geology of New York, pt. 1, 1843, p. 22.
180 GEOLOGY OF LONG ISLAND,

the coast, especially on the north shore. These sands occur at some places in beds from half an
inch to 4 inches thick, several feet wide, and 10 to 100 feet long. They are usually found well
above the ordinary water level at points where the waves have beaten at unusually high tides
or in times of storm. This is commonly at the very base of the bluffs. Farther down the beach
the grains may be either mixed with the coarse sand or gravel, as along parts of the north shore,
or they may occur as a surface film on the hard-packed sand, as on the more exposed beaches of
the south shore.

The sands are derived from the breaking up of the crystalline pebbles or bowlders of the
drift. The till contains much more of such material than the stratified drift, and the mag-
netic and garnetiferous sands on the beaches appear to be no more abundant in the vicinity
of the till than elsewhere. This, however, may be due to the fact that most of the till bluffs
stand in more exposed positions, where the wave action is so strong that the sands are washed
away, leaving only the heavier cobbles and bowlders on the beach. Few beds of magnetic sands
were observed on the south side of the island, owing to the general absence of crystalline mate-
rials except near Montauk, but they are reported on Fire Island Beach off Patchogue. The
most conspicuous deposits seen in the course of the present field work were near Orient Point
and between Wading River and Miller Place. The individual beds shift considerably in position
during each storm, but the general distribution of the sands probably remains fairly constant,
the present localities closely agreeing with those recorded by Mather in 1838 to 1843. In the
early days the sands were collected for a forge in Connecticut.

In order that the magnetite and garnet may be separated from the quartz grains, a thorough
stirring of the sand seems to be necessary. The advance and retreat of the ordinary small wave
simply produces a surface film of the heavier magnetite and garnet grains without forming a
bed. The sand must be churned up to a considerable depth by wave after wave before any
considerable amount is separated, hence the beds are usually formed only in time of storm, a
fact which also accounts for their high position on the beach.

WIND DEPOSITS.

CHARACTER AND GENERAL DISTRIBUTION.

Although not covering areas so extensive nor reaching heights so great as those of some
other localities along the Atlantic coast, the dunes of Long Island are at many points a con-
spicuous local feature. They have received attention from a number of writers, beginning in
1822 with Timothy Dwight,’ who in speaking of the Shinnecock Hills described them as bare
dunes still drifting with the winds. Drifting sands near Brooklyn were mentioned by John
Finch? in 1824. W.W. Mather * described the dunes of the island in detail in his three reports.
Elias Lewis‘ published in 1876 a detailed discussion of their composition, manner of accumu-
lation, distribution, and size. John Bryson® in 1891 referred the dunes of Easthampton to
deposits of subglacial streams.

The dunes in process of formation at the present time, with few exceptions, are limited to
the immediate vicinity of the beaches. At Easthampton, however, dune sands occur for a dis-
tance of 14 miles from the shore, and there is also a considerable area in the interior of the island,
between Patchogue and Port Jefferson, where wind action has been active in the past and 1s
observed locally even at the present time.

The dune sands consist almost entirely of fine quartz grains, well rounded, and little stained
by iron. Some garnet and magnetite and here and there grains of. other minerals occur, and
minute fragments of shells are not rare. The magnetite sands are sometimes rather conspicu-
ous on the sand surfaces after a long-continued period of winds with velocities just sufficient to
move the lighter quartz grains but not strong enough to transport the heavier magnetite.

 

1 Travels in New England and New York, vol. 3, 1822, p. 317.

2Am. Jour. Sci., Ist ser., vol. 7, 1824, pp. 31-43.

3 Rept. New York Geol. Survey, vol: 1,1837, pp. (1-95; vol. 2,1838, pp. 121-184; Geology of New York, pt. 1, 143, pp. 30-33.
4 Pop. Sci. Monthly, vol. 8, 1876, pp. 357-363.

6 Am Geologist, vol. 8, 1891, pp. 188-190.
RECENT SERIES. 181

The dunes generally rest on a black loamy soil zone, if they are of recent formation, or on a
brownish oxidized zone from which the organic matter has boen leached, if they are among

the older dunes.
DUNES AT NAPEAGUE BEACH.

Napeague Beach and vicinity constitute the most conspicuous dune area on the island.
Five miles long and nearly 2 miles wide it comprises little but irregular sand heaps from 10 to
30 feet or more in height, between which are many small marshes fed by the fresh waters caught
by the dunes. Leading westward from Napeague Harbor is a large fresh marsh, half a mile
wide, lying between the dunes of Napeague Beach on the south and Promised Land on the
north. The dunes reach their greatest development just east of the harbor, where they have an
elevation of 100 feet. It is possible, however, that a part of this height is due to Manhasset
materials, which may underlie them. The dunes of Napeague Beach have derived their
materials mainly from shore wash from the east; those east of Napeague Harbor seem to have
been supplied mainly from the same source with relatively little additions from the north side,
their accumulation taking place mainly under the action of the southwest winds. It is believed
that a part of the material of the dunes of Promised Land has had a similar source, being
blown from the south coast by southwest winds, and that a part has come from the shore
immediately to the west. The big marsh between the dune areas does not, however, convey
the impression of having been crossed by a moving mass of dunes, and it is possible that very
little of the material has come from the south.

DUNES AT EASTHAMPTON,

In the main the dunes of the south shore are confined to a narrow fringe along the beach,
but at Easthampton the drifting sands have progressed a considerable distance from the sea-
shore, typical dune topography west of the town being recognized as much as 14 miles inland,
or as far north as the railroad. The sandy character of the roads indicates that the area of drift-
ing sand probably has extended considerably north of the railroad and westward to and beyond
Georgica Pond, although this is not conspicuously shown by the topography. East of the town
the dunes take the form of broad bare hills with wind-swept surfaces and hoppers. West of
the town the dunes, though not so large, show an even more marked dune topography, the sharp
ridges and knobs being especially conspicuous. This area is now being covered with summer
residences, and the dunes are largely under control.

DUNES OF THE GREAT SOUTH BEACHES.

The barren beaches which extend along the south coast for nearly 90 miles are lined through-
out their length by more or less strongly developed dunes, generally 15 or 20 feet in height.
Along the inside of the outer beach the dunes form a rather uniform and continuous though
somewhat notched ridge some 20 feet in height and extending for miles along the shore. On
the inside of this barrier there is also very commonly a second ridge, which, however, is lower
and less continuous than the outer one. Between the two there is generally an area of lower
and flatter dunes among which are scattered knobs; many rise to a height of 20 or 30 feet.
Between the ridges or among the low intermediate dunes many fresh-water marshes are found.
Some of these merge with the salt marshes which line the inside of the barrier. The finest
development of dunes seems to be on the Fire Island and Rockaway beaches, although the
Rockaway dunes, as well as the once conspicuous dunes on Coney Island, have been much

modified by human agency.

DUNES AT SHINNECOCE HILLS.

The Shinnecock Hills are composed of the Manhasset formation, in which, in this area,
sand predominates. In the past this sand has often been taken up by the winds to form dunes,
and to this action a part of the irregular surface topography of the hills is due. A hundred
years ago much of the surface was composed of drifting sands,’ but now the sands are mostly
under control, although a little drifting still takes place.

 

1 Dwight, Timothy, Travels in New England and New York, vol. 3, 1822, pp. 283-336.
182 GEOLOGY OF LONG ISLAND.

DUNES OF THE NORTH COAST.

Practically every bluff section along Long Island Sound shows a layer of dune sand at the
top, and some small valleys are filled with it, as near Woodhull Landing northeast of Miller
Place. Usually this sand is only 2 to 5 feet deep, but some of the dunes are conspicuous hills
from 50 to 100 feet high. They all rest on an old soil zone marking the horizon of the original
surface (Pl. VIII, B, p. 34). Where the dunes are of relatively recent origin the zone is rep-
resented not only by the usual oxidized band but by bands of nearly black vegetable mold
as well.

On this side of the island the dunes are best developed between Baiting Hollow and North-
ville, north of Riverhead, where they form a high and nearly continuous ridge more than 8
miles long. They rest in part on the edge of the Manhasset terrace or on the low moraine
that traverses this locality. This coincidence of position with the drift ridge has led to the
classification of the entire ridge as moraine, but as a matter of fact the moraine is rarely more
than 10 or 20 feet thick and in many places is represented by only a few scattered bowlders.
The great mass of the ridge in this vicinity is composed of sand. Plate VIII, A, shows the
profile of the ridge usually classed as morainal, here over 50 feet in height, and Plate VIII, B,
shows that in reality it is a ridge of dune sand resting on the Manhasset terrace.

Many parts of the dune ridge are very old, so that the humus of the underlying soil zones
has been entirely leached out. Much of its surface is covered with forests. Elsewhere, how-
ever, the dune is still in process of formation. W. W. Mather’ in 1843 recorded the local
deposition of several feet of dune sand in a few hours during a storm in 1836. Jacob Hill,
northwest of Mattituck, was once much higher than Coopers Hill (Mattituck Hills?) east of it,
but the sand has blown off until it is now lower. Some arable land has been covered and a
cedar tree has been buried. Elias Lewis, jr.,? in 1876, stated that a farm near Baiting Hollow
had lost 30 acres by the encroachment of the dunes in 30 years and that 100 acres in all had
been recently covered.

Another important dune area is at Horton Beach, near Southold, where the shore back of
the beach is lined with dunes of moderate size. Though more or less covered with trees the
sand is still blowing. There are several small fresh-water marshes among the dunes and a
pond is inclosed between the drifting sand and the bluffs.

DUNES IN THE INTERIOR OF THE ISLAND.

In the western half of Long Island most of the surface deposits consist of fine gravels and
coarse sand, both of which are in places somewhat loamy. No distinct evidences of dune
formation have been observed in this region. Farther east, however, the surface deposits are
finer and there are considerable stretches where nothing but fine white sand is seen in the roads.
The fineness and looseness of the surface coating and its apparent lack of indications of aqueous
stratification suggest that it is of dune origin, although there is little distinct topographic
evidence of wind action. From Coram eastward sands perhaps of dune origin are common
both on the plains and over the moraines. The part of the moraine south of Riverhead and
southwest, south, and southeast of Sag Harbor is especially characterized by such sands. In
most places they were formed before the region was forested.

Very large areas of similar sandy surfaces lie north and northwest of Patchogue and between
Patchogue and the morainal ridge.

The moraine and the plains south of it are covered with forest or brush, and few evidences
of wind action were seen. At the north base of the ridge near Selden, however, and at points
eastward to Coram, westward to and beyond New Village, and northward halfway to Terry-
ville not only does the surface consist of fine sand but there were in 1903 many spots free
from trees and almost free from vegetation, showing a subdued dune topography. Some low
sand hillocks and hoppers are being formed at the present time (Pl. XXVI, B). It is believed
that this region was once forested and protected from the winds, as otherwise the dunes would.

 

1 Geology of New York, pt. 1, 1843, p. 31. 2 Formation of sand dunes: Pop. Sci. Monthly, vol. $, 1876, pp. 357-363.
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 82 PLATE XXVI

 

 

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A. UNDERMINED PEAT ON COAST NEAR PROSPECT POINT, MANHASSET NECK.

 

 

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B. SEMIDUNE SURFACE IN INTERIOR OF ISLAND, NEAR SELDEN.
U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 82 PLATE XXVII

 

  
 

 
 
   

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B.

MUD CONES MARKING ORIFICES OF SPRINGS IN MUD FLATS NEAR DOUGLASTON.
RECENT SERIES. 183

be much more strongly developed. The opportunity for the present wind action to arise is
thought to have been given by the destruction of the forests and the vegetable mold of the
soil by the fires that repeatedly passed over the region. What the ultimate results will be
can not now be foretold, for the conditions appear to be very nicely balanced. If the fires
continue and the barren patches become larger so that they are no longer protected by the
surrounding forests, the wind action may again become important and the dunes grow larger
and more destructive. If, on the other hand, fires can be kept out, vegetation will soon cover
the burns and restore the forest to its supposed former unbroken state.

MARSH DEPOSITS.

FRESH MARSHES.

Marshes of the south shore—Along the entire south coast of Long Island, except near
Montauk, the plains slope gently seaward at a rate of 10 to 20 feet to the mile. There are
almost no streams on these plains, except near the coast, all the rainfall entering the porous
sand and making its way seaward as ground water. Near the places where the plains reach
sea level this water emerges at the surface, converting the edge of the plains into a marsh extend-
ing with hardly an interruption from Coney Island to Islip, a distance of nearly 50 miles. Far-
ther east similar marshes, although not entirely continuous, occur at short intervals to Shinne-
cock Bay. The landward edge of the marsh is usually a luxurious meadow, which grades off
with an intermingling of fresh and brackish water vegetation into a salt marsh, yielding great
quantities of salt hay. The entire marsh may be a mile or more wide, although a width of a
quarter of a mile is more common. The relative widths of the fresh and salt portions depend
on the relative slopes of the land surface and the bottom of the bay, one or the other predomi-
nating according as one or the other slope is the gentler. The amount of ground water enter-
ing at a given level also has an important influence on the width of the fresh marsh.

Marshes in the valleys of the south side-—Where the plains of the south side of the island
are not cut by valleys the water emerges from the lower edge of each plain, but where valleys
are present the ground-water level is cut at some distance from the coast, and considerable
volumes of water emerge along the valleys, forming extensive marshes and even streams of
some size. Such a marsh is found in nearly every valley of the south shore, extending a mile
or so back from the coast in the shorter valleys and several miles in the longer ones. The
width is usually under a quarter of a mile. The principal streams bordered by marshes include
Cornell Creek, south of Jamaica; Valley Stream; the stream east of Lynbrook; Meadow Brook,
near Freeport; Jackson Creek, near Wantagh; Massatayun Creek, near Massapequa; Carlls
River, near Babylon; Connetquot Brook, near Islip; Patchogue Creek and Swan River, near
Patchogue; Carmans River, near Yaphank; Forge River, near Moriches; and a number of smaller
streams farther east. The most extensive marshes are along Peconic River, stretching from a
point west of Manorville to and beyond Riverhead, a distance of more than 10 miles. The
only stream of notable size on the north side is the Nissequogue, near Smithtown. This is
bordered by marshes for about 3 miles above its mouth.

Marshes near artificial ponds.—There are a number of artificial ponds and reservoirs along
the south side of the island, as at Valley Stream, northeast of Lynbrook, and near Freeport,
Wantagh, and Massapequa, and a few built for developing power or for other purposes at points
in the interior of the island, as between Babylon and Wyandancb. There are two such ponds
at Riverhead. The effect of damming the streams is to back the water up over the gently
sloping valley floors and create marshes or swamps. This is notably the case at Riverhead,
where the slack water extends upstream for some miles, forming considerable marshes.

Marshes in obstructed channels.—Some of the old channels, especially in the eastern half
of the island, were obstructed by drift left by the ice in an advance after their formation, and
surface waters have accumulated behind the obstructions, forming ponds or marshes. Grass
Pond, northwest of Manorville, is a particularly good example of such an accumulation. Another
is found in the valley 1 mile west of Middle Island, and still another in the valley north of this
184 GEOLOGY OF LONG ISLAND,

point, although these marshes are not so extensive as Grass Pond. Other examples may be
seen at many points. About 14 miles northwest of Lake Ronkonkoma is a series of marshes in
a channel seemingly obstructed by wash from a tributary valley.

Marshes in ketiles—Besides the marshes in obstructed channels, or kettle channels, as
some of them may be called, there are numerous irregular kettles occupied in whole or in part
by marshes. These are too numerous to mention singly, practically every kettle that con-
tains a pond also having a marsh around the whole or a part of its margin, and marshes are found
also in many others in which there is no open water. Among the ponds bordered in part by
marshes may be mentioned Lake Ronkonkoma; Artists Lake, near Middle Island; Long and
Grass ponds, between Wading River and Manorville; Swan and other ponds near Manorville;
the ponds south of Riverhead; and Poxabogue and other ponds near Bridgehampton. Many
marshes unaccompanied by ponds occur in kettles in the vicinity of Manorville and Bridge-
hampton; these have never received names.

Marshes behind beaches.—Beaches have been thrown up across many of the reentrants of
the north shore by the waves and currents, and behind some of these fresh waters have accumu-
lated and replaced the salt marshes that originally existed there. The fresh marshes of this
type appear to have been more extensive formerly than at present, for fresh-water peats con-
taining stumps and prostrate tree trunks are found beneath the present salt marshes at many
points, a condition apparently due to a relatively recent sinking of the land. (See pp. 212-216.)
This probably explains why most of the marshes at the present time maintain communication
with the salt water through narrow breaks in the barriers. In such places the fresh marshes
are found only around the edges.

Interdune marshes.—At many places on the south coast, especially on the great beaches,
the dunes occur in either scattered hillocks or more or less definite ridges, between which are
level areas of moderate size. These areas usually lie a foot or two above high-tide mark but
commonly have no surface-drainage connection with the sea, being, in fact, inclosed basins
surrounded by dunes. Receiving not only the rain falling upon their surfaces, but also the
seepage from the surrounding dunes, which absorb practically all the rainfall reaching them,
these areas are naturally kept in a damp state very favorable to marsh growth. Marshes
formed under such conditions, in fact, occur almost everywhere in the dune areas near sea level,
such as those of the south coast. The largest single example is the marsh between Napeague
Beach and Promised Land, on the South Fluke. Especially good examples can also be seen
on Fire Island Beach, and minor marshes are to be found on nearly every spit and beach. They
are absent from the dune areas of the interior, both at HKasthampton and between Patchogue
and Port Jefferson, where the depressions are well above the ground-water level.

SALT MARSHES.

Marshes of the south shore.—Inland from the edge of the fresh marshes, at a distance depend-
ing on the slope of the surface and the amount of seepage emerging, there is a change from
fresh to salt water vegetation owing to contact with the waters of the ocean. Outward from
this line to open water the marshes are for the most part salt meadows. Similar though less
extensive marshes are built out from the inside of the great south beaches throughout their
length of more than 75 miles. These marshes are almost entirely of the salt-water type, although
some are bordered with fresh-water vegetation supported by seepage from the dunes.

An interesting feature of the distribution of the larger marginal marshes on the south
coast is their limitation to the:region west of Ishp. This is due to a difference in the topo-
graphic character of the shores. West of Islip the average slope of the plains is much less
than east of it. From Jamaica Bay to Islip the 20-foot contour line is from 1 to 2 miles back
of the inner edge of the marsh—that is, the slope is from 10 to 20 feet to the mile and meets
the water at a very low angle. East of Islip, however, the 20-foot contour is in many places
only a few rods or a quarter of a mile from the shore, although locally retreating for a mile or
more, and the surface meets the water at a higher angle or even as a low bluff—a condition
that is unfavorable for marsh growth. The difference in topography is due to differences in
the geologic history of the deposits, those west of Islip belonging to the gently sloping outwash
SUMMARY OF GEOLOGIC FEATURES, 185

from the Wisconsin glacier, whereas considerable portions of those east of Islip belong to the
older, higher, and partly eroded Manhasset formation.

Marshes of the south-shore bays.—Besides the marginal marshes just described, large areas
of marsh have been built up from the bottoms of the shallow bays of the south shore. None
of these bays are more than 6 miles wide and most of them are much less. They are all very
shallow, 11 feet being the greatest depth in Shinnecock Bay, 10 feet in Moriches Bay, and 25 feet
in Great South Bay. The depth of 25 feet is found only in the tidal channel at the inlet, the
ordinary depth being not more than 11 or 12 feet. Statements were made by Elias Lewis!
in 1877 and by Warren Upham? in 1879 that channels connecting with the land valleys could
be traced across the south side bays, but an examination of the charts seems to show that the
few channels present are in no way connected with land valleys but are the direct result of
tidal scour near the present or former inlets.

The marshes begin to form wherever the water is shallow enough for eel grass to obtain
a foothold, usually a foot or two below low-water mark, and where no strong currents are
flowing. The dead grass and the fine silt entangled with it gradually accumulate until the
ground rises well above above low-water mark and marsh grass takes root uponit. The upbuild-
ing continues until the marsh reaches a level covered only by occasional high tides. Part of
the present salt marshes may have resulted from the advance of the sea over former fresh
marshes or swamps, with the substitution of a salt-water for a fresh-water fauna. At the
east end of Great South Bay, north of Long Beach, and in Jamaica Bay, where the water was
originally very shallow, the marshes have taken possession of the greater part of the space
inside the beaches, having a width in places of nearly 5 miles. They are not absolutely con-
tinuous, however, but are cut by many narrow and winding channels and here and there by
more open spaces, such as Middle and East bays, near Jones Inlet.

W. W. Mather,’ who gave considerable attention to these features, says:

I have been credibly informed that the grass now grows on a marsh near Rockaway, where vessels have floated
within the memory of my informant. On Coney Island also Mr. John Wyckoff informed me that many places which
were ponds and pools within his recollection now produce good crops of grass. A very aged man also recollects having
seen the surf roll in at the foot of the upland north of the marsh toward the east end of Coney Island. A broad marsh
now intervenes between the upland and the beach.

In fact, the whole line of geologic evidence shows that with a few local exceptions the
marshes are being rapidly extended along the south shore.

The marshes on the whole are rather stable when once formed and are seldom subjected
to much erosion, except where the waves break through the beaches and obtain access to them.

Marshes of the north-shore reentrants.—The formation of salt marshes in reentrants on the
north shore differs in no essential particular from the formation of marshes in the more exten-
sive waters of the south shore already described except that more of them have probably
resulted from the comparatively recent incursion of the sea over fresh-water accumulations.
They may be seen at many points. On the side toward the Sound they are usually bordered
by a barrier beach, but on the side toward the bay the beach is usually absent. Their transition
to fresh marsh has already been described.

SUMMARY OF GEOLOGIC FEATURES, BY LOCALITIES.

Owing to the fact that many of the deposits are in the present report considered in detail
for the first time, it has seemed desirable to bring together at one place the available facts
pertaining to each formation, making the discussions stratigraphic rather than geographic.
This has been done under ‘Stratigraphic geology.” Unfortunately by this method the dis-
cussion of adjacent localities may be found on widely separated pages. Supplementary
geographic discussions are desirable but would involve too much repetition. An attempt
has been made, however, to meet the needs of geologists and others interested in particular
regions by preparing the following tables, which summarize the chief points of geologic and

physiographic interest.

 

1Am. Jour. Sci., 3d ser., vol. 13, 1877, pp. 215-216. 2Idem, vol. 18, 1879, pp. 81-92. 3 Geology of New York, pt. 1, 1843, p. 17.
186 GEOLOGY OF LONG ISLAND.

To facilitate reference, the topographic and geologic maps are divided into rectangles
by lines of latitude and longitude, these rectangles being designated from bottom to top by
letters, and the columns of rectangles from left to right by numbers. The letters and numbers
make it easy to determine quickly the points of interest in a particular locality or on a particular
trip, and the page references make it practicable to look up details with the least possible loss
of time.

It should be borne in mind, however, that inasmuch as 10 years have elapsed since the
observations were made, few of the sections will be found exactly as described, especially
those along the north shore. Here, although the outcropping edges of the formations seen
in the bluffs often appear nearly horizontal, in reality many of the beds dip at high angles to the
south, as may be seen by comparing 8, figure 97 (p. 110), and ¢, figure 95 (p. 110), the former
being a section at right angles to the face of a bluff and the latter section parallel to the bluff
face. Under such conditions a bed that appears horizontal where the face of the bluff is parallel
with the strike may appear notably inclined where the bluff makes an angle with the strike, or
broadly arched where the coast line is curving. In many places it was impossible to deter-
mine the internal structure, and the greater part of the figures in the present report represent
only the apparent structure as shown in the bluffs. Where the dips are high, the cutting back
of a bluff as little as 5 feet will change the whole appearance of a section, and it is not to be
expected that any particular feature will be recognizable after the lapse of a few years.

Principal points of geologic interest on Long Island.

 

 

 

   
    
 
 
 
 

 

   
 
   

 

 

  
  
    
  

   

 

  
 
    

 

 

 

 

Coordi- az
nates ar Page of
on of sec- Locality. Features. ou
Plates 1| tion.a description.
and II.
1A.....| NE...| West of Coney Island....... MAD: SPLb AMO UNS oi. rerecwisier ss ies5 7s a5 obi tiacaes apSiace vera Sedicse/aad Seca AVE aaa oe 177-180
UB secret) a esas Near Fort Hamilton. --| Harbor Hill moraine, beginning of “inland scarp’’.. 53, 168
DA cca | IN ont Near Coney Island. ... of SMB ON CIOS BUN MRO BSG san co cranes & Sa gain a ROR eNlcatitinn palanwateisias en ne eucmild 184
2B....| C,8...} Southeast of Brooklyn......} Outwash from ice along Harbor Hill moraine..............0.2..2.20. 22.22 e eee eee 173
2B.. N Near Prospect Park. -| Harbor Hill moraine “inland scarp” ....... 2.2... 2.02.2 c eee eee eee eee eee 53, 158
2B. praesent OSsparn es Se cceeyeseces -| Confluent fans of outwash from ice along Harbor Hill moraine..............-..-... 36-37
2 cposcns --| On shore of East River -{| Wordham pneiss:out Crops s~ seacciecae ces sun m tama een eReeRih RA Re uv hdsiesiomniee bs asain? 66
Beye s GN Seeded Rockaway Beach... . 2) Barrier beach, dumes,is pits... vs. wes sseceis exieiseecn ace iad njasajcia aang & spnivssedyoeind deacaneed 178-180
3A....| NW...] Barren Island... -| Outlier of Manhasset formation (?)......-.-2-. 0.020 c ee cece eee cece eee e ccc e eee 113
3B....| SE....| Jamaica Bay.. -| Extensive salt marshes in process of formation.....-.........2.22..2-.-02-22002---- 185
3B....} W....| Bergen Beach..... Al ERS GU IIS cent bye Waar so Revd Sel Ss th Son ato nde acne S-aaeimsencarei aso 169-170
3B....| NE...| Near Remsen Landing. {ripest 0 oss si isla etre iittat einige ee ee 169-170
3C.....} S......| Near East New York....... Outwash from ice along Harbor Hill moraine ..............0. 0002.20 0 00 cece eee eee 172-173
3C.. C.....| Near Brooklyn Reservoir. ..| Harbor Hill moraine (till type), ‘‘imland scarp” ......2.......000 000000000 cee ease 34-35, 53
BC oi] Nie cA edit ayreeaateardare sear tencnarseyoteaine Wisconsin till; traces of Manhasset formation..............0..000.. 002-0000 eee eee 115, 158-160
3D.. a mile nerthwest of Stem: | Dramloidal bill. ...cc20.0scxsasawas secemuowennwaneevevegaeyss Gece ens vs ennsmame 161
way.
3D.. -| Near Lawrence Point.......|-..-. Oyo. sortsorad su 515 Sia areiciainrrarniniaiotaceiaelae iow latvia eeunyiadarae Zameieegepesesenmsacwyonaes 161
3D mile east of College Point. .| Light-gray micaceous Jacob sand...........2.-...-.202---020- 0-2 eee eee 108
3D_. -| Near Tallman Island........ Eprat OG AL TAN ere 5 aeca ape cnsscraen ero deeaeerejnieers EE gPSIGNS & einsays ore mpois mnsicrd insrd-cninecedee deeeoecvaintnted 161
ByD ssc SB sisrceais lemccryess az a matgen emsince .-| Wisconsin till and retreatal outwash.................2002-0c eee eee eee ee Map.
3D Flushing Bay... .-| Pre-Wisconsin valley enlarged by Wisconsin ice..... By Lob pe i Se peer Ci ie fagapedaynn eke 44-45
4B.. -| Far Rockaway. . --| Rockaway ridge (Herod gravel member of Manhasset formation).................... 118,127
4B.. ra esas erde ewnes eed cate tc .-| Emergence of ground waters, fresh and salt marshes............................... 183, 184
8 Ces eis --| Near Jamaica South. .-| Depression between outwash plains.
AGo. 2 -| North of Jamaica.. .-| Till of Harbor Hill moraine; “inland scarp” .............. 0.22.02 cece cceecee cece eee 34-35, 53
4C,. Sui assoarsremalontay easeaiwanin --| Thin till over modified surface of Manhasset formation............................. 158-160
4D.. Slender oadNe ae a RN RT lat eats Thick till, including some Montauk till member of Manhasset formation, with occa- 158-160
sional exposures of gravei of Manhasset formation.
4D....| W....| Near Whitestone Point. .... 20-foot: bowlder reported... « ..:.2.2:ca\s0 secuieem acide cine v4 o4)edueog Lace siedseccea ousevececheas 171-172
4D....) E Elm Point 2| Thiek bed of dark Cretaceous Cay ox.co0.c24.c40 082 ncneenconnn ues vanvnsecoccaeeew anos 69
4D... .| Pre-Wisconsin valley, modified by Wisconsin ice....................--.------..--. 44-45
5B... -| Double line of beaches er Rockaway and Hicks).
Or Bihes Rockaway ridge (Herod gravel member of Manhasset formation). Faulted pebbles 127
in pits.
Di Oe siiadl seca etiod agate pencueateeewepeee aeons Past Dis from ice along Harbor Hill and Ronkonkoma moraines; outwash 166-176
¢ els.
5 Cue Northwest of Creedmoor. ...) Harbor Hill moraine; “inland scarp”. .... 2.22... 0000ec cece cece cc cece cececccceeee 53, 158
5D.. -| Lake Success................ Largest kettle in till or mixed moraine....................2.22.0.-..--0--00. esses
5D.. -| } mile northeast of Lake Suc-| Outwash channel through moraine, crossing of Harbor Hill and Ronkonkoma 164,175
cess. . moraines; eastern limit of unmodified ‘inland scarp.””
5D.. -| Southeast of Manhasset.....| Bowlder 54 by 40 by 16 feet reported.......20.......ceccceececeeeccsececceeeeeeceee 171-172
5D.. -| North Hempstead...........| Bowlder ieee long, 20 to 40 feet wide, and 10 to 17 feet high reported; possibly 171-172
same as above.
6 Dec] Cores mile east of Thomaston... ./ Cretaceous sand in railroad cut... .......2.......0.20c20ceceececeeceececeececceeeees 69
5D....| W....| North of railroad, Creat | Beginning of characteristic Manhasset plateau (100-foot level); exposures of Herod (31, 125, 135, 152
Neck. ravel, Montauk till, and Hempstead gravel members of Manhasset formation, in
luffs (rather poor).
5D. Manhasset Neck... -| Manhasset plateau (180-foot level) projecting knobs of possible Mannetto gravel.... 30
5E. -| Base of Plum Point... -| Jacob sand in floor of abandoned pit..... 0.222.222 20. o cece cece cece eee ee eee selene 108
5E mile east of Plum Po -| Knob of contorted Jacob sand in old gravel pits............0--0002.00sc ssc sseeeee ee 108
5E£ arker Point : -| Montauk till member of Manhasset formation between Herod gravel member and 135
‘ Hempstead gravel member.
5E. -| Tom Point... Hegigaig cee! Gravel of Manhasset formation, folded by Wisconsin ice............2.....2---.---- 210
5E.. -| 4 mile north of Tom Point...| Large sand delta of Wisconsin age, fine fore and top sets.-......................... 177
5E.. -| North of Port Washington...) Many pits of Herod gravel member of Manhasset formation........................ 125

 

a Center is abbreviated C.
SUMMARY OF GEOLOGIC FEATURES,

Principal points of geologic interest on Long Island—Continued.

187

 

 

    

   

 

Coordi-
nates Page ot
on ity. re res %
ae Locality Features, description.
and II.
5E.... -| Northeast of Port Washing- | Scarp between high and low level Manhasset plateaus (from Port Washington Har- 31
ton. : bor to Mott Point). ;
BBs Prospect Point....-.-....... Morea till member of Manhasset formation in bluff; undermined and submerged a Plate
peat. XVI.
5E.. -| } mile south of Mott Point...) Bright-colored Cretaceous clays; Mannetto gravel................0..0000.00e0eee eee 69, 83-84
E.. 1 mile south of Mott Point...) Upturned Cretaceous and Mannetto gravel, 80 feet above sea level (on road cross- 69
ing neck to Port Washington). :
Bass Near Long Beach........... Detile betel and CUW6s w.ecas veceeavanus vendewecd a oaeeeeheu xp ig uke dea eas Skamania 180
B. Barnum Island... .......-... Outliers of Manhasset formation (?)................-. 30
Bises Emergence of ground water: fresh and salt marshes.. 183-184
B. Lobate margin of outwash plains 36,37
CO ueees Outwash plains, outwash channels, loam patches resembling “Jamesburg loam”’ 37, 48, 173

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Hempstead Harbor.

