,0 a^ .^ -^^ o 1'^ V .0 0, ,0o. %. .^- \^> ''^ ,0^ ,0^ •^^ ^^^. v^' ^^'"^^. .>^ ■'ie.^ A^^' -^y .^' ,0 C., A-*- J- <3> MARYLAND GEOLOGICAL SURVEY. WM. BULLOCK CLARK, State Geologist. THE ^^^c BUILDING AND DECORATIVE STONES OF MARYLAND Containing an Account of their Properties and Distribution. BY GEORGE P. MERRILL AND EDWARD B. MATHEWS. (Special Publication, Volume II. Part D.) THE JOHNS HOPKINS PRESS. Baltimore, October, 1898. ^-^4^ /y o I o PART II THE BUILDING AND DECORATIVE STONES OF MARYLAND BY GHORGE P. MERRILL and EDWARD B. MATHEWS CONTENTS IMCK PART II. THE BUILDING AND DECORATIVE STONES OF MARYLAND. Bv Gkougk p. .Mkiiiiii.i. .v.nd Enw.\ni) B. Matiikws. THE PHYSICAL, CHEMICAL, AND ECONOMIC PKOl'EKTIES l)l' 111 II.D- IN(i STONES. Bv (JKiimii; P. Mehhii.i 4 7 GESEKAL CoNSIDEU.tTlOSS 47 Classification 47 Diversity of Resources 4>i Geological Conditions 4'.i Formation and Present Position 4!) Variability in Composition and Structure .51 Position of Beds and Expense of Quarryinu' .5^' Thickness of Beds .')4 Beddiii!!; and Jointini;- .5.'; Efl'ects of Weathering and Erosion .57 Color of Rocks (i3 Geological Age 04 The Strength of Stones 0.5 Geographic Distribution of Stone in the State 65 Methods of Quarrying and Working 68 Relation of Maryland to Other Producing Areas SO Preliminary Oeueralitii's 80 Kinds of Stone Produced by Other States 81 WEATUEUl.Mi OF Bl'11,I>1NG STONE 00 Methods of Testing Buii-ding Stone Oil Tests to ascertain Permanence of Color 00 Tests to ascertain Resistance to Corrosion lOli Tests to ascertain Hesistiince to Abrasion 101 Tests to ascertain Absorptive Powers . . lO'J Tests to ascertain Resistance to Ereeziug 104 Tests to ascertain Ratio of E.\pansion and Contraction lO'.i Tests to ascertain the Fireproof Qualities of Stone Ill Tests to ascertain Resistance to Crushing Wi Tests to ascertain Elasticity of Stone 115 Tests to ascertain Resistance to Shearing 117 Tests to ascertain the Specific Gravity 110 The testing of Roofing Slates 110 Strength and Toughness 120 Corrosion by .Vcids 121 Softness or Capacity to Resist Abrasion 121 Conclusions 121 ) CONTENTS PAGE AN ACCOU.VT OF THE CHARACTER AND DISTRIBUTION OF MARY- LAND BUILDING STONES, tooetheu with a History of the Qi"AKRViNr; Industry, By Euward B. Mathews 125 iNTIiODrCTIOX 125 Previous Publicatious 136 Bibliosrapliy 131 The Qi'arries of Maryland 136 Oranites and Gneisses 136 Geological Occurrence 137 Discussion of Individual Quai-rv Areas 138 Granites 13S Port Deposit 138 Frenchtown 146 EUicott City 147 Woodstock 150 Gnilford 1 56 Minor Areas 158 Gneisses 160 Jones' Falls 161 Gwynn's Falls 166 Gabbro 168 Ampliibole Schist 169 Marbles and Limestones 169 JIarbles 171 Cockeysville and Texas 173 Marbles of Carroll County 185 " Potomac Marbles." 187 Serpentine or " Verde Antique." 193 Limestone 197 Sandstones 199 Triassic Sandstones 199 Paleozoic Sandstones 308 Micaceous Sandstones of Eastern Maryland 213 Slate 314 General Disiri lint ion 314 Peach Bottom Area 315 Ijanisville Area 331 The Building Stone Trade 333 Collection of Statistics 333 Annual Production in Maryland 334 Prices, Was-es, etc 337 THE PHYSICAL, CHHMICAL, AND ECONOMIC PROPERTIES OF BUILDING STONES BY GEORGE P. MHRRll.L GENERAL CONSIDERATIONS. There arc, in Maryland, four general classes of stone possessing siich natural qualities as to make them available for constructive as well as ornamental pnrjiose?. These four are (1) the granites and gneisses, (2) the common limestones and dolomites; the marbles (eiystalline limestones and dolomites): (3) the sandstones and conglomerates, and (4) the argillites or slates. In addition to these there are certain basic eruptive rocks Tised locally for pnrjjoses of rough constnu-tion, and other altered forms of eiiiptive rocks like the serpentines, which in some instances are of such color and texture as to render them of value as verdantique marbles. The individual characteristics of each of these groups will be taken up in detail later; in this preliiuinary chapter we will dwell rather on their geographic distribution in the state; and since this is due to geological causes, we will touch first upon the matter of their origin and the agencies which have been instrumental in making them accessible. Classificatiox. From a geological standpoint all those rock types mentioned above may be classed as (1) cniptives, (2) clastic sedimeutaries, and (3) meta- morphics. The tirst include only those types which, like granite and the gabbros, have resulted from the crystallization, and subsequent exposure tln-ough erosion, of molten matter forced up into overlying strata. The second includes those rocks made up cither of fragments of older, pre-existing rocks, or of calcareous materials derived from the 48 THE liUILDIAU AXD DECORATIVE STO^'ES shells and stony skeletons of niollnsks, corals and other lime-secretinji- marine animals. They are in short indurated beds of clay, sand, gravel or calcareous mnd which have been deposited on ancient sea- liottiims. The third i;'run}i comprises rocks of both the first and second, which have been changed from their original condition through processes known as metamorphic, and which usually accom- pany such foldings of the earth's ci'ust as are incideutal to the pro- ;iiii.' showiiii;- structure of the earth's i-'rust (utter U. S, G. S.). we may look for a greater variety of materials than in the le-\-el plains. This not merely because such have here been formed, but because through uplift and erosion they have been made accessible. By reference to a map of the United kStates it will be seen that the state of Maryland, in an east and west direction, stretches almost entirely across the Appalachian Mountain System. It occupies such a position with reference to this uplift and the less distiirbed ai-eas to the east and west as to lead vis to expect a great diversity of mater- ials even had not actual exploitation already shown them to exist. There is indeed probably no state in the American T'nion of the same area, that can be made to show a greater diversity in geological resources. -manvl.vxu geological sirvkv 49 Geological C'oxditioxs. In order to gain a satisfactory idea of the rclatiousliip of these various classes of rocks, let ns consider for a moment the diagram given helow. formation and peesent position. The oldest rocks of which we have knowledge, and wliich seem to form the floor npon wliich liave been built up all those since formed, are rocks of the gneissic and granitoid group. These, through super- ficial disintegration and decomposition, have yielded silts, sand^and gravels, which carried by stream action to the seas have been spread out in approximately horizontal layers to be once more consolidated into stony matter, and perhaps in part metamorphosed, as will be described later. Such being their method of formation, it is easy NOnTM MTN BlIlFPinrr CATOCTINMTN. r,„.o , n..-..T.. l/„ u IV BLUE RIDGE iHrn SUGAR LOAF MTN. Kio. 2. — Generalized section from Sugar Loaf Mountain to North Mountain (lifter Williams). to see that these later formed rocks would naturally lie in parallel beds, the oldest, or first formed, on the bottom and the youngest at the top. And as the character of the material forming these sedi- ments differed from time to time, both in texture and in chemical com- position, sometime? being mere clay, sometimes sand, gravel, ov calcareous matter, so it will be perceived these beds may differ, and wo may have in tlH> same horizontal series, sandstones, shales, lime- stones, slates and conglomerates. The character, thickness and lat- eral extent of such beds, vary almost indefinitely. As a rule, the beds of conglomerate are the least extensive, while the sandstones, limestones and shales may cover areas of many square miles. That these beds of stratified, or sedimcntaiy rocks as they are called, are not in all cases still lyino- horizontally, the oldest deeply buried and inaccessible, is due to the folding and faulting to which they have been subj.ectcd incidcntnl 1o the formation of the Appal- 50 THE BUILDING AND DECOEATIVE STONES achiau Mountains. Their present position is shown in Fig. 2, which ' represents an actual section across the State between Sngar Loai Mountain and North Mountain. Accompanying this uplifting there were in many mstances large quantities of igneous rocks forced between the older strata or into the rifts and fissures by which they were traversed, or m the form o± immense domeshaped masses beneath folds, as shown at R m the section. These cooled to foiin trappean rocks, diabases, pendotites and in some cases granites. But the -uplifting was productive of other effects than that ot merely rendering accessible. As is well known, pressure generates heat and heat accelerates chemical action. A series of chemical pro- cesses was thereby set in motion ^^•hich resulted in a more or less com- plete ehano-e in the stnicture and general textural features of the rocks, as well as,^in some cases, in color and in composition. Through these agencies many of the beds of limestone became converted mto mar- bles, the sandstones into schists and the argillites into cleavable slates, suitable for roofing purposes. In some instances this uplifting and metamorphism has gone on to such an extent as to practically ruin the stone for commercial pur- poses The reader can perhaps best gain an idea of what has occurred by takino' a pile of writin- paper or an ordinary magazine or paper- covered book, a half inch or more in thickness, andby pressing against the back and edges and throwing it into a /^^ shaped fold. By making first a pencil line directly across JJ Vv the edges at the end, i^t will be observed that, after th. folding, this line is no longer at right angles with the leaves, but cuts diagonally across them at an angle dependent upon the amount of folding. This means, of course, that the sheets of paper have moved over one another slightlv. Now fancy that each sheet of paper, or page of the book, as the case may be, represents a bed of stone, from a frac- tion of an inch to it may be several feet in thickness, and that all is weighted down by overlying rocks to such extent that the simple slip- ping of the bed^ one over the other as with the paper becomes a mat^ter of great difficultv. When then the folding takes place, it is accompanied bv more or less crushing and fracturing, and Imes of MARYLAND GEOLOGICAL SURVEY 51 A\-eakness, if not absolute rifts, arc opened. .Moreover, if the beds do not slip but remain themselves approximately stationary with relation to one another, it will readily be seen '^that those in the npper part of the fold will be subjected to a stretching process, per- haps even to the point of fracturing, while those in the lower portion will bo con-espondingly squeezed and enih^lud as shown in tli,. figure. Between these two extremes will be a zone practically unaffw^ted, and known to geologists as the zone of no strain. Now it is obvious that the condition of the material to be found in one of these folded areas will depend up.ui what portion of the fold is accessible. H erosion has exposed the materials in the zone of no strain {A C B) Folded rocks (:iftcr \au Rise). it may be good, but if only the superficial beds {D) or the very lowest {E) are accessible, the materials may be all so seriously shattered as to be full of joints, dry seams and other defects, so' as to render the production of blocks of large size an impossibility. Small sam- ples of great beauty may be found in abundance, but the beds as a whole are worthless. This condition of affairs actually exists in many parts of Maryland and Virginia, and in the latter state con- siderable sums of money have in one instance at least been lost in attempting to develop a quarry. VAKIABILITY IN COMPOSITIOX AND STRUCTURE. There are other geological features which are of importance to the quarryman. Stones which were laid down as sediments on seabottoms are more 52 THE BUILDING AND DECORATIVE STOKES variable both in composition and structure than are those of erupti^•c ori-in This for the reason tliat the character of the sediments depos- ited from time to time, vaiy. We may thus have in the same vertical sectiou