s 40L- H4J. £ y^ tO 10 CO CD CD c: 2 33 O s " ■< o 3D o «< Q Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/earthhistoryfiel1947illi feaA^w c^r rile S' Earth History Field Trip for High School Science Teachers West Chicago,. Illinois. Oct. 11. 1947 Sponsored by State Geological Survey Mr Mc Leighton, Chief Gilbert 0. Raasch, Conference Leader General Instructions: 1, Pleaso be prepared to leave promptly at 9; 00 a.M. 2. Cars will assemble at West Chicago High School, 3. Participants will provide themselves with lunches before starting. 4, At scheduled stops, please assemble promptly near leader to hear his dis- cussion before scattering for individual examination of points of interest; also please be prompt to leave upon signal, This is especially desirable if the group is large. Instructions for Car Drivers: To expedite the trip and for safety, please 1, Identify your car by attaching one of the tags provided. 2, Have your oar in line before the trip starts, 3, Follow carefully ana keep fairly close to the car ahead, with due regard to safety r 4: Keep all gaps in the caravan closed, especially while traveling through the city, in order to prevent other cars from inserting themselves in the caravan or crossing the caravan at intersections, 5,- Watch the cars ahead and behind for signals. 6,-, Keep your place in the caravan so far as possible; do not attempt to pass ahead of any in the caravan unless they drop out of line, nor to gain an advanced position at stops, n . If for accident or other reason you drop out of line, let those following you proceed, except for such help as may be needed; in case of accident to the rear car of the caravan, signal those ahead. 8-> Any car dropping out of line shall take up the rear when rejoining the caravan 9. : When parking in lino at stops, draw close to the car ahead; when parking parallel, do not leavo unnecessary space between cars. 10. . Ono passenger in each car, preferably sitting beside the driver, should read the itinerary and keep the driver adequately informed with regard to stops, turns, etc ^ a .;-■' •. ■;: • v«s3r * -2- ITINERARY. 0.0 West Chicago Community High School. S. D. Bishop, Principal* Assemble cars on oast sido of Joliet Street, headed north, 0.2 Stop, Geneva St,; tarn left (West)o 0.3 Turn right (North; on Wood St, 0.5 Turn right (East) or. Washington St e 1.1 Turn left (North) on Ingalton St 2.4 Stop, Junction with Highway G9; continue north on 5?, 3.4 STopL C r '0?s Highway 64 Highway 59 travels more or less along the crest of the West Chicago Moraine, which marks the maximum extent of the Cary Ice Sheet of the Wisconsin Glacjol Stage. Note flat country to west, which is outwash plain forced in front of the moraine.. We travel along the moraine for a distance of 6 miles. The rolling ccpography, ponds and undrainod depressions s occasional large erratic boulders are characteristic of terminal mcrainos. The "Yost Chicane Moraine is part of the Valparaiso Morainic System, a very prominent topographic feature extending widely through the western Great Lakes Region., 8.1 Cross road-, Turn left ( West), 8.5 STOP I. Short stop to examine exposure of typical glacial till :n road cut. 9.2 STOP II. West odgo of Wost Chicago Moraine, Note bill exposure and flat outwash plain lying to west of the moraine., 9.7 Caution, R- R.. crossing, 11.4 Highway Junction Turn right (North), 11.7 Stop ., Highway Junction, Turn left (West), 13.1 STOP III. Gravel pit in outwash terrace (formed at v 'ost Chicago Stage). Note sorting and stratification of sand and gravel, absence of clay, better rounding of pebbles (as compared with till), 13.2 Turn right (North) 13.5 Turn lefb (West) and cross R. R. and Fox River « 13.9 Stop . Highway Jet, Turn left (South') on Highway 31 , 16.3 STOP IV, Fox River Stone Co. Quarry, Quarrj xpeses about 35 foot of thin-bedded Silurian- Kankakee Dolomite, which contains fos-ils in- cluding corals, crinoids, hydrocorallines,, bryozoa, brachiopods, gastropods, cephalopoda, trilobites. At top of quarry is a "smooth surface" which widely marks the top of the Kankakee Formation, Above this may be seen a few inches of the buffy and more porous Joliet Dolomite, also Silurian in age, 16.8 SILVERGLEN: This glen cuts down through tho Silurian Dolomite into the Maquoketa Shale of Ordovician Age. The shale and included dolomite layers are fossiliferous (Visit to this locality will depend on the size of the party - limited parking space only)* 21 1 Stop , Turn left (East) in St., Charles. 