 

-| West of Sea Cliff. ...........

South side of Mosquito Cove.

.| East of railroad........---..

Near Glen Cove Landing... .

..| Near Red Spring Point......
.| Near Weeks Point.........-

    
 

W....| South of Wheatley...-....--

 

Near Syosset........-.---.--
Southeast of Brookville... ..

   

Near yster Bay...... Be
mile west of Moses Point. .
HITING ORS ccaisce-e.2- ose psaterore chine

mile south of Rocky Point.
oopers Bluff .......-.....--

.| Near Jones Beach..........-

COdStenecs csienesemaes
Massapequa River. .
armingdale..........
4 mile west of Farmingdale. .
1} miles east of Farmingdale.

  

:.:]} Southeast of Farmingdale...
.| 14 miles southwest of Plain-

view.

2<| Bethpage... s.cscsesccacnces2
.| East of
.| Northeast of

ethpage..........-.
lainview....--

1 mile west of Melville.......
Southwest of Melville. ......

.| 3 mile southwest of Wood-

ee
High Hill. seiecccwavesiieces s
Near High Hill......-.....--

.| Northeast of Syosset........

Near Cold Spring Station...

.| 2 miles east of Cold Spring...

14 miles east of Cold Spring. .

As south of Coopers Bluff.
coopers Bluff...........-.--

West shore of Cold Spring
Harbor.

(suaterete D0 siecsusieveesacatescdats

South of Lloyd Beach.......
South base of Lloyd Beach...

.| North base of Lloyd Beach..

-| Clay oe in Montauk till member of Manhasset formation (?

.--| Harbor Hill moraine; traces of modified “inland scarp”? (2
.| Highest point on Harbor Hill moraine; possible traces of Mannetto gravel. .

..| Harbor Hill moraine........
-| Numerous flowing wells.

.| Connecting beach...

.| Hills of Mannetto gravel; pre-Wisconsin erosion topography .

 

of New Jersey.

Mixed outwash from ice along Ronkonkoma and Harbor E£ ill moraines; ‘outwash
channels; morainic outliers; Ronkonkoma moraine (interrupted type).

Kettle plain between moraines; remnants of Manhasset formation OF

Terraced outwash channel from gap in moraine

   
 
 

Gravels of Manhasset formation beneath moraine.................02...205-5
Outwash channel through moraine...................0..0.0 0.00 e eee eee ee reagent
Montauk till member of Manhasset formation, between Herod and Hempstead
gravel members, finely exposed in many gravel pits.
Traces of Cretaceous clays and sands near landing and southward; Jacobsand knob
in floor of gravel pit near landing.
Local development of lower Manhasset plateau (100 foot)....
Hills of Mannetto gravel (with Wisconsin mantle)
High-level Manhasset plateau with semimorainal mantle of Wisconsin drift........
Fine sand pit.
Pre-Wisconsin valley enlarged by Wisconsin ice................2-2. cece eee cece eee
Cretaceous white sands and Mannetto gravel in blufl.................----22+.------
Cretaceous sand and Mannetto gravel in unconformable contact in gravel pit......
Deep, SE ere erosion valley in Manhasset formation...................-..
High-level Manhasset plateau (180-200 feet)........... 2.2.2.0 c eee cee ee eee eee eee
Montauk till member of Manhasset formation; yellow, pink, and black Cretaceous
clays, both north and south of landing.
Gray Gardiners clay with small quartz pebbles..............-......02-20022-e ee eee
Gardiners clay, Montauk till member of Manhasset formation, ete.
White and pinkish Cretaceous clay in pit......-..--..-.-.-.---
Connecting beaches; low-level Manhasset plateau... ..-
Beaches, spits, dunes.
Salt marshes..........
Lobate outwash margin; emergence of ground water; fresh and salt.marshes.......
Outwash plains and channels; loam............-... 2-20-2222 02e cece ee eee eee eee eee
Confluent outwash fans.............2-.2-..-02-0220--5-
Rodnkonkoma moraine, partly on Mannetto gravel...........
Old erosion forms in Mannetto gravel, mantled by Wisconsin drift.
Kettle plain between moraines.........-..-.-2-.2---.2-2-2++--
Harbor Bill moraines. sities 4 sogestnloceiemeagyaee
Dissected Manhasset plateau (Vineyard erosion).

 

 
 
 
 

  
  
 
 
 
 
 
  
 
 

Gardiners clay, etc., reported s
Remnant of high level Manhasset plateau. Cretaceous outcro

Cretaceous clays in
formation in bluffs.

Cretaceous thrown out in dredging harbor.............-....6 02-02 .ee eee eee eee eee

Jacob sand in beach; probably members of Manhasset formation (Herod gravel,
Montauk till, and Hempstead gravel) in bluff (poor exposure).

Double beach, dunes, salt marshes

Lobate outwash margin, marshes, etc 5

Depression between Hempstead and Babylon outwash plains; outwash channel...

 

 

.| Cretaceous clays in large DitSivsacasiajcus semriare Mesmnekee Capa ieta Pecunia 1 Pe eR erg Ie
@ mae

Terrace of gravel of Manhasset formation; outlying hills of Mannetto gravel.
Westerly member of ‘ Melville double channel’’
Extramorainal kettles of doubtful origin
Depression between outwash from ice along Ronkonkoma moraine and compound
outwash on the west. ; .
Cretaceous clays overlain by pseudotill (?) in clay pits................--22+-2 eee eee
Bethpage terrace of gravel of Manhasset formation :
Terraced outwash channel from Ronkonkoma moraine.......

 
 

  
 
 

 

Mannetto plateau; sharp erosion gullies on margins..........
Roadside section of Cretaceous clays, marl, etc.......
Western of Melville “double channels” .........-..--
Double moraine separated by flat outwash.............22-. 26.2. eee eee eee eee eee

Highest point of Ronkonkoma moraine........ AOR el Liye ame ce eee

Possible example of simple morainal cone; indications of Cretaceous or Mannetto
core (?). Fine development of rough gravelly moraine.

Kettle plain lsc hy se batiene eb Ga Os ae esa Sop ale clr fay fiate nies ON? free nea pare ede eden cies

Deep Vineyard erosion valley in Manhasset formation; much Wisconsin drift on
sides; some post-Wisconsin cutting.

Kettle plain, branching kettles.......-.---.-+ +2222 050-222 eee eee eee eee eee

Harbor Hill moraine (interrupted).

White sandy Cretaceous clay.....-..--- +--+ 22-222 eee eee cece cee eee eee eee ee

See 7 E (E). Nis, .

Cretaceous sands and clays (opposite village of Cold Spring Harbor)..........--.-.

Pre-Wisconsin valley shaped by Wisconsin ice........--...- sieigds ne seagate aces
Cretaceous clays, Montauk till member of Manhasset formation, etc., in old pits.
Mannetto gravel in Nils... 0. 4. voncwerpe se sense See ee
Cretaceous, Mannetto gravel and Gardiners clay in bluffs (poor exposures)

 

 
  

 

141

37, 48, 30, 165
43, 114

49

53,168

82, 170

116

175

135

69, 108

31, 178-179
177-182
184-185

208-212
42-43
188

GEOLOGY OF LONG ISLAND,

Principal points of geologic interest on Long Island—Continued.

 

 

 

 

 
 

Coordi- iil
nates ar
on of sec- Locality. Features. ese rc ean
PlatesI| tion. Pion,
and II. ‘
B82 West Neck..........--..---- Kettle plain of retreatal outwash on Manhasset formation........-.........2....--- 43,176
BW otves ..-| Huntington Harbor.........| Pre-Wisconsin valley, reshaped by Wisconsin ice....... 2 44-45
E. .| West side of Huntington | Trace of Gardiners clay 1 mile north of head of harbor 97
Harbor.
F .--| Lloyd Point........-...---- HANGS DIG) a2: os aoee ta iteainns foaled ue eGeceeeancwae pian womveraiuiea kauamtemaasees 179
F ...| 1 mile south of Lloyd Point .| Traces of Mannetto gravel in bluffs . 83
F .| $ mile southeast of Lloyd | Evidences of subsidence (submerged bushes) .-........-.-2.--2..0-0e eee ee cece eee 214
Point. e
F. .| 1 mile southeast of Lloyd | Crétaceous and Montauk till member of Manhasset formation in bluffs; big bowl- 136, 170-172

Coo 0 © 0D HODD OWOODOOHOHO OO OOWODOD © OM OHO © GD CW GMeM WMo
y bY booUD

et ol bl td ib Bitte

Pree eee OD OOO

osoooooeoooocseooo
SSSR Seo UAOO

 

 

 

 

 

 

 

oint.
.| 14 miles northwest of East
.| Northwest of East Fort

a) Carls Rivericc s.2:cnecesexe

.| Northeast of Colonial Springs
..| Near Wyandanch
.-| 14 miles north of Wyandanch|

...| }mile east of Melville
.| I mile northeast and 1 mile

vail D130 JEN Sos nctesicmune-crnsteiais feral
.| Southeast of Fairground... .

“| North of Dix Hills

.| 4 mile south of Halesite

aa 4 mile east of Eaton Point...
.| + mile southeast of Eaton

.| Base of moraine.

.| East of Commack...
.| 1 mile north of Fort Salonga.

‘oas'
.| North of railroad

t
.| Southeast of

Fort Point.

  
   
 

   

13 miles southwest of Bel-
mont Pond.

Half Hollow Hills...........

east of Melville.

Northwest of Dix Hills

13 miles south of Greenlawn.

1 mile northeast of Green-
lawn.

Northeast of Fairground. ...

Great Neck

1 mile northeast of Halesite..

Centerport and Northport
harbors.
Southwest of Little Neck
int:

oint.

Southeast of Little Neck
Point.

West Beach.........

Shores of Price Bend

 

Eaton Point................

Neck Lighthouse.
East Beach
mile east of East Beach... -
ak Island Beach...-..-..--

 
   
  

Edgewood. -

Near Dix Hills.............-

South of Commack..........

 
  

South of Larkfield.
North of railroad...

Fire Island Beach...........

     
  

 

Branch.
Near Smithtown
4% mile northeast of Smith-
town.
North of railroad............
Nissequogue River. .. ‘
Stony Brook Harbor.
COaSts ciirceucicettisey eats nis

  

 

.| Manhasset formation projecting above outwash

-| Ronkonkoma moraine (confluent cone type); small outwash fans; south border of

der.
Folded gravels of Manhasset formation (Hempstead gravel member)...............
Wisconsin till and Montauk till member of Manhasset formation in contact........

 

See 8 B.
Outwash from ice along Harbor Hill moraine; outwash channels...............-..-
Kettles of:dowbtfulioriginy. oj. cciscnsiwe sicvereinenn care cece oman aa iow meminectsninsteee

 

Eastern of Melville ‘‘double channels’’; depression between outwash from ice along
Ronkonkoma and Harbor Hill moraines.

Broad Hill moraine, outwash channel in harbor.

Cretaceous and Mannetto gravel in abandoned pits

Outwash from ice along Ronkonkoma moraine

Extramorainal bowlders near road ascending hills.

Slopes of Mannetto gravel; level top with small bowlders and shallow basins (Mon-
tauk till member of Manhasset formation).

Eastern of Melville ‘double channels”. ......---2+2-+00+-20ee cece eee ece ence ee ec eee

Distinct terraces of outwash from ice along Ronkonkoma moraine, standing above
the valley outwash from ice along Harbor Hill moraine.,

Ronkonkoma moraine on Mannetto gravel.

Kettle plain; branching kettles; kettle valley. -....

Late outwash from ice along Harbor Hill moraine

Hills of Mannetto gravel mantled with Wisconsin drift.-..

Cretaceous clays in wells, etc., on west edge of hills. .....

Head of Northport-Babylon outwash channel

 

 

   

ERAT DOE: FAN MORI TAG oes 2 2c eiscstcatn ya; 5sciad ys aysssaalSeaja ore Greed bye cassis Sogeg banal S apne de Dam eeeke Sees

Obstructed valleys (pre-Wisconsin); retreatal outwash on Manhasset formation. .

20-foot bowlder in Wisconsin filling of Manhasset valley.........-........-22..2...

White, gray, and chocolate-colored Cretaceous clays and talus of Mannetto gravel
shown in blufts at mouth of Centerport Harbor.

Pre-Wisconsin valleys modified by ice........-..-.-222- 202-2 e ee eee eee eee

Cretaceous dark clay and white sand in bluffs.-..............2.2-2--2-------0------

Thick Cretaceous white sands and some dark clays in pits and bluff; Hempstead
. gravel member of Manhasset formation unconformably on Cretaceous.
ine spit
Cretaceous clay, ravel, Gardiners clay, and Montauk member of
Manhasset formation, shown in amphitheaters along shore of Price Bend and
to north; Mannetto bowlders 2 feet orgmore in diameter.
Spit and dunes
ontauk till member of Manhasset formation in bluff near lighthouse.
Cretaceous, Mannetto gravel, and Montauk till member in bluff....................

 

   

 

Fine connecting beach and low dunes.........-.-20--.0-2 2 - cece ee eee ee ee cee eeee ee
Montauk till member in bluff...............2....0--.--
Barrier beaches, dunes, and salt marshes
Lobate border of outwash.......2-.---22-.222--2-002--+
Melville and HOC Uno re Babylon channels (Harbor Hill
Outwash from ice along Ronkonkoma moraine (unusua a
Northport-Babylon outwash channel (Harbor Hill).....-..-...

Confluent outwash fans. ........-..2---20--0e eee eee eee
Ronkonkoma moraine, in part on Mannetto gravel......
Mannetto gravel beneath Wisconsin drilt
Outwash from ice along Harbor Hill moraine over Manhasset formation. .
Barin outwash channel... .:.c:ccwcnwcsne in es ancioscaeecekeeseciet ees cesses

  
  
 
   

Thick outwash from ice along Harbor Hill moraine........

Harbor Hill moraine........-.0--. 00-0 eee ence eee e neces

Manhasset plateau, much dissected by Vineyard erosion..............222..2..-..--

Extensive ‘exposures of chocolate-colored and dark-gray Cretaceous clays, traces
of Mannetto prove and Montauk till member of Manhasset formation; immense
landslides affecting cliffs for 4 mile inland; landslide scarps. (This is the so-
ealled ‘‘ Broken Ground.’’)

Barrier beach, dunes, good examples of fresh marshes among dunes.

Lobate outwash margin

Compound topography (Manhasset formation and outwash

Smithtown “ driftless’’ area.
Smithtown ‘driftless” area; pre-Wisconsin topography
Head of Connetquot outwash channel ce
Erosion bluffs facing Connetquot channel; pre-Wisconsin valleys; post-
notching.
Manhasset formation (Hempstead gravel member) exposed in railroad cuts........
Esker (just north of road) extending from bottom of valley up hillside for } mile,
establishing pre-Wisconsin age of erosion.
Harbor Hill moraine
Pre-Wisconsin valley, little modified by ice.. a se
Pre-Wisconsin valley, much enlarged by ice..--.... 2.2.22... cece ee eee eee cree ee ee
Montauk till member of Manhasset formation resting on disturbed beds helonging

 

 

 

 

to Manhasset formation (between Nissequogue River and Stony Brook Harbor).

152
136

179
43,176

173,175
43-44

49,175
82
168
82, 141
49,175

168-170
52, 176
172

71
44-45
7

71, 153
179
71, 83
179, 182
137

137
179, 182

137
178,181, 185
7

162
174
168-170

30
56, 71,83, 137

178, 181, 183
37

118

118

32,36, 162

162, 208
175-176
175, 208, 212

153
116, 162

168-170
44-45
44-45

137
SUMMARY OF GEOLOGIC FEATURES.

Principal points of geologic interest on Long Island—Continued.

189

 

Part
of sec-
tion.

Features.

Page of
description.

 

   
     
   
  

 

 

 

Near Lake Ronkonkoma....

West of Lake Ronkonkoma.

i mile northwest of Lake
Ronkonkoma.

.-| North of Lake Ronkonkoma.
.-.| 14 miles north and } mile

west of Lake Ronkon-
koma.

.{ 2 mile northwest of Lake

Grove.

.| Near Lake Grove...........

...| South of Crane Neck Point...

.| South of railroad . .

Oldfield Point.
Setauket Beach.
Fire Island Beach.

  
 
  

1 mile west of Holtsville.....
.| South of Selden

North of Selden.....--......
Near Terryville.....-.......

 

   

 

.| Near Yaphank...........-..
.| Near Coram Hill
.| Near Middle Island

2 miles southwest of Middle
Island.
4 mile east of Middle Island. .

1 mile east of Middle Island. .
2 anilss north of Middle Is-
land.

-| 1 mile southwest of Rocky

Point.
1 mile southeast of Rocky

Point.
North of railroad...........-

.| # mile’ east of Woodhull

Landing.
4 mile east of Woodhull

Landing. :

4 mile west of Rocky Point

anding. .

4 mile west of Rocky Point
Landing.

$ mile west of Hallock Land-
ing.

1 wile east of Hallock Land-

ing.
Fire Island Beach.........--

..| Barrier beach and dunes
.| This region is at end of oxtensiv

-| Broad Connetquot outwash channel (Harbor Hill)

-| Largest kettle lake ofisland

_..| Fine spit on both sides of entrance to Port Jefferson Harbor. .

 

 

nis | 0 marshes (characteristic of outwash a

and beginning of erosional coast line (distinction of Manhasset surfaces). Being

transitional the forms are here indistinct.

Thin outwash from ice along Ronkonkoma moraine; Manhasset formation controls
the topography. — :

Ronkonkoma moraine (low and interrupted)

 

Depressed moraine
Terraced outflow channel leading from lake to Connetquot channel (now dry

. Shallow pond and marsh behind recent delta in old channel in Manhasset formation .

Kettle valley
Ridge in channel

TeTEAaCOd MO ttl Orci ecstic ss vesies netem se dace eeweie = Hass aeeuiny sos eeawes ae Ree ee eS

West end of great intermorainal fosse depression (shown by 100-foot contour)

Thin outwash from ice along Harbor Hill moraine on Manhasset formation (Man-
hasset controls topography).

Harbor Hill moraine; dissected Manhasset plateau............---------+-2-0eee eee

Dissected Manhasset plateau (Vineyard erosion)

Heavy Montauk till member of Manhasset formation, grading upward into Hemp-
stead gravel member; big bowlder.

Montauk till member shows in bluffs (exposures poor)...........-...2-2-2-2-2200 ee

 
 
 
 

Barrier beach and dunes

Erosion outline of coast; mainly Manhasset borde:

Thin outwash from ice along Ronkonkoma moraine on Manhasset ; Mal
hasset. frequently controls topography; channels partly Manhasset, partly Wis-
consin.

Double channel (} mile south of railroad)

Ronkonkoma moraine, probably exceptionally sandy, covered with old dune sands
at many points.

Great intermorainal fosse depression; surface largely covered with old dune sand,
some local drifting at present time; Manhasset formation controls topography.

Outwash topography gives way to Manhasset formation............-..-..-...----

Outwash from ice along Harbor Hill moraine

Harbor Hill moraine idee ope

Harbor Hill moraine depressed type; many immense kettles north of railroad......

Large gravel pit in Manhasset formation with moraine above; large bowlder (both
on road to station).

Indications of Montauk till member of Manhasset in lower part of bluffs on east side
of harbor; dissected Manhasset plateau (Vineyard erosion).

Cliffs of Manhasset formation overlain by one of the Wisconsin moraines; traces of
Montauk till member of Manhasset formation.

Old spit flanked, with. marsh ccccc0: os ee ciisenaiion Sancinewesisiaeive sedameaatienniecdisees

Barrier beach; dunes

Erosional coast line, mainly Manhasset formation

See 13 D.

oS Valley outwash from ice along Ronkonkoma moraine..........-.......--
ee 13 D.

Carmans Valley ovtwash with narrow channel of post-Ronkonkoma age...........

Ronkonkoma moraine; morainal gap at Carmans River...............-.--..-.---

Surface mantle of bowlders and some till-like patches (mainly Wisconsin till, possi-
bly some Montauk till member of Manhasset formation).

Kettle valley, kettle chain (branching and completely closed)............---.----.-

   

 
 

 

Vineyard erosion valley in Manhasset formation (modified by ice and by recent
érosion by Carmans River).

Kettle valley branching, partly open, occupied by Artists Lake............-......-

Branching kettle valleys.........----------00e- ences ee eee eee e eee n ence cet n cece ee eee

Thin outwash from ice along Harbor Hill moraine on Manhasset formation; Man-
hasset valleys and other pre-Wisconsin topographic features.
agente do
‘Numerous deep branching kettles and kettle valleys. .

 

Till-covered monadnock rising above outwash (morainal?).

Harbor Hill moraine resting on Manhasset formation; Manhasset Sop y
distinct on north side, many valleys being only partly obliterated by the
moraine. Manhasset terrace well developed east of Hallock Landing.

Poor exposure of mottled buff to gray Gardiners clay.....-.....----+--2--+2--000-+

Thick, gently folded beds of Herod gravel member of Manhasset formation.........

Sinall expostire of tough brown Gardimers:€lay ss. 4 cavsexseevanetevsceeeeresoesey ia

Salmon-colored micaceous clay belonging to the Gardiners clay or the Jacob sand..

Upturned clays along fault pee (Gardiners clay or Jacob sand). Folded beds of
erod gravel member of Manhasset formation.

Bowlder 25 by 10 feet, embedded in beach

Barrier beach, dunes, margin of Manhasset formation bordered by marsh (unusual).

Carmans Valley outwash with narrow channel of post-Ronkonkoma age

Manhasset formation with thin outwash from ice along Ronkonkoma moraine
local).

on kanes moraine; morainal gaps and depressed moraine. .... scaslarsicina sea nee

Manhasset surface with thin till or mantle of bowlders; deep Vineyard erosion
valle

 

 

.| Northwest of Ridge. ........

Kettle

ys.
valley systems

 

178, 181
175-176
168

165

40

165

47
183-184
42-43
50

40-41

48
“172

30, 168

30
137-138
138

179
177-178, 181
212
48-51, 172
50

165

48

168

172

170

40, 170
170, 172
30, 138

137
184
177-178, 181
212

168
168
165
162
42,43
46
42,43
42
172
172
42

116,170

97
126
97
97
98, 126
172
177,181
168
172

165
162

42
190

GEOLOGY OF LONG ISLAND.

Principal points of geologic interest on Long Island—Continued.

 

 

   

 

  
   

 

corel ate
Maes aE . Page of
on of sec- Locality. Features. :
PlatesI| tion. description.
and II.
Pixel Bamana yucntees sehen ten eta bese aemes See 15 E (C, N).
15 F....]| SE....| 1 mile southeast of Wading | Branching kettle-valley system (deep pond).............--..22222-00 ee ee eee cece ee 42-43
River station.
15 F....| SE.....| 2amiles southwest of Wading: |. <2: dO sx.c0200 20 2 sisie cieintisssiors Hvieeivin bem stsreeiee ay see See bce eneeme ERE Bele are ance ate 42-43
River station. : .
LMS well Caves 1} miles west of Wading | Bowlder (20 by 20 by 16 feet) near highway through moraine................------ 171,172
River station.
15 Bin | Ose. 2 mile northwest of Wading | Bowlder (20 by 18 by 15 feet) near edge of marsh............2-2...222-20022e-e eee 170,172
River station.
15 F....| W....| $ mile east of Woodville | Old brickyards and clay pit, probably in Gardiners clay and Jacob sand; upturned 109
Landing. Jacob gone in ravines; Montauk till member of Manhasset formation overlies
clay pits.
U5 Rl Cu wes Coasticascedeecotdass endo Lan bins along bluffs and fresh-water pools along beach, both suggestive of 56, 51, 180
Gardiners clay and Jacob sand beneath talus; many deep ravines and amphi-
theaters; magnetic and garnetiferous sands on beach.
Horizontal beds of Herod gravel member, overlain by Montauk till member of 126
Manhasset formation.
Barrier beach; erosion coast line; estuaries of pre-Wisconsin age.-.........-------- 177,178
Manhasset plain and valleys; local outwash from ice along Ronkonkoma moraine 118-119, 168
- (largely near moraine).
..| Local patches of loam, repembling “Jamesburg loam” of New Jersey......---.---- 172
.| Ronkonkoma moraine; depressed moraine at gaps (locally); compound type of 165
morainal ridge.
Morainal outliers.......... 165
.| Exceptionally heavy mor: 165
Peconic liver fosse......... foal 120
Modiied Manhasset surface with thin outwash; large kettles, kettle valleys, le 42-43, 120
chains, etc.
Manhasset surface with original drainage but slightly obscured; thin outwash near 117
moraine and elsewhere.
16 F....| SW...| Near Deep Pond......_.._.. Branching: kettle-valley systemic sec coccctdscwavwecsas costa sannuiae secede anaesce cs 42-43
16 Fisec) Bacwes South of Fresh Pond Land- | Kettle valley and kettle chain... 42-43
ing.
16 Fcc) (Gs oon: ‘Along OOAS Gi er maireass sens ect: Harbor Hill moraine rapidly diminishes; partly removed by sea; almost disap- 171,182
ears at Jericho Landing; development of dunes at top of bluff and along north
lace of moraine becomes important.
16F Gres COAS be ed wax cer dateseced aoac 3 Fairly clean bluifs commonly showing from 50 to 90 feet of Herod gravel member 51, 56, 126
of Manhasset Jormation; men amphitheaters; some landslips and springs sug-
gesting Gardiners clay or Jacob sand near beach level.
16F W....| Paine Landing.........-...- Montauk till member of Manhasset formation exposed in up er part of bluffs; 138
many big bowlders on beach; thick Herod gravel member of Manhasset.
16 F Cis 5 ayaa Hulse Landing..........-.-. Same as preceding; Montauk till member continues to Fresh Pond Meadows, 50 138
feet thick in places; thick Herod gravel member of Manhasset formation.
16: Be o.cc|) Bes sec: East of Fresh Pond Landing. ae bw gravel member; dunes at crest of bluffs.....-....-.....-.------------ 126, 182
ee 16 fs
See 16 D tN,
Bowlder 125 feet in diameter reported....... 2.2.02... 22002202 c cece eee eee eee eee 165
Ronkonkoma moraine (strong development), morainal channels, cones, kettles, | 32, 42,48, 165
etc., of all types; Bald Hill cone.
Peconic River fosse; Wisconsin outwash, etc., on Montauk formation; large ket- 43,120, 162

 

| Viana Creek...
...| North of moraine. .
.| Red Cedar Point

 
   

.| Near Baiting Hollow._._....

Along coast.........-.---.-.
Coast.

Near Friars Head......-...-

+ mile east of Roanoke
Landing.

Near Roanoke Point

ALONG COASTS oj scswinzcicesiccs
4 mile west of Jacob Point...
Near Jacob Point

Near Luce Landing
Hampton Beach
Coast

   
 

Shinnecock Canal............

Mattituck Inlet. .

 

 

-| Along coast

 

 

Near Oregon Hills

 

-| Ronkonkoma moraine (see 17 tee depressed moraine at broad ga

---| Outwash from ice along Ronkonkoma moraine

--| Submerged kettle valley in Manhasset surface

tles (Great Pond, etc.).
Vineyard erosion valleys in Manhasset formation; kettle valleys, kettle chains, etc...
Outwash from ice along Harbor Hill moraine over Manhasset formation. .
Numerous branching kettles (kettle-valley type)
Harbor Hill moraine (weak development). ......... 00.02.2020 cece eee cee eee eee
Steep bluffs cut by deep amphitheaters; dunes at crest of blufls; many exposures

of Herod gravel member of Manhasset formation.
Typical exposures of banded and cemented Montauk till member of Manhasset

formation eroded into pinnacles and knife-edge ridges (in amphitheaters).
Upturned clay (Gardiners)

Folded and overturned Gardiners clay and Jacob sand

 

 
 

11] See 16 D (3).

See 16 D (N).

Wisconsin outwash, etc., on Manhasset formation; many small kettles, pre-
Wisconsin valleys.

Outwash from ice along Harbor Hill moraine over Manhasset formation; numerous
kettles and kettle valleys; some Vineyard erosion valleys.

Harbor Hill moraine capping Manhasset terrace (weak development with many
gaps); partly covered with dunes.

Bow)lder 38 by:20: Dy 11 feet aco. secewiewu newen ceuinenn iaskisjsedeedeerenas suet nbae ns

Tough dark Gardiners clay; Jacob sand; Herod gravel member of Manhasset, for-
mation; Montauk till member of Manhasset formation near top of bluffs. .

Pinnacles of Gardiners clay and Jacob sand; possible Jameco gravel; Herod gravel
member of Manhasset formation; Montauk till member of Manhasset formation,
near top of bluffs.

Submerged peat and: Stumps i<..:ie sissieiveiven oes sce seecaec coast osseysseveeceeaeseusies

Barrier beach; dunes, marshes. ......-..--....-..6+

Erosion coast line in Manhasset formation .........

Manhasset plains with thin outwash.........-..-....

Ronkonkoma moraine (depressed at gap)........-..---

Late narrow outwash channel in Ronkonkoma moraine. .

een outwash on Manhasset formation; kettles; Vineyard erosion topography.

Fine spi

Montauk till member of Manhasset formation and Gardiners clay in overturned
folds in bluffs; Triassic bowlders in Montauk till member.

Herod eave member of Manhasset formation in bluffs... ..

See 18 F (C,S

Outwash from ice along Harbor Hill moraine on Manhasset. formation; ‘outwash
channels near Oregon Hills.

Moraine largely eroded, only low narrow ridge remaining; several important gaps. .

Montauk till member of Manhasset formation (with many Triassic bowlders) in

  

 

 

bed in middle of bluff,

42-43, 117
174

174

171

51, 126, 182
138-139

98

98

165

43,162

174

171, 182

172
98,109,126, 139
98, 109,126,139
213

17, 181

118

121

165

49

168

43, 162, 208
179

141-142

127

42,117
174

171-172
140
SUMMARY OF GEOLOGIC FEATURES.

Principal points of geologic interest on Long Island—Continued.

 

191

 

 

 

 

 

 

Coordi-
nates | Part
on of sec- Locality, Features,

Plates} tion.

and II.

19 G...| SE....| Middle of Oregon Hills...... Bowlder 15 foet:in.dinmetotieis 2 cssnccwiess wonderads 3 ener amas sheee enum Boden <

19 Gees) Beis $ ae southwest of Duck | Bowlder 23 by 20 by 15 feet............ 0.00. c cee ence eee eee eee eee eee eens

ond.

20 E...| SE....| Hampton Beach... Barrier Poach!) Gunes: «ess cinq sda ae gascejs ee tinge ene sna caiciacanien chee erences

20E. s -+--| Shinnecock Hills... Hills of Manhasset formation shoved and dragged by ice; old dune sands.........-

20E...) W. 4 mile east of Shinnecock | Old clay pit showing Gardimers clay grading into Montauk till member of Manhas-

Canal. : set formation; Herod gravel member of Manhasset formation.
20 Bis xc (Nias monn of Cold Spring | Gardiners clay and Montauk till member of Manhasset formation in bluffs......-.--
ond.

20 F ...| SE....| Near Cow Neck......----.-- Irregular areas of Manhasset formation Spparantly laid down around ice blocks.

20 F ...) C......| West side of Robins Island..| Gardiners clay, Jacob sand, Herod gravel member of Manhasset formation, and
Hon tani till member of Manhasset formation in bluffs (generally folded); fossils
ocally.

-| East side of Robins Island. - ay ered. gravel member of Manhasset formation with some Montauk till

member.