rocks varving from conglomerates to sandstones, layers of sandstone altei-nating vith shale or with limestone. Sound, firm beds of desiralile material may be separated from one another by layers of shale which are absolutely worthless; beds of white homogeneous marble may be interbedded with impure layers can-ying pynte and micaceous minerals which wholly ruin it for commercial purposes. In quarrying, all these matters have to be taken into consideration, since, as 'waste products they must be removed, and the proportions existing between such and the merchantable stone may he the sole factor In deciding whether any quany can or cannot be worked sue- c6ssiiAlly. Ao^ain, the amount of tilting and crushing beds have undergone duriitg the process of uplifting is an important item. If the beds lie nearly horizontally and (luarrying is commenced upon the upper beds, it is obvious that only one grade of material can be produced at a time Each layer, as it is passed through successively, as the quarry increases in depth, yields its own grade of material which may or may not agree with that above or below. This is the case m the quarries of brown sandstone in Connecticut. When a quarry is opened in a liiUside. or ravine, where a number of beds have been exposed through erosion, or on the upturned edge of beds steeply in- clined as in the sketch, it is obvious that the quarry may at the same time be producing a great variety of ,naterials. Some of the marble, quarries of Vermont, for instance, which are opened on such upturned edo-es, produce from the various l,eds which are being worked simul- taneously, marbles of pure white, clouded, dark veined, nght water blue and dai-k bluish or greenish tints, the colors being dependent upon the amount and character of the impurities in the original sedi- ments. POSITIOX OF BEDS AXD EXPEXSE OF QUABRYIXG. The position of the beds has, further, an important bearing on the cost .d- quarrvino.. It is self-evident that where the beds lie almost horizontally, 'and quarrving is resolved into merely cutting through MAIfYr.AM) GEOLOGICAL SURVEY 53 54 THE BUILDING AND DECOEATIVB STONES one bed after the other, as in the sand and limestone quarries of the upper Mississippi valk.y. The ^vork can be carried on comparatively cheaply, provided that there is not too much preliminaiT stripping (Plate' lY Fio- 1). When, however, the beds stand at high angle, or are exposed'only in a hillside, quarrying must be carried on either on a highly inclined floor, as in the quarries of gneiss north and west of Baltimore, or directly across the edge of beds, whereby considerable extra trouble and expense are involved. THICKNESS OF BEDS. In looking for new quarry sites, the geological structure of the countrv should always be taken into consideration. When the beds Pjp 5 — Diagram showing relation between thlcliness and exposure of beds. lie horizontally it is obvious that the character of any but the upper- most beds can be ascertained only by investigation in hi Isides and along the banks of ravines. Where they are highly mclmed, it is in inanv instances suflicient to explore superficially along a line a right angles with the lateral extension, or .infce of the beds, as it technically called, that is to say, to follow along the line A B m lig. 5. The character of the various beds exposed can thus be ascertained and when one sufficiently promising is found, its extent can be best made out by following it out .long the line of strike. Since the actual thickness of a bed of stone may be a ma ter of importance, it may be well to state how this can be best ascertamed. MARYLAND GEOLOGICAL SURVEY 55 It is obvious that with hods iiu-liiu'd ;is in the figure, tlie width of exposure on the iuiniediate surface is vastly greater than that of the true tliiekness of the bed itself. In such cases the apparent thickness is greater the smaller the amount of inclination. Sir Archibald Gcikic, is his Text Book of Geology, gives the fol- lowing general rule to be followed when the inclination is less than 45°, and it is in such cases that the greatest discrepancies exist. The real thickness of an inclined strata, or bed, may be taken to be 1/12 of its apparent thickness for every five degrees of dip. That is, if, as in the sketch we have a series of beds outcropping on the surface along the line A B and dipping as shown, to the right, at an angle of 15°, the actual thickness of one of the beds, X Y, will not be the distance — say 100 feet — measured between these points, but 1/12 of 100 multiplied by 3, or 25 feet. The amount of dip which beds may have and the character of the overlying rock should receive careful consideration before quarrying is commenced. In the case shown in tlie figure, if .Y — Y is the workable bed, it is evident at once that the quariy must sometime cease to be an open cut, and must then be followed underground. If the overlying rock forming the roof is soimd and strong, this can be done with comparati\-e safety by leaving occasional pillars for support. But if of a weak, or friable natiu'e, it must be continually removed by stripping, thus increasing the cost. It is fortunate tliat in the majority of cases the amount of area exposed on the immediate surface is so large that it is not necessary to follow the beds to great depths, though in Vermont some of the marble quarries are even now over 200 feet in depth and partake more of the nature of mines than quarries, as the word is commonly understood. Naturally such deep quarries are nuich more expensive to work since not only must the cost of hoisting both merchantable material and waste lie very con- isiderable, but steam pumps must be continiially at work to carry off th(^ water which would otherwise collect to a depth of very many feet, even filling the entire quarry to vithin a few feet of the surface. BEDDING AND .lOIXTING. Among the unaltered eruptive rocks there is a total absence of bedding planes or other like structural features, the rocks being homo- Ob THE BUILDING AND DECORATIVE STONES geneons and capable oi being worked with almost equal facility in any direction, presenting on all sides the same appearance. Such do, it is true, have two definite directions at I'ight angles with one another, along which they can be relied to split most readily. These are knoM-n as rift and grain, and though wholly inconspicuous to the ordinary observer, are readily detected by an experienced stone cutter. Bedded and stratified rocks, on the other hand, almost invariably present readily recognizable structural features. It rarely happens that an unaltered or even metamorphosed sedimentary rock is of such uniform composition that the lines of bedding, the original lines of deposition, are not easily traced. Along these the rock will split more easily than across them. Such lines when too pronounced may be a great detriment, not merely as concerns appearances, but what is of more importance, as affecting the weathering qualities of the stone also. Such stone, when used in ashlar -work, are often sawn or split parallel with the bedding, since not merely can the work be done in this manner at less cost, but a face of more uniform color and texture is thus obtained. That the custom is open to serious objection is noted in another chairter (p. 93). Joints in rocks are matters of interest for still other reasons than those noted above, since upon their character and abundance is largely dependent the size and shape of blocks that may he extracted. To illustrate this point more fully: Plate IV, Fig. 2, shows a quan-y in which the rock is traversed by a series of nearly horizontal joints so strongly developed that A'ery little labor is necessary to free the sheets one from another. Large, flat blocks, with lieautifully fresh and even surfaces that can be cut up to any desired size, even to sizes too large for transportation, can thus be I'eadily and cheaply obtained. Such quarries will furnish blocks for building, for monumental work, for monolithic columns or for any purpose to which the rock is lithologi- cally fitted. In other cases, where it may be these horizontal, or holiom joints, as they are called, are equally well developed, there exists a second series of vertical joints running at right angles with the first. Such necessarily limit the length or breadth of the blocks MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE IV. lie. 1.- IHJIUZONTAL BKDS. Fig. 2.-PROMINENT " BKIIDTNT. • .lOI NTS. MAEVLANn GEOLOGICAL SURVEY .')" ()l>t:iiiialilc. 'I'hcsc quarries are best suited for the prodiictioii warrant the letting of a contract. On examination, there was found in one locality, and almost on the immediate surface, a bed some two feet in thickness of a beautiful fine white, almost translucent marble. This dipped at a low angle beneath the surface soil and to the inexperienced observer might, and did seem very promising. On careful inspection, however, such an inspection as could be made only by one acquainted with the ffeoloaical structure of the countrv and the action of the (j3 the building and decorative stones atinospliere on rocks of tins class, it was discovered that, on all sides, everywhere indeed within reach of practical quarrying operations, this Led had become almost entirely dissolved away, leaving only here and there small areas too insignificant to be worthy of consideration. By exploring along a deep trench that had l)een opened across the face of the bed, it was discovered, too, that the lower beds were not only quite siliceous and hard but variable in color and often carried the deleterious material pyrite. In short, all of the material of any value that the quarry could lie relied upon to produce was the small amount actually in sight, aggregating at most but a few thousand cubic feet. Unfortunately the " practical " quarryman was in this case unwilling to accept the conclusions of the geologist and persisted in attempting to develop a quarry, only to discover when too late that he was wrong and that both his money and his energies had been wasted. As a general rule the solvent and decomposing action of water goes on most rapidly in the softest and weakest portion of the rock, so that the residual bo^vldcr-like masses may represent the better quality of the material. Excepting then that nature's method is extremely wasteful such results can be considered as scarcely detrimental. A quarry under such conditions may be actually producing a better, more uniform class of material, than one which has escaped solution altogether. In making search for new localities for opening quarries, it is always well to note the manner in which the indi^ddual beds have weathered. The soundest and best will as a rule be found standing out in relief wliile the more perishable have crumbled away. All stone as it lies in the ground contains a certain amount of interstitial water, wdiich holds in solution more or less mineral matter. This is commonly known as quariy water. When stones are re- moved from the quarry bed, this water is drawn to the surface and evaporated, leaving its mineral matter to serve as a cement to bind the grains together. A superficial induration or hardening thus takes place. This phenomenon has been long since recognized by quarry- men, though the cause of the same has not been generally known. MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE V. s \ ' "T: ff^ li'-' I'ic.].— UUAHliY S1I()\\'I\(; Sl:\Eli.\L SEIUKS Ol-' .IIIIXTS. Fii;. •J.