21*3 Sto p" lig ht. Turn right (South), 23.4 Stop sign. State Street, Geneva. Continue ahead. 26 * 2 Stop light in Batavia. Straight ahead, 25.6 Turn left into Quarry Park, Batavia. LUNCH STOP, (V). 25 „6 Leave Quarry Park and turn right (North) on Highway 31. 27,0 Step light. Turn right (East) and cross Fox River. 27,3 Stop light , Turn right (South) on Highway 25, 27.7 STOP VI. Exposure of upper beds of Joliet Formation in quarry. -3- This is the upper part of this Middle Silurian formation, characterized by layers full of white chert nodules, lelow this are more clayey dolomites, the bedding planes of which are marked by the furrows of unknown organisms that scavenged the ancient sea bottom Noto conspicuous west dip. 27,7 Reverse route north en Highway 2 5 c 28.0 Sto p light; Turn loft (West) and cross Fox River. 28.4 Stop li ght j Turn left (South) on Highway 31. 28.7 Turn rigUS ("Jest) 30,7 Turn left (South) on side road, Route for next two miles passes over a portion of the Marseilles Moraine, Note marshes and undrained de- pressions „ 32.7 Turn sharp right (North), 33.8 STGF VII. Peat Deposit from extinct lake which once occupied a deprersior in old channel of the "Fox River Cut-off", 34.1 Sto p, Turn left (^Jost) on Black top road (Batavia Road). For next twe miles, to Eu.ld Knob, route crosses Fox Rivor Cut-off channel. (For further inf orma+'ion see section on geologic history),, 36.1 Bald Knob, Cross Sugar Grove - Genevj Road- Bald I'nob is made up primarily of glaei&l til 1 of Gilbert's age. 'hut has gravel of Marseilles Age on its summit . Johnson ; s Mound, 2 miles northwest is a true kame of the "moulin' : type Both those features suggest that Gilbert's iue became stagnant, and por'.ior.s of it melted ^ery slowly, 36.6 Junction with road north to LaFxc, Centime west, Route for next tw> miles over Gilberts ground moraine, in place.-; overlain by Marseilles outwe.shr 39.2 STOF VIII, Gravel pit in kame, A number of kames were formed along the small oast-west valley here, indicating it was a drainage. Shanne} under the Gilberts glacier, 39.4 Stop Highway 4 n , Turn left (South) on 47. 41.8 Turn right ("Test), leaving highway 47. 42.5 Cross Kanoville Esker, Deep gravel pit on left u 42.8 Turn left (Southeast). Kaneville Esker on left. 44*0 Stop, Junction with Highway 47. Continue ahead on Highway 47, Kaneville Esker on left, 44,8 Turn left (Northeast) and cross creek. 45 6 STOP IX., Gravel Fit in Kaneville Esker. This Esker marks the channel of a glacial stream which flowed between ice walls under the Gilbert's Glacier. This is the largest esker in Illinois, It extends 5 miles northwest from this pit and 2 l/2 miles easterly,, In the latter direction it was over-ridden by the ice of the Marseilles Glacier which advanced almost to this point. Sugar Grove is two miles south; Aurora 6 miles east, BON VOYAGE; GENERALIZED GEOLOGIC COLUMN FOR WEST CHICAGO AREA. Prepared by the Illinois State Geological Survey ERAS © rH «H Ctf o •H £ •H ^ j~ O 3 w -P P=H O fl ti 03 ^ » I <*! r-i j o h © '•J , < a r e: mi an Pennsylvanian Mississippi an <+■( to o -o T 10 U (0 © •p 05 O ,Q © -P -< (D Prooerozoic Archeozoic Devonian Silurian Ordcvician Cambrian Pliocene Miocene Oligocene Eocene Upper Lower Upper Middle Lower Upper Middle Lower FORMAT I 0NS *Recent post-glacial stage ♦Wisconsin glacial stage ♦Sangamon intorglacial stage *Illinoian glacial stage Yarmouth intorglacial stage Kansan glacial stage Aftonian intorglacial stage Nebrasican glacial stage Not present in '.Test Chicago Area Present in extreme sou '.horn Illinois only Hot present in Illinois Not present in Illinois Not present in Illinois Not present in West Chicago Area Not present in West Chicago Area Not present in West Chicago Area Joliet dolomite Kankakee lclcmite Eagewood dolomite Maquoketa shales & limestones Dolomites & sandstones lying 200 feet below surface Sandstones and dolomites lyii over 1000 feet below the sur- face Oct., 1947 RWE •~ Referred to as "Fre-Cambrian" time. * Deposits present in West Chicago Area. -4- GEOLOGIC HISTORY OF THE AREA DEEPLY BURIED FORMATIONS The oldest bedrock which comes to the surface in the field trip aroa is shale and limestone of late Ordovician age. From the accompanying geologic col - umn, it can be seen that these