20 F...| NW-...] New Suffolk... Outlier of Manhasset formation...........2..0.. 00 cece ec ce nee e ee eee cece nee enn eeeee

20 Gasca? Cars aisis |b enisiciety aia seins Smsmieareescigieee Outwash from ice along Harbor Hill moraine on Manhasset formation. . :

20G. SW...| 1 mile southwest of Cut- | Kettle with till rim near Mattituck highway..........22...0.. 222200 e cence eee ee ee

 

‘ Near Watermill
.' 2 miles northwest of South-

 

 

-| Near Horton Point........--

-| West side of Jessup Neck...

.| 4 mile southwest of Rocky
Point.

.| Long Pond

.| Northwest point of Hog
Neck.

.| Shelter Island

.| Hay Beach Point...

.| Long Beach....-..--

.| South side of fluke. -

.| South and east of Easthamp-

.| 1 milenorth of Freetown.

..| West of Sammys Beach

chogue.
Along coast. ...........--.--
West of Goldsmith Inlet....

Horton Beach............-.-

ampton.

Great Hog Neck

 

Hashamomuck Pond........
4 mile northeast of Hasha-
momuck Pond.
South side of fluke. .
West of Greenport
Shelter Island...
Along coast
Coast bluffs

   
    

2 miles southwest of Sag
Harbor.

Long Beach: se2ssecavrsae+

South of South Ferry.
Ram Island, etc......-

    

 

 

Truman Beach......

 

 

Coast

ton.
“2 miles northeast of Hard-
scrabble.
Near Freetown......-.-.-. 4

  
 

 

 

Cedar Point, Sammys Beach.

-| Manhasset formation practically without outwash

.| Narrow and interrupted morainal belt, li

 

Narrow belt of Harbor Hill moraine (hardly forms a ridge)..........-.-.--.---------
vee some apparently Montauk till member of Manhasset formation, shows in
S.

Fine pocket beach backed by dunes inclosing large pond........--.--..------+-+-+

Bluffs, apparently till from top to bottom; many large bowlders on beach; one
bowlder 25 feet in diameter in water 14 miles east of point.

Outwash from ice along Ronkonkoma moraine with margin truncated by sea;
estuaries converted into ponds.

Ronkonkoma moraine

Watermill pond kettle....-

Kettle with outwash rim

 

Manhasset formation overlain by thin outwash
Strongly developed Ronkonkoma moraine

Deeply eroded Manhasset formation with thin mantle of Wisconsin till
Herod gravel and Montauk till members of Manhasset formation in bluffs..........
Outlier of Manhasset formation with mantle of Wisconsin till
Manhasset formation with thin mantle of outwash
Thick deposits of Manhasset formation with Vineyard erosion topography; mantle
of Wisconsin till; fine spit at Shell Beach; bays of south side due to presence of
tee as blocks. Small show of Gardiners clay or Jacob sand opposite Conk-
ing Point.
Submerged ‘kettle valleys: cc.cicicsicccneadeide raacaiiairaidaes oeseren caee ess needs ¢
Kettle valley filled with marsh deposits (this and the one next preceding bounding
a remnant of Manhasset formation, formerly an island).

 
  

Big fresh marsh in depression in Manhasset formation .
See 21 G (NE)

 

     

e@ of ridge...-..- ai 4

Bluffs mainly of till, probably largely Montauk till member of Manhasset formation;
pavements and great heaps of bowlders on beach; some exposures of stratified
gravels, probably Herod gravel member of Manhasset.

Bowlder 25 by 25 by 30 feet in water..............-. 22.2 e eee eee eee ce ee eee eee

   

Barrier beach; Manhasset plains
Manhasset plains with thin outwash
Kettle valley, kettle chains, connected kettles; kettle channels, etc

Estuary ae off from sea by beach (depression between Manhasset formation and

outwash).

Part of kettle valley
Outwash on Manhasset formation (outwash controls topography); loam in places. .
Strongly developed Ronkonkoma moraine.... 3
Kettles in outwash channels through moraine. .
Outcrops of Gardiners clay at considerable altitudes in moraine

See 21 F (NW).
Connecting: beach wvccs sacsnecnsceas ese stateceges eRe eeeemest saad neneeuuaases SeOETeS
Possible Jameco gravel beneath reworked fossiliferous Gardiners clay; Montauk

till and Hempstead gravel member of Manhasset formation.

See 21 G (NE).

Flats of thick till (Montauk till member of Manhasset formation)

Islands united by connecting beaches.............--.----.--.-----2 2000

Low till bluffs (Montauk till member of Manhasset formation)

Spit, dunes, marshes

Beach connecting island me

Manhasset formation with mantle of outwash............-.....2.--22-2--+--2-22------

Moraine isa more pronounced ridge than forsome distance west; bluffs largely Herod
member of Manhasset formation, overlain by thick till (in part Montauk till mem-
ber of Manhasset formation).

Many exposures of Gardiners clay and Jacob sand, highly folded and overlain by
Montauk till member of Manhasset formation; possible Jameco gravel under the
Gardiners oe

Estuary closed by beach. .

Outwash from ice along Ronkonkoma moraine. .......-....-----.---2-2222 eee 22:

Dunes over outwash, till and bowlders reported to have been washed out by waves
on beach.

Heavy Ronkonkoma moraine ;

Morainal gap; outwash valley; depressed morain

 

    

 
 

   

 

Outwash channel through Manhasset formation.

Ronkonkoma moraine s é :

Manhasset formation with thin mantle of Wisconsin drift; topography m|
Vineyard erosion, modified by Wisconsin ice; kettles.

Montauk till member of Manhasset formation overlying folded Herod gravel mem-

 

ie

 

ber.
Fine spits. ..... \ Sd ston Sack da diedjbee Seis eka SCeeheses Soha wee ses 1. eeeceedase ty

 

Pago of
description.

172
172

177-178, 181
34-35, 181
99; 127

99
110, 128, 145

128
117
174
174

171
140

179
172

168
166
40
41

121
166

119
127, 142
1202121

120
110, 121, 129,
162, 179

42
183-184

120

183-184

171

126, 140, 171
172

121,178

121

42-43

178
89, 142

146
179

146

179, 182, 185
179

120
126,140,170

89, 98

168
163,181

166
168
166
121
127-128
179
192

GEOLOGY OF LONG ISLAND,

Principal points of geologic interest on Long Island—Continued.

 

 

 

   
 
   
   
   
 
 
    
   
    
   
 
 
      

 

 
 

 
  

 

 

 
 
 
  

 

 

 
 
   

  

 

 

 

 

 

 
 

oor ee
nates ar’ Page of
on | ofsec- Locality, Features. Pte
Plates I) tion. deseription.
and II.
28 Gs) Bisse. 2a Southwest of Hog Creek | Low plain of till (Montauk till member of Manhasset formation)...............--.- 142-143
Point.
23 H...| NW...| Near Orient Point.......... Mainly Manhasset formation; some outwash; magnetic sands on beach............ 126, 179-180
231.._.| SE....| North side of Plum Island..| Gardiners clay; Jacob sand and Herod gravel member of Manhasset formation are | 100-101, 111,
involved in small folds; much till in bluffs (probably largely Montauk till mem- 1
ber of Manhasset formation). Several faultsin Herod member.
231....| SE....| South side of Plum Island...| Broad plain of Montauk till member of Manhasset formation on southwest end; | 100-101,111,
faulted Herod gravel member of Manhasset; folded_Gardiners clay, Jacob sand, 130, 146
and Herod member; Montauk till member, east of Fort Terry.
Coast......-- .| Belt of dunes of considerable width...........--.+-----.eee ere eee es 181
Along railroad... Hills of Manhasset formation with little outwash.. 121
eater achiley ea yolete Strong mrorainal rid gO i.e) < sacroacacns apse aie atvjoaieaie:s « cid amare sistem asians amine stews ieee 170
ites Pananmite se enereleee .| General upland of Manhasset formation, with Vineyard topography; broad low- 121
lands of Montauk till member of Manhasset formation.
24G. SW...) Acabonack Harbor.......... Sand spitand marshes...........-.....--- a selnsinde dade sidegeavie we eeasrenins aPEeey 179, 184
% Near Hog Creek Point. ......| Montauk till member of Manhasset formation in fo. Tavel member.
.’ Ram Island, etc.... .| Spit in process of formation, largely below sea level.......---..--------+----- 179
Great Pond .| Pond inclosed by V-shaped spit..-...-.-.-.---- conisigieearase ate 2 179
West side of Gardiners Is- | Montauk till member of Manhasset formation ni ‘ond; Herod gravel 100, 129, 146
land. member of Manhasset formation; reddish clays and clayey sands 1 mile north of
Great Pond (Gardiners clay or Jacob sand). :
South of Tobacco Lot Pond..| Jacob sand, Gardiners clay, and Montauk till member of Manhasset formation, 100, 105,
(generally folded); fossils in Gardiners clay and Jacob sand. 116, 146
East of Cherry Hill Point....| Fine section of red and black fossiliferous Gardiners clay overlain by Jacob sand.... 105
Southwest of Bostwick Bay. Tab a with ripples; Herod gravel and Montauk till member of Manhasset 110,129
lormation.
betes, sees Oisiccememcmeee ..| Fine V-shaped spit inclosing pond.........-2..-.-+--2- 222s eee eee e eee eee eee 179
' Gardiners Point... ..-| Sandy island making continuation of Gardiners Island spit.
.| Northeast coast of Gardiners | Cretaceous possibly present; Jameco gravel under Gardiners clay (doubtful); 90, 100, 110,
Island. Gardiners clay, Jacob sand, and Herod gravel member of Manhasset formation © 129,146
involved - complex folds. Montauk till member of Manhasset commonly poorly
developed.
.| Inland on Gardiners Island. .| Ridges due to folding 35
.| Tobacco Lot Pond oca| BAY. DEP gcerseccana sareuec decors cistals wralen cram sina sie'eamreeme wanes eee mate cass tes aea 177-178
Dapeue Beach. .- Big Gonnectle beach; high dunes; fresh marsh among dunes 1p, 181, iB
keane De side crceeicis saya oe 10.» sicinierd Noein abe Nam Ree oeau cece es ealentenar Mosc cfecieenma: ¥akemaudencennimndlams ,181,
eet eee een eee ..| Moraine (thin) on Manhasset formation; old dunes on surface; Manhasset erosion..} 166, 180-181
.| Quince Tree Landing.. ..| Montauk tilland Herod gravel members of Manhasset formation. .......-.....--+-- 128, 143
..| Goff Point, Hicks Island....| Hooked spits.......-..------.-- eee eee e cece reer eee tenner eee 179
.-| Eastern Plain Point.... .| Herod gravel and Montauk till member of Manhasset formation . . . 129, 146
...{ South coast...... ..| Thick Herod gravel member overlain by Montauk till member ........--..-.--.-.- 128,143
i LRCOLLOR «. sieeciere cio stersicisiansersnieys Hills of Manhasset formation with superficial mantles of morainal drift ( Wisconsin) 121
and dune sand (local). - Fs
.| 2 mile southwest of Rocky | Intermorainal fosse channels. ..........----+++--+eeeee cence reece ee tee eee eee 47
Point.
1 mile west of Rocky Point..| Jacob sand under Herod gravel, member of Manhasset formation i
d Herod gravel and Montauk till members of Manhasset formation 128, 143
Bay Dalasquwescwsisinsmumers steciajsie'a spintsiets siniols vie craleisiv-eicioreicte a areiersersieitis Tarnponcmeerens 177-178
a Pond inclosed by pa7 bar 177-178
.| South of Fort Pond. . .| Barrier of Montauk till member of Manhasset formation ................-.. 145
.| Montauk station..... .| Uplands of Manhasset formation. (See 26 G, SW.) .....-.------- ee eee eee eee 121
South of Culloden Po sete iat member of Manhasset formation under heavy till, possibly Montauk 128
ill member.
Near Ditch Plain_.......... Low plain of Montauk till member of Manhasset formation.........----....----.- 145
Great Ponde....cicccsscseses Pond seen by bay bar, the latter characterized by dunes, fresh marsh, and 177-178,
ponds. 181, 183
.| South coast... sss.cesceseeves Mainly Montauk till member, often double or triple and including stratified sands; 89, 99, 1 i
several outcrops of Gardiners clay and Jacob sand; Herod gravel member of 144, 156
Manhasset occasionally seen; possibly some Hempstead gravel member of Man-
hasset. Sands below clays may belong to Jameco gravel.
27 Go os: Nassee Montauk Point.............. Thick Montauk till member of Manhasset formation overlain by stratified gravel 144
(Hempstead member of Manhasset).
27 Gas wal] Nias won North of Montauk Point....| Folded gravels (Hempstead member or gravelly phage of Montauk till member). . 156
2 Gesell Nicene Southeast of False Point....] Montauk till member of Manhasset formation in bluffs...............-.2-.-.---+05 144
27 Geen.) Nissen 3 mile west of False Point...) Dark chocolate-colored Gardiners clay; Jacob sand; Herod gravel member of Man- 99,111
hasset formation.
27 Gise.| Nesews 1 mile west of False Point...) Montauk till member of Manhasset formation exposed at point 143
27 G....| NW...| Oyster Pond............-... Pond: behind bay bar cac.esccsecnse siscdax sor omen ecceweniee canine 177-178
27 G....| NW...! Near Shagwong Point....... Montauk till member of Manhasset formation 143
27 G....| NW...; Reed Pond..............--.. Pond. behind bay dale sac cce ccccsiccecins oveocewewee ses sedesmusinss soe a cee 177-178

 

 

 

 

GEOLOGIC HISTORY.

PRE-CRETACEOUS EVENTS.!

Little evidence is afforded by the older rocks of the Long Island region as to the conditions

existing on the island in Archean and Algonkian time.

The Fordham gneiss, which

occurs at

the west end of the island, is of pre-Cambrian age, but as it may be either a metamorphosed
sedimentary bed or an igneous rock, its exact relationship can not be told. Its quartzitic
bands, which strongly suggest sedimentary origin, are parallel to the bedding of the Cambrian
rocks, and in most places there is little evidence of any considerable unconformity between

 

1 For a full discussion of the geologic history of the New York region, see New York City folio (No. 83), Geol. Atlas U. 8., U.S. Geol. Survey, 1902.
GEOLOGIC HISTORY. 193

them. At a few points, however, important breaks exist. The region appears to have been
under water through a part of the Cambrian at least, for a quartzite of this age is found at a
number of points in the vicinity of New York. The quartzite is followed conformably, so far
as is known, by the Stockbridge dolomite, indicating the presence of open water during late
Cambrian and early Ordovician time. Similar conditions also continued without material
break into late Ordovician time, as indicated by the conformable Hudson schist overlying the
dolomite. There is no record of the Devonian and Carboniferous periods in the rocks of the
region, and it is probable that during these periods the land was above water much of the time
and was subjected to extensive erosion by streams. A little farther north considerable mountain
masses were uplifted in Devonian time and were later reduced by erosion, and it is not impossible
that some uplift occurred in the Long Island region, although not until near the close of the
Carboniferous was the compression of the rocks into sharp folds (fig. 54, p. 66) finally com-
pleted. In the meantime there had been considerable igneous activity in the region, manifested
in the intrusion of the granitic masses in the Fordham gneiss of Long Island. Some of these
masses on Long Island are so sheared, presumably as a result of the folding, that they now
have a decidedly gneissic structure.

After the period of mountain building there was a long period of erosion, during which
the land was worn down to a low rolling surface. In the New Jersey region a shallow basin
was gradually formed, and in late Triassic or early Jurassic time this basin was occupied by a
body of brackish water, in which the red sandstones and shales of the Newark group were
laid down. During the deposition of these beds there was a second period of igneous activity,
producing both intrusions and surface sheets of diabase or ‘‘trap rock,”’ among which is the great
mass known as the Palisades.

Later, in Jurassic time, the entire eastern part of the United States became dry land and
was worn down by streams until the whole surface was reduced to a gently undulating plain,
with afew unreduced remnants or monadnocks. This plain, which was covered with the clayey
products of decomposition, is known as the Schooley peneplain and extended from the Atlantic
coast over what are now the Appalachian Mountains well into the interior of the country.
Toward the close of the Jurassic period a tilting of the plain began, the part southeast of central]
New Jersey sinking below sea level and the part northwest of it rising.

CRETACEOUS EVENTS.

The elevation of the land in the northwest led tu a more active erosion, and the sand and
clayey materials derived from the decomposition of the rocks were swept seaward and deposited
along the coast, forming what is known as the Potomac group of New Jersey and regions farther
south. The absence of marine shells and the presence of numerous leaves and other vegetable
remains have led to the belief that the Potomac group is a fresh or brackish water formation
deposited by meandering rivers or in estuaries or lagoons practically cut off from the sea by
barrier beaches. Several hundred feet of the clayey deposits were laid down. The deposition
of the Raritan formation seems to have been completed in the early part of the Upper Cre-
taceous epoch and in New Jersey was followed during the remainder of Cretaceous time by the
deposition of more or less marly sediments characteristic of deeper water and indicating a con-
tinued tilting, which eventually carried the old crystalline surface well below sea level. When
the tilting was completed the land in the vicinity of Schooley Mountain, in New Jersey, had
been elevated 1,500 feet, and the surface along the Atlantic coast sloped off beneath the sea at
the rate of 100 feet to a mile. In the Long Island region the late Cretaceous depression was
Jess marked, clays and sands derived from the erosion of the uplifted peneplain continuing to
be deposited while the marls were forming off the New Jersey coast. The fragments of fossil
shells found here and there in wells or in the drift indicate that the clays and sands of Long
Island were not all fresh or brackish water deposits, but were at least in part marine. The
marl bed at the top of the hill near Melville (p. 68) suggests that fairly deep water covered this
part of the island at the close of the period.

1629°—14——_14
194 GEOLOGY OF LONG ISLAND.

TERTIARY EVENTS.
EOCENE EPOCH.

Although there seem to have been slight interruptions in the deposition of the Cretaceous
beds in certain parts of the New Jersey region,’ the exposures on Long Island are too poor to
admit of their recognition even if evidence of them is present. Between the Cretaceous and the
Eocene deposits there was no strong break in New Jersey, for although a slight unconformity
exists the deposits of the Eocene and the upper part of the Cretaceous are alike in character if
not practically continuous in deposition. Where the Eocene deposits are seen they do not
differ greatly in thickness but occur as a practically uniform bed across the State. This uni-
formity would seem to indicate the absence of any strong unconformity, the thinness of the
Cretaceous being due to nondeposition rather than to subsequent erosion. There is, however,
evidence of a slight unconformity at the top of the Eocene, but no extensive erosion of either
the Eocene or the underlying Cretaceous beds seems to have occurred. Physiographic evidence
elsewhere seems to indicate that the Eocene may have been marked by the completion of a
peneplanation begun in the Cretaceous, and that the surface stood at a low level, land erosion
being nearly at a standstill.

MIOCENE EPOCH.

At the close of Eocene time there was a further differential tilting of the land, in the early
stages of which the Eocene deposits may have been somewhat eroded. Later, however, the
Coastal Plain was depressed and the sea advanced across the Eocene and over the Cretaceous
deposits on the west. This depression probably completed the principal tilting of the early
Tertiary peneplain. Over both the Eocene and the part of the Cretaceous covered by the
ocean the sandy beds of the Miocene were deposited. These were thin near their western
limit but somewhat thicker seaward, burying and obliterating the erosion surface cut in the
Cretaceous and Eocene deposits.

EARLY PLIOCENE EPOCH.

After the deposition of the Miocene sediments there was a decided uplift, which raised the
deposits above sea level and brought on a period of active erosion, which in the New Jersey
region removed considerable portions of the Miocene beds and cut into the underlying Eocene
and Cretaceous.

LATE PLIOCENE (?) EPOCH (LAFAYETTE FORMATION).

The early Pliocene was followed generally throughout the Atlantic Coastal Plain by a period
of deposition during which the Lafayette formation, consisting of a mantle of sands and clays
derived mainly from the underlying Cretaceous and other beds, was deposited over the Coastal
Plain, even overlapping the metamorphic rocks in places and apparently obliterating the
topography developed in the early Pliocene. It has usually been assumed that the deposition
took place during the period of submergence that has been postulated by most geologists as
occurring at this time, but Chamberlin and Salisbury * have recently argued that the Lafayette
was laid down in eastward-transgressing zones of stream deposition, which filled the valleys
and spread somewhat widely over the coastal peneplain that had been developed in the less
resistant deposits in Eocene and Miocene time. The transgression they consider to be due to a
moderate “bowing” of the peneplain rather than to submergence. They also supposed that
the conditions affecting vegetation and precipitation had an important influence on the nature
of the erosion and deposition.

It seems certain, however, whether the formation is marine or fluviatile, that the land
could not have been far above sea level, for the widely spreading mantle of clays and sands
could not well have been formed at its present elevation of 300 or 400 feet had the streams
possessed the fall that this would require between the landward limit of the formation and
the then existing coast, which could not have been far east of its present position.

 

1 Clark, W. B., Science, new ser., vol. 4, 1896, p. 759.

2 Clark, W. B., Correlation papers—Eocene: Bull. U. S. Geol. Survey No. 83, 1891.

3 Chamberlin, T. C., and Salisbury, R. D., Geology, vol. 3, 1906, pp. 305-308. Compare views of Hill and Vaughan, Eighteenth Ann. Rept.
U.S. Geol. Survey, pt. 2, 1898, pp. 246-247.
QUATERNARY EVENTS. 195

The general absence of glacial erratics in the Lafayette has led most authorities to refer
the formation to the Pliocene, but Hilgard referred the similar deposits of the Mississippi Valley
to the Pleistocene. The granitic materials at N atchez, on which his opinion was based, have
since been shown by Chamberlin and Salisbury‘ to rest unconformably on the Lafayette,
which they retain in the Pliocene. It has been suggested that the light sands overlying the
known Cretaceous on Long Island (p. 80) might doubtfully be Lafayette, but they are destitute
of crystalline pebbles, and this would seem to indicate a pre-Pleistocene origin.

POST-LAFAYETTE EROSION.

The deposition of the Lafayette formation was followed by a period of active erosion,
during which the Tertiary and Cretaceous deposits were cut down in places in the Long Island
region from an altitude of about 300 feet above the present sea level to one somewhat below
it. The exact depth to which the erosion extended could not be determined with certainty,
owing to the difficulty of recognizing the Mannetto-Cretaceous contact from well records and
samples. .The Mannetto gravel (the earliest Pleistocene deposit) is found resting on the Cre-
taceous down to sea level and the unconformity probably extends considerably lower.

The northward slope of the general Cretaceous surface and the buried pre-Pleistocene
valleys in the Cretaceous show that a powerful drainage system existed north of the present
island, and there is little doubt that extensive excavation took place in the Long Island Sound
region at this time. The magnitude of the unconformity resulting from this erosion, which was
many times greater than that producing the post-Miocene unconformity farther south, is the
chief reason for placing it after the Lafayette. So far as the island is concerned, it is the only
period of erosion between the Cretaceous and the Pleistocene of which a record has been left.

QUATERNARY EVENTS.
PLEISTOCENE EPOCH.
MANNETTO GLACIAL STAGE.

The earliest of the Long Island deposits that have been referred to the Pleistocene is the
Mannetto gravel, which has been described elsewhere, and the reasons for its assignment to the
glacial series have been there presented (p. 85). The term ‘“‘Mannetto stage” is applied to the
period of its deposition.

The large percentage of quartz and the sporadic yellowish clays in this formation are
strongly suggestive of a derivation of the Mannetto material from the formations of the Coastal
Plain like the Cretaceous and Miocene, or from glacial material forming a mantle of residual
soil. Over 99 per cent of the material is probably from one or the other of these sources. The
remaining fraction of 1 per cent consists of granitic pebbles and erratic bowlders, apparently,
to judge from their absence in the Cretaceous and Tertiary deposits, derived directly or indirectly
through some agent not acting in the earlier periods of deposition. Although it is possible
that the deposits are strictly fluvial, it is thought more probable that glacial ice played a part
in their accumulation, being the agent to which the peculiarities pointed out are due.

The deposits are now found up to a maximum altitude of about 330 feet, at or near which
extensive remnants of an old flat surface of Mannetto gravel still exist. This fact may possibly
indicate that the land stood 330 feet lower than at present and that a broad, flat sheet of gravel
was built up to that level, at least in parts of the island. The slope of this surface from 330
feet at its north end to 270 feet at its south end, or at a rate of 15 to 20 feet to the mile, is
very similar to that of the present outwash plain in the same region, and the flow and
plunge structure of the two are identical so far as can be seen. On the other hand, the erratic
bowlders of the Mannetto have no counterpart in the outwash on Long Island, although the
Wisconsin ice is known to have abounded in such bowlders.

The slope of the old Mannetto surface and the internal structure of the deposit would favor
an outwash origin. The evidence of the bowlders might seem to point to submergence, at

1 Op. cit., p. 308.
196 GEOLOGY OF LONG ISLAND.

least enough to admit of flotation by thin ice, but transportation by floating ice, such as might
occur in the shallow deploying streams of an outwash plain, may readily be conceived, although
nothing of the sort appears to have taken place in the Long Island region under what must be
acknowledged as equally favorable conditions in Wisconsin time. It is possible that the lower
part of the deposits in which the bowlders were found was formed below sea level, and
that the upper part was a sloping subaerial outwash plain similar to those now existing on the
island. The presence of the well-stratified clayey layers at low levels is also favorable to the
hypothesis of partial submergence, for such clays have not been found in the later outwash
deposits of the island and would be difficult to account for in those positions owing to the
absence of any probable causes of ponding. (See Bridgeton formation, p. 223.)

The Sound depression already existed in pre-Mannetto time, as shown by the Cretaceous
topography beneath the Mannetto, but it is possible that large Cretaceous deposits existed
along the Connecticut coast and supplied much of the gravel making up the Mannetto
formation.

The granite bowlders are found near the bottom of the Mannetto, as exposed on the island
and granitic pebbles occur up to the very top, hence the ice invasion began early in the Man-
netto stage and continued to its close. That the period of ice invasion was long seems to be
indicated also by the great thickness of the deposit.

The small percentage of granite pebbles may be due to a long period of attrition beneath
the ice or in waters near its margin, which effectively reduced most of the fragments. On the
other hand, the fact that the first ice moved across an area of residual soils, where a large part
of the materials picked up must have been disintegration products consisting largely of clay
and quartz, with a few fresh granitic fragments, may be the chief reason for the small per-
centage of granitic pebbles in the Mannetto compared with the later Pleistocene gravels.

The exact place where the ice margin rested is largely a matter of speculation. It may
have halted in the Sound trough a little north of the present edge of the island.

POST-MANNETTO INTERGLACIAL STAGE.

The deposition of the Mannetto gravel was followed by a period of extensive erosion during
which the formation, originally 100 to 300 feet or more thick over western Long Island, was so
completely reduced that only a few isolated knobs remained at the beginning of the Jameco
deposition. The term post-Mannetto is applied to this apparently interglacial stage of erosion,
which is well represented by the Wheatley Hills, near the village of the same name, the essen-
tial topographic expression of which, the superficial coating of till. being disregarded, is due to
erosion in this epoch.

The highest remnant of the Mannetto surface is found in the West or Mannetto IIills, in
the northern part of which it has an elevation of 330 feet above sea level. In the Wheatley
Hills remnants of the Mannetto probably occur as high as 300 feet. From this altitude, which
appears to mark the upper limit of the formation in western Long Island, valleys were cut
down to a point not less than 300 feet below the present sea level, the depth to which the suc-
ceeding Jameco gravel has been recognized in wells.

Whether the Mannetto gravel lay at a similar altitude over eastern Long Island is not
known, but its development was probably somewhat less in this direction. Large masses,
nevertheless, probably existed and the fact that the deposits as a whole were eroded until only
scattered remnants were left points to a period either of very rapid or of long-continued erosion,
or most likely both. The elevation as estimated from the Hudson submarine channels, which
are assumed to have been formed at this time, appears to have varied from 1,300 feet in the
earlier part of the stage to over a mile in the later part (p. 60).

The post-Mannetto erosion presumably followed, in its broader features, the lines of pre-
Mannetto drainage, as the Mannetto gravel was probably somewhat lower over the deep Cre-
taceous valleys than over the Cretaceous knobs, in the same way that the Wisconsin outwash
is lowest where the underlying Manhasset formation is low and highest where the Manhasset
is high. That this is true in the Mannetto Hills region is shown by the section at this point
PLEISTOCENE EPOCH. 197

(fig. 57, p. 81), the Mannetto and Cretaceous erosion surfaces being almost parallel. Where
the Cretaceous relief was less marked, however, the erosion was independent of the old topog-
raphy and cut indiscriminately into Mannetto and Cretaceous. This type of erosion was
probably especially characteristic of the north-shore districts. In general, however, the land
at the close of the post-Mannetto interglacial stage appears to have been not greatly different
in extent and topography from that existing at the beginning of the Mannetto stage. The
larger Cretaceous remnants appear to have been very nearly the same as before, the principa-
differences apparently being the presence of a mantle of Mannetto gravel that covered and
obscured the older deposits in places and the deeper trenching of those deposits elsewhere.

JAMECO GLACIAL STAGE.

The extensive erosion epoch just described was followed by an influx of material whose
granitic character seems to indicate a glacial source. The position of the deposits below sea
level and the necessity of depending on well records for a knowledge of them make the deter-
mination of their exact character and structure practically impossible, and it is not definitely
known whether or not the ice actually invaded Long Island. The high percentage of granl
itic pebbles present locally may mean the near proximity of the ice sheet, but the deposits as
a whole do not differ greatly, so far as appears from weil records, from the later Manhasset or
from the Wisconsin outwash deposits, and they may have a similar origin, in which case the
ice front presumably lay somewhere in the Sound. The distribution of the Jameco gravel on
Long Island and the islands east of it would seem to indicate that the front extended along the
Sound beyond Orient Point, passed north of Block Island, crossed southeastern Massachusetts
(probably between Plymouth and Boston), and passed north of Truro, Cape Cod.

The deposits appear to have accumulated in part in the space between the ice front and
the Cretaceous-Mannetto core of Long Island, and in part outside of and around the then
existing land masses, the materials being swept westward and southward through the depression
east of Jamaica and eastward and southward around the east end of the existing land beyond
the Mannetto Hills. The depression of the land at this time seems to have been 150 feet or
more (p. 218).

The erosion by the ice in the immediate vicinity of its margin appears, if we may judge
by the relatively small amounts of quartz and other locally derived materials, much less pro-
nounced than during the first invasion. In fact, the almost entire absence of recognizable
material derived from the underlying Cretaceous or the Mannetto gravel would seem to indicate
either a nearly stagnant condition of the ice near its margin or a sheet so overloaded with
material that it could no longer erode.

GARDINERS INTERGLACIAL STAGE.

The Jameco gravel gives way abruptly to the Gardiners clay, as if the source of materials
was suddenly removed, as it doubtless was by the retreat of the ice sheet from the vicinity of
the island. So far as known there is no unconformity between the two formations, the lignitic,
marshlike, and fossiliferous phase of the Gardiners following without any important time
break upon the cessation of Jameco deposition. |

The land masses during the deposition of the Gardiners clay remained essentially as during
the Jameco deposition. No conspicuous change of level took place either at the beginning of
or during the Gardiners deposition, although there was a slow subsidence, which kept pace
with the accumulation, the top of the formation always remaining at or below sea level. The
subsidence could have been little if any more rapid than the deposition, as there is apparently
an entire absence of locally derived materials, such as would be present if the sea encroached
upon the Cretaceous and Mannetto land masses to any extent. The actual position of the
land, to judge from the general occurrence of the clays below sea level at the present time,
appears to have been generally a little higher than the present level, the few occurrences of
clays above sea level being apparently due to folding.
198 GEOLOGY OF LONG ISLAND.

In western Long Island the clays appear to have accumulated in the form of marsh deposits
bordering the preexisting land masses, but in eastern Long Island peat, muck, and other indi-
cations of marsh origin are less common, and the nonorganic character of the bulk of the deposits
appears to indicate an offshore origin of the formation, except perhaps of the earliest phases.