-GLACIAL STHllM'KU QCAUUY. MARYLAND GKOLOGICAL SfRVKV 03 That a stone is soft when first quarried ami hardens on exposure, is one of the commonest araiinients nsed hv qiiarriers with reference to their material, though they fail to remember that such induration may be temporary, and the rock in time cnimble in spite of it. Sand- stones are f>eculiarly liable to such induration, even in exposed o\it- erops in the quarr\- bed, so that casual inspection will give quite erro- neous ideas as to the actual quality of the stone. A slight change in color, from the surface downward, is also a not infrequent occur- rence, as is noted in the chapter on Weathering (p. 90). Color of Rocks. The subject of the color of a rock, when fii-st quarried, after iiro- longed exposure, aud after working is one that should be brietly con- sidered. Among siliceous crystalline rocks the colors are due mainly to the presence of colored minerals, or to the physical condition of the feldspars. Tlius the gray color of granites is due largely to an admixture of white feldspars imd ])laek mica or hornblende; the red colors to red feldspars; the dark greenish, sometimes almost l>lack colors to clear pellucid feldsp.nrs. and the white, to white feldspiirs. The dark colors of the diabases aud the gabbros are due to the pellucid feldspars and the dark pyroxenes they carry. Pure limestones and dolomites are white simply because that is the color of tlie calcite or dolomite which forms their chief con.stituent. The dark color com- mon in this class of rocks is due as a rule to the presence of carbcm- aceous matter: the red. to iron oxides, though the pink and red colors of some of the onyx marbles seem to be due in part also to organic matter. The red, brown and yellow- colors of sandstones are due to iron oxides. The changes in color which these rocks are likely to undergo, on exposure, are noted in the remarks on rock-weathering. It may not be out of place to state here, however, that nearly any feldspathie rock is likely to become lighter in color during the incip- ient stages of weathering owing to the. opening up of the cleavage l)l:incs in the feldspars. It is for this same reason that the hammered surface of one of these rocks is of a lighter color than the natural rock face or polished surface. The impact of the hammer breaks up the graniiles on the immediate surface so that the light falling upon it 04 THE BUILDING AND DECOJtATIVE STONES is reflected, instead of absorbed, and the resultant effect npon the eye is that of whiteness. The darker color of a polished surface is due mei'ely to the fact that through careful grinding all these iiTegularities and reflecting surfaces are removed, the light pene- trating the stone is absorbed, and the effect upon the eye is that of a more or less complete absence of light or darkness. Obvioiisly then the more transparent the feldspars and the greater the abundance of (lark minerals, the greater will be the contrast between hammered and polished surfaces. This is a matter worthy of consideration in cases where it is wished, as in a monument, to have a polished die, sur- rounded by a margin of hammered work to give contrast. Often when a piece of work of this nature is exposed, the contrast between ham- mered and polished work diminishes slightly owing to the gradual weathering out of the particles splintered through hammering. The contrast is less when the stone is wet than when dry, because the water fills all the little rifts and crevices and by its refracting power tends to produce tlie same effect as though the stone were polished. Geological Age. The matter of geological age is only of very general economic inter- est. It is indeed true that the process of metamorphism — the change from the amorphous or fragmental condition to one more or less crys- talline — has as a riile gone on more extensively among the older rocks, than among those later formed, but the rule is by no means universal, and moreover metamorphism is not always productive of such characteristics as make a stone adapted for either building, monu- mentnl or decorative work. "While metamorphism may render a stone crystalline, it may also render it granular and friable; while it may develop color, it may also develop schistosity and other blem- ishes. So far as the United States are concerned, one can say, how- ever, that few stones are used to any extent that are of later date than the Triassic, and that few if any of our marbles are younger than Silurian, wliilc nearly all our granites, as now quarried, belong at least to Paleozoic or Archaean times. Stones of later than Triassic age, are, so far as relates to the Eastern United States so friable, or so poor in color, as to be of little value. mauvi.and geological survey 65 The Strength of Stones. ]\riicli lias ill times past been written on the subject of rlie erushing strength of building stones, and hundreds of tests have been made, the results of a few of which are given in this work. A few words only on the subject are here necessary. It is doubtful if in any but the most extreme cases it is necessary to continue this line of inves- tigation. The results thus far obtained are sufficient for us to for- mulate general rules, and the average results obtained are so vastly in excess of all ordinary r("i|iiirements that they may safely be ignored. A stone so weak as to be likely to crush in the walls of a building, or even in a window stool, caj) or pillar, bears so visible marks of its unfitness as to deceive no one with more than an extremely rudimen- tary knowledge on the subject. It is rare to find a stone that %vill not slidw, under the methods of testing now in vogue, a cnishing strength of at least 6000 lbs. to the square inch, while many stones, particularly those of the granite group, will range as high as 20,000 to 30,000 lbs. to the square inch. Since the first named amount is ten- fdld mure than is likely to be re(|uircd of it in any l)ut the most extreme cases, the absurdity of making further tests is manifest. The few that have he're been made, were made in recognition of the still prevailiTig — though mistaken — demand for tests of this nature. They show, as was to be ex|)ected, that the matter of the strength of those of the ^[aryland stones now on the market, may well be left out of consideration in the future, .and this for the reasons above suggested. In fact, it is the weathering (piality of a stone more than its ulti- mate strength, tiiat should concern ns, and a careful examination of the natural outcrops, old (piarry faces and buildings, will give a more correct idea to an experienced man, than will all the tests that can be made in the laboratory. This view the writer expressed some years agv ri'ferring to the ma]! of Maryland (Plate VI, Vol. I), it will be seen that the state is dixided into ihi'ee well defined topographic ])rov- ' Stoiu's for liiiildint;' :iiul Decoration, Wiley and Sons, .\. Y. 5 66 THE BUILDING AND DECORATIVE STONES inces, which are intimately related to its geologic structure and hence have a bearing upon its mineral yielding capability. It will therefore be worth our while to devote a little space to a consideration of this branch of the subject, bearing in mind, the while, that much that is said here regarding Maryland is true to a certain extent of the entire Eastern United States. The most easterly of these topographic provinces, kiio-\vii as the Coastal Plain, comprises the area between the Atlantic Ocean and a line passing X. E. to S. W. from Wilmington (Delaware) to Wash- ington, D. C, through Baltimore. The region is about 100 miles broad in its widest part, and includes very nearly 5000 square miles of territory or about one-half the area of the entire state. It is characterized by broad level-topped stretches of countiw, which ex- tend with gradually increasing elevations, from the Coastal border, where the land is scarcely at all elevated above sea-leA^el, to its Avestern edge, where heights of 500 feet and more are to be found. Tlie underl\-ing rocks are as a rule but slightly indurated, consisting mainly of clays and sands, sometimes locally cemented into ferruginous sand- stones and conglomerates and never of such consistency as to be of value in their natural state for building purposes. We may therefore dismiss this portion of the state fiMui further consideration. The second province, known as the Piedmont Plateaii, borders the Coastal Plain on the west and extends to the base of the Catoctin ]\Iountain. It is nearly 40 miles in .vidth in the southern portion of the region, but broadens towai'd the north until it reaches 65 miles in width, comprising altogether an area of approximately 2500 square miles, and including Cecil, Harford, Baltimore, Howard, Montgom- ery, Carroll and Frederick counties. As it is this proA-ince which furnishes by far the larger amount and greater ^-ariety of building stones and marliles, it will be worth the while to consider it in some detail. The Plateau, as a whole, is divided very nearly in its central portion by an area of high land known as Parr's Eidge, into an eastern and a western district. To the east of this ridge lie the gneisses, granites, galibro.s, ciwstalline dolomites (marbles), serpentines, and roofing slates, the main portion of the area being occupied by the MARYLAND GEOLOOICAL SURVEY 6T gneisses, througli whieli have boon sporadically iiitnulcd the granites and iialiliros wliicli, by erosion, are now exposed in tlie form of isolated patclies of comiiarativcly limited extent, as shown on the map. The building marbles of the state arc limited almost wholly to this eastern division, as shown in the areas north of the city of Baltimore. This eastern division has, on account of its crystalline rocks and their complicated structure, a diversified to])ojira])liy. Along the eastern ni;iri;in the land attains, at several ])oints. heights exceeding 400 feet, reaching at Catonsville 525 feet above sea-level. To the west the conntry gradnally increases in elevation nntil it culminates in Parr's Kidae, which exceeds S50 feet in Carroll connty. 'I'lie drainage of the eastern district is to the east and southeast. On its northern and southern boundaries it is traversed by the Sus- quehanna and Potomac rivers, which have their sotirces without the area, while the smaller streams, which lie betweeti them either drain directly to the Chesapeake Bay or into the two main rivers. Among tli(> larger of the intermediate sti'canis are the Patuxent, Patapsco and (Tunpowder rivers, whose headwaters are situated upon Parr's Ridge. The Patapsco especially flows in a deep rocky gorge nntil it reaches the Relay, where it debouches into the Coastal Plain. All these streams have ra]iid currents as far as the eastern border of the Pied- mont Plateau, and even in th(> case of the largest rivers are not navi- gable. This last is an important item since it precludes the possibility of shipment of (piarrird material by other than rail, canal or wagon routes. The western division extends from Parr's Ridge to Catoctin ^Nfotm- tain. Along its western side is the broad limestone valley in which Frederick is situated, and through wliich flows the llonoeacy River from north to sontli, entering the Potomac River at the boundary line between ]\[outgomerv and Fn'derick counties. The valley near Fred- erick has an elevation of :io0 feet above tide, which changes slowly to the eastward toward Parr's Ridge, and very rapidly to the westward toward Catoctin ^lountain. Situated on the eastern side of the valley, just above the mouth of the Monocacy River, and breaking 68 THE BUILDING AND DECORATIVE STONES the regularity of this surface outline, is Sugar Loaf ilountaiii, which rises rapidly to a height of 1250 feet. The underlying rocks of this division are as a rule far less crystalline than those of the eastern, consisting mainly of blue gray limestone, red brown sandstones, phyllites, and other siliceous and argillaceous rocks which are largely unsuited for construction purposes and hence need no mention here. There are, however, in Carroll and Frederick counties several comparatively small included areas of highly crystal- line limestones capable of furnishing in small blocks material of such color and texture as to make them of value as marbles. The third or Appalachian region borders on the Piedmont Plateau and fiirms the entire western portitjn of the state. It includes the western portion of Frederick, and all of Allegany and Garrett coun- ties, an area of some 2000 square miles. This is the most mountain- ous region of the state, consisting indeed of little more than a series of parallel mountain ranges with deep narrow intervening valleys which at the southern limit of the state are cut almost at right angles by the Potomac River. This area has as yet furnished practically nothing in the way of structural material though it does not neces- sai'ily