beds, lying low in the Paleozoic System, are very ancient, Deep well borings show that beneath them are older dolomites and sand- stones of Ordovician age, under which lies a thick series of Cambrian sandstones, dolomites t and shales. Deepest borings reveal reJ sandstones belonging to the very ..ncient pre -Cambrian complex. Many of the Cambrian and Ordovician layers contain abundant fcssils of marine animals. These show clearly that ancient seas covered Illinois and the interior of the North American Continent, ORDOVICIAN STRAiA The Upper Ordovician shales and limestones v/hich outcrop beneath jutting ledges of Silurian cblciite along the Fox River belong to the Maquoketa Formation, The beds contain an abundance of fossils, notably brachiopod shells and the coral- like bryozoa. Because the shales are soft and weak and the overlying Silurian dolomite is strong and firm, this combination of strata has caused small cascades to develop in the rocky glens along the Fox from Elgin to St, Charles, SILURIAN STRATA The Silurian strata that lie above the Maquoketa Formation are dolomites belonging to the Edgewood, Kankakee, and Joliet Formations, in that ascending order. These formations range from Lower to Middle Silurian in age and are dis- tinguished from one another by differences in character of the dolomite and of the fossil content. These dolomites are a valuable mineral resource quarried for building stone, crushed to use for roads and concrete, and ground for agstone to sweeten the soil* YOUNGER PALEOZOIC STRATA The Silurian strataare the youngest bedrock layers present in the area, but it most is most probable that younger strata, of Mississippian Age once covered the region,, with a possibility that Devonian and Pennsylvanian strata also were once present, LONG INTERVAL OF EROSION HTCiether or not any or all these beds existed in the area, there has beer ample time for their subsequent removal by the wearing-down forces of erosion . From late in the Paleozoic Era until the present day, the region has beon a land aroa, from which earth and stone have been worn away by water and wind. As a result of these circumstances, there remains little or no direct evidence of the geologic events that took place during those hundreds of millions of years of ceolcgic time. Not until the geologic yesterday, when the glacial ice sheets mcved down from the arctic, do we again find deposits, in the form of glacial debris, which can be used as evidence in the reconstruction of the area's geo- logic history. -5- GLACIAL PERIOD To the geologist, the Glacial^ or Pleistocene. Period merges insensibly with the present, A mere 25,000 years or so his elapsed since the last ice sliest melted away, and in that short span, erosion has only just begun to strip ^-lav the glacial deposits Thus we can work out the Pleistocene history in very con- siderable detail^ We knew, for instance., that during the Ice Age there were four separate ma-jor advances of continental glaciers, ,vith warm climate interva lu between. These intervals were far longer in duration than has boon the length of time since the last ice sheet, the Wisconsin, disappeared from this regie?., Before the Wisconsin Ice Sheet, was the Illinoian, preceded by the iaoo'-n, and that in burn by the Netraskar? > We do not know., through lack of evidence, whether all four of those ice sheets covered the present area- but there is definite record of the Illinoiar and abundant evidence cf the Wisconsin, Between these two glacial invasions, there intervened a mild climate period of a couple of hundred thousand years a Under these conditions, bhere at first accumulated over the uplands a blanket of wind blown dust that the winds picked up from the raw glacial deposits in the sediment-choked rivers and sifted gently across the prairies and highlands.. In time, soils developed, ana the humic acids and downward percolating rain waters (high in carbonic acid) leached and chemically changed the underlying glacial drift and debris s MORAINES The region visited by the field excursion is one famous in North America for the complexity of its glacial history and the remarkable preservation of its glacial deposits. The deposits of continental glaciers assume many forms and conditions.