The question whether the deposition took place during a true interglacial stage or simply
during a temporary retreatal stage is somewhat puzzling. The presence of fossils in the clays
at several places indicates a period of sufficient length to permit the reoccupation of the formerly
glacial waters by animal life, and although this might, under favorable circumstances, take but
a few years, the character of the remains indicates a climate no colder than that of the Maine
coast at the present time, hence it is probable that the ice had drawn back to the northern por-
tion of the continent, if it had not entirely disappeared. The lignite present in the clays on
western Long Island and elsewhere and the general blackish color, presumably due to organic
matter, of the same clays on the Massachusetts islands and on Cape Cod indicate that plant
life had also extended itself over the region. The thickness of the clays themselves, taken in
connection with their apparently slow accumulation, likewise points to a period whose length
is more compatible with an interglacial stage than with temporary retreat.

JACOB TRANSITIONAL STAGE.

The fact that the transitional Jacob sand gives place to the glacial Herod gravel member
of the Manhasset formation without any recognizable time break, and that the latter in
turn gives way by transition to the great Montauk till member of the Manhasset, would make
plausible the supposition that the advent of new materials from the advancing ice sheet brought
about the change from the marine Gardiners clay to the more quartzose Jacob sand. It is not
unreasonable to suppose that the change of material marking the beginning of Jacob deposition
took place as soon as the advancing ice front reached the headwaters of the Connecticut and
began to discharge its drainage down the valley of that river. Under such conditions only
the finer material would be borne to the river’s mouth and distributed in the surrounding
region. The quantity of materials, if the supposition as to origin is correct, would indicate a
very slow advance, as the Jacob sand reaches a thickness of at least 30 feet.

Although the materials seem to be of glacial derivation, the Jacob is essentially a marine
formation. It extends from western Long Island to southeastern Massachusetts and its per-
sistency points clearly to marine deposition rather than to accumulation in valleys or basins
above sea level; moreover, its marine fossils fix its origin beyond dispute.

Evidence of any material change of level is lacking. That no considerable elevation took
place is shown by the entire absence of any evidences of stream erosion in the deposits at this
horizon, the only unconformities being those due to the scouring action of the overriding
Montauk ice.

During the period of Gardiners deposition, as elsewhere pointed out, the land appears to
have slowly subsided, the sinking just about keeping pace with the accumulation, as indicated
by the fossils and salt-marsh deposits at the various horizons.

Such marsh deposits are absent, however, from the Jacob. This fact, taken in connection
with the persistency of the beds, the regularity of the lamination, and the general absence of
ripple marks, suggests a sinking of the crust and a deepening of the water. As noted on another
page, however, faceted pebbles elsewhere in the immediately overlying Herod gravel member
of the Manhasset point to a subaerial accumulation of the Herod; hence it is probable that the
subsidence was slight, possibly only a few feet, or a little more than enough to keep pace with
the accumulation. This slight depression probably resulted in a further contraction of the land
masses of the island, so that, except in the Mannetto, Wheatley, and Half Hollow hills and
certain other parts of western Long Island, marine currents had free sweep over the region.
PLEISTOCENE EPOCH. 199

MANHASSET GLACIAL STAGE.

HEROD GLACIAL SUBSTAGE,

The change from the fine sandy silts of the Jacob to the glacial gravels of the Herod member
of the Manhasset formation indicates a nearer approach of the ice that supplied the materials.
The sandy nature of the lower beds, the more gravelly character of the upper layers, and the
final transition into the Montauk till member would seem to mark various stages of the advance
of the ice, the front possibly just reaching the Sound at the time of the earlier deposition,
advancing close to the north shore of Long Island in the later Herod accumulation, and
eventually invading the island in the succeeding Montauk substage.

The Herod accumulation was marked by the development of strong currents, far more
swift and powerful than those of the Gardiners and Jacob stages of deposition. In fact, no
clay or fine silts could have been deposited if currents of like strength had existed during those
stages. These currents may be regarded either as glacial streams, emerging from the near-by
ice front and deploying over a subaerial outwash plain, or as tidal or other currents of the sea,
according to the elevation of the region with reference to sea level.

The Jacob accumulation certainly took place below sea level, and in the absence of any
evidences of stream erosion at its upper contact there is almost equal certainty that it was
not lifted above sea level before the beginning of the conformable Herod deposition. The
lower beds of the Herod must therefore have been deposited at or below sea level. Higher up
in the Herod member, however, wind-faceted pebbles point to subaerial accumulation, making
it seem probable that subsidence either was not going on at this time or did not keep pace with
the upbuilding. This part of the Herod seems most likely to have been formed as an outwash
plain similar to those of the Wisconsin stage, though on a larger scale. The accumulation
appears to have been very slow, the surface being exposed for long periods before being covered
by the succeeding layer. That the surface was probably nearly or quite devoid of vegetation
and that it was subject to strong winds, transporting sharp sand as in a sand blast, and in fact
possessed many of the characteristics of a desert, is shown by the faceted pebbles. That these
conditions were widespread rather than local, furthermore, is shown by the presence of similar
pebbles at the same horizon on Nantucket and Cape Cod.

It seems probable that different conditions prevailed toward the close of the Herod accu-
mulation, the deposition of the overlying Montauk till member apparently taking place below
sea level. It would seem, therefore, that the subsidence, which started at least as early as the
beginning of the Gardiners deposition but which barely kept pace with the accumulation in
the Gardiners and Jacob stages, went on more rapidly during the later part of the Herod sub-
stage; so that, notwithstanding the upbuilding of the earlier deposits to some height above sea
level and the continued rapid deposition, the whole of the Herod was carried below sea level
before the advance of the ice marking the close of its deposition.

The Herod member differs in thickness from point to point, as all deposits must whose
materials are supplied by glacial streams, but on the whole the member displays remarkable
persistency and uniformity for a glacial deposit. It seems to have had the form of a single
broad southward-sloping cuesta-like outwash plain, partly subaerial and partly submarine,
rather than that of a series of small outwash fans.

MONTAUK GLACIAL SUBSTAGE,

FIRST ADVANCE OF THE ICE.

Position of ice margin.—The ice, which was still remote at the beginning of the deposition
of the Jacob sand, had approached nearer during the deposition of the Herod gravel member
of the Manhasset, and it actually invaded the Long Island area at the beginning of the Montauk
substage, as indicated by the change of the deposits from gravel to till. The ice is thought to
have reached south in western Long Island in a lobe extending down the old Jameco valley
between Jamaica and Brooklyn, depressing the Gardiners clay beneath its weight in that
vicinity and giving rise to a doming at its edge, as recorded in the wells of the Rockaway Ridge.
200 GEOLOGY OF LONG ISLAND.

Eastward from this region the ice front, for the most part, probably rested against the side
of the Mannetto and Half Hollow hills, although bowlders in the Half Hollow Hills and a structure-
less mass resembling till resting upon the Cretaceous in the Bethpage pits suggest a temporary
advance extending much farther south. Beyond the hills mentioned the margin bent to the
southeast and passed off beyond the present coast line at a point somewhere west of the till
exposures in the Easthampton beaches. Its invasion is marked in western Long Island by the
bowlder bed of Hempstead Harbor and by the bowlders and till in the wells of the exterior of
the island, and in central Long Island by a thick bed of till. On the North Fluke its work was
mainly erosion, but it also laid down a certain amount of till, and on the South Fluke it accom-
plished both severe erosion and heavy deposition.

Erosion by the Montauk ice sheet.—The erosion unconformity at the base of the Montauk
till member of the Manhasset formation has been described elsewhere (p. 134). It extends from
Long Island through Block Island, Marthas Vineyard, and Cape Cod to the Maine coast or
beyond and is nearly everywhere characterized by evidences of drag, by ice-shoved bowlders
and till deposits, or by superficial thrust faults, folds, and contortions. In fact, the evidences
are so clear-cut and decisive as to establish without question the eroding agency as the Montauk
ice sheet.

The ice on its advent was strong and vigorous, as is characteristic of an underloaded
glacier, and although it produced some folding, mainly of the open type, its work was largely
erosion and consisted in scouring broad, shallow trenches and basins and in beveling the
upturned beds of the arches and folds. Later its vigor appears to have decreased, probably
through overloading by material picked up in its earlier stage, and deposition of the great beds
of till which are characteristic of the Montauk member followed.

Accumulation of the earlier deposits of the Montauk till member.—The evidence bearing upon
the conditions existing during the accumulation of the Montauk till member presents many
puzzling features. The most characteristic phase of the Montauk is the till, and of this the
most distinctive feature is its peculiar banding or lamination. This lamination, which is
described in detail in another place (p. 133), is unquestionably the result of accumulation in
the presence of water and may be conceived as due to deposition in local basins on a land
surface, to purely aqueous deposition in the sea, to extremely rapid deposition in front of the
ice margin by unconfined glacial waters above sea level, or to accumulation beneath the ice
sheet overriding the water-saturated Herod gravel member and other deposits below sea level.

That the deposition did not take place in local land basins appears to be indicated by the
extent of the Montauk member as well as by the absence of the necessary barriers; that it
was not the result of unconfined glacial waters deploying upon the land is shown by the per-
sistent character and horizontal position of the bedding, the member exhibiting neither the
high angles of aqueous morainal accumulations nor the definite stratification that it would
have if it were an outwash deposit; and that it does not represent marginal deposition below
sea level is made apparent, likewise, by the absence of any well-marked assortment, such as
would inevitably result from purely aqueous deposition of this nature. The member is filled
with erratics irregularly distributed through its mass in far greater number than can be readily
conceived as arising in any way other than by direct deposition as ground moraine beneath
an ice sheet. The banding, however, is far more conspicuous than in any ordinary subaerial
accumulation of till. Accumulation beneath the ice sheet in the presence of abundant water
appears, therefore, to be the most probable origin of these deposits. It seems likely that the
lamination results from dragging a loose body of drift, obtained by erosion or from the ice by
basal melting, and its readjustment in the presence of water. The extent of the Montauk
member seems to indicate that the water was a general rather than a local feature and suggests
that the deposits were most probably laid down below sea level.

That the deposition of the gravel phase of the Montauk took place below sea level would
of necessity follow if the interpretation of the origin of the till is correct, as the two have the
same stratigraphic position, one grading laterally into the other. The angle of bedding, high
in many places, the rapid change in direction of the dip, and the presence of delta and other
PLEISTOCENE EPOCH. 201

flow and plunge structures and of contemporaneous unconformities of erosion and deposition
are all in harmony with the assumed conditions of rapid submarine accumulation at the margin
of the ice sheet. The bowlders, too, seem to point to an aqueous origin, for although ice-rafted
bowlders are not uncommonly borne down the shallow streams of outwash plains and left in
the gravels, such definite and continuous beds as characterize the Montauk horizon on Long
Island are seldom formed in that way.

The absence of fossils, except those of secondary origin, in the reworked deposits of the
Gardiners clay points to shallow water. In Inglefield Gulf, Greenland, overlooked on three
sides by ice caps, abundant marine life was found by T. C. Chamberlin, who states! that 80
crinoids and numerous more common forms were obtained from a single haul of the dredge.
If deep water had prevailed along the Montauk margin, similar evidence of life would be
expected; but if the water was very shallow, the quantity of silt known to have been constantly
discharged into it by glacial streams and the rapid upbuilding of the deposits by the coarser
material would tend to prevent the occupation of the water by marine forms along the imme-
diate border of the ice. The severity of the erosion by the Montauk ice indicates that the
depth of the water was too slight to affect materially (through its powers of flotation) the
scouring action of the glacier. On the whole it seems probable that the Montauk accumulation
took place in very shallow water, possibly only a few feet in depth, with perhaps numerous
islands, due to folding, rising above its surface. The actual depression of the land with refer-
ence to the present sea level appears to have been from 75 to 100 feet.

FOLDING DURING MONTAUK SUBSTAGE.

Extent—The most marked feature of the Montauk till member, aside from the deposits
themselves, is the great folding that the underlying beds exhibit. This folding is of widespread
distribution, being found from Brooklyn on the west to Orient and Montauk points on the
east, as well as on the adjoining islands. East of Long Island it is developed on a large scale
on Fishers, Block, Marthas Vineyard, and Nantucket islands and on Cape Cod and the Maine
coast. The magnitude of the disturbance is in places very great, at least for a surface feature,
not a few of the folds reaching a height of 100 feet and some measuring 150 feet or more. The
folds always present their steepest faces to the south or are overturned in that direction.
Many of them pass into faults, almost always of the thrust type, the upthrow being on the
north.

The disturbances affecting the beds are of at least five orders of magnitude—(1) tilting
affecting the island as a whole; (2) low arches several miles in diameter and extending through-
out the greater part of the length of the island, such as the North and South fluke ridges and
their extensions; (3) low flat arches several hundred yards in diameter, representing irregulari-
ties in the broader arches of the second class; (4) steep, closed folds of considerable length but
of slight breadth, many of them overturned and faulted; and (5) the minor crumplings of the
individual layers of the sharp folds of class 4. These classes are not, of course, sharply differ-
entiated from one another, all gradations between them being noted. Although the flexures
differ in details of formation, all except those of the first class appear to have been the result
of the same general agency, the nature of which is considered in the following paragraphs.

Anticlinal nature of the fluke ridges—The anticlinal nature of the fluke ridges is brought
out by the height of the Gardiners clay lying upon and near them. This formation on each
fluke is commonly at or slightly above or below sea level, whereas between the flukes and, so
far as can be determined from well records, both north and south of the flukes proper or of the
Manhasset belts (p. 119) which mark their continuation to the west its height is about 50 feet
lower. These ridges are therefore to be regarded as broad flexures having an altitude of about
50 feet and a length of not less than 50 miles on Long Island, to say nothing of their eastward
continuations—the northern one through Fishers Island, Watch Hill, Point Judith, Elizabeth
Islands, and Cape Cod, and the southern through Block Island, Marthas Vineyard, and Nan-

tucket.

1 Personal communication.
902 GEOLOGY OF LONG ISLAND.

These broad flexures are not simple arches but compound folds or anticlinaria, being
characterized by both minor local warpings and sharp, overturned folds and faults. The main
warping affected all the Pleistocene formations and extended down into the underlying Creta-
ceous beds, as shown by the occurrence of the latter in many places along the axis of the arch
farther east, as on Block Island and Marthas Vineyard. The minor warpings probably affected
all but the lowest of the Pleistocene accumulations, but the sharper and smaller folds and the
faults are still more superficial, the disturbance becoming rapidly less downward and in many
places disappearing entirely, even in the cliff sections. It is doubtful if the beds lying 50 feet
below the surface are much if any disturbed by even the more pronounced folds.

Possible causes of the flecures—Reaching down into the Cretaceous, the disturbance could
have been produced only by an agency of great power. Crustal warping at once suggests itself
as this agency, but there are many reasons against accepting it as the real cause. If the two
flukes and their prolongations were part of a single uplift, the arching would be of a magnitude
that would make the theory of crustal warping seem somewhat reasonable, but as a matter of
fact the arches, though long, are relatively narrow, their extent transverse to the axis being
apparently far less than is to be looked for in true crustal warping. Their occurrence in two
groups, separated by a broad undisturbed area, points to a repetition of local causes rather than a
general cause such as crustal warping. It is believed, therefore, that such warping, if it played
any part in the formation of the anticlinal ridges, was merely a subordinate agency. On the
other hand, it seems equally certain that the ridges have resulted from causes differing also from
those that produced the minor folds. They are too broad, low, and flat (some being several

Zz, miles wide and only 50 to 100 feet high) to have resulted from
L_-1¢’ tangential thrust, and furthermore the deposits consist of incohe-
Pas rent sands, clays, and other material entirely incapable of trans-

'

 

 

\@ \
mitting thrust.

y
i
| That the anticlinoria are due to a warping of the surface in

gen
-

\ their vicinity seems clear, but that they were mainly the result of

a general crustal warping is very doubtful. It is more likely that

they are due chiefly to a warping of the unconsolidated deposits

é 4, through agencies other than crustal movements.

FicuRE 198.—Diagram illustrating com- Sediments vary greatly in bulk according to the arrangement
pression of beds through rearrangement or ‘‘nacking’’ of the component grains or fragments. Being de-
of grains. a « a a *

posited without application of external pressure and exerting
only about two-thirds of the pressure of their normal weight (owing to the buoyancy of the
water) the particles of the sediments are at first very loosely arranged. As the deposits thicken
they may undergo some readjustments leading to a decrease in bulk, but they remain far below
their maximum density.

Tf the fragments were spherical they might be arranged (1) so that the lines connecting the
centers of adjacent spheres would form rectangles, as shown by a-a—a-—a in figure 198; (2) so
that the connecting lines would form rhombs with an acute angle of 60°, as a—a—b-b; or (3)
so that the lines would form rhombs intermediate between the rectangle and the 60° rhomb.
The first arrangement gives the maximum and the second the minimum vertical thickness. If
the grains of a sedimentary bed were originally deposited in the first manner and were subse-
quently forced by pressure to rearrange themselves into the second form, there would be a
shortening of the vertical space taken up by the grains, represented by

 

 

 

 

 

 

 

2(r—r cos 30°) =2 r(1—cos 380°) =0.268 r.

The last factor is the equivalent of 13.4 per cent of the thickness of a given deposit
(d-d’, fig. 198). If it is assumed that the original thickness of the Pleistocene deposits before
the folding was 300 feet and that in the original deposition the fragments took an arrangement
equivalent to the one first described, then if by the pressure of the ice their arrangement was
later changed to the second form, there would have been a compacting of the deposits that
reduced their thickness about 40 feet.
PLEISTOCENE EPOCH. 2038

Of course, it is doubtless true that the grains never possessed as a whole the arrangement
suggested, but observations on soils show that the grains may be far from uniformly in contact
with one another, many vacant spaces occurring among them. The application of pressure
would be even more likely to close such spaces than it would to rearrange the grains.

Actual tests on natural silts and sands, the properties of which may be taken as indicating
the arrangement of the grains, show that although the average theoretical pore space is only
about 30 per cent and the highest theoretical pore space only 47.64 per cent of the volume, the
actual porosity,’ as indicated by the water absorbed (which may amount to 50 per cent of the
weight of the material ”), is sometimes as high as 75 per cent. Pressure applied to such material
could not fail to produce a very considerable compacting, probably fully equal to the theoretical
amount due to the rearrangement of the grains. Experiments made on gravel under the
writer’s direction in 1912 showed that a pressure of 10 pounds to the square inch, correspond-
ing roughly to the weight of 10 feet of material, resulted in a reduction of 5 per cent in the
volume of the gravel tested. Higher pressures, up to and including 100 pounds, gave 1 per
cent additional compacting.

In the rearrangement of grains just described the decrease in vertical thickness is not the
only result. Figure 198 shows that this decrease in thickness is accompanied by an increase
in lateral extent. This increase (c—c’), which is equal to the radius of the grain, is not cumula-
tive, however, being the same in a horizontal distance of a mile as in a fraction of an inch,
hence it can play no part in the warping.

It is well known, however, that clays flow readily under relatively slight pressure, as has
been brought out many times by the movement of clays beneath even relatively low dams and
railroad embankments. The long ridges of mud forced up on each side of the railroad fills
recently built across a wide stretch of Great Salt Lake and the flow of the clays underlying the
Gatun Dam at Panama are cases in point. The likelihood of such flow is now universally
recognized by engineers, and in all important constructions great precautions are taken to avoid
building upon clayey materials. If the flow is so pronounced in 15 to 20 foot embankments, it
must have been much greater under the pressure of hundreds of feet of ice. The deposits over
which the ice sheet passed were unquestionably saturated with water and the clays and fine
sands, which when wet flow like quicksands, must have been very plastic. It is not improbable,
therefore, that flowage toward the anticlinorial axes actually took place on a considerable
scale, as it is known to have occurred in small degree in the case of some of the minor folds.
The lateral flow of the clay may be conceived to have taken place either with or without an
accompaniment of folding. Flows accompanying folding may be seen at many points on
Long Island and the New England islands, being manifested by the squeezing of materials
from the compressed parts of anticlines into the parts that were under less pressure.

Notwithstanding the competency of an ice sheet to materially compact the deposits which
it overrides, the anticlinorial ridges of the north and south flukes can not be referred to such
an agency acting upon a uniform series of deposits. Ice overriding such an accumulation
might indeed compress the materials and reduce their thickness, but the result would be broad,
even depressions stretching from the outer limit attained by the margin of the ice back to the
hard rocks of the mainland, leaving the extramarginal deposits in their original horizontal posi-
tion (fig. 199, p. 204). Such compression would, therefore, account only for the northward slope
of the arches, as the compacting would take place only on that side of the belt, failing entirely
to explain the equally conspicuous southward slope. In other words, the materials north of
the flukes have not simply been depressed, but the deposits beneath the flukes appear to have
been actually raised, as they stand materially higher than in the extraglacial region on the

outh.

: It may be conceived, however, that the compacting was differential rather than uniform,
the variation in amount being due either to differences in the character of the Pleistocene
materials or to differences in the altitude of the underlying Cretaceous and consequently in the

 

1 Slichter, C. S., Theoretical investigation of the motion of ground waters: Nineteenth Ann. Rept. U.S. Geol. Survey, pl. 2, 1899, p. 309.
2 King, F. H., Principles and conditions of the movements of ground water: Idem, p. 70.
204° GEOLOGY OF LONG ISLAND.

thickness of the Pleistocene,deposits. There does not appear to be sufficient variation in the
character of the Pleistocene deposits in the region to account for the abnormal difference between
their altitude in the moraine and their level elsewhere; hence this aid to differential compacting
need not be considered. An ice sheet moving over a region, such as that shown in figure 200,
where porous glacial materials rest upon an irregular surface of more dense and resistant
Cretaceous rocks, may be readily imagined to produce a considerable warping through com-
pacting. It must be acknowledged, however, that though this may be a possible cause, the
information at present available, either in the surface exposures or in well records, is insufficient
to afford any absolute confirmation.

On the whole, squeezing and flowage of the clays appear to be an entirely competent cause
of the arching, the materials being assumed to have been pressed outward, or to the south,

 

 

 

 

 

 

 

FIGURE 199.—Diagram showing supposed compression of b2ds under ice load in the Long Island region. @, Mon-
tauk ice sheet; b, Herod gravel member of Manhasset formation; c, Gardiners clay; d, Jameco gravel; e, Mannetto
gravel; f, Cretaceous.

under the weight of the ice sheet, which, to judge from the presence of ice-deposited material
at the top of the Mannetto Hills, could not have been less than 410 feet thick at its margin and
may have been much more. Beyond the margin of the ice the pressure would be largely
removed and the clay would tend to thicken and rise, lifting the overlying beds. Under this
assumption the larger and more pronounced ridge would be formed at the outer limit reached
by the ice, and a smaller ridge would be associated with a retreatal halt, for the clay would be
less mobile and possibly thinner at the time of the halt, having already been subjected to the
probably more severe pressure of the early advance. Although of the several causes suggested
flowage of the underly-
ing clays seems best to
explain the features ob-
served, the writer is loth
to advocate the theory

of a transfer of mate-

FIGURE 200.—Diagram showing supposed influence of Cretaceous masses in controlling the compression of rial on the necess ary
the Pleistocene deposits under ice load. @, Herod gravel member of Manhasset formation; 6, Gardiners ]
clay; c, Mannetto and Jameco gravels; d, Cretaceous. scale. At the same

time warping and com-
pacting seem, with the evidence now at hand, even more improbable explanations. Perhaps
the least objectionable view is that which ascribes the origin of the arches to a number of
agencies supplementing one another, of which crustal warping, compacting of deposits by
pressure, and flow of plastic materials under pressure are the most important. Whatever
the cause may be that raised the arches, it appears to have been assisted by the drag and folding
due to the overriding ice. That the elevation of the anticlinoria has been considerably increased
by such folding can not be questioned. In asection on Gardiners Island (fig. 80, p. 100) meas-
uring about 1,350 feet, beds of a length of 2,500 feet have been compressed, giving rise to an
increased elevation which, before the subsequent erosion of the folds, must have amounted to

 

 
PLEISTOCENE EPOCH. 205

at least 100 feet. On Fishers Island (fig. 85, p. 102) the original elevation due to folding appears
likewise to have been nearly double this amount, and on Marthas Vineyard the thickening is
still greater.

Minor warpings.—Under the head of minor warpings are included the undulations (many
of them isoclinal), usually reaching only a few feet in height and a few hundred yards in length,
which are seen in many bluff sections and which give rise to a large part of the variations in
the level of the beds. In some places warping of this particular type is more apparent than
real, being due to the truncation of the sharper folds of the class described below along lines
more or less parallel with their axes. There are, nevertheless, many warpings that are not
associated with such folds, and it is the origin of these that is considered here.

Differential settling, which, as has been seen, is likely to take place in any thick formation,
especially where there are, as in the Pleistocene deposits of the Long Island region, more or less
minor variations in composition and texture, doubtless took place to a certain extent under the
weight of the deposit itself, although the warpings so produced would be likely to be very slight.
The principal readjustment, however, was probably due to the overriding ice sheet of the
Montauk substage, which because of its great weight exerted a profound influence upon the
overridden beds. Its action was especially pronounced in the later part of the invasion, when
through differential erosion and deposition the surface had become more or less irregular and
the weight of the ice was unequally applied at different points. Direct shove upon the irregu-
larities of the surface under such conditions may have been an important factor in the produc-
tion of the warpings. Ice pressure against the stiffer and more clayey beds at their outcrops
may also have been transmitted beneath the overlying gravels, giving rise to warpings at some
points of weakness.

Open and closed folds. —Although differing in magnitude, the open and closed folds are of
the same general origin and may best be considered together. They include everything from
an undulation barely well enough defined to be recognizable as a fold to the closely compressed
and overturned and recumbent folds. In altitude they vary from perhaps 5 feet to 150 feet
or more and in breadth from a few feet to an eighth of a mile or more. Their axes are generally
parallel with the trend of the anticlinoria of the North and South flukes, of which they are a
superficial feature, having a roughly east-west direction. Very few of the folds are symmetrical,
almost all showing more gentle slopes on the north than on the south. Overturning, where
present, is always toward the south.

Orogenic movements were postulated by many of the early workers as the cause of folding
on Long Island, but the evidences against such movements are very definite. Arthur Hollick
some years ago pointed out the superficial character of the folding and the undisturbed condi-
tion of the underlying beds. Very conclusive evidence was brought out by well records collected
by A. C. Veatch during the present investigation, the logs showing the Cretaceous strata to dip
uniformly at the rate of a few feet to the mile regardless of the disturbance of the superficial
beds. Furthermore, the present field work brought to light many sections along the coast in
which the folding could be seen dying out downward. (See figs. 98, p. 110, and 133, p. 130.)

The slipping in mass of a bed or series of beds down a dip or structural slope may cause
the compression of the lower part of the mass into folds which are called slip folds. The move-
ment takes place along bedding planes, which may have been more or less tilted. The most
favorable localities for slip folding are in basins toward the center of which the beds dip steeply,
but it may occur also on any monoclinal slope.

The origin of the Long Island folds and those of the New England islands farther east has
sometimes been attributed to slip folding, the slipping movement being assumed to have pro-
ceeded from north to south because the beds were overturned in that direction. One of the
chief difficulties in the way of accepting such an origin is the absence of any slope adequate to
cause the slipping of the beds. The present normal attitude of the Pleistocene beds is almost
horizontal, and the dip of the Cretaceous appears to be only a few feet to the mile, or a small
fraction of 1°, and it is not probable that the original dips were any steeper.

’
206 GEOLOGY OF LONG ISLAND.

Slip folding would seem to be more likely to characterize the clayey beds than the more
sandy deposits. No such difference was observed, however, the clays being no more disturbed
than the sands. In fact, the folding is in many places greater in the sandy material at the
surface and much less in the underlying clays.

Slip folding would necessarily be accompanied by the production of a slip or fault plane,
which in the present instance would have to be several miles broad and more than 100 miles
long. That no such slip plane is present on the greater part of Long Island is unmistakably
shown by the bluff sections, which, though reaching in places below the level of folding, nowhere
afford indications of any but local breaks due to slipping. On the contrary the upper folded beds
with a few minor exceptions grade downward into the lower undisturbed beds without breaks
of any sort, showing beyond question that the beds are in place and that the folding is only a
superficial disturbance. Where the folding is more profound and extends below sea level it
is more difficult to prove the absence of the slip plane, although there is no evidence of its
existence.

Among the phenomena associated with the folding and affording a clue to its origin may be
mentioned (1) its maximum development along the borders of depressions, such as Long Island
Sound and the bays between the flukes farther east, or along northward-facing escarpments;
(2) its minimum development over flat surfaces such as the upper part of the Herod gravel
member of the Manhasset formation; (3) its usual development at the Montauk horizon and at
that horizon only; (4) the superficial character of the disturbance; (5) the rapid disappearance
of the folding below the Montauk; (6) the absence of disturbance above the Montauk (except
locally at the base of the Wisconsin till); (7) the constant association with the Montauk till
member; (8) the evidences of drag in the incorporation of the underlying gravels into the till,
(9) logal evidences of the plowing of the underlying surfaces by bowlders; (10) the almost univer-
sal evidences of ice erosion at the Montauk horizon; (11) the massing of till against undisturbed
beds; (12) the association of the folding with thrust faulting on planes at high angles; and (13)
the overturning of the folds always toward the south.

It is to be emphasized that the folding is everywhere associated with the Montauk ice
invasion; that it is practically absent at other horizons; that it was most marked where
elevations rose above the surrounding level so as to present bold faces to the advancing ice
sheet; that it was associated with notable ice drag and erosion; and that the faulting and folding
were always in the direction of the ice movement.

Notwithstanding the general absence of folded beds beneath the glacial deposits of the
country as a whole, the absence of any extended folding on Long Island by the Wisconsin ice,
which reaches a thickness of more than 400 feet, and the general ease with which ice is known
to override morainal and other unconsolidated deposits without material disturbance, there
seems to be no question that it is to the ice sheet invading the region in Montauk time that the
conspicuous folding is due. The theory accounts for all the associated phenomena, makes
use of an agency that is known to have been at hand, and leaves nothing but its unusual vigor
unexplained.

The cause of the unusual vigor of the ice in the Long Island region, as indicated by the
extraordinary disturbance of the beds over which it passed, presents an interesting problem,
the key to which is probably to be found partly in the thickness of the ice sheet, partly in topo-
graphic conditions, partly in the subaqueous nature of the deposition, and partly in the climatic
conditions. The scarcity of folding in the glacial deposits of the American continent as a whole
and its insignificant development as compared to that in the Long Island region are probably
due largely to the general absence of scarps or other topographic forms adapted to reccive the
brunt of the attack of the advancing ice. In the Long Island region, on the contrary, the Mon-
tauk ice found opposed to its advance the thick series of gravels (Herod gravel member) pre-
viously deposited at its front. Against these it impinged with great force, bending, folding,
shoving, and faulting them on a grand scale, the disturbance involving also the underlying
clays, especially in the later stages of the advance, when considerable portions of the gravels
PLEISTOCENE EPOCH. 207

had been eroded. Similar conditions likewise prevailed in the region between the flukes and
along the South Fluke.

It is true that, notwithstanding the even more marked scarps opposed to the Wisconsin
glacier, the folding it accomplished was much less than that due to the Montauk ice. Prob-
ably the greater effectiveness of the Montauk ice was due largely to the greater thickness of
the glacier and to the greater vigor of its movement.

That the Montauk ice was thicker than the Wisconsin in the Long Island region seems to
be indicated by the fact that it reached a more southerly limit, and that it was more vigorous
is shown by the relatively great erosion that it accomplished as well as by the greater thickness
of drift that it laid down, not only on Long Island but over a large section of the country.
The fact that the beds over which the Montauk ice passed lay beneath the sea and were satu-
rated with water, and hence possibly presented more favorable conditions for folding than the
incoherent surface gravels over which the Wisconsin ice sheet moved may have had something
to do with the more extensive folding by the older ice sheet. Again, the clay beds, which are
most. susceptible to folding, were more thinly covered in Montauk time than in Wisconsin
time, and being thus much more accessible to the ice they consequently suffered greater dis-
turbance. Still another factor favorable to greater erosion during the Montauk was the sub-
mergence, which was enough to prevent the accumulation of snow, though not enough to affect
the erosion materially. The surface was therefore free from the mantle of snow or stagnant
ice, which was present outside of the glacier in a part at least of Wisconsin time, and over which
the glacier proper passed with little effect, as indicated by the Smithtown ‘‘driftless” area.