follow that satisfactory materials do not exist. The rocks con- sist mainly of .sandstones, shales and limestones, none of the latter being sufficiently metamorphosed to make them of value as marbles. The possible resources of this region will be discussed later. Methods of QuAREviNa and Woekinc;. In the work of extracting stone from the quarry, and reducing it to the desired shapes for use, there are two considerations of primary importance. These are, 1st, the accomplishing of the work with the least possible injury to the material, and, 2nd, the accomplishing of it cheaply. I'nfortunately the two methods are almost directly opposed to each other, and equally unfortunately the cheaper methods are those, as a rule, most likely to produce injurious results. This last is only partially true, however, since where the work is carried on on a large scale, the better way proves in the end the cheapest. In many kinds of manufacture complaint is made that machine-made goods are inferior to those made by the old-time hand processes. In lfARrr.AXD GEOLOGICAL SrRVEY 69 stone work tins is coi-tainly not correct, liowcvcr. AVilli iiiacliiiics it is possible to produce better results, in less time than by liaml meth- ods. This is particnlarly tnie rcgai-ding quari-ving, sawing, grinding and poiisliing. There are of course certain kinds of work, certain forms of finish, for the satisfactory performance of which no machines have been designed. [before considering in detail the methods employed in stone (piarrv- ing and stone working, let ns first consider the conditions under wliich the stone exists in the quarry, what difficulties are to be overcome, wliat methods can be ])nrsuc(l with safety, and what must 1)(' avoided. All stone that is used at all extensively for structural purposes has the property of splitting, or breaking with fairly flat and even faces, along two directions at right angles to each other. The direction of greatest ease is known as the rift, that at right angles as the grain. The cause of this tcndcuey to split .nloug definite lines is not fully tmderstood. It is enough for our present purposes that it exists. The rift is often very ])ronounced, and its direction is indicated by and some is due to a parallel arrangement of the constituent minerals as in the gneisses and schists. In other rocks, like the more massive granites, it is wholly inconspicuous and the direction can be deter- mined only by an experienced stone-worker. Xothing is more sur- prising to one who has given no attention to the subject, than the ease with which a workman, with no other tool than a scpiare-faced hammer will break out by a few well directed blows a rectangidar block of the required size and shape for street pavements, while an inexper- ienced person, with the expenditui'e of twice the amount of time and triple the amount of energy will produce only a shapeless mass, with bulging faces and rounded connn's, utterly worthless and unfit for use. Here then are two important factors which must be taken into con- sideration. Another is the jointing. To this property attention has been called on p. 55, and the matter need not be wholly repeated here. It shonld be stated, however, that these joints may b(> either a help or hindrance to quarrying according to their prominence, abundance, and the directions at which they traverse the stone. As a very gen- eral rule those massive rocks which are extcTisively quarried owe their 70 THE BUILDING AND DECORATIVE STONES availability to the presence of two series of joints which like the rift and grain cut the stone in directions pi'actically at right angles with each other. This condition of affairs is described on p. 50, and a figure is given shomng the utility of joints in quarrying. Hence nothing more need be said on the subject here. Among sedimentary rocks — the sandstones and limestones — the better grades of stone lie in well defined beds, or layers, separated from one another by other beds of inferior or worthless material. The quarrier has to consider not only how to get out the good material, but also how to get rid of that which is worthless. One method must be resorted to for the first, and another less expensive for the second. Another feature which must not be lost sight of, here, is the difference in degree of hardness and toughness of A-arious classes of rocks. A method of treatment allowable in one case, as with granites, woidd be wholly impracticable in another, as with limestones. For- tunately those rocks which are sp tender as to be likely to become injured by the more violent methods of quarrying, as by blasting, are sufficiently soft to permit of their extraction by other means. The quarrier has to remember that stones have but a comparatively small amount of elasticity, that thev are brittle, and any sudden jar, like that from an explosion of powder or dynamite, is likely to develop fla-ws and fractures, which, while they may be quite inappreciable at first, become injuriously conspicuous by weathering. But enough has been said to show that quarrying is not quite so simple a process as may have at first appeared. Let us now devote a few pages to a consideration of the methods in vogue. The old time and simplest method of quarrying which needs be considered here, is that of blasting out the rock by means of powder exploded in a cavity made by hand drills. This method, aside from being too slow for modern purposes, results in the production of only irregularly shaped blocks requiring a proportionately large amount of labor to rediice them to the desired sizes and shape. Moreover, the explosion of a single, large charge of powder, is likely to produce a shattering which can be wholly done away with if the charge is dis- tributed along a line among several holes which are exploded simul- MAKYLAXD GKOLOGICAL SUKVEY 71 taneoiislv. This nu'thod is rendered possible through the invention of a steam drill sneh as is shinvn in Fig. 7. As may be seen it consists of little more than a steam cylinder mounted on a tripod with Fig. 7. — lugersoU-Sergeant steam drill. the drill attached to the piston. The machine is held in place by means of heavy weights on the legs of the tripod. The steam being (3 THE BUILDING AND DECOBATIVE STONES conveyed from the boiler to llie drill by means of a ilcxil)le hose, which allows the use of the drill in any part of the (jiiariy. A differ- ent form of drill answering the same purpose is shown in Fig. S. By means of these machines a series of two or more holes are drilled along the line where it is desired the stone shall break. These are then charged lightly with powder, and fired simultaneously by means of electricity instead of by a fuse. The result is that a large mass of rock is freed from the quarry bed, with a comparatively slight amcnint Fio -lugersoll-Sergeaut quarry bar drill. of jar, the aim of the quarrier always being not to move the block any appreciable distance, but simply to free it, after which it is re- duced to blocks of the required size by hand implements, to be noted later. Where the bottom joints in a quaiTy are well defined as at Vinal Haven, Maine, masses of granite some 300 feet in length and 20 feet in width liave been loosened at a single Ijlast.' In cases where bottom joints are not sufficiently developed, or are at too great a dis- ' Stones for Building and Decoration, 3nd Ed., p. 241. .MAKYI.AM) liKOLOGICM. SIRVKV 73 tance apart, it is soiiietiiucs necessary to resmt In drilling and blasting to free the rock from the quarry bed. Once loosened fnnii the bed, as described abnve, a blcjck of granite or other hard rock, is ent u]) into (l(>sii-eil sizes by means of ])lngs and feathers. liy means of hand drills or a quarry bar drill, a series of Fic. '1. — Warchvell oliaiiuellimr machine. IidIcs, niit over an inch in diaiiK'ter and a few inches deep, is drilled along the line where it is desired the stone shall break. Into each of these is then placed two half round wedge-shaped pieces of soft iron, the thicker ends downward, and between them is inserted a small steel wedge. When the wedges or plugs are all in place tiie workman 74 THE BUILDING AND DECORATIVE STONES n strikes them one after the other with his haiumer, driving- them all alike, thus produeing a uniform strain along the line, until the block falls apart. The method is commonly known as " plug and feather " splitting. In the softer rocks, as the sandstones, a somewhat diiferent metliod is resorted to. Instead of drill holes, grooves are first cut with picks, and into the gTooves large steel wedges are i-Hi. 10. — luLiorseill-SeliiX-ant chauiielliiiu" liiachilif. inserted which are then driven with heavv striking hammers or sledges, in the same manner as before. Blasting by means of powder furnishes the only aA'uilahle means for quarrying rocks of the granitic type, owing to their hardness. But the method should be used reasonalily and with discretion. Material from a quarry where, as one sometimes reads, hundreds or even thousands of tons of stone have been loosened by a single blast, JIARYLAXD GEOLOGICAI, SfKVEY 75 should always be accepted with hesitation, if at all, for building pur- poses, since as above noted the jar from such a couccutrated explo- sion is likely to produce incipient fracture and injuriously (hnejo]) latent joints. Fig. 11. — Kcvolvins drum and hoist for derrick. (Forntshed by American Hoist and Derrick Co.. St. Paul. Minn.) In quarrying softer 'rocks like the sandstones, limestones and mar- bles, channelling machines are now used in nearly all American quar- ries. Two distinct types of these machines are used (Figs. 9 and 10), 76 THE BUILDING AXD DECORATIVE STONES but with both the results are essentially the same. The machines are constructed to run forward and backward over temporary tracks laid on the quarry floor and to cut as they go straight smooth channels into the stone beneath, the channels, l)y repeated passage of the ma- chine, being cut to any desired depth up to perhaps six or more feet. The rock on the floor of the quarry is thus divided up into a series of Fui. V: -Lincoln stone jilaner. blocks which need only to be freed from the quarry bed to become available. This freeing from the bed is usually done by means of machines known as undercutting or " gadding " machines. These are sometimes ordinary impact steam drills, or again diamond drills. In either ease a series of holes is drilled along the desired line, and the stone then broken out by wedges, or perhaps by means of another machine wliicli simply cuts out the partitions between the holes. MARYLAND GEOLOGICAL SIK\EY II V>y tlic niil iif pucli inachinps blocks of any dpsirerl size may be ob- tained, and what i-< of ('(pial inijiortance, scloctcd uuitorial can he taken (Hit wiili niissil)le daiiii'cr of injury as hv lilastini;'. The renioxal of Kiocks fmni tlic iiiiarry to the slied is accimiplishod liy iioists using hoi'sc, steam or clectric-ity fin' powi'r, the rnnninii- licar passinji' over tiie arm of a ih-rriek as in Plates X and XIV, or through a truck on a cable as in Plate XXXTT. Tiie cable permits the lifting of blocks from any portion . 144). Once removed from the i|iiarries stones are cut and tinislied by processes, which within certain limits vary aecordini; to I he hard- ness of the material, ihongh I he nature of the rift or liedding mit- nrallv has much to tlo in the matter, (iranites and hard rocks of this nature are as a ruli' reduced to the desired size and shape by idug and feather splitting and by hand cutting with chisel and hammer. Steam saws eonsisting of a thin blade of soft irou fed with small globules of ehilled iron or a sand com])osed of crtished steel are used to some extent. .Monolithic cohnnns are in some instances turned on giant lathes, the cutting tools being revolving discs of steel. A ])laner with cutting discs of the same nature is sometimes used (see Fig. 12). Smooth surfaces for ]iolishing are ]iroduced by grinding, the bloidc being placed on a horizontally re\-iihing iron bed, the cutting material being the chilled iron, sand or i mery as the case may li(>; or, where the block is too large there is used a movable grinder such as is shown in !