- First,, there are the moraines, composed largely of glacial till. Till is a mixed and unsorted mass of clay, silt, sand, pebbles, cobbles, boulders •• whatever material was incorporated in the glacial ice and was left behind when the glacier melted away. Till is generally present as a more or less continuous blanket covering the surface over which the glacier moved. In areas where the glacier advanced rapidly the till blanket may be relatively level and thin; this is the '-ground moraine". Where melting and forward movement were nicely balanced, sc that ths ice margin was stable for a long period, "terminal moraines" developed the- are characterized by greater elevation, by a rolling or "knoll and kettle" topography, and commonly show numbers of large glacial boulders, or "erraties" . In addition to the till deposits are glacio~fluvial or glacio- -lacustrine deposits. - that i r j_, glacial drift that has been effected by transportation and deposition in glacial lakes or streams. The most outstanding manifestations of this type are glacial outwash, eskors 3 and kames, GLACIAL OUTWASH When the ground in front of a melting glacier slopes gently away from the ice front, the waters streaming down slope from the melting ice, deposit sand and gravel in alluvial fans a These fans eventually coelesce to form an outwash apron or outwash plain. The most evident outwash plain to be observed a]ong the conference route is that in front of thw West Chicago Moraine, -6- KAMES When ground in front of a glacier slopae toward the glacier, the waters from the melti'is ice are ponded and glacial lakes arc formed, surrounded by high ground on the one baud and by the high ice wall on the other a ''"hen streams flowing out of the melting ijo enter such temporary lakes, deltas are formed which have one Tide built against the ice wall, When the ice wail melts away,, this delta slumps bo i rounded knoll of sand and grovel, called a "kame'',- A typical kame may be seen east of the Junction between Highway 47 and the Batavia Read FSTf?;IvJ The streams which flow upon or under a melting glacier, deposit sand ani gravel in their channels just as other streams do* When the ice which wailed th~ b-VLiks of these glacial streams melts away, the stream bed is left as a more cr loss winding . raised embankment stretching across the country like a meander- ing railroad grade Generally its interior will have boon hollowed out by man, because eskers are important sources of clean, fresh sand and gravel. The Kanoville Esker northwest of Sugar Grove is the longest in Illinois. MORAINES IN THE WEST CHICAGO REGION In that tract of country lying between Illinois Highways 59 and 47 along the general latitude of Lily Lake - I, Chicago, the following moraine lines are encountered in going from east to west: Cary Sub-epoch Wes-c Chicago Moraine Tazewell Sub-epoch Mi no oka Moraine Marseilles Moraine Gilberts Moraine Marengo Ridge HISTORY OF FOX RIVER Before the coming of the Wisconsin Glacier, the Fox River did not exist, A study of the bedrock surface shows the existence of a well developed natural drainage pattern that has no relation to that existing in this area today „ The first occurrence of a sizeable stream along the general course of the present day Fox appears to have developed late in the Marseilles stage of glaciation, when the ice front had melted back until it lay east of where the river now flows, Water from the melting ice, in seeking to find its way south- ward down slope in front of the glacier developed this ancestral Fox Valley. Then, during the next, or Minooka stage, the glacier pushed forward again and crossed the ancestral Fox from St, Charles north to Elgin. This caused the river there to swing westward and carve a new channel well shown in the vicinity of the State School for boys 3 miles west of St, Charles. -7- The conference route crosses this Fox River Cut-off just east cf Bald Knob. Southward the cut-off followed several different courses at different times « Finally, when the Minooka readvance was dissipated by meltings the river regained its old valley,, Later,, when the Late Wisconsin glacier stood along the line of the West Chicago Moraine „ groat quantities of sard and grave] wore discharged westward into the valley _, which built its floor of sediment up to the high level of the grovel terrace which flanks the river today, Since then., the river has been lowering its channel as it proceeds to cut awa2 r this load of West Chicago glacial outwash 3 01, 13 > 1 M o o ^ s fc a J "b