FIRST RECESSION OF MONTAUK ICE.

The fact that extensive deposition followed the active erosion of the first advance shows
a decrease in the vigor of the invasion, doubtless due in part to the overloading of the ice by
débris. There seems, however, to have been a decrease in ice movement, marked first by the
several minor advances and retreats recorded in the alternating beds of till and gravel in the
Montauk region, and finally by a more marked retreat during which the ice front was moved
back at least as far as the north side of the Middle Island belt of the Manhasset formation
(fig. 107, p. 120). It then rested about on a line reaching from the vicinity of Manorville along
Peconic River, through Riverhead, north of New Suffolk through Cutchogue, northwest of
Great Hog Neck, and along the north side of Shelter Island. The North Fluke proper was
probably still covered by ice, as there is no record in the shape of deposits to indicate that the
ice retreated beyond its southern border. In western Long Island the ice front lay somewhere
north of the southern coast.

During the retreat of the ice there was more or less deposition by glacial streams, marked
by the gravels found here and there between the erosion unconformities of the earher and later
Montauk ice invasions, but on the whole the deposition was on a very small scale until the ice
came to a halt along the line just traced. On this line the margin probably remained sta-
tionary or nearly so for a period during which considerable accumulations of gravel were laid
down. The greater part of the gravel deposits of Robins Island, Nassau Point, Great Hog
Neck, and Shelter Island were apparently accumulated at this time, probably as sand and
gravel deltas at the mouths of glacial streams. From the outline and topography of the various
masses, due weight being allowed to subsequent wave erosion, it appears that the deposition took
place not in an open body of water, but rather in irregular spaces among a number of detached
residuary ice masses occupying the greater part of the interfluke area. It is not improbable
that many small ice masses were buried beneath the gravel accumulations at this time and by
their subsequent melting gave rise to some of the warpings now observed in the beds as well
as to many of the numerous kettles. .

As to the altitude of the land at this time very little is known. The heights of the deposits
are not accordant and afford no indication of any common factor in the determination of their
levels. Cuesta-like surfaces such as characterize both the late Manhasset and the Wisconsin
208 GEOLOGY OF LONG ISLAND.

outwash deposits are entirely absent, and traces of beaches, if any were ever formed, were
removed by the later ice advances. The topography in a broad way resembles the kettle or
broken plains of morainal aspect, such as are not uncommonly associated with subaerial outwash
deposits laid down over and around ice blocks.

READVANCE OF THE MONTAUK ICE.

Evidence of the readvance is afforded by the strong scouring and folding of the beds laid
down during the recession, which thus lie between two strong unconformities of ice erosion.
The advance was least in western Long Island, where the ice appears to have reached little or
not at all beyond the north coast, and was greatest in the vicinity of the South Fluke, where it
extended beyond the south shore into the sea. It is to this readvance that the strong folding
and faulting of the Middle Island Manhasset belt is referred. The advance was vigorous and
the ice was even more active in erosion than during the earlier invasion, both scouring and
folding occurring on a larger scale than, at any previous time.

HEMPSTEAD GLACIAL SUBSTAGE.
FINAL RETREAT OF THE MONTAUK ICE.

The activity of the ice sheet on the second invasion seems to have terminated rather
suddenly, the period of vigorous erosion giving place to one of extended aqueous deposition
without the usual intervening period of till deposition, except in the Middle Island belt. To
this period between the cessation of erosion and the beginning of the ice retreat is referred
the formation of the older outwash deposits (Hempstead),
which here and there project through the Wisconsin outwash
on the south side of the island.

Ya Mile After the retreat of the ice from the region of the South

FIGURE 201.—Profle of imperfect 40-foot terrace Fluke no deposits of consequence were laid down until the

east of Fort Pond, Montauk, as seenlookingfrom ice reached a line close to the north shore of the island.

Sen ee tence ett Manhassetand mo Tere the ice seems to have made a somewhat extended

halt, and broad sloping outwash plains were laid down

along its front. Traces of these old plains in the form of kettle valleys and other old

drainage lines (many of them likewise partly filled with later drift) are found at many points,
as elsewhere described (p. 174), from Muller Place, near Port Jefferson, to Orient Point.

Although these old gravel plains are everywhere obscured and many are completely buried
by the later Wisconsin outwash, they appear to possess, in their upper parts at least, the typical
fan shape and structure of subaerial deposits. Whether or not the lower parts were below
sea level can not, owing to the general absence of beach lines or other marine phenomena, be
determined with certainty, such features, if ever formed, now being hidden by the mantle of
Wisconsin outwash. The terraces (fig. 201) at the 40-foot level on Montauk, which appear to
have been formed soon after the completion of the Hempstead deposition, would appear,
however, to point to a submergence at this time.

 

 

VINEYARD INTERGLACIAL STAGE.
EROSION.

The deposition of the Manhasset formation (including the Herod gravel member, Montauk
till member, and Hempstead gravel member) was followed by an interval of strong subaerial
erosion, known as the Vineyard stage, during which the deposits were trenched from an elevation
of 200 feet or more above to at least 150 feet below the present sea level, and extensive drainage
systems with many branches and dendritic headwaters, such as the Nissequogue system near
Smithtown, were developed. The erosion of this stage was at least 50 and probably 100 times
greater than that which has been effected in post-Wisconsin time. In fact the two are com-
parable in magnitude to a river valley and a small gully—the post-Wisconsin work consisting
of hardly more than the formation of a few amphitheaters, a slight notching of the cliffs extend-
ing back only a fraction of a mile, or an insignificant trenching of the old valleys. It is probable
PLEISTOCENE EPOCH. 209

that the Vineyard stage of erosion was of much longer duration than the post-Wisconsin,
although from the fact that the land is known to have stood considerably higher in the earlier
period it is difficult to make accurate comparisons. The climatic conditions were probably
not materially different, and even if they were more favorable to erosion in the earlier than
in the later stage, the difference could not, with any reasonable assumption as to rainfall and
absence of vegetation, have been very great. In fact, with porous materials such as the sands
and gravels of Long Island, the amount of precipitation has relatively little effect on erosion,
except close to the sea, unless it comes in the heavy downfalls of so-called cloud-bursts.

In the later part of this period of erosion the land stood at least 150 feet higher than at
present, as indicated by the depth of the submarine channels off Montauk, and the depth of the
Hudson submarine channel suggests that it probably stood considerably higher than that. On
Montauk there are evidences of a 40-foot terrace, which if due to erosion would indicate a sub-
mergence as well as an uplift during the Vineyard interval. In a view looking eastward from the
hills on the west shore of Fort Pond Bay the terrace stands out distinctly, having the appearance
shown in figure 201. It has a coating of Wisconsin drift, which would indicate that it was
formed in the preceding or earlier stage of the Pleistocene.

On the New Jersey coast and farther south there is a persistent marine or terrestrial terrace
known as the Cape May, formed practically at sea level, and now standing at an altitude of
40 feet or less, which has generally been regarded as of post-Wisconsin origin. This terrace
is not developed on the Wisconsin outwash deposits in western Long Island, although on
Raritan Bay, only 10 miles distant, where the supply of material was no greater and the exposure
was much less, it has a typical development. These facts strongly suggest that the terrace,
if formed on Long Island, antedates the Wisconsin outwash and lies buried beneath it. It is
thought, therefore, that there was a rather widespread subsidence in the Long Island region,
during which the land stood about 40 feet lower than at present. The date of this subsidence
was probably the early part of the Vineyard interval, before the uplift which brought on the

stream erosion.
DEPOSITION.

Owing to the elevation of the Long Island region in the Vineyard interglacial stage, no
general mantle of deposits could be formed over its surface. The conditions were, however,
not unfavorable to the development of soils over the surface, of peat and marsh deposits along
the streams, and of fossiliferous beach deposits upon its borders. Such accumulations were,
indeed, formed at many points and may still be recognized when penetrated by wells. The
maximum elevation, as shown by the submarine Hudson valley, appears to have been at least
700 feet (see p. 63), but erosion had not attained any such depth on Long Island, most of the
deposits of the Vineyard stage lying less than 100 feet below sea level. They would there-
fore appear to mark the closing stages of the interval, when the subsidence had progressed nearly
to the present point.

WISCONSIN GLACIAL STAGE.
FIRST ADVANCE OF THE ICE.

The only evidence as to the nature of the climate during the long period of Vineyard erosion
is that afforded by the shells obtained from wells. These seem to indicate that it was no colder
than during the Gardiners deposition, when, as has been seen (p. 198), the climate was not far
different from the present climate of northern New England. Toward the close of the stage,
however, the climate became colder, or at least more favorable for the collection and retention
of snow, and the region eventually became covered with ice.

Whether the ice invaded the region as an advancing glacier, like those pushing their way
down the valleys in the Alps, or whether the region was first covered with snow which later
thickened and changed to ice is not positively known. There are several indications pointing
to the latter alternative. For instance, it seems impossible to account for the complete preser-
vation of the drainage system west of Smithtown on the hypothesis of an advancing glacier
plowing its way over the loose gravels, but the absence of erosion is easily accounted for if it is
assumed that the valleys were previously filled with snow or snow ice, over which the ice moved

1629°—14——15
210 GEOLOGY OF LONG ISLAND,

without coming into direct contact with the surface itself. Again, the absence of till outside
of the moraine in the Bridgehampton region is better accounted for on the theory that the masses
giving rise to the kettles of the outwash plain at this point represented extramorainal accumu-
lations of snow rather than residual ice blocks from a true glacial advance.

The climate along the borders of the glacier during the maximum known advance of the ice,
when its front rested along the line of the Ronkonkoma moraine, was probably very severe, at
least in regard to the amount of precipitation as snow, being in all probability even more
rigorous than in the region of the semicontinental ice sheet of Greenland at the present time.
In the Greenland region the scattered valley glaciers are able to take care of the excess of accumu-
lation of the central ice cap, whereas in
the Wisconsin stage on the continent a
continuous front of thousands of miles
was necessary to accomplish the same
result.

Stratified glacial deposits are found
up to an elevation of 410 feet; hence the
ice must have risen to at least that height

 

 

FIGURE 202.—Section at top of bluffs between Woodhull and Rocky Point landings, ae .
showing folding produced by the Wisconsin ice sheet. The figure illustratesthe above the sea level. Ina living glacier

breaking up of the folds where in contact with the ice at the top and their disap- th e i ce in th e imme diate vicinity of its

pearance at lower levels. 3 : z
front is commonly at least twice as high

as the moraine. If this relation held in Long Island, the ice may have reached a height of 1,000
feetalongthemargin. Notwithstanding its considerable thickness, which could hardly be assumed
as less than 500 feet, the Wisconsin ice sheet was not vigorous in its erosion, indicating either
an overloaded condition or a very slow movement. Inasmuch as there is no evidence of any
considerable amount of englacial material, it is probable that the sluggishness of movement
accounts for the insignificance of its erosion and explains the relative scarcity of Wisconsin till.

The deficiency of vigor compared to that of the Montauk ice is well brought out by the
smaller scale of the folding. In many places the Wisconsin ice overrode the Manhasset forma-

 

 

74° 73° 12 7° 70°

pon

   

MARTHAS

NY } RB ‘(06 © VINEYARD 1D.

Ys 75)
KOK i 163 RDINERS Ip. BLOCK 1D.

SORE G Us Uh Montauk Point ar
ae LEGEND

NS LSS
EN MOrK Lo eed Ze Covered with ioe at the Ronkonkoma stage
ax

AN Covered with ice at the Harbor Hill stage
|

14° 73° q2° 7 70°

oJ
41

 

 

Sandy Hook

 

 

 

 

 

 

 

 

FIGURE 203.—Sketch map showing relative positions of ice during the Ronkonkoma and Harbor Hill substages of the Wisconsin stage.

tion without producing the slightest recognizable disturbance; elsewhere the folding was limited
to a disturbance of the beds within a foot or two of the surface (fig. 202). Here and there, how-
ever, the disturbance was somewhat more extensive, reaching some distance below the surface,
as shown in Plate XIX, A (p. 114). Nowhere were such profound folds observed as the larger of
those produced by the older invasion, although there are indications that in many places where
bluffs and other steep slopes opposed the ice movement the folding was considerable.

There was, however, more or less material, both beneath and within the glacier, that was
either set free directly from the ice upon its melting or indirectly deposited by minor rivulets
issuing from the margin and building up the great Ronkonkoma moraine (fig. 203) and
PLEISTOCENE EPOCH, 211

the more or less detached gravel fans, which became joined into the nearly continuous plain of
outwash from ice along the Ronkonkoma moraine. The sandy or pebbly loam present locally
on the outwash presumably represents a ‘‘finishing deposit” laid down in the closing stages of
deposition. Definite channels, representing the lines ot outflow of the water just before the
supply was cut off by the final retreat of the ice, lead from the moraine to the shore.

Estimates as to the duration of the ice invasion can not be made with accuracy in the
absence of any definite criteria upon which to base calculations. According to F. J. H. Merrill,
however, bowlders from as remote a source as the Adirondacks have been recognized in the
moraines, and a journey of 200 miles is not improbable for many of the erratics. The rate of
movement of a continental glacier is not known, but it must be many times slower than that of
glaciers of the Alpine type, for these are fed by collecting areas several times as large as the
distributing glaciers; whereas in continental ice sheets the opposite is true, the area of the
sheet subjected to melting being larger than the area of collection. Probably the movement
was not more than a few feet a year. Even at the rate of 100 feet a year, which is more than
many valley glaciers average, it would take over 10,000 years to bring a single bowlder from the
Adirondacks to Long Island. Itis not unlikely that the duration even of the Ronkonkoma
substage was several times as great.

FIRST RECESSION OF THE ICE,

The upbuilding of the Ronkonkoma moraine and the related outwash plain continued as
long as the ice front remained stationary; or, in other words, as long as the melting of the ice
margin was just counterbalanced by the advance ot the glacier. This period was succeeded by
one of the greater general warmth or lessened precipitation, which caused a retreat of the ice
front from its position along the moraine throughout the region east of Lake Success, south
of Manhasset Bay. The retreat began at the east end of the island and was taken up progres-
sively westward. West of Lake Success the morainal deposits of the succeeding substage lie
south of those of the Ronkonkoma substage, and it is doubtful if any retreat of the ice occurred
in this region. If there was any it was more than counterbalanced by the later advance. It is
likewise unknown whether in the region east of Lake Success the ice retreated any considerable
distance to the north and then readvanced to the line of the moraine, or whether it halted on
reaching the line now marked by the Harbor Hill moraine. The presence of kettles in the
subsequent outwash from ice along the Harbor Hill moraine indicates, however, that the
upbuilding of the late moraine followed very quickly after the recession of the ice and before the
residual blocks had had time to melt. The retreat does not appear to have been uniform and
continuous, but was rather marked by temporary halts, during which accumulations of consid-
erable importance were laid down in the intermorainic area.

READVANCE OF THE GLACIER,

After the influence causing recession became exhausted the ice took on new activity,
advancing with a regular front to the line now marked by the Harbor Hill moraine (fig. 203),
and bringing on a new period of moraine and outwash accumulation. The conditions prevailing,
however, differed somewhat from those of the earlier stage. A larger proportion of till was
brought to the moraine, but the supply of sand and gravel, as indicated both by the smaller
extent of the outwash deposits and by the smaller quantity of material in the moraine, was
considerably less. In fact, the pronounced channels leading southward from the moraine of this
stage show that the glacial waters, instead of being overloaded with gravel and sand, often pos-
sessed relatively little such material, and their work at such times became erosion rather than
deposition. What deposition there was followed very quickly upon the retreat, for the numerous
kettles of the outwash plains indicate the existence of residual ice blocks at many points.

As to the duration of the second stage of activity little definite evidence is at hand. The
large quantity of till and bowlders suggests a prolonged ice movement, but the small quantity of
outwash suggests the reverse. There is no basis for concluding that it differed greatly in length
from the first advance. .
212 GEOLOGY OF LONG ISLAND.
FINAL RETREAT OF THE ICE.

The final retreat of the ice seems to have been rather abrupt and to have taken place
without notable halt in the Long Island region, as is testified by the general absence of retreatal
deposits. It is probable that as the climatic conditions ameliorated, the activity of the ice
movement gradually lessened and finally ceased, and the margin of the ice sheet became broken
up into detached masses as the ice melted. The masses occupying the valleys doubtless per-
sisted longest, especially where covered with retreatal outwash and other débris. Under such
conditions buried masses may have lingered for hundreds of years, possibly even after the
region had become clothed with forests, as at the Malaspina Glacier in Alaska to-day. The
porosity of the deposits and the free circulation of the ground waters would tend, however,
to hasten the melting of such blocks. "

In the earlier stages of the recession numerous lakelets probably existed between the ice
front and the highlands of the north side of the island, but in general they seem to have been of
short duration. No beach lines and only very small deposits have been recognized, the Port
Washington delta and the outwash on Lloyd Neck being the only marked exceptions.

RECENT EPOCH.
WORK OF WIND AND WATER.

The final retreat of the Wisconsin ice sheet left the island standing a few feet higher than
at the present time and probably nearly or quite destitute of vegetation, so that wind, streams,
and waves were free to begin their work of reshaping the island. The work of the wind did not
continue long, for except in the region south of Port Jefferson and along the coasts there is
little evidence of dune formation, notwithstanding the favorable character of the materials,
and none whatever of pebble faceting such as is found in parts of the Manhasset formation.
It is probable that the small amount of wind work over the island as a whole is due to the fact
that vegetation almost immediately covered the surface. Dunes have, however, continued to
form on the coast to the present day, constituting high belts all along the south shore and
capping the bluffs of the north shore at many points east of Port Jefferson.

Upon the retreat of the ice, waves and ocean currents began to sculpture the shore and to
form numerous spits, bars, and connecting beaches. The result has been a straightening of the
coast line by the formation of the great barrier beach on the south side and the truncation
of the projections of the north shore. In fact, where the highlands come to the shore there is
scarcely a point that is not marked by sea cliffs, most of them free from vegetation and not a
few still undergoing active erosion.

Details of the work of the various agencies acting in post-Wisconsin times are given in the
discussion of Recent deposits (p. 176).

SUBSIDENCE OF THE LAND.

EVIDENCE.

Submerged tree stumps and beds of peat on Long Island have been described by many
writers. W. W. Mather,! in 1843, reported stumps and logs beneath the water near Peacock
Point, between Oyster Bay and Hempstead Harbor. In 1857 George H. Cook? mentioned
buried timber in the towns of Hempstead, Babylon, and Islip. At Hempstead an island
covered with trees within the memory of Cook’s informant was a salt marsh at the time he wrote,
the highest part of the former island being lower than the meadow then existing. Elias
Lewis, jr.,? in 1869 recorded a series of observations indicating that large areas which formerly
had been swamp and woodland were then below the water level. Remains of fresh-water

 

1 Geology of New York, pt. 1, 1843, p. 21.
2 On a subsidence of the land on the seacoast. of New Jersey and Long Island: Am. Jour. Sci., 2d ser., vol 24, 1857, pp. 341-355.
3 Evidences of coast depression along the shores of Long Island: Am. Naturalist, vol. 2, 1869, pp. 334-336.
RECENT EPOCH. 213

vegetation were abundant 4 to 91 feet below the surfaces of the marshes on the south side of the
island (then about at sea level). Lewis described roots in place 10 fect below sca level. Near
Fort Hamilton the tide overflowed marshes with trees still standing, and stumps were seen far
out. It is said that 100 years earlier stumps abounded in Great South Bay, especially east of
Islip. A line of fence posts put in a hundred years before were found in place beneath the
sand at extremely low tide. Submerged meadows were seen at several places on the north
shore, one a few miles east of Port Jefferson extending half a mile from the shore and to a depth
of 16 feet in a compact mass. In a later paper t Lewis presents a number of additional observa-
tions. At Islip many stumps, the remainder of a forest still growing on the shore, were standing
on meadows of William Nicol. The absence of kitchen middens is accounted for by the rela-
tively recent submergence of the former marshes of Great South Bay. A large number of sub-
merged pine stumps were seen in a bay a few miles east of Islip. Many stumps stood about
the head of Great Peconic Bay and off the marsh north of the lighthouse at Montauk Point.
Lewis also mentions many instances of lignite being brought up in wells, but these beds are now
known to be pre-Wisconsin and hence do not bear on the question of recent subsidence. More
recently Veatch has reported marsh muck to a depth of 23 feet at Fort Lafayette, peat at 25
feet at the Brooklyn Navy Yard, and tree trunks from the surface to a depth of 9 feet near
Patchogue.

In addition to the evidence mentioned in the foregoing paragraphs most of the earlier
writers cited the occurrence of oyster and other shells at considerable depths in wells. It is
now known, however, that most if not all of these were from the Gardiners clay, the Jacob sand,
or the Vineyard formation, and not being of postglacial origin they afford no evidence of recent
subsidence. The same is true of the wood reported at considerable depths, this being found in
the Vineyard formation, the Gardiners clay, and the Cretaceous beds, as well as in the Recent
deposits.

Phenomena of the nature cited have been generally accepted as evidence of recent sub-
sidence, but recently there has been a tendency on the part of some geologists to question such
an interpretation. A number of occurrences noted in connection with the present field work
threw doubt on certain of the supposed evidences and emphasized the necessity of caution in
using submerged vegetable accumulations as criteria of subsidence.

Thus, in the vicinity of Luce Landing, north of Riverhead, the peat, with its included tree
stumps, appears to have been largely let down to its present position on the beach below high-
tide level by undermining. Near Prospect Point, north of Port Washington, the process of
undermining could be seen in actual operation, the layers of peat projecting through the sand
being bent and cracked as they are let down (Pl. XXVI, A, p. 182), although sufficiently con-
nected to form a more or less continuous sheet at a level below their original position. In
both places the beds have been exposed by the encroachment of the sea on marsh and swamp
deposits behind barrier beaches.

In addition to the evidences cited there are important botanical indications of subsidence
in comparatively recent time. These are afforded by the ranges of the common salt-marsh
plants, which, according to C. A. Davis, are as follows:

Range of common salt-marsh plants.

 

 

Species. Range. Time covered by soa.
york NCTE: GT ASS) ssscsccinderete cn tieeaaies #6 moweres ese ee Between level of ordinary tide and | Covered by spring tides about
Juncus gerardi Loisal (black grass) : upper limit of spring tides. (wien again
“Spartina patens association” (salt-marsh grass): Spartina patens (Ail.) | Extends 9 to 12 inches above and below | Covered about 1 hour cach
Mul. and Distichtis spicata (1..) Greene. Soe een neh deandinaitds, | Gmndapoutimirart
MERE MAE THAT Toate EHATHNE cinco ooh: Sada a Oa aR ag overe alf of time.
Spartina glabra Muhl. (salt thatch). . .. or mean sea level. :
Zostera marina L. (eel grass)....-2.--- 22222 sees rere cence eee eett ett estes Below low-tide limit................. .| Permanently covered.

 

 

1 Ups and downs of the Long Island coast; Pop. Sci. Monthly, vol. 10, 1877, pp. 434-446.
214 GEOLOGY OF LONG ISLAND.

Mr. Davis, who made a special study of the peats of the island for the Geological Survey
in 1911, making a large. number of borings and taking samples at short intervals from the
surface to a depth of 10 feet, is also the authority for most of the following descriptions.

At the salt marsh west of the head of Mount Sinai Harbor, about 14 miles northeast of
Port Jefferson, borings showed the ‘Spartina patens association,’ which is characteristic of
the zone at high-tide level, to extend from the present surface to the underlying gravel at a
depth of 5 feet, apparently indicating long-continued subsidence, with an upbuilding of peat
at a corresponding rate.

A 9-foot test hole in a salt marsh 14 miles east of Riverhead showed a semifluid fresh-water
peat for the entire depth below the thin surface mat of salt-water plants, indicating that the
marsh has been covered by the tides only at a very recent date.

At the Mill Creek marsh, 5 miles east of Riverhead, the boggy wooded swamps above
tide level give place downstream to a brush-covered area containing tree remains, followed by
an, open, fresh marsh with scattered stumps and shrubs, and this in turn by a marsh with the
“Spartina patens association,” overlying nearly 9 feet of fresh-water peat with abundant stumps
and roots, principally about 5feet below the surface The incursion of the sea, as at the locality
described above, is evidently very recent. The salt marsh along the east tributary of the main
creek contains many stumps and logs at and below the surface and was clearly a forested
swamp, also only recently invaded by the sea.

At the end of Pine Point, east of the marsh last described, pine roots show in the beach to
or below low-tide level. <A cliff about 24 feet high, cut in the peat by the waves on the west
side of the point, showed a gradation from a blackened sand soil at the base to Spartina patens
turf at the top.

Another marsh a few miles east of Riverhead showed 8 feet of Spartina patens peat overlying
a foot or more of brackish-water peat. Near the boat landing east of Meeting House Creek,
24 miles east of Riverhead, 34 feet of Spartina patens peat was found above a blackened sandy
gravel soil bed.

Swan. River Marsh, near East Patchogue, has the appearance of occupying a drowned
valley. Toward the sea a wooded swamp gives way first to shrubs, next to fresh marsh, then
to brackish marsh, and finally to salt marsh of the “Spartina patens association.” Partly or
completely buried stumps abound below the salt turf, here about a foot thick. An essentially
similar sequence was noted along Mud Creek in the same locality.

The conditions along the north shore are less favorable for study, but examples of submerged
peats and of progressive subsidence doubtless occur at a number of points. Near Lloyd Point,
on Lloyd Neck, Huntington, the following succession was noted by the present writer at a point
where the marsh laps up on the gently sloping surface of the upland: (1) Brush-covered upland;
(2) marginal upland zone where bushes that had been recently killed by salt water reaching
the roots through the porous sands still remained practically intact, even to the smaller twigs;
(3) border of marsh with nearly intact bushes projecting through several inches of peat; (4)
belt located a few feet outward from edge of marsh with only trunks of shrubs remaining; (5) a
‘ zone several rods from the edge with only low stumps visible; and (6) an outer area showing
only the salt-marsh turf.

The occurrences noted appear to be too widely distributed and too variable in surroundings
to admit of explanation by any other than a single general cause, seemingly a slow, long-con-
tinued, and apparently fairly uniform subsidence of the land with reference to sea level.

All authorities are probably agreed that such a subsidence has occurred in comparatively
recent time, but there is a radical difference of opinion as to whether the sinking has continued
down to the present day and is now going on.

The peat sections, as developed by borings made by Mr. Davis, show no variation in char-
acter that would indicate a halt in accumulation at the present time, and his observations on
the rate of accumulation of Spartina patens peat near Lynn, Mass., based on cinders incorporated
in the material since the building of the railroad more than 50 years ago (6 to 8 inches in a cep-
tury), would seem to indicate that if there had been any halt in a movement of corresponding
RECENT EPOCH. 215

rapidity the upper limit of salt-marsh growth would soon be reached and it would be replaced
by fresh-water turf. This is manifestly not the case.

On the other hand, it has been urged by D. W. Johnson that the belts of beach ridges of
essentially the same height, formed progressively one after another at a number of points along
the Atlantic shores, are evidences of present stability of the coast line. Johnson also considers
that dead trees in conspicuous numbers, which he believes would inevitably be of general dis-
tribution under the hypothesis of present subsidence, are really of local occurrence and are
rarely found except where a breach has been made through some protecting barrier, or where
physiographic factors have produced changes in tidal levels.

CONCLUSIONS.

The fact seems to be established that a subsidence of many feet has taken place since the
retreat of the latest or Wisconsin ice sheet, and that salt water now invades scores of marshes
in which trees grew so recently that the stumps still project above the surface.

It is perfectly plausible to attribute, as Johnson has done, the invasion in individual places
to variations in size, shape, or location of the openings through which the tidal waters obtain
access to the marshes, or to changes in the character or position of the beach ridges or other
protecting barriers themselves. Such changes would be expected, however, to favor the
exclusion of salt water quite as frequently as they would its admission, and fresh-water peat
should be found overlying salt-water peat as commonly as salt-water peat overlying fresh-
water peat. Although the former succession may exist, the thousands of borings made by Mr.
Davis show, except where the sea has been shut off by dikes or otherwise excluded, a practically
entire absence of such succession, the nearly universal order being salt-water forms above
fresh-water forms. According to Mr. Davis, in some of the places where there has been a recent
incursion of salt water, as in certain of the inlets near Portsmouth, N. H., there are no evidences
of either present or past barriers that could have influenced tidal levels. The writer also has
noted a number of localities where there seems to be no probability of former barriers.

The apparent changes in the level of bench marks at several points along the coast appear
to be inconclusive, as radical changes in tidal levels are likely to result from artificial causes,
such as the building of docks or the dredging of channels, but the fact that these changes always
point in the same direction, namely toward subsidence, seems to indicate that they should be
given considerable weight.

Although there are no broad or extended belts of dead trees, except where changes of tidal
levels of considerable magnitude have occurred suddenly through the breaking of barriers or
changes in inlets, Mr. Davis states that dead trees are not only generally distributed along the
whole coast but are fully as numerous as the conditions of subsidence would suggest.

The action of salt water upon vegetation is in a high degree selective, and while prolonged
or repeated submergence would produce a general belt of dead vegetation, the incursion of
single high tides, which, especially during periods of subsidence, always advance well beyond the
normal tidal limits, would kill only the weaker species. More resistant species would survive
but might appear sickly or partly dead. Still others might survive for many years. As oaks
and other hard-wood stumps last an average of only 15 or 20 years, they may entirely disappear,
while trees or shrubs not vitally injured by the tides that killed the oaks are still living.

This transitional or sickly belt is not conspicuous, but may usually be recognized without
difficulty by careful observers. From what the writer has seen he believes the condition to be
general in New England and on Long Island. It points strongly toward a present downward
movement of the crust. It can hardly be otherwise if the limitations of the vertical range of
salt-marsh flora are as stated by Mr. Davis.

The chief evidence against present subsidence is that afforded by the parallel beach ridges
described by D. W. Johnson. At Cape Canaveral, Florida, for example, there is a broad belt,
half a mile or more in width, of low parallel sand ridges having the appearance of beaches formed
one after another and all of essentially the same height. These ridges are certainly very sug-
gestive of stability of elevation with reference to sea level. Farther north, although similar
216 GEOLOGY OF LONG ISLAND.

ridges exist, the width of the belts and the number of ridges is less and their evidence is more
open to question. It seems to the writer that so many factors of uncertain value enter into the
computation of the time required to form such beaches as that at Nantasket, Mass., even on the
assumption that there has been no material change of level during the period of their formation,
as to outweigh the mass of evidence favoring continued subsidence.

On the whole, the view that the subsidence has continued down to the present time and is
now going on is regarded by the present writer as the most probable. The rate suggested by
Mr. Davis is perhaps higher than would be expected, but recent additional unpublished data
collected by him seem to bear out the assumption of a rapid crustal movement.

The subsidence in the Long Island region since the retreat of the Wisconsin ice sheet is
apparently not more than 25 feet, which at an average rate of 6 inches a century would require
a period of 5,000 years. That the movement has been much more gradual in the past is pos-
sible, but the uniformity of material to the depth reached by borings (10 feet) seems to indicate
that it has been uninterrupted for a considerable period of time. Earlier interruptions or
reversed movements are entirely possible, but the evidences of them, if any exist, are pre-
sumably now some distance below sea level.

LENGTHS OF PLEISTOCENE AND RECENT STAGES AND SUBSTAGES.