• ig. b!. The necessary smooth surface lia\ing been produced, the ]iolish is im- parted by means of a revolving wdieel covered with felt. 1'his is kept wet and a white powder, known to the trade as " iiolishing putty" is sprinkled over the surface occasionally, the friction from the revolving wheel aided by the putty shortly in-oducing the desired 78 THE BUILDING AND DECORATIVE STONES results. All almost perfect surface is the first essential to the pro- duction of a good polish. Sandstones, limestones and marbles are sawn by the reciprocating blades of soft iron mentioned aliove, which are usually mounted several or many in a frame, an inch or more Fig 13. — Stone pulisher. aj)art according to the thickness of the slabs or blocks which are to be cut, the cutting material as before being sand or chilled iron. Sand is preferable Avhen the material to be cut is not too hard, since not likely to stain the stone, through nisting. Moreover little parti- cles of the iron or steel are likely to become imbedded in the stone MARYLAND fiEOl.OGlCAL SURVEY Tl) (luring the early stages of grinding and these breaking loose during the later stages, when the surface is nearly smooth, do much damage by scratching or else remain pernuniently imbedded to give rise to rust spots wlien the stone is exposed to moisture. These softer stones are also planed by machines operating on the same principles as those used in jjlaning metals. A modification of the same machine is used in producing moulding'^. Caived surfaces ar(> still ]iroduced mainly by band, banmicr and chiscb thuugli machines operating like minia- ture stream drills have been enipbiyed for this purjiose. N'arinus fcu'ms of finish are applied to the sin-facos of stones, and arc called by names as a rule indi<-ativ(' of the means employed. A rock fa( (• t!iiisli is till' natural fracture uf the rock, scarcely toucliciug before quarrying can be commenced. This latter fact is well kuown to Maryland quarricrs, and is shown iu the views of quarries given on Plates XVIII and XX. KINDS OF STO.NE rKODUCED HY OTUKK STATES. In Maine there are in operation to-day only quarries of granite, gneiss and gabbro, and of roofing slate. Very many of the granite quarries lie so near the water's edge that cost of transpoi-tation is reduced to the mininum, and hence qiuirriers are enabled to compete with others, even iu markets at a great distance. The roofing slates lie remote from Avatcr ways and only the general excellence of the materials enables them to compete with othere beyond the state limit. The output of these materials for ISS!) was: of granite 0,701,340 cubic feet valued at $2,225,839.00, and of slate 41,000 squares, valued at $201,.^(i(i.()0. Neiv Ilinnpshire has only quarries of granite and gnei.-is that need be here considered. These are all dependent upon railroads for transportation, but the quality of some of the granites, notably those of Concord, enables them to compete successfully with others more G 82 THE BUILDING AND DECORATIVE STONES favorably situated. The entire ovitput for the year 1S89 was 2,822,- 026 cubic feet, valued at $727,531.00. Vermont produces a greater variety of materials than either of the above mentioned states, including granites, marbles and roofing slates, although few of the granites are of such a nature as to lead to their being transported beyond the state limits, so long as the transporta- tion is limited wholly to railways. The mai-bles and roofing slates are, however, of siicli quality as to lead to tlieir use, even imdcr these adverse conditions, in nearly every state in the Union. During 1889 the statistics of production of the three classes of stone mentioned above were as below: granite (and allied nicks) 1,073,936 cubic feet, valued at $581,870.00; marbles 1,068,305 cubic feet, valued at $2,169,560.00; roofing slates 236,350 squares, valued at $596,997.00. The marble of Vermont, it should be stated, is, with the exception of the colored varieties of Mallett's Bay, almost wholly crystalline limestone and of such a nature as to make it better adapted for monu- mental and decorating work than general building, while those of [Maryland are dolomites, and, so far as now developed, almost wholly building marbles. Massachusetts. This state produces for other than local uses only granites, marbles and sandstones. With the exception of the granites which lie along the coast, as those of Gloucester, Eockport and Quincy, the transportation is wholly by rail. ISTevertheless the qual- ity of the stone, the early date at which the quarries were opened, and the energy of the operators has been such that they have been widely iised, and in many cases to the entire exclusion of equally good material from close at hand. The jnarbles are crystalline granular dolomites and wholly of the building type, and on casual inspection are scarcely to be distinguished from those of Cockeysville, J\laryland. Sandstones are produced only in tlie southern central part of the state, as near East Long Meadows, the stone bearing a general resemblance to that of Seneca Creek in Maryland, though perhaps of a warmer hue. Many of the granites, as those oi Quincy, Dedham and Milford, MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE XXVII. RED SANDSTONE. SENECA, MONTGOMERY COUNTY. jrAKVI.AXD GKOLOGICAI- SUBVEY S3 are of a tv|)e quite lackinsi' in other states. Tlic output of the three classes durino: 1889 was as below, no statistics for inai'blc being avail- able: granite 9,587.996 enbic feet, valued at $2,503,503.00; and sandstone 1.907,179 cubic feet, valued at $649,097.00. Bhode Island. Only the granites of this state need consideration from our present standpoint. Xear Westerly are quarries of a fine, evenly textured stone of gray or sometimes pink color, that has come to be extensively utilized for monumental work in all our cities and towns. The transportation is both by rail and water. Westerly being at the extreme western border of the state, with direct rail communication to New York and Boston and but a few miles from Long; Island Sound. The outptit of granite for tlie entire state for 1889 was 2,878,239 cubic feet, valued at $931,216.00. Connecticut like Massachusetts produces granites, marbles and sand- stones. The marbles like those of Massachusetts are white, crystalline granular, in part dolomites and in part limestones. The granites, with the exception of some coarsely variegated gneissoid rocks occur- ring at Stony ( 'r(!<>k, are little used outside of the state. The sand- stones, and especially those along the Connecticut River, as at Port- land and Cromwell, are very extensively qiiarried and owing to the ready transportation facilities offered by the river, arc cxtensi^'ely util- ized in all the Eastern cities, and have even been sent around Cape Ilorii to San Francisco. These sandstones are brown Triassic stones of the same type as those of Seneca Creek and other points in Fred- erick county, Maryland, and it is only that they so lie as to offer exceptionally favorable facilities for quarrying and transshipment that the Man-land st(nie has not thus far jiroven a more successful com- petitor. The statistics for the state for 1889 so far as available are as follows: granite 3,835,704 cubic feet, valued at $1,061,202.00, and sandstone 2,821,430 cubic feet, valued at $120,061.00. Neiv York: This state, like Pennsylvania, yet to be noted, is so situated with reference to the Appalachian system, and comprises so large an area, that its resources are great and varied. Within its &■ 84 THE BUILDING AND DECOKATIVE STONES liorders are to lu- found f|uaiTics of iiTaiiite and allied rocks, marbles, sandstones, quartzites and slate. The p-anites, of both red and gray colors, are eminently suited for building, decorative or monu- mental purposes. The quarries are, however, largely in the northern central part of the state and i-emote from waterways, so that the stones are little used for general building outside of the state. Dolo- mitic marbles, coarsely or granular crystalline in structure and util- ized only for general building, occur in the southeastern counties of the state. Those ('(unjiare clusely with those of ( 'ockeysville in Mary- land, and will compete with them on about even terras. In St. Lawrence county are other coarsely crystalline, gray building marbles, which are, however, little used lieyond the state limits. Black, gray and variegated marliles suita]")le fur interior decoration occur in the northei'n and eastern j)art of the state, but being of a type wholly distinct from any known to exist within the limits of Maryland, may for the present he omitted from consideration. Sandstones and quart- zites, suited for building and flagging, occur in inexhaustible quan- tities widely distriliuted throughout almost the entire length and breadth of the state, some of the better known being the Potsdam quai-tzites of St. Lawrence county, the Medina sandstones of Monroe, ^Niagara and intermediate counties and the so-called " bluestone " or "flagstone" of Albany, Green and Ulster counties. The Potsdam stones are accessible by rail, and the water routes of the Great Lakes; the Medina, also, while the flagstones last named are largely within comparatively easy reach of the Hudson Eiver. Hence all these .stones are widely and for the most part favorably known. The slate producing areas are limited wholly to the extreme eastern portion of the state, Washington county alone being a constant producer. The material is of red or green color, and on this accoimt does not enter into direct competition with that of Maryland. The quarry statistics (if the state for 1S89 are as below: Granite 1,515,511 cu. ft. valued at $ 222,773.00 Marble 1,171,500 cu. ft. 354,197.00 Sandstone f;,490,406 cu. ft. 1,177,822.00 Slate l(i,7()7 squares 81,726.00 MAini.A.vr) nKoi.ooTrAL sruvEv 8» Xeic Jersey. This state produces only brown Triassic sandstones, similar tn those of Frederick and ^Montiioinery counties in ifarvland. wliicli need consideration here. Tlie close proximity of the state to the leadin": markets, as of those of Xew York, Piiiiadelphia, Balti- more and "Wasliiiigton renders it possible to transport the quarry l)roduct at comparatively low rates, even though such transportation ' must be made mainly by rail. The Triassic belt extends from the Xew York state line southwesterly to the Delaware Eivcr. 'I'he ]iriuci|in! (piarries are in Passaic, Essex, Hunterdon and Mercer counties. The stone resembles that of Connecticut perhaps more closely than that of ^faryland, but nevertheless the general resem- blance is so close that as a rule the selling price of the material will be the controlling item in deciding which shall be used. According tn the retiirns of ihe 11th census, some <;.()10,:.'12 cu. ft. of sandstone were produced during the year 1SS9, valued at $.597,- ;5on,oo. Delaware produces little in the way of building stone except for local iise. Certain gabbros and gneisses have been q\iarried for pur- poses of rough construction, but do not need consideration here. Pennsylvania. As noted above the quarry ])roduct of this state is large and varied. Singularly enough, however, there is little in the way of granitic rocks that need consideration. Good building mar- bles and serpentines occur in Montgomery and Chester counties and in both instances the stone so closely resembles that of Maryland that the price at which the material can be put upon the market must be the controlling factor of commercial importance. The ^laryland quarries are nearest to the markets of Baltimore and "Washington, but those of Pennsylvania to those of Philadelpliia and Xew York. Brown Triassic .sandstones, similar in a general way to those of I'red- erick and Montgomery ccjuntics, l)ut of a more uniform iu'own hue, are quarried at Hummelstown in Dauphin county, and enormous qiiantities of gray and blue, gray thin bedded sandstones and " blue- stones," used for general Iniilding and flagging, in Pike, Carbon, Luzerne, Wyoming and Susquehanna counties. "With tlu' exception 86 THE BUILDING AND DECORATIVE STONES of the '■ Wyoming Valley " stone, as that of Wyoming county is commercially known, few of the latter find their way beyond the state limits. Blue-black roofing slates, such as must compete with those of Maryland, occur in the soiif-.hwesterly part of the state, in Berks, Dauphin, Cimiberland and Franklin counties, and also in enormous quantities in the northern parts of ISTorthampton and Lehigh counties. For many years these deposits have been systematically worked, the product being used for roofing, billiard tables, sinks and school purposes all over the United States. The statistics given below will convey better than words some idea of the magnitude of the quarrying operations here carried on. Granite 5,782,887 cubic feet, valued at $623,252.00;' marble, sta- tistics not given; sandstone 19,119,357 cubic feet, valued at $1,942,- 979.00; serpentine statistics not given; slate 476,038 squares, valued at $1,541,003.00.' Virginia produces granites, sandstones and slates only, and as transportation of the quarry output is wholly by rail and there is little competition in the carrying trade, but little of the material finds its way into the general markets. The granites near Bichmond have been used in some of the important buildings of Washington, and the red-brown Triassic sandstones from near Manassas are in de- mand for the construction of dwellings. The statistics of the state are given below: Granite 1,073,936 cubic feet, valued at $5Sl,.s70.00; sandstone 70,800 cubic feet, valued at $11,500.00; slate 30,457 squares, valued at $113,079.00. North Carolina. With the possible exception of one granite and a few Triassic sandstones this state at present produces nothing find- ing a market beyond its limits. There are, it is true, in the western half, granites in abundance, and several promising beds of marble, but ' It is difficult to say what is included here under the name of granite, since there is scarcely a quarry of true granite within the state limits. Presumably it includes everything not otherwise classified. - Some $370,723 worth used for other purposes, in addition. MAKYLAXD GEOLOGICAL SURVEY 87 SO far tlicy have been so little workofl tliat nothing definite can be said regarding them. In the southern central part of the state are beds of brown sandstone, the equivalents of the Triassic beds in the states to the nnrtlirasi. 'i'liesc have been worked spasmodically and the quarry product shipped to coastal cities iiu-Iuding Baltimore and Washington. The total output in 1SS9 so far as statistics are avail- able is as follows: Granite 708,267 cubic feet, valued at $146,627.00; sandstone 50,001 1 cubic feet, valued at *1 2,000.00. So^t^h Carolina. Although there is an aluindance of granite in Fairfield, Tiichland, Xewbcrry, ]>e.\iugfou, Edgefield and .Vikcn coun- ties none of the material finds its way beyond the state limits. Mate- rial to the value of $5.">,320.00 i« stated to have liecn quarried in 1896. Georgia. This state has several ([uarries of granite, and in its northern portion extensive deposits of coarse crystalline granular building marble. This last named is coming into very general use for building, monumental nud interior work, even in cities as far north as Boston. Its consideration is thei-efore important here. A deep dark gray, nearly black roofing slate also occurs a: Kockuuu't in Polk county which is fiiuliug a slight market outside of the state. The statistics for 1889 as given are as below: (Jrauite 2,425,622 cubic feet, valued at $752,481.00; slate 3,050 sqxuire feet, valued at .$14,s.")(i.()(i; ui irblc 25,000 square feet, valued at $196,250.00. The quarries, it should be noted, are all remote from waterways, and transportation is therefore limited to railroads. Tennessee. In this state only the .uarbles need consideration from our present standpoint, and these only on the supposition that at sonu' time the i)ropositiou may be entcu-taincd df dpcuiug u]i quarries in the colored uuu-bics of Carroll and Frederick counties. The Ten- nessee stones are dark clioci)late and white, fossiliferous, and gray and pink crystalline granular limestones. The latter are used both for general building and intcu-ior woi-k aud the first for interior work only. 88 THE BUILDING AND DECORATIVE STONES Tliere are in addition to the stones above mentioned, certain otliers from more remote sources which, owing to their peculiar lithological natures, are to he found in all the principal markets of the country. The so-called Bedford stone or Bedford Oolites and the Berea sand- stones are of this type. The first mentioned of these is a very pure limestone but differs from those of the states above mentioned in that it is made u]i almost wholly of minute rounded or oval concretionary grains, often of almost microscopic dimensions. It is of a very light grayish color, sometimes almost buff, soft, very readily workable, and occurs in nearly horizdutally lying beds covering a large extent of country. It can therefore be quarried and worked very cheaply, and as it is, on the whole, of a pleasing color and fairly durable nature, it iinds a ready market in most of our larger cities. The second stone mentioned, that of Berea, Ohio, is a fine grained sandstone belonging to the Waverly series of the carboniferous forma- tions. This rock is an ideal " freestone " in so far as this term refers to working qualities, since its even granular structure and not too pronounced lamination permit it to be worked with the greatest facility in any direction. The prevailing colors are light gray to buff, and though from the standpoint of durability no better, nor perhaps so good as many stones nearer at hand, it too, on account of its cheapness and color, finds its way into markets at such a distance as would cause it to be excluded l)y cost of transportation under less favorable conditions. Reference in passing should also be made to such stones as are brought to our markets from foreign sources. As a very general rule it may be stated that the stones thus introduced are of a different type, so far as color and texture are concerned, from those produced locally, and that they are lirought in in response to the pul)lic demand for a greater variety. This is not, however, invariably the case since, as is the case with certain of the Italian marbles, easy quarrying facili- ties and cheapness of labor enable the producers to put the stone upon the American market at Iowim' rates than the domestic product, not- withstanding the discrepancies of distance and consequent cost of transportation. Xaturally a large proportion of the imported mate- MARYI.AXn GEOLOGICAT, SURVEY SO rials arc iiiarlilcs since, aside from licinc; most expensive, such are used verv largely in the form of thin slabs for veneering, rather than in solid blocks of masonrv. There are, however, a few stones of the granitic type, used more particularly for moinimcntal work, which find their way into our markets in considerable quantities. Of the marliles which come to our market we need mention more particu- larly the deep i-ed and yellow often brecciatcd varieties from Algeria, the so-caliod Xuiniclinn marbles; the wliit(\ lilue-gray, often veined, black and yellow mottled varieties from Xorthcrn Italy, particu- larly from ( arrai'a and Sienna; and the green or so-called Verd- antiqiie iiiarl)les (serpentines) from Genoa and near Prato. Stones very similar to these last are found in various parts of the United States, particularly in \'ermont, but are excluded from competi- tion by the high ]irices of labor prevalent in America. Stones of this same general nature, but of more uniform green color, occur in ^laryland and adjacent portions of Pennsylvania, but though from time to time ([uarriiMl, have never been worked upon a scale sufRcient to exclude the imported material even were the character of the marble the same. Other marbles than those mentioned, that come to us from abroad, are the so-called Formosa and Bougard marbles of (Jcrmany and tlir (Triottes of France. Xearly all of the granitic rocks which reach the Amei'ican markets from abroad are what arc known as momnnental stones. With the exception of those that are introduced from nearby sources, as Xew Bmnswick, the cost of transpoi-tation is too great to warrant the bringing in of materials that nni>r be sidd sufficiently cliea]) to compete with the native product in ordinary structural work. Among the more important of the gTanitcs introduced are the red and gray so- called .Scotch granites, from near Peterhead in Aberdeenshire, Scot- land. .\ coarse, ]ior]>liyritic stone, showing large pink orthoclase crystals in a gray groiind mass comes from Sliap in Xorthem England. Of greater interest on account of their beauty are a few types of aranitic ro(dercolating over the surface and filtering downward through the joints, brings about a disintegration and decomposition, whereby the soimd rock gives way 1o sand, y-ravel and clay, all very likely di.scolored by iron oxides set free tlirou<;h decomposition from the micas and other ferruginous silicates. Since on joint-blocks this weatli(>ring, which may well be compared with tlic r is a ferruginous sand and clay; of sandstones a sand, and of argillite and limestones a ferruginous clay. In some instances weathering nuiy be productive of a local induration causing soft and friable stones to become harder and more durable, though this is far from being a general and wide- spread phenomenon. In many instances the preliminaiy stages of weathering are manifested by a change of color, due to the whitening of the fcldspatliic constituent, or, as a rvdc, to the o.Kidation an\. New York, 1897. 92 THE BUILDING AXI) DECOliATIVE STONES on exposure, assumes a niiifornily biiff or yellowish hue, which is known, commonly, as '" mcllowina,"' and which is not at all undesir- al)le. Changes of this kind arc limited mainly to light coloi'ed sedi- mentary rocks, and smdi as hiwv hccn qnaiTied from Ijclow the per- manent water level. This for the reason that exposure in the quarry bed above the water level has already brought about the oxidation and cobir change, so that when qiiarried and placed in the walls of a build- ing nil furtlier cliaiige takes ])lace. Ijiit tlie effects mited above arc mainly the products, it may be of geological periods, of years so many as to be quite incomprehensible from a human standpoint. We need consider here only those effects which may be brought almut liy these same agencies operating throughout a few score or pcrliaps bunilreds of years. Stone taken from the ground and exposed in the walls of a building- is subject to two agencies both destructive and tending toward disin- tegration. As already noted, the one is physical and the other chemi- cab 1 luring' a hot summer day, stones exposed to the direct rays of the sun may become, on tlii' immediate surface, heated to a tempera- ture of even 150° Fahr. On the going down of the sun, a gradual cooling takes place. In the coldest weather of winter the tempera- ture may sink as low as zero. iSTow, as it is well known, Jieat causes expansion and cold contraction. Let the reader then picture to him- self what here takes place. The mass of the stone is made up of an adnnxture of mineral particles without definite order of arrangement and all practically in actual contact with one another. As the tem- ]ieratures rise each mineral expands exev so slightly and crowds against its neighbor; but aside from the unequal expansion of minerals of different species, the process is further complicated by their ten- dency to expand unequally along their different crystallographic axes. So all through that portion of the stone thus warmed there arises a condition of very unequal tension, which is naturally greater the greater the amount of heat. As temperatures fall a corresponding contraction takes place; but in material so granular and inelastic as stone the particles do not again recover exactly their original relative positions. Minute rifts are opened, not merely between the granules. MAIiVI.AXD GF.OLOOUAI, SURVEY 93 but also along the cleavage planes of the minerals themselves, so that in time all cohesion is lost and the srone becomes so weak as to fall away to tiie (■(mdition of sand, or as is more commonly the case, absorbs so large an aniduut