The lengths of the several Pleistocene stages and substages are very difficult to determine
because of the lack of knowledge of the many local conditions that always enter into problems
of erosion and deposition. This difficulty is greatest in comparing stages of accumulations with
those of degradation. It is possible, however, to recognize a progressive change in length from
the earlier to the later stages, estimates of which are given in the following table, in which the
unit A is taken as the length of the Recent epoch and B as the length of the Wisconsin stage of
glaciation. The estimates are, of course, only approximate, especially as to the length of the
stages or substages compared with the time units, but in general the relations are probably not
far wrong. For example, it is almost certain that the Vinevard erosion interval was at least
five times as long as the Recent epoch, that the period represented by the Gardiners and
Jacob stages, as indicated by erosion in New Jersey, was even longer than that of the Vineyard
degradation, and that the post-Mannetto stage was to all appearances longer than all subse-
quent Pleistocene time. The comparisons of the glacial stages are less reliable, but it is certain
that there has been a variation similar to that indicated in the table.
SUMMARY OF OROGENIC MOVEMENTS. 217

Relative lengths of Pleistocene stages and substages on Long Island.

 

 

 

 

Estimated
length as
Epoch. Stage. Substage. Nature. Chief work. Remarks. ae
or to

Wisconsin.

Recent. Postglacial. Insignificant erosion and depo- i,

sition.
Deposition of 5 10 20 feet of till, :
i ; ‘ : : Short period as compared to
Wisconsin. Glacial. thiek outwash, and high mo- preceding glacial stage. B.
Vineyard. Interglacial. Extensive erosion of older drift. ge tee ott a greater bxXA.

 

Hempstead. Glacial. Accumulation of 25 to 100 feet of

 

 

 

 

 

gravel.
Thickness o deposits points
. . . to great length as com-
Manhasset. Montauk. Glacial. Accumulation of 50 feet of till. pared to the Wisconsin 5xB.
stage.
r : Accumulation of 100 feet or more
Herod. Glacial. of gravel.
Pleistocene. Jacob. Transitional. Accumulation of 25 feet of clayey Thickness of clay and ex-
sand. tensive erosion in New
Jersey show that these 10XA
‘ stagesrepresent an exceed- i
Gardiners. Interglacial. Accumulation of 50 to 100 feet of ingly long interval.

clay.

 

Exposures of contemporane-
ous deposits in New Jer-
sey (Pensauken forma-

Jameco, Glacial. Accumulation of Jameco gravel. tion) show this to have | 10XB.

been the most important

period of deposition next
to the Mannetto stage.

 

Reduction and nearly complete

Temoval of Mannetto wravel. Longest interglacial stage. 20XA.

Post-Mannetto. Interglacial.

 

Accumulation of 600 feet of

gravel. Longest glacial stage. 20x B.

Mannetto. Glacial.

 

 

 

 

 

 

 

SUMMARY OF PLEISTOCENE AND RECENT OROGENIC MOVEMENTS.

In the earlier stages of the present investigation it was assumed that the principal Pleistocene
deposits were of the nature of coastal-plain formation and that their upper surfaces indicated
approximately the position of the sea level at the time of theirformation. On these assumptions
a depression of 300 feet was postulated as taking place during the deposition of the Mannetto
gravel and 200 to 250 feet by the completion of the Manhasset accumulation. Further study,
however, has shown that the Manhasset and, to a lesser extent, the Mannetto exhibit many
features analogous to those of the Wisconsin outwash plains developed on the south side of the
island, and it is now thought that they are in large measure of similar origin. It has been
necessary, therefore, to turn to the adjacent coast of New Jersey for evidence as to submergence.
Similarly it was ascertained in the course of the investigation that the data afforded by the
erosion valleys were insufficient to determine the amount of uplift, and recourse to the s:b-
marine Hudson Valley was necessary. The movements are shown graphically in figure 204
(p. 218).

Mannetto depression.—As pointed out above, it is not improbable that the Mannetto gravel
of Long Island is in part of the nature of an outwash plain and was formed above sea level.
For this reason it is impossible to determine its position with reference to sea level from the
elevation of its remnants on the island. The Bridgeton formation, however, which seems to be
the New Jersey representative of the Mannetto, was not developed in the vicinity of the ice
sheet but rather as a coastal-plain formation. Considerable areas of it face the open sea, and
whether due to the action of the waves or to drainage at low gradient, their development could
218 GEOLOGY OF LONG ISLAND.

have taken place only near sea level. In no other way (in the absence of barriers) could the
slack drainage necessary for the development of the flat terraces, under the hypothesis of depo-
sition by streams of low gradient, be maintained. The present elevation of the Bridgeton
formation on the New Jersey coast ranges from about 100 feet in the southern part to 200 feet
in the central part, and indicates a submergence increasing from about 100 feet in southern
New Jersey to 200 feet or more farther north. A continuation with the same grade would give
a depression of 200 to 250 feet in the Long Island region at the time of the Mannetto deposition.
Figure 204 gives 200 feet, the greatest depression actually known.

Post- Mannetto uplift—As brought out in the discussion of the submarine Hudson chan-
nels, the deposition of the Mannetto gravel was followed by a long period of erosion, during
which the rock gorge of the Hudson was probably cut to a depth of 700 feet. After the excava-
tion of this gorge and its seaward prolongation, which probably occupied by far the greater
part of the post-Mannetto interglacial stage, there was, if the submarine canyon is to be referred
to stream erosion, an uplift of the land far surpassing in magnitude any known Pleistocene
movement in the region before or since. The surface, to judge from the depth of the canyon,

Manhasset

3 Early post-Mannetto, interglacial (Basis: 700-foot Hudson channel)
o
(Basis ; Outer submarine canyon, amount doubtful)

Vineyard, interglacial (Basis: Inner submarine channel of Hudson)

 

 

Gardiners, interglacial (Basis: Present elevation of clay)

Jacob (Basis: Composition and present elevation)
Herod (Basis: Faceted pebbles, elevation of contact with Montauk till member)

Mannefto (Basis: Bridgeton formation of New Jersey)
Jameco (Basis: Pensauken formationof New Jersey)
Montauk (Basis: Structure and elevation)
Hempstead (Basis: Character of deposits, terraces, etc.)
Wisconsin (Basis: Lower Cape May terrace)
Early post-Wisconsin (Basis: Submerged peat, tree trunks, et¢,)

Late post-Mannetto, interglacial,

Present

 

 

pete Spee-ee oo eae 0 to 75" =100 1-100 to 0 20
FIGURE 204.—Position of land with reference to present sea level in the Pleistocene stages and substages. Figures indicate feet.

 

must have stood 4,800 feet or more higher than at present. Although there is considerable
doubt that an uplift of this magnitude really took place, its occurrence is tentatively accepted
as best explaining the character and form of the canyon as described on page 61.

Jameco depression.—The Jameco gravel probably does not lie at the surface anywhere on
Long Island, hence evidences of its origin that might be afforded by its structure are lacking.
Moreover, as it is a glacial or glaciofluviatile formation, its position below sea level is of no
significance. The only evidence, therefore, as to the elevation of the land in Jameco time is
that afforded by its probable New Jersey equivalent, the Pensauken formation. The great
body of the Pensauken formation was deposited in a trough, 10 to 15 miles wide, crossing the
State from the vicinity of Raritan Bay to Trenton and thence extending down Delaware River.
This accumulation seems to have been the result of deposition by streams of low gradient in a
more or less closed basin, hence its elevation of 150 feet between Trenton and Raritan Bay is
not necessarily an indication of submergence to that depth. Pensauken remnants are, however,
found at similar elevations on the open coast, as northeast of Manchester and northwest of
Asbury Park, hence there is every reason to believe that there was actually a submergence to
a depth of about 150 feet. The fact that the submergence increased from 90 feet in south
New Jersey to 150 feet in north New Jersey suggests that it may have been somewhat greater
than 150 feet on Long Island.
CORRELATIONS OF THE LONG ISLAND PLEISTOCENE FORMATIONS, 219

Gardiners wplift——The marsh deposits found at several horizons in the Gardiners clay
show that this formation at times reached sea level, indicating an uplift of at least 200 feet
after the Jameco deposition, as the contemporaneous Pensauken formation of New Jersey is
now 150 feet above sea level, whereas the Gardiners clay is commonly 50 feet or more below
sea level.

Jacob depression.—The Jacob sand is free from marsh deposits, but carries an extensive
shallow-water fauna, indicating a depth of water not much greater than during the Gardiners
deposition. It is probable that the depression was not more than 25 feet.

Herod and Montauk depression.—The subsidence, which during the Gardiners and Jacob
stages about kept pace with accumulation, seems to have continued through the Herod sub-
stage of the Manhasset, so that on the advance of the Montauk ice the water stood 75 to 100 feet
above the present sea level, as shown by the character of the Montauk till member (p. 200).
The depression did not, however, keep pace with accumulation at all times, as is shown by the
wind-faceted pebbles in parts of the Manhasset formation.

Hempstead uplift-—After the deposition of the Montauk till member of the Manhasset
formation there seems to have been an uplift of 100 feet or more, as the later Hempstead gravel
member of the Manhasset has the form of a normal outwash plain with contemporaneous
drainage channels cut to the present sea level or below. A possible halt at about halfway up
is suggested by the 40-foot terraces on the Montauk peninsula.

Vineyard uplift—The valleys in the Manhasset formation were cut to a depth somewhat
below the present sea level, hence a considerable uplift must have followed the previous period
of deposition, but because of the modifications by the Wisconsin ice sheet and of more or less
Wisconsin deposition it is impossible to determine with any degree of accuracy the actual
amount of uplift, and it is necessary to turn again to the submarine valley of the Hudson for
a definite measurement. As shown elsewhere (p. 64), the upper channel appears to have been
cut in post-Manhasset time, and as it reaches a depth of 350 feet at its outer edge, an uplift of
this amount seems to be established.

Wisconsin depression.—There appears to have been in Wisconsin time a depression which
brought the land to a level about 20 feet lower than at present, as shown in New Jersey by the
lower marine or low-gradient stream terrace of the Cape May formation, as developed along the
New Jersey coast from Cape May to Raritan Bay. This depression is not recorded on Long
Island, hence it is thought to antedate the completion of the outwash deposits.

Recent movements.—After the disappearance of the Wisconsin ice the land seems to have
stood somewhat higher than at present, as indicated by the buried and submerged peats along
the coast, the difference in level being perhaps 25 feet. This would indicate the elevation of
45 feet in late Wisconsin or post-Wisconsin time. In recent years there has been depression
estimated at the rate of 6 inches to 2 feet in 100 years. A sinking of not more than 25 feet
apparently has occurred since the beginning of this movement.

CORRELATIONS OF THE LONG ISLAND PLEISTOCENE FORMATIONS.
PROBABLE EXTENSION OF THE FORMATIONS ALONG THE NEW ENGLAND COAST,

MANNETTO GRAVEL.

The Mannetto gravel, which on Long Island is the oldest of the Pleistocene deposits, was
originally the thickest glacial deposit on the island, but its deposition was followed by an
erosion stage of such length that the formation was reduced in western Long Island to a few
remnants, and in the eastern part it was nearly or entirely swept away. This formation, owing
to either its slighter development or the greater erosion, was likewise largely removed from
the coastal region of New England, if it existed there, so that the Cretaceous, where seen, is
almost invariably overlain directly by deposits correlated with the Jameco gravel rather than
by those of Mannetto age. This is notably true of the Cretaceous beds of Block Island and
Marthas Vineyard, but in an exposure near Scituate, Mass., remnants of gravels which closely
220 GEOLOGY OF LONG ISLAND.

resemble the Mannetto have been seen, strongly suggesting that the formation originally
extended at least to this point. Beyond this locality, however, the ice seems to have reached
the coast, and the Mannetto materials, if any were deposited, were probably laid down in the
region now covered by the sea.

JAMECO GRAVEL.

The Jameco gravel seems to be much more persistent in its present occurrence than the
Mannetto. A gravel at the same horizon as the Jameco is, in fact, well developed beneath Cape
Cod to Highland Light, Truro, and possibly locally along the west shore of Cape Cod Bay to
the vicinity of Plymouth, its absence farther north being due to actual occupation of the region
by ice. On Block Island the Jameco gravel appears to be represented by sands and fine gravels
with granitic pebbles, having an aggregate thickness of 30 feet or more, occurring between the
Cratacaans and the clay which is correlated with the Gardiners clay near Clay Head and Balls
Point and beneath the dark-gray to black clay correlated with the Gardiners at several points
west of Southeast Light. On Marthas Vineyard similar gravels having a thickness of at ieast
50 feet are seen beneath the great bed of dark-colored clay correlated with the Gardiners clay
at the Nashaquitsa Cliffs. On Cape Cod similar gravels occur near Highland Light, with a
thickness of 30 to 50 feet, below clays which occupy the position and are of the type of the
Gardiners clay. On the main coast similar gravels are seen beneath clay at Indian Head, 8
miles southeast of Plymouth.

GARDINERS CLAY.

The Gardiners clay likewise appears to be a very persistent formation, a clay of the normal
Gardiners type and position being found at short intervals all the way from New York Bay
to Boston Harbor. Besides the development of the Gardiners clay on Long and Fishers islands,
as described in this paper, a similar clay is found on Block Island, notably in the vicinity of
Clay Head and Balls Point, near Black Rock Point, and locally west of Southeast Light. On
the Rhode Island coast a clay of this type and horizon is seen in places between Watch Hill
and Point Judith. A similar clay appears on the Elizabeth Islands of Massachusetts; on Marthas
Vineyard it is strongly developed at the Nashaquitsa Cliffs, and on the Massachusetts main-
land thick beds are found at Highland Light on Cape Cod; at many points on the coast between
Orleans and Chatham; at Indian Head, southeast of Plymouth; at Third Cliff, Scituate; and
beneath the drumlins in Boston Harbor. It reaches a maximum thickness of about 100 feet.
Boston Harbor appears to mark the northern limit of the clay, although a stratigraphically
higher clay with a different fauna extends north along the Maine coast and beyond. It is not
known whether the absence of the clay north of Boston is due to nondeposition or to erosion
by Montauk ice.

JACOB SAND.

The Jacob sand seems to have been originally rather widely distributed, but it was much
more generally removed by the Montauk ice invasion than the underlying formations. A
fine clayey sand of the Jacob type is found, however, on Block Island, overlying the supposed
equivalent of the Gardiners clay in the vicinity of Clay Head and Balls Point. At Nashaquitsa
Cliffs, Marthas Vineyard, the Jacob horizon is represented by alternating clays, sands, and
gravels; on Nantucket it is represented by the gray clay and sands furnishing an extensive
fauna at Sankaty Head; and at Highland Light, Cape Cod, it is represented by fine, mealy
yellow sand.

MANHASSET FORMATION.

Herod gravel member.—The Herod gravel member of the Manhasset formation appears
to be one of the most extensive of the Pleistocene deposits, a gravel resembling it apparently
outcropping nearly everywhere from Long Island to the vicinity of Boston, including Block
 

 

 

 

 

 

 

Approximate correlations of the Pleistocene formations of Long Island with deposits of other areas.

 

 

 

Truro, CapeCod, I

Thin sandy to clay
in places only s«
bowlders.

 

 

 

 

 

 

 

 

 

 

 

 

 

Undifferentiabl
younger drift.

Erosion unconformity

Not definitely recog
probably sparingly
oped locally.

 

 

 

 

 

 

 

 

 

 

 

 

Banded pebbly-clay t
worked material
older formations).

 

 

 

 

Thick sands present 1

 

 

Not separable from t
derlying clay.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Thick dark gray to
clays in bluffs at
house.

 

30 to 50 feet of gray
neath above-des
clay at lighthouse.

 

 

 

 

Long Island.
Fishers Island, N. Y. Block Island, R. I. Marthas Vineyard, Mass. Nantucket, Mass. Elizabeth Island, Mass. West Barnstable, Mass. Buzzards Bay, Mass.
Stage. Substage. Origin. Represented by— Position of ice front. Altitude of land.
2 ‘ " Thin sandy till with bowl-
e : : 3 7 ‘ 3 . ‘ A ly thick bowlder saat et
; Harbor Hill moraine and asso- | At Harbor Hill or inner Thin sheet of morainal Relatively thin morainal Thin to fairly Ss ders; in places represented
Harbor Hill. ciated till and outwash. moraine. drift. Absent. Absent. Absent. drift; numieeous bowlders. we rar coca mo- | solely by scattered bowl-
Wisconsin. ial. About 20 feet lower ‘ ve ders.
1 : Sagal than at present. i sen a
is Ronkonkoma moraine and asso- | At Ronkonkoma or outer Undifferentiable from | Relatively thin mantle of : 3 p . Undifferentiable from | Undifferentiable from | Undifferentiable from
Bonkonroms: ciated till and outwash. moraine. younger drift. jioraionl drift. Moraine and outwash plains. | Moraine and outwash plains. younger drift. younger drift. younger drift.
Great erosion unconformity; 350-
foot submarine Hudson chan-
nel; channels (later) of Long
7 . Island Sound and of sea bot-| No evidence of any ap- About 350 feet higher g r
Vineyard. Interglacial. tom off Montauk; and Vine-| proach of ice near enough 8 Erosion unconformity.| Erosion unconformity. Erosion unconformity. Erosion uneonformity. Frosion unconformity. Erosion unconformity. Erosion unconformity.
Bota : than at present
| ea : ee Consisting of to be marked by deposits. De
ossiliferous sands and muc
peaty deposits, etc., in buried
valleys; soil zones, etc.
Probably north of Long | About 40 feet lower | Questionable terraces | . ; Possibly the 40-foot terrace ; ; Seated Imperfect terrace remnants
40-foot terrace (?). | “ T31and Sound. than at present. at about 40 feet. Not recognized. near Vineyard Haven. Not recognized. Not recognized. Not recognized. at about 40 feet.
Hempstead
Hiemipstead: Glacial. g ra vie Near north coast of island in «
member. Upper Manhasset east; along scarp between | About 100 feet lower | Possibly some local | Gravel on east and south tial ae or ge ee a det Poe Uppermost of the pre-Wis- | Upper gravels beneath mo- | Gravels of upper terrace or
ateau. upper and lower aa than at present. gravel patches. coasts. worth) part of island consin gravels. raine. plateau (100 to 125 feet).
set plateaus in west. : ;
eS and At south shore or beyond.
‘Temporary reces- Island and
Manhasset. sion (local depo- | North of Shelter Tsland an : ; Banded till or poorly as- pein i oa Probably the heavy tills,
7 Mee Montank till] — sition of gravel). “Middle Island belt.” 75 to 100 feet lower | Local deposits of | Heavy handed till near Clay | handed till in bluffs of | sorted gravels in bluffs ae -clay till (re- | Banded padi till (re- |“ Which’in places form hills
Montauk. Glacial. ; . Head, Balls Point, and worked material from worked material from cs
member than at é , n r ands
i present. banded till. west of Southeast Light. north coast. ee Head and older formations) older formations) Hs Spee e the sands and
northward. 7 : gravels.
First advance
a ee ee Near Bethpage in west; be-
sition of thick yond south coast in east.
till).
About 75 feet below : ;
: _ : Folded gravels present lo- | Cut out by ice erosion un-
In Long Island Sound, prob- present level in gi ) :
, YMacia 6s soak : -| 7 — " ° s cally; in some places cut conformity along coast; : ates Pata
Herod. Glacial. Herod gravel member. aay Bee north coast of a ee ee Folded gravels. Folded gravels. Folded gravels. Disturbed gravels. out by ice erosion uncon- probably present in high: Probably below sea level.
: times. formity. ands of interior.
Probably south of the head- | Probably about 20 ‘ Howish d alter fossilif Possibly some of clays on
Jacob. Transitional. | Jacob sand. waters of Connecticut | feet above present | Gray clayey sands. Thin buff sands. Thin yellowish sand alter- | Clayey sands and fossilifer- | 754 seen, Not seen. Burgess Neck and in val-
River. level. nating with clay lamin. ous bedsat Sankaty Head. ley of Monument River.
3 ly represented by
Dark gray to black clays Probab! y ‘ .
‘ enna Sate aa the blue clay formerly ex- : The clays below the re-| Possibly some of clays in
; ‘al oes No traces of ice within drain- About 50 feet above | Chocolate, gray, and near Clay Head, Bal Dark gray to black clay at posed beneath the fossilif- Probably occurs just below Worked’ MiAterial “atc thie valley of Monument htiver
Gardiners. Interglacial. tardiners clay. age areas of Siteams ontet present level. red clays. Point, Black Rock Foint, | Nashaquitsa and locally | Prous ‘beds at Sankaty | {thereworkedclaysatora| cay pit are probably | and below sea level else.
ing Long Island Sound. ? oe of Southeast on north coast. head lan 4 by the blu ° clave little below sea level. Gardinersclay. 3 ae s
: reported below sea level.
| 30 feet of sand and_fine se
| i in Li Island if - Hl 30 to 50 feet of granitic
Jameco. Glacial. Jameco gravel. Pe ae sae anid ioea below a sea level if pres Balls Point, and Sg gravels at Nashaquitsa | Below sea level. Below sea level. Below sea level. Below sea level.
Southeast Light. .
4,800+ feet above
Great erosion unconformity; present level(?).
nearly complete removal of
thick Mannetto oe ae a ie
. of outer submarine valley an . A 700+ feet above pres- | Unconformity below | Unconformity at top of Cre- | Unconformity at top of Cre- | Unconformity below sea | Unconformity below sea | Unconformity below sea Unconformity below sea
Post-Mannetto. Interglacial. canyon and of rock gorge of | No evidence of ice. ent level. sea level. taceous. taceous. level. level. 4 level. 2 level. y ie
udson River; excavation of
Long Island Sound (principal
stage). Slightly lower than at
present.
A Probably about 200 | Probably cut out by , ;
7 Probably in Long Island a | Absent; probably cut out | Absent; probably cut out | Probably cut out by post- | Probably cut out by post- Probably cut out by post- | Probably cut out by post-
Mannetto. Glacial. Mannetto gravel. Sound or vicinity. ad present eal annetto ero by post-Mannetto erosion. by post-Mannetto erosion. Mannetto erosion. Mannetto erosion. Mannetto erosion. © . Mannetto erosion. oe
1629°—14. (To face page 220.)

 

Uneonformity
level.

belo)

Probably cut out b:
Mannetto erosion.
roximate correlations of the Pleistocene formations of Long Island with deposits of other areas.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

New Jersey. Supposed
time
equiva-
5 Elizabeth Island, Mass. West Barnstable, Mass. Buzzards Bay, Mass. |p C: Indian Hill, Plymouth e Boston Harbor and vicinity, Massa- | Northeastern New England lents in
, , y, Mass ruro, Cape Cod, Mass. Chatham, Mass. Mass. 3 Manomet Hill, Plymouth, Mass. chusetts. (Clapp). the Missis-
Nonglacial formations. Glacial deposits. |sippiand
Ohio val-
leys, etc.
Ape . sale Thin sandy till with bowl- | »,. i * 5
ativ i ; Thin to fairly thick bowlder ad Phin sandy to clayey till; | Th ill; : fate esa ‘ # | Upper part
a Spanos eee till, in places with mo- sate; in places represented in: places one inbianad hlae nese locdlige eons Thin sandy till with seat-| Sandy till, with some bowlders; thick- “Trenton gravels.””| of till
: . rainal topography. a re) y by scattered bowl- bowlders. y has morainal topography. tered bowlders. ness unknown, but probably small. : sheet. Early
js 5 : see io i : 4 Wis-
| le a - Superficial mantle of postdrumlin till. | Older Wisconsin drift. Lower Cape ay g % consin.
= n . eos 3 2 : terrace of Dela- ower part
i Undifferentiable from | Undifferentiable from | Undiff tiable f Undiff i i i i ; 2 i
lains. 7 a ndifferentiable from ndifferentiable from | Undifferentiable fro Undifferentiable f A « ‘ vare Vailey. a f till
P younger drift. younger drift. younger drift. younger drift. younger drift. ra younger drift, wm | Undifferentiable from younger drift. ote c EB sheet.
Peorian
> Dp ?
ons eee upon lower slopes “Leda clay.” Erosion interval (?)
mee between higher
r. Erosion unconformity. Erosion unconformity. Erosion unconformity. Erosion unconformity. Frosion unconformity. Erosion unconformity. Erosion unconformity. tay TOG Or Erosion interval. : 2) ae
Delaware Val-
Erosion unconformity. Erosion unconformity. ley. Sanga-
mon(?)
+ ‘ - Tr fe . = : 4
Not recognized. Not recognized. rae aie ee reninants Not recognized. Low, imperfect terraces. 5
3
Not definitely recognized; r el Z &
7 probably fet ringly” devel. | Local gravels. aes some of wash lines on drum- aoe fea and un- E
rihera | UPpermost of the pre-Wis- | Upper gravels beneath mo- | Gravels of upper terrace or | Ped locally. s y : Bs
consin gravels. raine. plateau (100 to 125 feet). 30 feet of gravel. Gravels of plateau bordering shore. g
oO
a
= 3S
oO
Higher Cape May
terrace of ane
Delaware al-
ly as- i; i p Probably the heavy tills - , ley; higher (40 Tllinoian.
Banded pebbly-clay till (re- | Banded pebbly-clay till (re- Spite y Us, | Banded pebbly-cl ll (re- | Banded pebbly-clay till (re- Heavy ld i Y ‘ C . 3
bluffs y-clay y-clay : 4 pi y-clay till (r pebbly-clay till (re eavy bowlder till at beach level ™ “ , er
d aa wart material from worked material from Peo orm worked material from | worked material from | Banded pebbly-clay layer. near Manomet; bowlder till forming | Greater part of the drumlins. mw sheet ee eee ee ee er
older formations). older formations). gravels =e older formations). older formations). bluffs west of Rocky Point. clay’; most of drumlins. Bay, ete.
b
oe gravels ee lo- | Cut out by ice pEenon. un- Cut out locally by ice erosion |
cally; in some places cut conformity along coast; . 2 5 Tint calls : oa oa ‘ unconformity but prob- | Below sea level along coast but ma , 3 . ‘ st |
out by ice erosion uncon-| probably present in high- | Probably below sea level. Mhick sands present locally. | Sands and gravels in blufis. ably present in races rise to a considerable height in hill, | “T@vels beneath drumlins. Thin gravels:(10 feet), |
formity. lands of interior. along coast. | |
~ at
silifer- Possibly some of clays on . Not seen; generally below sea level; |
allifer Not seen. Not seen. Burgess Neck and in val- eee from the un- a eee from the un- Ne seoeanls from the un- Bulow tex ieve alongcoast; probably ossibly represented by fossiliferous | Absent.
3 ley of Monument River. INE ay FUNG Clay: riying clay. urs! . eds encountered in wells.
ane Erosion Feces he and Erosion interval. Yar-
’ j : 4 7 a ‘ tream deposits. oa ; z mouth.
rly ex- ; The clays below the re-| Possibly some of clays in ae Thick gray or greenish to + Fossiliferous clays of outer harbor re- . |
ossilif- | P rely secure Just see worked material at the | valley of Monument River, ee: ee nd ue Wet black clays exposed in ee uart2 | Below sea level along coast; probably worked into drumlins; fossiliferous | 4, sont |
nkaty : ) clay pit are probably | and below sea level else- y Sot |  anticlinal folds along coast | P* ttuuing Lower | occurs in hill. blue clay beneath drumlins at Great :
> clays little below sea level. Gardiners clay. where, house. (east). part of clay beds in bluff. Head. etc.
level.
30 to 50 feet of gravel be- , ; 7 ae A Probably represented by
Below sea level. Below sea level. Below sea level. neath above-described | Below sea level. Gravels. Below sea level along coast; probably | Possibly some of gravels reported in | “some ‘of the predrumlin | Pensauken formation. Kansan.
i occurs in hill. harbor wells. i
clay at lighthouse. tills.
y sea | Unconformity below sea | Unconformity below sea | Unconformity below sea} Unconformity below sea | Unconformity ‘below sea | Unconformity below sea | Unconformity probably above sea | Unconformity at top of Cretaceous Scenes ee Erosion interval and Erosion interval Aftonian
level. level. level. level. level. level. level but not exposed. (recognized in borings). ent) 8 stream deposits. 7 i *
Pn . . . Mannetto gravel probably present |
ost- | Probably cut out by post- | Probably cut out by post- | Probably cut out by post- | Probably cut out by post- | Probably cut out by post- | Probably cut out by post- Mdeposits int this ‘il exeads com above Cretaceous al Scituate. Probably represented by ; : ; Pre-
Pp Macinecte erosion Maniniatto erosion: Mannetto erosion. Mannetto erosion." Mannetto erosion.” Mannétto erosion.” bined post-Mannetto formations; la part of predrumlin | Bridgeton formation. Jerseyan drift. Tansey:

 

 

 

 

 

 

Cretaceous either rises high above
sea or Mannetto gravel is present.

 

Possibly represented by weathered
and oxidized tills of interior.

 

 

 

 

 
CORRELATIONS OF THE LONG ISLAND PLEISTOCENE FORMATIONS. 221

Island, the Rhode Island coast, Elizabeth Islands, Marthas Vineyard, Nantucket, Cape Cod,
and the Massachusetts coast as far as Marshfield and Scituate. The member appears to be
represented by the stratified sands and gravels found beneath some of the drumlins on the
shores and islands of Boston Harbor and by similar materials found here and there beneath
the thick till along the coast of New Hampshire and Maine. These deposits reach a thick-
ness of at least 100 feet in places, generally constituting a large part of the bluffs at the Rhode
Island and Massachusetts localities mentioned. North of Boston their thickness is greatly
reduced, 10 feet being a common maximum, and at many points the gravels are absent. As
on Long Island, most of the deposits of the Herod horizon have been extensively folded, and
many of them have been eroded, presumably by the Montauk ice.

Montauk till member—The Montauk member of the Manhasset formation is the most
persistent of the Long Island deposits. On Block Island what appears to be the till phase
of the Montauk is even better developed than on Long Island, constituting a heavy folded
bed in the cliffs near Clay Head and Balls Point and forming a large part of the bluffs west of
Southeast Light. On Marthas Vineyard a similar till is seen at several points in the bluffs
on the north shore. Similar conditions exist in Nantucket, although the till phase does not
seem to be strongly represented. On Cape Cod it is found mainly in the form of reworked
clay (probably Gardiners clay) from older formations, with a few pebbles and bowlders incor-
porated in it. The best localities for observing the deposit are at the West Barnstable clay
pits in the Chatham region and on the west side of the cape near Wellfleet. On the main coast
however, the development seems to be much stronger, the till being a thick sheet filled with
bowlders, giving rise to the bowlder pavements near Manomet Hill, south of Plymouth, and, it
is believed, to the till hills and big drumlins of the Boston region. In northeastern New England
it apparently continues to be the principal till, ranging from 20 to 300 feet in thickness. The
invasion in New England, as on Long Island, seems to have been dual, the first advance deposit-
ing the greater part of the material and the second advance accomplishing most of the folding.
In fact, the later advance is in some places represented solely by its erosion unconformity.
The folding is characteristic of the advance throughout, being found in northeastern New
England as well as on Long Island.

Hempstead gravel member.—The Hempstead gravel member of the Manhasset formation
is limited as a continuous deposit to the western half of Long Island but seems to be developed
as an interrupted sheet along the coast throughout New England. Gravel of this horizon
is seen above the supposed Montauk till member on both the east and south coasts of Block
Island; it caps the bluffs at many points on the north coast of Marthas Vineyard; it occurs
above the fossiliferous beds at Sankaty Head, Nantucket; and it is seen at numerous places
on the Elizabeth Islands and Cape Cod and along the Massachusetts coast to Plymouth and
beyond. It is also found in New Hampshire and Maine above drift correlated with the Mon-
tauk member, in places reaching a thickness of over 100 feet.

VINEYARD EROSION INVERVAL.

The extensive erosion unconformity developed in the stage following the deposition of
the Hempstead gravel member of the Manhasset formation, is fully as well developed in southern
New England as on Long Island, the terraces of Block Island, Marthas Vineyard, Nantucket,
Elizabeth Islands, Cape Cod, and the Massachusetts coast showing substantially the same
deep stream cutting previous to the deposition of the Wisconsin till as is found between Man-
hasset Bay and Port Jefferson on Long Island. North of Boston little erosion occurred in
early Vineyard time largely because of the submergence which continued through a considerable
part of the stage and during which the “ Leda clay” of the Maine coast was deposited. In the
later part of the stage, however, a considerable uplift accompanied by erosion appears to
have occurred in northeastern New England.
222 GEOLOGY OF LONG ISLAND.