of water that when freezing ensues, disintegration results. Since any stone will absorb the most water along the bed- ding or lamination jilaues, and since too the stone is weakest, the cohesion of the particles least, along these planes, so it follows that laminated stones, like sandstones, often show signs of scaling on their outer surfaces even after an exposure of but a few years in the walls of a building. It is this form of disintegration which is so conspicuous and unfortunate a feature in many buildings constructed of brown, laiiiinafod sandstone, in Baltimore and other cities. Such a tendency mav b(! larc'elv overcome bv laving this stone ou its natural Ix'd, but any stone whatever its nature is more or less susceptible. Ina,s- much as stones are but poor conductors of heat, that is, as the heat penetrates but slowly, and to biit slight depths, such a f(jrm of disintegration is limited to the immediate surface. Where, however, the disintegrated material is removed so soon as formed, the process may go on indefinitely until a finely carved front or cornice may be entirely nnned. It follows from the above tliat, other things being equal, a stone in which the various mineral particles are closely interknit will lie more durable than one of granular structure. One of the most serious of the destructive agencies to which stone in the walls of a building are subjected is the freezing of absorbed water. All stone as they lie in the ground contain more or less mois- ture or quarry xcater, as it is called, which in time dries out after the stone is quarried. More water is however likely to be absorbed on exposure to rains, and since water in freezing exerts an expansive force equal to some 150 tons to the scjuare foot it may be readily undi-r- stood that if the amount of moisture contained in the pores of a stone is at aU large, serious disintegration may result. It is to this cause that is largely due, as already noted, the scaling and crumbling of the brown sandstone so commonly used in house construction througliout the Eastern United States. Other things being equal again, a stone 94 ■JIIE BUILDING AKD DECORATIVE STONES possessing low absorptive power will be more durable in moist, tem- perate and frigid climates than one that will absorb a large amount. Figures showing the relative amount of water absorbed by stones of various kinds are eiven in the followiii"- table. ABSORPTION TESTS I. Klnil of SKiue. Marble, Cockeysville, Suudstriue, Seneca, Granite, Port Deposit, (iranite, Woodstock, Gneiss, Baltimore, Sandstone, Taneytown, Quartzite, Eminitsburg, Wgt. after drying 24 hours at 212 F. Wgt. after IniTiiersion 24 hdurs in water. Grams. Gain in weight. Grams. Percentage of absorption. 367.1.5 367.93 0.78 0.312 367.07 367.86 0.79 0.315 313.35 331.38 7.93 3.530 313.7.5 331.18 7.43 3.368 351.33 353.33 0.S9 0.3.53 341.34 343.00 0.66 0.196 340.43 341.31 0.88 0.358 340.45 341.34 0.79 0.332 3.54.37 355.07 0.70 0.197 323.36 336.97 3.61 1.116 320.33 334.05 3.83 1. 196 347.58 347.87 0.29 0.083 ABSORPTION TESTS II. Marble, Cockeysville, Sandstone, Seneca, Granite, Woodstock, Gneiss, Baltimore, Sandstone, Taneytown, (Juartzite, Eminitsbiirs;, 344. .50 Wgt. air dry. Grams. Wgt. after Immersion one liour. Grams. Wgt. after immersion one day. Grama. Wgt. after immersion one weeli. Grams. Galu in wgt. Grams. Percent- age of ab- sorption. 367.35 307.30 .367.60 367.60 0.35 0.09 1003.70 1007.70 1010.80 1011.70 8.05 0.07 34.5.00 345.. 50 34.5. .50 34 .5. .55 0.05 nil 3.50.70 350.65 3.50.70 3.50.67 nil 329.60 330.. 50 330.90 331.55 1.95 0..59 344. .50 344.. 50 344.85 0.35 0,10 In the second set of experiments which were conducted by Dr. Mathews, the blocks were all of the same size (two inches cube) as those of the first set, except in the case of the Seneca sandstone, where a block four inches square and one and a half inches thick was em- ployed. The weighings were made after the blocks had been swabbed until no glistening water remained. These tests show that little water is taken up by the specimens beyond that carried after remaining over MAKYI.ANl) GKOLOOICAL SURVEY 95 a yoai' in tlif wariii air of an otHce. 'I'lic wcatiici- diiriiifi- the cxjieri- iiicutiiii;' was wanu (85°-95° F. ), and the limnidity was approxiuiatflv seventy per cent. Tlie water wliieli comes to the earth in rainfalls is never absolntcdy jiure, bnt contains a variety of mechanically and chemically admixed iiiijiiiritics. ^Xmoni: ihc (•li(iiii<'ally .nlmixed, or dissolved ini|niritics, which arc the only ones that need here he considered, carbonic acid is the must widespread and abnndant, while in smaller anioniits and ])articularly near large cities there may be traces of hydrochloric and sniplniric acids. These all arc cajiablc of exerting a solvent action on the iiialci-ial composing imilding stone, particularly (in lime car- bonate. The aniotint of material that will be dissolved during a single shower may be infinitesimal, or during a year scarcely np])rcciable. ^'et there are many stones, p.ii'ticnhirly those composed of ptire lime carlHinate (limestones), or of siliceous grannies cemented by lime carbonate, whicdi in time suffer severely. The ronghened surface and loss (d' polish seen so fre(]nently (m marble tombstones and exterior work of any kind is nsnally due to this solvent action of rain water and its dissolved acids. • The adajitability of a stone for strnctnral purposes depends then, in no small degree, n])on its weathering qualities, that is to say tipon its power to withstand for cenlin-ies even, exposure in iiie walls of a building, without serious discoloration, disintegration or solution. Let us now take into consideration these weathering (pnilities as dis- l)layed by the various types of rocks, although a full disctission of the subject mtist h(" left for moi-e I'omprehcnsive treatises.' Granites and gneisses possessing very low ratios of absorption (see table above) and lieing made up so largely of silica and silicate minerals, are very little all'ected by freezing and solution. The chief causes of disintegration with rocks of this class, are temperature changes, such as pi'oducc^ grantdation. Aside from a weakening of the cohesion ]iower between ti:e individual constituents, the feldspars may split up along cleavage lines, and a disintegration follows which may be sufficiently evident to catise small spawls to fall along the 'See Kocks. i;o<-k-\vcatluTini>- and Soils, the M.acmillan Company. Xew York, and Stones for Bnildiiiir and Decoration, Wiley and Sons;, N'ew York. 96 THE BUILDING AND DECORATIVE STONES joints between the blocks, or perhaps to ruin fine carvings. In some instances deleterious minerals like pyrite may be present in sufficient quantity to cause unsightly discoloration. All tilings considered, n fine grained liomogeneons rrick will 1)P found more durable than one that is of coarser grain. Also a rock in which the individual particles are closely interkuit, dovetailed to- gether, as it were, will resist disintegration longer than one that is of a granular structure at the start. Serpentines are likewise only slightly absorptive and when homo- geneous little affected by solution. Nearly all serpentines of such quality as to be used as verdantique marble contain, however, veins and spots of calcite, dolomite or magnesite, and many dry seams. Such rocks, therefore, weather unevenly, lose their polish, and may shortly crack and split along these dry seams when exposed to tlie weather. These marbles should then be used only where protected from the weather. Crystalline limestones and dolomites (marbles) are extremely varialile in their weathering qualities, are likely bo carry pyjite, and great care needs always be exercised in their selec- tion. A limestone marble, i. e. one composed essentially of lime carbonate, is likely in time to suffer from solution whereby corners become rounded, surfaces roughened and perhaps inscriptions oblit- erated. The mechanical agencies are here also operative as in granite, so that, as a rule, a stone of this class is less durable than a good granite. The pure white stones are, as a rule, more granular and weaker than the gray and blue gray. Dolomites being less soluble than limestones might at first thought seem promising of greater dur- ability than the limestones. Unfortunately this is not altogether the case, since such stones often possess a more granular structure thau do limestones, and hence suffer more from disintegration. Indeed a dolomitie marlik- can, nut infrequently, lie distinguished from one of pure limestone, simply from the way it weathers iu the natural out- crop. In the case of the dolomite, the surface of the outcrop may be found covered here and there with a sand composed of angular parti- cles which results merely from the mechanical disaggregation of the stone, while in the second case the stone loses almost wholly liy MAUYLAXD GEOLOGICAL SLEVEY 97 solution, and we find it passing superficially into a clay without the production of sand. The light colors cliaracteristic of most marbles render iron stains peculiarly objectionable, and as pyrite is a very common constituent of such rocks, much care is necessitated in its selection. The ordi- nary unmetamorphosed limestones, like the deep blue-gray varieties from the Trenton formation are scarcely at all absorptive, and weather fairlv well, Imt tlioir sombre colors are somethine; of a drawback. Fifi. U. — Pliotiimicnurrapli of Scnecii Samlstone (masriiitii-il ten diameters). Sandstones, on account of the widely varying character of the materials of which they are made up, variation in texture, degrees of porosity, etc., are perhaps as a whole more variable in their weathering qualities than any other class of rocks. In order to fully appreciate this variability, we must remember that we have to do here with what are but beds of indurated sand; that these stones are made up of sand 7 98 THE BUILDING AND DECORjVTlVE STONES particles lield together by simply being closely compacted by finer material, or by means of a cement composed of lime carbonate, iron oxides or silica (see Fig. 14). Where the sand is loosely compacted, or the sand grannies are interspersed with much finer, clayey matter, the stone will absorb comparatively large amounts of water and is likely to become injured on freezing. Where the cementing matter is carbonate of lime, rain water trickling over the surface is likely to remove it in solution, leaving the stone to fall away, superficially, to the condition of sand once more. Ferruginous cements are likewise slightly affected, though in a much less degree. The siliceous cement is least affected of all, and provided the amount of induration be the same, a purely siliceous sandstone, cemented by a siliceous cement, is one of the most indestructible of building materials. Many sandstones have a distinctly laminated structure; that is, their jiarticles are laid down in parallel layers, differing somewhat in size, color and degrees of compactness. The result is that some layers will absorb more water than others and the rock will undergo a splitting up into thin flakes. When such a rock is stood on edge in the walls of a building and the water filters do\vn along these porous layers and there freezes, serious results follow, particularly when the stone is carved. Pyrite is a common constituent of sandstones, particularly the gray varieties, and is likely to prodiice staining. Its presence needs to be looked for with care. A fine-grained sandstone is often fully as absorptive as one that is coarse, and fully as likely to injure from freezing. A ratio of absorption of more than 4 per cent by weight must be regarded as unfavorable. Eoofing slates or argillites represent as a rule the indurated qnd otherwise changed argillaceous products of the weathering, or rotting as we might say, of pre-existing rocks. They are in short made up from the most indestructible of natural materials, and on first thought might themselves seem indestructible. Unfortimately those capable of being split sufiiciently thin for roofing purposes are not in all cases indestructible, nor are they equally resisting in all parts. In nearly all slates