WISCONSIN DRIFT.

The Wisconsin till sheet forms a mantle over the whole of New England essentially the
same as on Long Island. On the whole it seems to be but little better developed than on the
island, although in some places it reaches a somewhat greater thickness. F. G. Clapp’ gives
its maximum thickness in northeastern New England as 20 feet, which is about the same as
the average in southern New England and Long Island.

CORRELATION WITH THE NEW JERSEY NONGLACIAL FORMATIONS.’
GENERAL CONDITIONS.

The conditions in New Jersey were so unlike those on Long Island and the nature of the
deposits is so different that with the information at present available the correlations are of
necessity doubtful, except perhaps in the vicinity of Staten Island. In the Long Island region
the ice advanced with a long front facing the sea, into or along the borders of which it emptied
its débris-laden waters. In New Jersey, on the other hand, the ice margin lay well back from
the coast and its till and outwash accumulated on the surface of the land. The ice was not
the only source of the material in the New Jersey region nor was the vicinity of the ice margin
the only place of deposition. The Cretaceous and Tertiary highlands were everywhere being
cut down and their materials were being deposited along the valleys, which in places were
ageraded to elevations of 150 to 200 feet above the sea level.

CORRELATIONS.

The chief Pleistocene deposits of New Jersey and their correlation with the deposits of
Long Island are shown in the table facing page 220.

Lower Cape May terrace.—The lower Cape May terrace is composed of a quartz or granitic
gravel, locally somewhat sandy, occurring as a low terrace about 20 feet above Delaware River

Trenton 3
“Trenton gravels

Higher Cape May terrace

Lower Cape May terrace
Sea level

ee ee oe eae SS Se ee Se ee i ee Se a eee SS eS SS a ee Se SS SS SS ee

FIGURE 205.—Diagram showing the relations of the higher and lower Cape May terraces to the so-called “Trenton gravel’’ along Delaware
River in New Jersey.

below Camden, as a broad, flat terrace bordering the sea at about the same elevation at Cape
May, and as similar terraces in the reentrants of Raritan Bay and elsewhere. Along the Dela-
ware it rises upstream, apparently rising above the higher Cape May terrace beyond Trenton
and merging into the so-called ‘Trenton gravels,” a local development of the Cape May forma-
tion. The relations appear to be as shown in figure 205 and would point to the completion of
the valley phase of the Cape May in late Wisconsin time. The marine phase, however, seems
to be somewhat older, apparently antedating the Wisconsin outwash, as no traces of it are found
on Long Island, although the conditions were presumably as favorable for its formation as at
the typical locality on the shores of Raritan Bay only a few miles away. The writer believes
that the Delaware development of the Cape May corresponds with the great outwash streams
of the Harbor Hill substage and regards the marine phase as having been developed at a some-
what earlier stage, supposedly contemporaneous with the cutting of the great inland scarp
bordering the Harbor Hull moraine from Brooklyn to beyond Jamaica.

Higher Cape May terrace.—The deposits of the higher Cape May terrace are more quartzose
than those of the lower terrace and carry a greater percentage of iron crusts from the Pensauken
formation. Along the Delaware Valley they include a considerable admixture of northern
material, including fresh subangular granites, but in the tributary streams and coastal phases

 

1 Bull. Geol. Soc. America, vol. 18, 1908, table opp. p. 512.

2 In studying the correlations the writer spent several days in going over the best New Jersey localities wilh Mr. G.N. Knapp, of the New Jersey
Geological Survey, in 1903, and-two weeks in company with Dr. H. B. Kimmel, State geologist, in 1907. Cordial thanks are due for the many
courtesies and the valuable assistance received from the State Survey during these visits.
CORRELATIONS OF THE LONG ISLAND PLEISTOCENE FORMATIONS. 223

the materials are wholly of local derivation. The higher Cape May terrace has a maximum
elevation of 40 to 60 feet on the borders of Raritan Bay, along the New Jersey coast, and in the
open Delaware Valley, but may rise to considerably higher levels in the tributary valleys.
Inasmuch as the granites of the deposits are fresh, whereas in the next older formation (the
Pensauken) they are invariably weathered or rotten, it seems likely that the higher Cape May
terrace of the Delaware Valley corresponds with the Manhasset formation of Long Island, in
which the pebbles are likewise fresh. No deposit is known on Long Island with which the
higher terraces of Raritan Bay and the coast can be correlated, unless it may be the 40-foot
terraces (Hempstead gravel member) on the Montauk peninsula.

Intermediate stream deposits.—Deposits of locally derived gravels have been formed mainly
in the valleys cut in the underlying Pensauken by tributary streams entering the Delaware
trough. They are lower than the Pensauken and higher than the uppermost Cape May, and
represent the deposits of the intervening stage, constituting a subaerial formation probably
contemporaneous with the marine Gardiners clay of Long Island.

Pensauken formation.—The principal development of the Pensauken formation is in the
great trough in the Cretaceous deposits extending across the State from Raritan Bay to Trenton
and down the Delaware Valley to Salem County. In this region the formation is commonly
an arkosic ferruginous sand or quartz gravel containing numerous pebbles of rotten red shale
and deeply weathered granites but no fresh pebbles. The formation in the tributary valleys
and along the coast is composed of local materials derived largely from the Bridgeton formation.
In the trough mentioned the formation attains a maximum altitude of 150 to 200 feet, but
along the coast it stands at about 90 feet. In general it lies in troughs or valleys eroded in the
Bridgeton formation.

The presence of bowlders apparently ice rafted along the Delaware belt suggests that it
was formed during an ice advance, but there are many difficulties in the way of definite cor-
relation with the deposits of Long Island. Weathering is, on the whole, distinctly more
advanced in this formation than in most of the Manhasset of Long Island, although not more
than in certain phases such as those at Lloyd Neck (p. 136). According to the sequence of
events it should be correlated with the Jameco gravel, but a grave difficulty is encountered
in the fact that the upper surface of the Jameco is 50 feet or more below sea level, and that
of the Pensauken formation along the coast is at least 90 feet above it, although the localities
are only a few miles apart. The Jameco is a glacial formation and may have been deposited
at some depth below the sea while the nonglacial Pensauken formation was accumulating at a
considerable elevation above it. Such an origin of the Jameco demands a subsidence, as the land
stood considerably higher both immediately before its formation (as shown by the post-Mannetto
erosion valleys) and immediately after it (as indicated by the marsh deposits and the shallow-
water fauna of the Gardiners clay). Unless another glacial stage is introduced, of which there
is no other indication, there seems to be nothing besides the Jameco with which the Pensauken
can be logically correlated. In being a valley formation in an erosional depression of an older
surface, it agrees with the Jameco.

Bridgeton formation.—The Bridgeton formation is largely a cross-bedded quartzose gravel
of the Mannetto type, with some rotten cherts and granites, and was developed over extensive
upland areas in southern, central, and northern New Jersey. It was afterwards largely removed
in the central part, where it is now found only as caps on the higher hills. In elevation it varies
from 100 feet at the southern limits to 200 feet in Camden County. Its habit is the same as
that of the Mannetto gravel of Long Island, the formation occurring as a broad, sloping terrace,
which as a rule covers and obliterates the underlying Cretaceous uplands of New Jersey in
the same manner as the Mannetto gravel covers the Cretaceous remnants in the Mannetto
Hills of Long Island. The character of the Bridgeton formation and its position in the Pleis-
tocene series are so similar to those of the Mannetto gravel that its correlation with the Mannetto
seems reasonably certain. The two formations are probably contemporaneous with the extra-
morainal drift farther north in New Jersey.
INDEX.

  
 
 

 

A Page.

Acknowledgments to those aiding.............0....00cceeeeeeeeee 3

Albertson, record of commission’s test well near.............--... 149

Alluvial phase of Long Island geology..............2.0222-20eee0- 4-5
Amagansett, Manhasset and outwash topography near, plate

BILE iach wihosntwieind Soicmmenicasies WOR automate nenaien 118

Amphitheaters, formation of cress z 51

formation of, figure showing.......... 3 51

» “plan-of figures sHowite. 4 scenes sevensa~a yh tvecncwmasnns vaste 51

B.
Babylon, channel near 175

 
 
 
  
 

outwash near.
Backbone of the island, nature of_..............0..22-22-22.-0-00-- 1
Baiting Hollow, Montauk till member near..... --- 138-139
Montauk till member near, figures showing. . --+ 126,139
Bald Hill, morainalcharacter of.................- Ser 33

 

Barnum Island, section near, figure showing... 93
Basalclays, application of the term 67
Bayside, record of commission’s test wellnear.................-.. 149
Beaches, connecting, location of--........-....22..22...226-222- 178-179

formation and location of... 177-178

   
   
 
  
 
  

marshes behind. .
south shore, formation of mstisisbapcedia ceetatcheemice alee eieecmee
Bedrock, position of, in western Long Island, map showing...
Bethpage, Cretaceous exposure at....----.......------222---
Manhasset formation near
Mannetto gravel neat... oceccticsascceacce weepencaciadcdennere
terraces of the Herod gravel member at..........-.....-----
BUPMOSTADNY. aso: te ees ined arn dawicsetsitesachiestes inaaitanak oe
Biuffs, shore, character and examples of.
Bowlder beach, typical, of North Fluke, plate showing.
Bowlders, decomposed, example of, plate showing ecavete 23
layge jOCCUITCNCS Ol canoes sexe eiedetens horceekecengys yee
Bowman, Isaiah, acknowledgments to........-..---.----2--+-+-+--
Brentwood, Manhasset formation near...................2-2.2-+-
Bridgehampton, kettle valley and kettle chain near, plate showing. 42

184

 

 

 

  
  

  

Manhasset formation near...........-.-----------------++-+-- 119
record of Sanford & Son’s wellat - 75
Bridgeton formation, correlation of- . -- 228
Brighton Beach, location of..........-..-----+-------2-e0e see e eee 178
Broken Ground, landslide at...........-..----------+----.-------- 56
landslide area at, plates showing..........--.------.--.--+- 54, 55, 56
Manneéttoigravel Ot: ncc2ceheeeeenarereeeeeedececes ts aerer sts 83
Brooklyn, Bartlett St. and Flushing Ave., record of wellat...... 86-87
Brooklyn Aqueduct and New York Ave., record of test well
INO: Ati s oa icisicis bustle onset eho asen made ee aoe RS 87
confluent fans in 37
Meeker and Kingsland avenues, record of wellat........-..- 73
modified scarps near, plate showing 52
OULWASH eee eceisin als cacise cecaiss.s petaememne ee ces 173
section in, figure showing. . 89
Wisconsin till in .....jc2cises geececauies yee steconeses ooze 160
Brown Hills, Gardiners clay at..-....--.------+---+----------0+5+ 98
Jacob sand in.. 2.2.22. 2... eee nec eee cece eee cee cee 110
figures showing.........-----;++++--220ee 2 eee cere 109, 110
section at, figure showing......-..--- ae 98
Browns Point, sections near, figure showing........----.--------- 93
Cc.
Cape May terraces, correlations with ........-.-----++-+++++++++ 222-223
relations of, to Trenton gravels, figure showing..--.....-.---- 222
Carmans River outwash channel, description of. ... 176
profile of, figure showing....-------- 168
Center Island, Cretaceous outcrops on..... ais _

Centerport-Babylon channel, description of......-..-.--------++--
1629°—14—-—16

 

 

 

Page.

Central Islip, confluent fans near..............2-.0002ee eee eee ee 36-37
Manhasset formation near..............2-. 2220002 ccc eect eee 118
Channels of streams, deposits in.............2-...220 eee eee eee eee 177
Channels, outflow, formation of 47
outwash, formation, types, and relations of ........-.......-. 4x51
sections of, figure showing.......-. 50
terraced, sections of, figure showing . 49
Clapp, F. G., acknowledgments to...... 3
Clays, movements of, a cause of landslides 56
Cold Spring outwashimeaty cat cnedteeasscaes aenceccenmare ae smenee 173
Cold Spring Harbor, Cretaceous deposits on 2 70

 

Cretaceous deposits on, section of.............-.----2+---222-- 70

 

 
  
 

Montauk till member near.......- 137
section near, figure showing. 96
Wisconsin till near_..-...-.-...- 161
College Point, Hempstead gravel member near, probable de
DOSIt Ole pedutet Saas aarccsoe line Bu Seemann SeeeaaSOS 152
J&COD SANG Ate ices co ntecasacs ead a eRe Ane eee RORNEGRE 108
Montauk till member near....-......-.--2-222-22220200-2 225+ 135
figure showing............. 135
record of railroad test boring near..-....-....--.... 131
Compression of beds, possible mode of, figure showing. . - 202
under ive load, figures illustrating. vi.co.esssceuy veesensersees 204
Connecticut, material from............----- 81, 88, 95, 123, 134, 151, 159
Connetquot channel, description of...........-..--.-.2--2++---- 175-176

Coram, dunes near
Montauk till member near.

 

 
 

 

  

  

 

elevation of surface of, in western L_ng Island, map showing... 76
excavation of Long Island Sound in..............2.-2....---- 57-60
folding and faulting“ oficcccncos sanatencnaasa sh ceeemeaaceerias 76
POSSI SHIN 2: 2ocis sieieeinvateras saints s See maw aeee MEER EM Sema T7-79
influence of, on the compression of overlying deposits, figure
SHOW Giccaccciec us sovinekenwliies chine heuees : - 204
on the topography. 29
OCCUPTCNCE Of sisi: water aiciahih art dees Soigaasres Yeeeeaseses 54
on Lloyd Neck, plate showing.........-...----------2-----+-- 56
relation of Long Island Sound to, map showing..........-... 59
SUMMACO.Of 5-2-6 seve adaeara ele adacad naman te ineeerndemet a veReeree 77
unconformable contact of, with Hempstead gravel member, on
Little Neck, Huntington, plate showing... 152
VAMC YS Tes cre ciesstarcrersaisials clarsinnss pistereierersinnetes Bla emerge sane 44
Cretaceous formations, clays of, at base of landslip mass, plate
SHOWING stenac. exreenaee ts yenngnyere ers Wade wer teens’ 55
on Little Neck, plate showing. ...........--....-.2-.----- 82
columnar section of, figure showing.......-....-...2..-.----- 67
distribution of, on Western Long Island, map showing. - 69
Cretaceous time, events of...........--.----- 2-22 eee eee eee 193
Dall, W. H., acknowledgments to 3
Deltas, nature and occurrence of 177
Diluvial phase of Long Island geology. : 5-6
Dix Hills, Cretaceous exposure in........-.------2 2-26 e ee eee eee val
Marinetto pravel ity .icn.4..¢ se ected ot <6 SAR eteees 82
Mannetto valleys in 45
Wisconsin ti!] near.......-.....--..----------- Srna ei aeni hansen 162
Wisconsin till on old gravels in, plate showing...........--.- 162
229,
226

INDEX,
Dolomi 7 Page. Page.
Olomite, Stockbridge, occurrence of ......0.........ceeceee eee 66 | Friars Head, dunes near, plate showing................22--.0000- 34

Dosoris Pond, record of D. F, Bush’s well near

 

sisi sion Gey privaia se euerts 104

Douglaston, Manhasset plateaus near, figure showing. 30
mud cones around springs near, plate SHOWING) so¢ ees e uae cxct 183
Drainage system, hypothetical, figures showing .................. 35

Drift phase, early, of Long Island geology
later, of Long Island OOOO ie aex. satan ecas
Duck Pond Point, Herod gravel near, figure showing. .
Montauk till member near
figures showing

section east of

    
 
  

  
   
 
 
 
  
 
 
 
 
 

E.

Easthampton, dunes at..... 22... 0.0.00. 0c eee eceecceee eee ee eee ee 181
Manhasset formation near..... ..........222.--00. 119
Eastport, great bowlder near............0-...2.0000. cece eee 165
East River, channel of, how produced....................... - 24-25
East Williston, Montauk till member at, probable bed of......... 141
record of commission’s test well near............-2...-...---- 149
section inclay pit at.........0.......ccececeecccceceaceeccces 141
Eaton Neck, Cretaceous outcrops on....2....-.200..ee0ecc cc eeeee 71
Gardiners clay on, possible exposure of.............22-.0-..-- 97
Jacob sand absent from... ..........2.2 222 cece eee eeccececeees 109
Manhasset plateaus, figure showing.................220.0eee0- 31
Manne tiv gravel Git pg yessiwinia aa jaw aanscaamnand dumiuewmvcwar® 83
Montauk till member on and near............000000200000-008 137
figure showing 97

record of L. A. Bevin’s wellon.. 74
section north of, figure showing................02..0222.02--- 97
iim. Point, Cretaceous outerop at. 2.22.4. <yecseencnxvavesyaveeees 68
Eocene deposits, evidence of. ..-............22 0.220 c cece ee eee 79
Hocene tiie, vents Of x, cocks (ccnecdvenaas ot dacadenwesaicenseoes 194

Erosion by the Montauk ice sheet. .
early Pliocene, summary Of..........2-.. 22.0222. e eee ence eee
post-Lafayette, evidence of....... 20.220... eee eee eee eee eee

summary of
post-Mannetto, summary of....
pre-Wisconsin scarp formed by, plate showing.............-.
Recent scarp formed by, plate showing.
Vineyard, summary of.........-
£xogyra costata, occurrence of

Faceting, pebbles showing
Fans, alluvial, nature and occurrence of............-..--.--+-4++-
compound, character and examples of.
profile of, figure showing.......
confluent, formation and examples of
simple, formation Of.........------+---- 22-22 eee reer eee eres

 

 

Farmingdale, Cretaceous exposure at 72
Mannetto gravel near 82
Far Rockaway, record of James Caffery's well near..........-.... 87

Far Rockaway Beach, location of.......--..---+--++eeeeee eset
Field work, periods of...........-----
Fire Island Beach, description of...
CLOSIONIOL 2.0.22 sceeeainws saeco
Fishers Island, Gardiners clay on
Gardiners clay on, sections of, figures showing.......-.--.--

 

 

 

  

Herod gravel member on. 130
figures showing......--.-.-----+--++ese eter cree 101, 102, 130, 147

index map Of.........-----0.20 eee eee eee ee ete ceteris 101
Jacob'sand O0..2.2s00-e%c2ccte eens 112
figures showing....--..-------- -- 101,102, 112, 147
Montauk till member on 147
figure showing... .....--.------ + +2202 ee ee eeeere reece eee 147
Folding during Montauk substage, causes and character of... . . 201-207
Folding by the Wisconsin ice sheet, figure showing 210
Fort Salonga, section on coast near, figure showing... , 125
Fosse channels, parallel, on Montauk peninsula, plate showing... 34
Fosses, morainal, formation and varieties of. .......--+--------+-- 47-48
morainal, profiles of, figures showing...........---+-.--++-++- 47, 48

Fossils in the Gardiners clay
in the Jacob sand........-.--------++-++ .

Yresh Pond Landing, ketlic valley near, plate showing
Manhasset formation near. ........---0--20-e2e ee ee eee eee

 

 

 
 
  

Hempstead gravel member near... -- 153
figures SHOWIN <4 ‘45 vee. cemsncseaaeaaisteisccdd deaslbieiiecic oes 153
Herod gravel member near, figures showing.............-.. 126, 158
Montauk till member near, plate showing................2... 114

G
(rar diners Day, Ravmetlon Of o.. cninesmins siesatunuliocs meeeginaageyy 27-28

Gardiners clay, age of.
character of

   

POSSUS Me. oat piace adneaeice tayaiecccenied

on Gardiners Island, plate showing..................2222-.005 110
OFigin (Of MAMET: ei susad dacs: GS aw aaeadai alias deateteind ai te 92
relation of, to older deposits.............22.2....0002200eee eee 94

source of materials of ae
SELUCEING: Of oioss sicc scarce sismsvsinresaisrewters a sineesicialeucis 2 ws sasiteeee eae
Phaichkmess Ofesc.isietccimaemmclececiiiiss acadciiien oe aoe Anerisens
upper contact of, character of.........-....
wells penetrating, 2. ccicene-ascesancesoneeccues os
Gardiners interglacial stage, events of
Gardiners Island, fossils on...........02..200-002-0 000 cence eeeeee
Gardiners clay on
sections of, figure showing

 

 
  
 
   
 
 
   

PE CN ae item Gxeatoamnns Ramundiacen as ate
Hempstead gravel member on............-2....022-.0222 cece ee
figure showing cc. scmccseed esearawevier ss cesta oe
Herod gravel member on - 129
Fipares GROWING cage canoas ss wermceuverepeyerans 100, 110, 129, 146
PaCOU S8Hd Wine eeveencsmy sa teadeseni nl ie accewmwiwh ne one 110-111

figures showing.

plate showing....
Jameco gravel on, possibility of.
Montauk till member on.
figures showing.........

section near Cherry Hill Point................22.22..000020005
section on, near Eastern Plain Point, figure showing.........
section on northeast shore of, figure showing
Wisconsin tillom.cica.scicicisce oe ucios snontsningiewe ss yeresecaenes
Geologic features, list Of....2. sss oscsaueseacec cesses dhesececen
Geologic map, character of........
Glaciation, Hempstead, summary of.
Jameco, summary of.....-...
Mannetto, summary of..............22. 22.02 e cece eee eee
MOUIAU: SUTIIATY Ol oo sccaitescnsxe senccmmaaaaas eewmavinaies
Vineyard, summary of
Wisconsin, sketch map showing extent of
Wisconsin, summary of.............02.2...2.2.02 ee eee
Glen Cove, Cretaceous outcrop at:
Montauk till member near .
ABUT SHOWING es. 5.cfes.nechasaccscisie eoaeien acres Shenatevaeeed

record of F. E. Willets’s well near
Gneiss, Fordham, occurrence of.............220002 0000 ec eeeeeeeee
Gravels on Lloyd Neck, plate showing
Great Neck, Huntington, Cretaceous outcrops on.............-... 7

100, 110, 129

  
  
 
  
 
 
  
  
 
 
 
 

  

Mannetto gravel Ottsi:s2sjcise oxsoceees aa aseceane £4 Fae ease 83
PILL Moraes. OMe wisn creenpacevsiee ve Nee Says nine eeeaateraseuns ade 35
Great Neck, North Hempstead, Hempstead gravel member on... 152

Herod gravel member on...
Manhasset formation on.......2.......000.0222cee scene eeeeees

  
 
  

topographic map of
Great Peconic Bay, formation of.................00.02.2...- ae
Great South beaches, dunes of....-........2....022000-0008 Bice
Greenport, Montauk till member near.....................220.5

Montauk till member near, figures showing............

record of well of Greenport waterworks..........
Gull Island, record of United States Army well on

H.

Halesite, record of wellof Huntington Light & Power Co. near ....
Half Hollow Hills, Manhasset formation in
DTI ER WEL IN ots ce iaeinern See eat aaias naor iearndecdercatn
Montauk tillmember in, probable deposit of..................
Hallock Landing, Gardiners clay near, evidence of
Herod gravel member near, figure showing..........
JaCOb SANA MEAs soss4 asedeoe caw vase scepsingice saammriaed

 
 

 

  

 

 

 

  
 
 
 
 
  

 

 

INDEX.
Page. Page.
Hallock Landing, section west of, figure showing................. 98 | Jacob Till, Jacob sand at amd nears .c... 5 escascesass veever era 109-110
Hampton Beach, description of... 22... 2.2.02... 0.00. c eee e ees 177-178 * ATP UPOR SHG WANG ioia.c.tc dctcoieied-niaiassicuk pesinigiereielast aaa csaeceeisale ses 109
Harbor Hill moraine, bowldery part of, plate showing............ 32 Jameco gravel at, possible occurrence of.......-..-.2...--2-+- 89
character and source of material in -- 169 section near, figures showing
istributionr ol ows wee ance owacmiooae wa sesaieiiesceceauindacce 169-172 | Jacob sand age ‘Ol: :cisssccicc vecsssiesuits veicemsnelawiacins oy cadieen
origin. and exten tiOle nc. csesads 4004 vas accnaess nettens ee eeeds 168 GHATACTEL Of scons ceesaeas boaew eeu mex ny Recents Seas Eanes
outwash plain along, plate showing...............2......-.-- 32 GorrelationsiOf. (202.4 2.4.07 6. seccee
profile of, figure showing... . 2.2.22... 2... eee cee cece eee eee 32 GUISEEN DU GION: Of 5 ace iiccitictorsierg acnonsizecsasenaj sez sis soe eiareleiey aceicle deanstnste 108-113
Hauppauge, moraine near, plate showing ne 34 AOGSUS I so epcsesetnceredeedtas tenes -- 111, 113-114
Hempstead glacial substage, events of... 2.2... 222 022.222 eee ee eee 208 on Gardiners Island, plate showing...............2-.2-0..-20- 110
Hempstead gravel member, age of... .. 2.2... 2.622. .e cece eee eee ee 157 Telation of, to older deposits.............. ..-.2ee eee eee eee
character of... -<..26.sese.ses5 source of
distribution of. . . structure of. .
position of..........-.. wells penetrating...............2-.2-4-
relations of, to older deposits Jacob transitional stage, events of
unconformable contact of, with Cretaceous deposits, plate Jamaica, outwash nOar. <.. ase 006 eardee sade seeniser edindmereiese si «2
SHOWN ox cratwies occtes sae aeknceise Spoaeeaeces Senate 152 till moraine near, plate showing ... zi 32
‘wells penetra ting)..sc<issinss sc'scac swage ane sewelnnd siateeneees 156-157 | Jameco glacial stage, events of.......-........22-22-0022 22 ce eee eee 197
Hempstead Harbor, Cretaceous outcrops near............2...--.- 6S } Jameco gravel, AG0 Ofesciwascss sevevsressiwy 2s Uekew deat rat seed 92
Gardiners Clay at. sc.:05 sosss8s seeds scess es 96 CharactenriOlecee<jasccuictenkeecgenes
Herod gravel member near 125 COrTelatiOns: Of. ois o.2cjecses pees oeiiensoe
Jacob sand near. .............. 6... e eee eee eee : 108 distribution of. a
Manhasset formation near............-------220..222e ee eee eee 116 OFIPIM Ol NAMEOl vanccasasaeas sete meena eee emai aamatt 85
Manhasset plateaus near, plate showing.............--..----- 32 relations of, to older deposits.......2..... 05.02. e cece cece ee 88
Mannetto gravel near 8 83 oe
section north of Weeks Point on, figure showing.........--.- 108 , Wells penetrating: .i.c.cciwe oi eas cee seeds va sya veer ceeepaawes ue

Hempstead, Manhasset formation in
Outwash Near. <2. ssosessceteee thei
Hempstead Plains, outwash character of... -
SETUCTUIE Ofc tetdee nies WGdieiieie daese :
Hempstead time, uplift in... 22.22.22... 22 eee eee eee ee
Herod glacial substage, events of........-......22-22-2--22-0--20-
Subsidence ins... sso; ssigsccsccins sacemsscininns
Herod gravel member, age of.
character of, in Centraland Eastern Long Island.......... 122-123
in Western Long Island
distribution of.............222...22---
on Gardiners Island, plate showing.... :
POSIION Of assess t wwtnensaae see easecaseceteam essed sone
pseudobedding in, figure showing.................-..2-------
relation of, to other deposits

  
 
 
 
 
 
  
  

section of, near Quince Tree Landing, figure showing. ......-- 124
Structure Of. os ...ccdcseeated ceeweaess See eseaeng ce tederoass 124
wells penetrating.........--.----.2--. 202s eee eee eee eee 130-132
Herod Point, Herod gravel member near, figure showing.......-- 126
Hewlett Point, record of G. B. Wilson’s well near.............--- 112
Hicksville, confluent fans near. .....-..-.---2--2+-s+ee eee eee eee 37
High Hill, morainal character of... ...........22- +0202 eee ee eee 32

relation of, to the Ronkonkoma moraine
History, geologic, outline of...........---- +--+. eee eee ee eee

 

 

 

 

  

 

 

Hog Creek Point, Hempstead gravel member near..........----- 155
Hempstead gravel member near, figures showing... 128, 142, 143, 155
Montauk till member near. ......-.----.---- 142-143

figures showing...........-..----- 142,143

Hog Neck, Gardiners Clay on, evidence of.........-.-..--+-++---- 99
Jameco gravel on, possible occurrence of........--.-------+++- 89
Montauk till member on 142

Hollick, Arthur, acknowledgments to.....------.-+-+++++25--+-++ 3

Hooks, formation of .......-.-..------- +2 2-25 cece eee eee eee ee eee 179

Hoppers. See Amphitheaters.

Hudson River, rock channel of, origin of. ...........-----+++++++- 62-64
rock channel of, probable depth of.....-...-..-- oy 61
submarine channels of, cross section of, figure showing... ..-.. 61

description of. ....-..-...02-e cee eee e cece eee cece eee ees 61-62
map showing 60
relations of, figure showing.......------.------+-++++----- 61

Huntington, Manhasset formation near... .......-.-------------- 116
outwash near... 2.22.22. 2.2 eee eee eee eee ee teens 173-174

ds

Ice, shove and drag by ......------.4--02 2202 eee e eee erect e tees 34-35

Isabella Beach, section of, figure showing ..........-..--.-------+ 102

Islets, joining of, to main island........--.--------+++-+++ee- +++ 178-179

J.

Jacob Hill, Gardiners clay at.....-..-.-.-- 98

Hempstead gravel member near, 154
figures Showings... cascncances sedawenese eterenccteny ew sne 154
Herod gravel member near, figures showing ......-.----..-- 109, 143

 

Jameco time, subsidence in.................-.2----2--22----200-
Jamesburg loam, deposits resembling

Kettle chains, near Bridgehampton, plate showing............-..
OXAMIPIES Ol a2 caiceecctsasinw Gases ctsinceewseses
northwest of Riverhead, plate showing...
Kettle channels, character of............-.--
character of, figure showing.....-..--...-.--.2. 00 - eee eee eens
Kettle plains, character and examples of..............--2.--2.-0-0-
profile of, figure showing
Kettle valleys, branching, example of, plate showing
example of, near Bridgehampton, plate showing
near Fresh Pond Landing, plate showing....
formation and examples of.........-..-..-
formation of, figures showing.............. :
northwest of Riverhead, plate showing........-...-.-.2----4-
Kettles, double, examples of.........-.....2--2-- 2222s eee eee eee eee
elevated rims of, formation of. 3
formation of, figures showing...............--.-----2-24-
from buried ice blocks, formation of...............-..--.--26-
formation of, figure showing.......-.
from projecting ice masses, character of
formation 0f-=...¢¢2..2.-.s:sasanegeeceeseeees
figure showing...
slopes of sides of... ..
figure showing...

 

 

 
 
   
  
  
  

of doubtful origin, examples of...............222...22-..205-5

of the Manhasset surface, formation of

of the outwash deposits, character and varieties of............

of the stratified moraines, character of...........-2..---.--2--

of the till moraines, character of

origin and varieties of...........--

relation of channels to.........---.

terraced , formation.Of os.ccc202ecacaimeaseewenenetncenes vases
formation of, figures showing...........-.--.--22+-.22-00++

typical forms of, examples of................--2--2---2-- 0202

Lafayette formation, deposition of
OVIONCS Oli: dacinceigs SFseslakwekuiges Hae addons ses aeeetE
Lake Ronkonkoma, topographic features near, plate showing.....
Landslides, area of, at Broken Ground, plates showing........ 54,
causes and examples of
displacement in, figure showing. .........--.------+2+-+++++--
Lattingtown, Cretaceous outcrop near........--..---2..+-2 eee eee
Lignite, occurrence of
Literature on Long Island, periods of............-...------+---+---

 

 

 

, 55, 56

 

69

 

4-20
228

 

 

   

INDEX.
Page.

Little Neck, Huntington, Cretaceous deposits on................. 71 | Mannetto glacial stage, events of..........222.2.002eeeeeeeeeeee
Cretaceous clays on, plate showing 82 interglacial period following, events of
Hempstead gravel member on....-.......2..22.-202000-. 200s 153 | Mannetto gravel, age of. .

MgUreBhOWANG cioses zaps. aiecancuy ce akieeeeasaydenes ey 153 CHARA CHET Of a ccs sustacraaceeecacmcacenieueides
Mannetto gravel on 83
Montauk till member on... .... 22.2022... 2ccece cece tec e eee e ee 137
unconformable contact between Hempstead gravel member
and Cretaceous deposits on, plate showing............ 152
Little Neck Bay, Herod gravel member west of.................- 125 origin of name of

Wisconsin till near 2
Little Peconic Bay, formation of
Lioyd. Beach, section north Of- ..<cc0c: seccisecilos cowueeaces cease
Lloyd Neck, clays on, section of .

Cretaceous: deposits! 00. e.c6.xies 0 soncaauesveencdees a vEEeeEe

plate ShOWiNg: .<.ccus exciecaeeese assy eeuesks oxoeeeeeseenes
SOCUONOM oa rss eae easier ee eee ee aeaaans

Gardiners clay on, possible exposure of..

gravels on, plate showing............---- ‘

Hempstead gravel member on.......--..2---.2--22+-002 222+

figures SHOWING 22s itas onz ences panzesucie res ceeds ae ae

Jacob sand absent from... 222 sccc.ssessscesees enemies

Manhasset plateaus near, figure showing...-.....-.........--

Manmetto gravel One... -excsesepedseses ecyeres emery coeree eee

Montauk till member on.

figures showing. -. --
plate showing..........

Wisconsin till on, plate showing
Lloyd sand, application of the term...................-..-.2---..
Long Beach, location of. -......-....-.-2-.-.-22222---5

record of well of Long Beach Association at.............--.--
Long Island, cross sections of, figure showing................-..--

  
   
 
   
   
 
 
 
  

 

 

PKCNCIOS PLOMUCING + Hoe wisy mse erremeeesuyNeomees yeeeeee
Peologie Msp Ole. veeacaueecmess oeesecies es Wee ates
geologic relations of._..
index map showing. -
IOCATION O les. ut Sepaecctecedibh secede desea tome ogee e2
north-south profile of, figure showing................2.2------
topographiowap Ole cuc.cscsccsmarcas 33 teense wane ecices

Long Island City, Wisconsin tillin..............2...22.22.2...- 160-161
Long Island Sound, Cretaceous structure and-submarine channels
of, map showing
development of......--
later channels in

  

 

  

 

 

  
   
 
  

   
  
 
  
 
 
 
 
 
 
 
 
 
  

Luce Landing, Herod gravel member near, figure showing........ 140
Montauk till member near...-...-..-.2-22-0--02 02-22 eee eee 139-140
figures showing 109, 140, 154
section east of 139

M.

Manhasset formation, belts formed by...........--..----------+ 119-121
COTOlATIONS OM sa.c sean GedeGedaahw Sees seams eEee cases 220-221
distribution of - 115-121
folded beds of, plates showing...............-.-...---- - 114, 152
older valleys in ... 45-46
Origin: of nNAMG Ole scx ec aeeecsosesesesesases ce amewmaciaes vd ode 114-115
plateausioll. su specongeseseecscascinsnimcencion apadenuinaces sees 30-31

figures showing. - - 30,31
SourCe Of Material Of.cs2.. sescesseerrenssesads yeas chase ee 123-124

  

topography formed by, figure showing..............-.-..----
plates showing

Wells. PONGITALNG ccc icewereweneranessmkienesererinn
Manhasset glacial stage, events of....-....-....--------
Manhasset Neck, Hempstead gravel member on
Hempstead gravel member on, figure showing...........----
Herod gravel member on
figure showing... -.
Manhasset formation on...
Mannetto gravel on.-..........-------- 2-2 ee eee eee eee
Montauk till member on
figure showing a

petrea tal Gepost WiBen xa sacncen ss soereeadan ser rewenaiesuememan
topographic map Of....-.-..2. 022-0 - ee eee ence eee eee eens
undermined peat on, plate showing
Manhasset plateau, figures showing.....-....--.-.----
plate showing :
Manhattan Beach, location of......-..-....-.--+---2-+eee eee eee

    
 
  
 
 

relations of, to older deposits
figure showing
SETUCUOTG Of yes c cd ccadeistanseccenee Rnaesvaee
topography of, plate showing
WANG S Mi cc) sAjcd giooas Lot cee eysieiaaemresimeemenesenoeiemaaeee
wells penetrating
Mannetto Hills, Manhasset formation near
Mannetto: gravel. mt .a0cecieoesserize «ye eoneaaean ok ceeeeeeee st
valleys Mie cvxceseeyoecacaceves vexeeedce
region of, topographic map of
Mannetto plateau, remnant of
Mannetto time, subsidence in.............2.2222-.222--0-222----
Marine deposits, kinds and occurrence of
Marl, beds containing, section of
Marshes, fresh, formation Of. . ...1ccceeuseecee cesses steeercnees
produced by damming streams
salt, formation of.

 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 

Mattituck, kettle valley near, plate showing...

Manhasset formation near..............--2--2--2-222-22-200-
Mattituck Inlet, former character of
Melville, Cretaceous exposure near

Cretaceous exposure near, section of.

Mannetto gravel Near. .c.cs2cccecwsossessacnstec ens ceanenese ce

marly beds near, section of........-.-.-.----

Melville channels, description of
Middle Island, Manhasset formation near.............-----
topographic features near, plate showing... .-

Wisconsin till near.........-----.----2-2----
Mill Neck, Cretaceous outcrop on............--...
Miller Place, end of the Manhasset plateau near
Miocene deposits, evidence of.
Miocene time, events of.

   

Montauk, bluff section near ‘‘ First House” at...................- 156
Montauk glacial substage, events of.--...........2..2--22.---00- 199-208
SURI 6 TH uve desveceedesumaryyd ind ctckawns 219
Montauk peninsula, fosse channels on, plate showing. . 2 34
Hempstead gravel member on.................------------- 155-156

figures showing
HGPOd PTA VCROM: ss, 2054 nacimaeeasevaes Se ceocensine vier Raclremetaienne
figures showing... ........-.0+0s------
Montauk till member on
figures showing.........-

 

 

  
 
  
  

 

section on, figure showing 151
Montauk Point, Gardiners clay on. ......2.2.. 22.0.0 2.2. cee eee eee 99
JACOBS GINGA: cz ienc.ucciseiccteninsntarseees Dia dedeemawerabeanenes ill
figures showing... -.-.. seesaw eee were 89, 99, 107, 128
Jameco gravel on, possible occurrence of...........-.....----- 89
sections on, figures showing............. - 89,99, 107
Montauk till member, age of. . 2.22.22. .22 20... e cece eee ee eee 149-150
banded, near Friars Head, plate showing..................... 114
CHETACTONG fe 55.0.0:ka eis sacs iiran cise ous otie Boeiet -- 132-134
contact of with Wisconsin till, plate showing................- 136
CIStIDWEHON Of occec succtacatesea teacs aware seeewereee cececed 135-149
position of 132
relation of, to other deposits..........-----02ss020cceeeceeeees 134
section of, west of Hulse Landing..............2....2...--.+- 138

source of materials of
structure of. .......-...-

  

 

 
   

wells penetrating..................
Moraines, cone-shaped, formation of.

cone-shaped, profiles of, figure showing. .............-...-.-- 32
depressed, example of, near Hauppauge . 165
example of, near Port Jefferson............----2--------+- 170
near Port Jefferson, plate showing........-....--..--- 34
A GUT Ole Yee eee ir ec nu eae ee Se eae ede 33-34
relation to outwash, figure showing ....-....-........-.-- 34
due to ice shove and drag, description of...-...............-- 34-35
of sand and gravel, example of, plate showing................ 32

 
 

 

 

  
 
 

  

 

 

 

 

 

 
 

 

 

 

 

 

 

 

 
 
 
 
 
 
 
 
 
 

 
 

  

 

 

INDEX, 229
Page Page.
Moraines, ridge-shaped, example of, plate showing................ 34 | Pensauken formation, correlation with.................-..------- 223
ridge-shaped, formation of ............2....0.....20005 Plain, confluent, formation of ............0.....0000ce cece eee ees 37
stratified, normal profile of, figure showing Plainview, Mannetto gravel near...........-....2-.2.--222--020-- 82
till, character and varieties of.................... Sit avves Plants, sali-marsh, range of 213
example of, plate showing...........22..2...02-002-cee eee Pleistocene formations, correlations of..............-..--.--++++ 219-223
Mud cones near Douglaston, plate showing................-...--+ correlations of, status Of..........0.0.eeeceee ee cence ee etee ees
Mulford Point, Jameco gravel near, possible occurrence of........ 89 in New Jersey, literature of.
N record of
Napeague Beach, dunes at... 2.2.0.2... eee eee cee cece eeeee 181 Pleistocene time; Svatits Oh ee seeeereeeeeere ees
New England, correlation with deposits in. . lengths of stages a i oe
southern, index map showing............2..--.cccceeeeeecces 1 ; Position of land with reference to sea level in, figure showing. . 218
New Jorge Cr tay a its of lati ith _. | Pliocene time, events of 5
Be EROS COB OSL SO SCORTS BELO WALI sich geiesid ot 7) plum Island, Gardiners clay on 100-101
nonglacial formations in, correlation with................-. 222-223 fhe 'y Bhar tes | tnd eae As eee
Pleistonerie:dapsiails te: titerafote of «<<. Gardiners clay on, section of, figure showing..........-.-..++. 101
New Jersey State Geological Survey, acknowledgments to, note.. 222 Hempstead ptavel member on
North Fluke, bowlder beach of, plate showing.................-- 162 figure showing...........---2.22++--221+e-
Manhasset formation on.. 117 Herod gravel member ON. --..------ 22-2222 eee
IR A a ta ARUTOS SHOWING xnsnsnn onceves eruiainanonas vanes
Wisconsin till near... 0... 26. 0ee cece ce eeceeeeee cece cece 162 AD SE BU oy
Northport, Cretaceous clays near, plate showing.............-.... 82 se hears oni Eg a Se reg i 7 ate
Cretaceous outcrop near.........2.....2.2 2.2 e eee eee ee ee 7 Ree ergs ae iag ne er a aie Dee Oe ae eee
Herod gravel oa near. 125 figures showing Beer rt ere eee ee ee were
landslide area near, plates showing..................2.2.2- 54,55, 56 record of United States Army Well OW sa catutiagrareteat tian
Montauk till membernsie. esc ce 137 Port Jefferson, depressed moraine Near. -....---+--.++-+2-- 22+
fire shoWink <<. -o-ocec.c. cc sosncececaseséeceseccccen 125 depressed moraine near, plate showing
North shore, contour of, east of Port Jefferson.................... 27 Hempstead gravel Member Neate: «.xssscaenesssHresoe=mkenns
REG aoe ee te ance er Pt el tee 182 Manhasset formation TIO AR sascia.e gis iaiate cis sioeaisleteinc setae momentonts
harbors of, formation of ..........2.22-2-20cecceeeeceecececeee 25-26 Montauk till member near.
original and present cross sections of, figure showing... ... 26 Out wash Nears poser ar
Marshes Of nv5 ose seeks ve eee 185 3 plate showing. ,
searp of, formation of Bate 25 Masconsin WU DOR i oienetinsinns He 2asaindewssienns Sree ee
successive forms of, figure showing.................... 25 Port Washington, folded beds of Manhasset formation near, plate
Notched cliffs, production of......-........ 20002. c cece eee eee eens 51-52 SHOWING... 2---/2seesssnsntencdgesiascucaiacce Means tt
profile of, figure showing 52 TaCOb SANG Ab. as sncsmeeemanentnect pen keaemtenteren anes 108
record of well of Dodge estate near...............2.-.-222005- 113
oO. Pre-Cretaceous rocks, character and occurrence of..........-....-- 65-66
Oak Island Beach, location of..............2.2220000 ee eee eee e eens 178 SOCtIODS SHOWING 2652 )cxtis wercooinanaes svete sckted aoae ae ee 66
Oregon Hills, Hempstead gravel member near..............-..-- 154 | Pre-Cretaceous time, events of........-.--. 22222-22022 eee eee eee 192-193
Hempstead gravel member near, figure showing.............. 140 | Pseudokettles, varieties of......-.-..-......2 002 e eee eee eee eee 44
Montauk till member in. 140 | Pseudomoraines, character of. ... 35
MGR SHO WINE soo) oa Geasd ea dcae wemustene ieee mee eeeedets 140 example of, near Friars Head, plate showing..........-..--.- 34
Orogenic movements, Pleistocene and Recent, summary of... .. 217-219
Outwash deposits, along Harbor Hill moraine, character of_...... 172-173 Q.
along Harbor Hill moraine, distribution of................- 173-176. | Quaternary: time, events Of 2.200 2c0ec see se xceeeewees cies teeeeee 195-219
‘plate ShowiDE wc. decuicssxssncites oer deeee nh penile 32 TOPIMATIONSIOLS (ccciccpenia:e Grate. xdnavsicize azreciniesctehed sminiens at oeleeleeewe 80-185
along Ronkonkoma moraine, character and source of material R
i 166-167 ;
167-168 | Ravines, obstruction of...........2..- 2222-2 cece eee ee eee eee 52
Metede leds eek eat Lae: 167 obstruction of, figure showing - eS a ae Ae atl a ale 52
175-176 FOHMING Ole ey. 2 vetects aks ceece es enieisenedubse dak phadeace 52
Ses Serer fame See anata a hes ee 36-38 MPRA SIO WAN Eee aise ica Rhein kadacdeoaGeas heal ih oaiae 52
near Port Jefferson, plate showing. Recent time, deposits of ...-......--2--4+0ee0eeeec eee eee eee
secondary features Of........0.02.0ec2ececeeecececeecerececeee erosion scarp of, plate showing.
topography of, near Amagansett, plate showing.............. 118 events of. . ST PERSEUS ENOE STOEL Ga Se cee oa
near Southampton, plate showing. ..............2--2--02+ 11g | Red Cedar Point, Gardiners clay near............-..--+2--2+-+++- 99
Oyster Bay; Hempstend gravel member naat 152 | Retreatal deposits, nature and occurrence of..........2..224+24+- 176
Hempstead gravel member near, figure showing.............. g6 | Richmond Hill, confluent fans near. ......-...-2----2..0sseeeee
Herod gravel member near.........22...2eeeeceeeeeeeeeceeees 195 | Riverhead, dunes near.......---.--2.- 22-22-00 eec eter tense eee ees
figure ShoWiNg....2..2.0-22ceeeeeeeececeeceecsececeeceeee 125 RGttles|SOUtM Of a: cSctsaugaceesqdincis deadiege dues ans Me sekoes
ET Ais Sando oai ns scrote ke oped shatter cel baad e, 108 Manhasset formation near...........2..2--.2-2--20000. 202220
Manhasset formation near..........2..2.2.20ce0cececeeeeeeeee 116 marshes formed at
Manhasset plateaus near, figure showing.............-....---. 30 Montauk till member near..........--2---.22-0002+-02eeree ee
Montauk till member near..........-.....2-2--------2+2----+5 136 figures showing.......-..-.-- See gees tas oe pe ek
figure showing 96 moraine southwest of, plate showing. .
Wisconsin till near 161 Outwash deposits Nears. 2 .ncicsweess car enasesiogeshs oh eeaeeey
Peal deposits Nears ase: ee eseeescmsesa eas senscinee-Sasas usuode
P. Roanoke Landing, Hempstead gravel member near-..-.........- 154
Paine Landing, Herod gravel member near, figure showing....... 126 Hempstead gravel member near, figures showing........... 139, 153
Paleontologic phase, early, of Long Island geology.....-......---- 6-9 Jacob sand near, figure showing.............---.---2---2+++-- 98
Patchogue, dunes near: ses.206c0seenesecesazesees denser eeeeeceses 182 | Roanoke Point, Gardiners clay near, evidence of................. 98
Peacock Point, record of C. O. Gates’s well near..............---- 74 Herod gravel member near, figure showing..............----- 139
‘Peat: GCCUPPONCE, Of .2..2.24cqce adage nad scdesebocesedneceneseaeses 213, 214 sections east of, figure showing...............2..02.. eee eee eee 98
undermined, on Manhasset Neck, plate showing............-- 182:| Robins Island, 'Gardinersiclay OMi..2 0 .<0ss0see cceees ot aesemeners 98-99
Peconic Bay, origin of ...........----202eceeeee eee ee eee eee eeee es 27-28 Hempstead gravel member on..............-----+++----+2+-- 156
Peconic River, former course Of, .0.05ceccccss oe ccnece nes serene 28 figures showing....... 145, 156. 157
fosse' Position Ofe ..s.cie2ci re seazacauncuines Ya cememire emeceaE 120 Herod gravel member on. 128-129
Wisconsin: till Nears. sckaseiwajes seascioe viste sis eanatie ssn neces 162 figures showing............. yeeiecy aa rega aps ecb ree? 99,110, 127, 156

 

 
230

   

 

  

  

  

   

INDEX,
Page. Page.
Robins Island, Jacob sand on ......... 222.220.222.222 e ee ee eee eee 110 | Smithtown harbor, hooked sandspit at entrance to, plateshowing. 178
Jacob sand on, figures showing. /_..-............ 000022202002 99,110 | South Fluke, Herod gravel member on..............-.--------+ 127-128
Manhasset formation OM, sc. ese sehermess aeeedwei lees cae 117-118 Manhassét 16kMation Of... .cacsssecsk seecnenceasseveseseceee 118
Montauk till member on... 2... 2.2.2... 22222 e cece ee ence eee 145 W ASCONSIT tH] GI oo nce-c siavscsercectaciserae scrnseraciese so eekeeneaeene 163
figureshowing_........ 145 | South shore, marshes of..._._..........--0eeeececeeceeeeeee 183, 184-185
sections on, figure showing. ........-.--.-- i 99 MONI CRTN GS Of crapescocrecoastess helene bodaarey as extol ap Minagnnich pees ei ele eta dAieiensaie 28-29
WHSCOnsittiWOM. 2 oscc0sceceuetuneenaced 162-163 | Southampton, outwash topography near, plate showing. 118
Rockaway: Beach, location:ofs wis sccacciees scaec pes eeaniereescieee as 178 | Spartina patens association, occurrence of........... 214
Rockaway Ridge, gravel of............---2-2---+--22-e2eeee ee eee 127 | Spit, hooked, at entrance to Smithtown harbor, plate showing..... 178
Manhasset formation on. 118 | Spits, formation of.... 2.1.0.2... eee cece eee eee ee eee 177-178
Rocky Point, Cold Spring Harbor, Gardiners clay on...-......-- 96 | Springfield pumping station, well sections at..............----.-- 87
Rocky Point Landing, Gardiners clay near......-... -.. 97 | Springs, work of, in causing landslides................----------- 55-56
sections near, figures showing............-..-22-2--2--2-220 97-210 | Stony Brook, Herod gravel member near............!.-..-------- 125
Rocky Point, north of Greenport, Hempstead gravel membernear. 154 Herod gravel member near, figure showing. . 137
SeCHONSOUChiOl ace aasce jeanne Onee ences see ReWermee me @eecets 154 Montauk till member near................-. 137
Rocky Point village, Manhasset formation near.............-...- 7 figure showing......._...
outwash. deposits Mear’...... 212. ces caceeeecesccee oie cecmecces 174 | Stream channels, deposits in
Ronkonkoma moraine, character and source of material in..._. 163,164 | Subsidence, evidence of.......... 0.20. cee eee cece ee eee cece eee
distribution of.........- vida Reteye nein vlnenerensintle weld . 164-166 in Mannetto time, summary of...........2..22-.20-220-2204- 217-218
Ronkonkoma, Manhasset formation near. . 118 in Pleistocene stages, figure showing...............--.-22...- 218
profile of, figure showing...........-- s+ 22
relations of, to older deposits..........--..2-22--+.22222202000> 164 Ts
Roslyn, Manhasset formation near.......-....2----22..--2--2--05+ 116
Montauk till membernear........... 2.000200 2 2.00022 ce eee eee 135 sie Ake profile of, figure Showing. ..-..2-.--22222-02eeeesseeeeee 208
ati bwashGoposits Heated resco ya bkltae w oncceee ees. 173 | Tertiary time, deposits of...-.-....... 2.2 2-222.-2222 2c eee 79-80
Roslyn channel, description of..............--222-202-0 0020 eee e eee 115 OVOIUS Ol ise as staasuinee sees dg
Thomaston, Cretaceous outcrop at. 68

Sag Harbor, Gardiners clay near. .....-..-...------..2-22-- eee eee
Hempstead gravel member near.
OPUTES SHOWINGS weer cncegans st Retewaemanees ere sonecest
Herod gravel member near. ..-........-2.--.22-222020---06+
sections of, figures showing ...._......-.---+--+--.-------
Montauk till member near._.....-.....---2 222222222 eee eee eee
figures showing... .-
Salisbury, R. D., cited..... :
Sands, mmagnetie. and garnetiferous, nature and distribution of. 179-180
Sankaty beds of Woodworth and of Veatch, difference between . 92
Scarp, great inland, of Western Long Island , character and origin of 53-54

 

 

 

  

inner, in Broken Ground landslip area, plate showing .......-. 56
modified, examples of, plate showing.._.....-.......-...-----. 52
north shore, how formed......-... 25
pre- Wisconsin, plate showing. - 52
Recent, plate showing ........---.- ase 52
Scarps, inland, character and examples of...........-.....-------- 53
Scope of this Te port. <sjc0sssccaccccesaceteecsed ekaswdes une aees 3, 20-22
Scuttle Hole kettle valley, description of..............2.2..2.-.-2-+- 42-43
Sea Cliff, Cretaceous outcrops at.......--.-. 2.22 eee eee ee eee eee 69
Sebonac Neck, Gardiners clay on. 99
Selden, dunesnear................----- 182
semidune surface near, plate showing..........-... * 182
Shelter Island, Herod gravel member on, indications of...........- 129

Jacob sand on
Manhasset formation on.......-.22..--2--00+0--2- 22-2 e eee
Montauk till member on, probability of..........--.-..---.-
Wisconsin tllon...... sccscnsssucescce vee
Shinnecock Bay, Herod gravel member near 2
sections in Herod gravel member near, figures showing .
Manhasset formation near... ......2.2.2-2- sce en cence ee en eee
Shinnecock Canal, Gardiners clay near...
Hempstead gravel member near
TRUS SHOWIN Sox as iets Ginineechexs semasiSeacece ew aySS
Montauk till member near.............2-.---.---2--2- 00-20
Figures ShoWiNg. sc cacscceceracumnce cer sesereneres verse
Shinnecock Hills, dunes at.......
partly morainal character of..

 

 

   
   

  

 

relation of, to the Ronkonkoma m THOTOINO Ls. scccrecce cisine se rivixarwiete 165
Short. Beach, location Of: <v.cmcvssnoeesensaceeerercees yereueessss 178
Smithtown, dendritic drainage system at..........--...22..-2.66++ 26

Manhasset formation near..........--.2...-..2--2-2-2-02 2-2 eee 116

outwashidéposits COM. os cnacasnacaneawamveunatemsest teteeetne 174

topographic features near, plate showing. ..... 46
Smithtown Bay, Hempstead gravel member near. . . 153

Hempstead gravel member near, figure showing - 137
Smithtown driftless area, location and features of... . 162

 

   
  
  
 
 

Till, kettle rim of, figure showing..........
Montauk, banding of............22........
moraine of, near Jamaica, plate showing.

Till sheet, character of
Wis IDWEOWIOL eure wu edientnwy eee ecweeinenie cemosavus osiecioae
figure showing relations and structure of. .__.

174

 

 

 

 

 

  
 
 
 

PIG SO Of ees. Sito ise cereals nm sciegaisice
source of material of. . ._ ‘
Topography, significance of.........-2.. 22-2022. 22 cece ee eee eee
Trenton gravel, relations of, to Cape May terraces, figure show-
Dil fion cpccasumaidnniantrawctnnemale areca mdaiuds snaxminedsh 222
U,
United States, eastern, physiographic provinces of, map showing. 2
Uplift, Pleistocene, figure showing - 218
post-Mannetto, summary of..._......222-2 222.022 22 eee eee eee 212
¥.
Valley Stream, section near, figure showing.....................- 89
Valleys associated with the moraines, varieties of.............--- 46-48
Valleys, difference in steepness of banks of............... - 50-51
difference in steepness of banks of, figure showing... . 50°
hanging, production of 52
production of, figure showing...............2..-..-- E 52
Mannetto, formation and examples of................-..22--- “44-45
north shore, original and present cross sections of, figure show-

i 26:
post-Wisconsin, types and formation of....................... 51-52
pre-Mannetto, influence of..........2...22..022202-222ee cece eee 44

Veatch, A. C., acknowledgments to.....-....-.-.. 3
Vineyard formation, character and occurrences of. - 157-158

Vineyard interglacial stage, correlations of...

 
 

 

events of
Wey

Wading River, Manhasset, formation near._.................-.--- 117
Montauk till member near. - 138
figure showing..... ae 126
Water, work of 212.
Waves, work of, in causing landslides. ....................2...--- 55.
Wells penetrating Gardiners clay, list of .............0-02...-.- 102-103.
Hempstead gravel member, list of...........-2.2.22...-2-.2-- 157
Herod gravel member, list of.........22..22...202022.-00--- 130-132

TAMECO:STAVel, ISH OLS line ccs ces Ae en dagaies Be Dawn
Manhasset formation, list of .
Mannetto gravel, list of .....-..2.022 2-22-0220 220 e eee eee eee
Montauk till member, list of............0...2-2-2-0-2-2---0-
West Hill, possible Cretaceous core of

 
INDEX. 231

Page. Page.
West Hills, H. L. Stimpson’s well in, samples from_............. 84 | Wisconsin till, contact of, with Montauk till member, plateshowing. 136
West Neck, Herod gravel member on............... .. 125 | Wisconsin time, subsidence in.............22.. 0.20.00. e eee eee eee 219

   
 
  
 
   

record of Mrs. M. H. Clots’s well on 113 | Woodhull Landing, Gardiners clay at, possible exposure of ......- 97

  

Wheatley, topography near, plate showing ma Herod gravel member near...........22-.02-2222ece eee ee eee 126
Wheatley Hills, Mannetto gravel in....................22-.0-.0-. MP ULG AHOWAN P22 .5 << ocenenmecycae He tamu ERES MEDRRE RD 125
Mannetto valleys in... 2.2.22... eee cece ee eee section of, figure Showing..........--...2--...-eecer eee ee 125
outwash deposits near.. wg section at top of bluffs near, figure showing. 210
Wind, work of.............. va Woodville Landing, Jacob sand near..............--2-02-22- 22 eee
Wind deposits, character and distribution of...... =e Jacob sand near, figure showing ..................-.0--2--00-
Winkle Point, Mannetto gravel near, section of 83 | Woodworth, J. B., cited...............-.----
“Wistanist c1Fift, CORP ATON OL. 00 oo ccnene tarmewnmunsen sonneneee Wyandanch, Cretaceous outcrops near
IVAISIONSO bic.c3 cc. ae cee naenains sekermarses omeeeme Y
Wisconsin glacial stage, events of .
Wisconsin till, banded, in Dix Hills, plate showing............... 162 | Yaphank, Manhasset formation near..............------------+-+ 118

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U. S. GEOLOGICAL SURVEY
GEORGE OTIS SMITH, DIRECTOR

 

 

 

 

 

 

 

 

 

     
 

 

 

 

 

 

 

 

55/ 3 50’ 4 45’ 5 A0' 6
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GEOLOGIC MAP OF

LONG ISLAND, NEW YORK

BY MYRON L. FULLER

BASE ENGRAVED FROM U.S.GEOLOGICAL SURVEY TOPOGRAPHIC SHEETS

1
Scale 125,000

1 oO ] 2? 3 4 ny

 
 
   

 

 

 

 

 

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SECrLES

Pleistocene

 

TT PECEND

 

Beach deposits
Gravelly near blurs but nearly rree from pebbles
garnet

at a distance. Carry magnetite and |

 

Dune sand ,
Meunly quartz sand but with some magnetite ard
Se. Generally high on coasts but locally vay

oe welerlor

    

Swamp and marsh deposits
Include both rresh and saltwater accurralattor

 

T
Generally less than 5 feet thick, loose and oxidized;
raredy banded

 

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cenerally more than 5 feet thick, loose ard
oxidized, rardy bardet

   
 
 

 

Retreatal outwash
trregular sand plains of kettle-plain type rormed
north of Harbor Hill moraine

Outwash in channels
fnolules AEposuts occupying Aannes clit th
outwash depostts associated with both
MOPALNES

 

Harbor Hill moraine
Carrtes mitch till, especially at west end of
island, many large bowlders or north fluke

  

Outwash from ice along

a Harbor Full Tnoreine
Sloping sandy plains, the osits generally of,
rant Caches, Ying on the Manhiosoet nae ,

heen shows through here and there

 

@ @,8°"s
Thin outwash from ice along Harbor Hill
moraine,;with outcrops of Manhasset
Very thin dep its, aOR. Peis s;underty
ery osits, For sandy, s 2
Manhasset formation. shows Tough and in reer
controls the topography

 
 

Undifferentiated outwash

from Ronkonkoma and Harbor

Hull moraines, where separation ts impracticable

= Ronis nkoma moraine
evi ravelly or sandy ; stro;
ttle od. p43 Diana i

Outwash from ice along
ae Ronkonkoma moraine
pi Sa. y plains, tt lve
Manhasee Pormationiwh toh » SHOWS rough
Places

 

 

QUATERNARY

 

 
GEOLOGIC MAP OF

ONG ISLAND, NEW YORK

BY MYRON L. FULLER +

3ASE ENGRAVED FROM U.S.GEOLOGICAL SURVEY TOPOGRAPHIC SHEETS

ul
Seale 125,000

1 Oo 1 2 3 4 5 6 7 8 oy 10 Miles
=== ——S—— SSS SaaS —— 0 eel

l oO 1 2 3 4 5 6 a 8 9 10 Kilometers
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Datum ts mean sea level at Willets Point

TOTS

 

 

Pleistocene sertes

 

Outwash feom ik ice along
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Sto; sandy plains, the osus geerally of no
gre Une bing on th the Manhasset formeakton ,
‘which shows ae here and there

 

Wisconstn. stag

e
Thin outwash fron ice antoris Harbor Hill
moraine,with outcrops of Manhasset
os 2 formation en
Very tin oOsus, forming Saray Plas; Urderly a
METS ADEE shows through and in plices
controls the topography

QUATERNARY

 

Undifferentiated outwash
Lreludes materials trom Ronkonkoma ard Harbor
Hill moraines, where separation ts tmpracticable

 

 

Ronkonkoma moraine
LTeVaL EGS G, gravelly or sandy; strong
kettle Snob topograph wy

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i ee oe
SlOptng Sa. plas, the ost ly on
Manhasset ‘ormation;which shows a
ir places

 

Thin outwash from ice along Ronkonkoma
moraine with outcrops of Manhasset
formation
Very thin eee forming sandy plains; the
underlying Manhasset formation shows through
aradin Ee controts the topography

Ea

Manhasset formation
Includes the Herod gravel, Montauk til,
and Hempstead gravel members

Montauk till member

of Manhasset t formation
Generally banded. unoxidtzed till ;
shown only where. ees ‘from other members

Jacob sand and Gardiners clay
Former, fine graytsh ee te, SANAS, ele,
stuf brown, gray, red, black ata ‘lay

Murnvette gravel
Stained guartz Seve wth rotten granite
pererr and bowlder:

Clays and sands
of many colors

 

 

 

 
 
    

 

  

»

 

CRETACEOUS

Note - The patterns of the glacial deposits
are printed over the colors representing the
Manhasset and Mannetto formations,the extent
of which under cover is thus shown.

!

26 55 27

JULIUS BIEN CO LITH N.Y

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