there are to be found dark colored bands or ribbons, containing deleterious minerals like pyrite or marcasite, wliich are less MAKYLAXD GEOLOGICAL SUKVEY 99 durable than are the other portions. Moreover the exposed position of slates, when on a roof, is such as to try to the utmost their lasting qualities. It is here that the extremes of temperature are greatest and the acid action of rains most manifest. It is little to be wondered at therefore that in time the slates become brittle and break, or at least crack, a condition of affairs soon indicated by leaking. A slight fading in color is also a not uncommon feature of many slates, the exact cause of which does not seem to be yet fully apparent. Methods of Testing Building Stone. How to ascertain liv any series of lests that can be performed in a laboratory the durability or general suitability for construction of any stone is a problem with which builders have long struggled and which is yet far from solution. In order to !i]iprociate the difficidty in thr ])rolilciii, let us liriefly recapitidate. Stone in the walls of a building is exposed to the chemical action of the atmosphere, the physical action of temperature changes and to the crushing and shearing forces incidental to its position in the wall. Satisfactory tests, then, must .show the ability of the stone to with- stand to-day any of the agencies enumerated above, and must also indicate its ability to withstand them after years of exposure. A stone which to-day will withstand effectively any of the tests which can be a])p]icd may, through the prolonged action of external agencies, become so weakened as to be valueless or so discolored as to be unsightly. In this chapter it is proposed to give a general summary of the tests which have thus far been applied, to show in how far they are suc- cessful, and to make such suggestions as seem pertinent to the subject. It will not be necessaiy to give in full all the details of these tests, as they have from time to time been made. It will be sufficient, rather, to refer only to such as are historically interesting or of value on account of the results they may have yielded. (1) Tests to ascertain permanence of color. The change of color in a rock, on exposure in a biiilding, is due mainly to a change in the 100 THE BUILDING AND DECORATIVE STONES form of combination of the iron. Rocks taken from below the water level often carry iron in the form of protoxide carbonate (Fe CO3) or pyrite (Fe S2). Either on exposure to the air is likely to become oxi- dized as noted under the head of weathering. The tests that can be applied in the laboratory are made (1st) to ascertain the presence of sulphur, indicating pyrite, and (2nd) the effects of an artificial atmos- phere in accelerating oxidation. The following is the method for this last mentioned test as adopted by Prof. J. A. Dodge.' The specimens tested were rectangiilar in outline, and from an inch to an inch and a half in diameter. These were dried in a water bath (temp. 212° F.) till all the absorbed moisture was expelled, cooled and weighed. They were then placed upon a set of glass shelves standing in a porcelain pan containing strong muriatic (hydro- chloric) acid. An open bottle containing nitric acid, and one containing hydro- chloric acid and black oxide of manganese were placed close by, and the whole covered by a bell glass, foi-ming an air-tight chamber. The fumes from the acids, together with the chlorine fumes from the manganese and hydrochloric acid, filled the chamber and exercised a powerful coiTosive and oxidizing effect on the samples. After a period of seven weeks the stones were removed and washed, and the change in color, if any, noted. A similar series of tests was made by Prof. A. Wendell Jackson in 1887 on California building stones,' and the efficiency of the method seems fairly well established. (2) Tests to ascertain resistance to corrosion. The question to be settled here is one relating chiefly to calcareous rocks, to limestones and marbles, or to sandstones containing a calcareous cement. The most satisfactory method available, is apparently that of Prof. Dodge, given in the publication above referred to, which is as follows: A set of pieces of essentially the same size and shape as those used in the last mentioned tests were selected and dried and weighed in the same manner. These were then suspended by strings in a glass ' Final Report Geological and Natural History Survey of Minnesota, vol. i, 1873-83 (1884), p. 185. = Seventh Ann. Keport State Jlineralogist of t'a]., 1887 (1S88), p. 205. MARYLAND GEOLOGICAL SURVEY VOLUME II, PLATE VI. KKAGMl'iXTS ()!■■ r.rul'JS AKiKK CltlJSli I \r.. 1L4.EYLAND GEOLOGICAL SURVEY 101 vessel of water, not in contact witli one another, and a stream of car- bonic acid gas was run through the water for several hours at short intervals, so as to keep the water pretty well saturated. The gas was washed before entering tlie vessel containing the stones, and the water in the vessel was changed every few days by means of a siphon. The action was continued for a period of six weeks, when the specimens were removed, washed in pure water, dried and weighed. Tlie differ- ence between the first and second weighing indicated the amount of material dissolved by the carbonic acid water. Tn the case of some limestones this was found to be over 1 per cent, though as a rule much less, and in the case of some granites so small as to be scarcely appre- ciable. (3) Tests to ascertain resistance to abrasion. Tests of this nature are necessary only in cases where, as in steps and walks, the material is subject to the friction of feet, or where as in dams and breakwaters, it is subject to the action of running water and waves. In some in- stances it is ]iossible that stones may be so situated as to be subjected to the action of windblown sjind. In the selection of Belgian blocks for street pavements, it is naturally an important matter. The resistance to wear, it may be stated, depends not more, perhaps even less, upon the actual hardness of the constituent particles of a stone, than upon the firmness with which they adhere to one another. This is well illustrated in the case of many sandstones, which though made up of the hard and difiicultly destructible mineral quartz, are so friable as to be practically worthless. In making a series of tests of this nature, it is well to consider the uniform as well as actual hard- ness of the stone. Many stones wear unevenly, owing to their une- qual hardness in various parts, and are even more objectionable than though uniformly soft throughout. The serpentinous steatite used many years ago for steps and sills in Philadelphia wore very unevenly owing to the siiperior hardness of the serpentine over the steatite, causing the former in time to stand out like knots in decaying logs. The power of any stone to resist abrasion can in the writer's belief, and as he has elsewhere ' stated, be ascertained by observing the manner in which it works under the chisel. ' Stones for Building- and Decoration, 2ud Ed., p. 445. 102 THE BUILDING AND DECORATIVE STONES Resistance to the action of windblown sand could readily be ascer- tained by subjecting prepared samples to the action of an artificial sandblast such as is used in the Tilghman process of stone caridng. A fairly accurate idea of the resistance 1o actual wear can be obtained by the rate at which the samples can be ground down on a common grinding bed. It is diificult to perfect this method, since so much depends on the weight applied and the constancy of the supply of emery, sand or whatever may be the cutting medium. (4) Tests to ascertain the absorptive powers. These tests have a direct bearing upon those which are to follow, since it is largely through freezing of absorbed water that cold produces disintegration. The test of the absorptive poAvers is therefore one of the most import- ant, and for a single test perhaps the most conclusive of any, as the writer has also elsewhere stated.^ For reasons noted below it cannot be relied upon altogether. There are two absorptive tests commonly made; the one to deter- mine the absorption of moisture from a damp atmosphere, and the other the amount of absorption of water through actual soaking. Of the two the last is by far the more important. The method of determining the absorption from a damp atmos- phere as carried out l)y Prof. Dodge" is as follows: The samples of stone Avere placed in the cells of a hot-water bath for several days, to expel their hygToscopic moisture, after which they were allowed to cool in desiccators, over sulphuric acid, and weighed. They were then placed upon a set of glass shelves standing in a pan of water, and a tight cylinder was inserted over the shelves, the mouth of the cylinder being sealed by the water, after the manner of a gas holder. The apparatus remained thus in a room the temperature of which was pretty uniform (from fiC to 70° Fahrenheit) for seven weeks, the water being replenished from time to time so as to maintain a constant closure of the cylinder. The stones were then removed to bell-jars in which they were supported over water, and thus taken to the balance and weighed. The samples submitted to this test were somewhat larger than those used for making the determination of specific gravity. They had an a^^'erage weight of about 70 grammes, ' Op. cit., p. 439. - Op. cit., p. 1S5. SIAUVLAND GKOLOGICAL SURVEY 103 and were roiiplily shaped. The ininiimnii absorption of moisture .03 per cent of the weight of the stone, is so small in amoimt as to be practically nothing. The maximum 3.94 per cent of the weight of the stone seems qnite considerable. It seems probable that, in the atmosphere saturated -n-ith moisture in which they were kept for seven weeks, some of the stones absorbed all the moisture they were capable of taking up, while others by a longer exposure to the same conditions would Jiave shown still higher figures. In determining the amount of absorption by soaking it is best to have the specimens as nearly rectangular as possible, with faces ground smooth, and for purposes of comparison as well as for possible subsequent use in other tests it is well to have them approximately in the form of 2-inch, culies. These should be thoroughly dried and weiglied, as in the tests previously mentioned and placed in a porce- lain dish with sufficient water to cover them and allowed to stand until fully saturated — say a period of 3 or 4 days at least. The cubes sho\d»l then be carefully removed, the water absorbed from tlie immediate surface by means of blotting or any form of bibulous paper, and then weighed. The drying and weighing should be accomplished with as little delay as possible, to avoid loss by evaporation. The in- crease in weight of the cubes is of course due to the water absorbed, and tlic percentages can thus be readily calculated. The results of a few tests of this nature are given on p. 94. As here shown, and as an almost universal ride, the sandstones are the most absorptive. It may be said further, that the absorption takes place most rapidly and in the largest amounts along the bedding planes. While the absorp- tion of more than 3 or 4 per cent of water is a matter that can as a rule be regarded as detrimental, still it does not necessarily follow that such a stone will siifFer most on freezing. This for the reason that a coarsely porous stone will dry more quickly than one of finer grain and moreover the size and shape of the interstitial cavities is such that the expansive action of freezing water finds relief without forcing apart the granules as noted below. It is sufficient to note here that a high rate of absorption is more detrimental to a fine than a coarse grained stone, and also that experiment has indicated that such 104 THE BUILDING AND DECORATIVE STONES stones are weaker, will crush under less load, wlien saturated with water than when dry. (5) Tests to ascertain resistance to freezing. The power of a stone to resist the action of frost is naturally largely dependent upon its absorptive qualities, as noted above, since it is the freezing of the absorbed moisture that produces disintegration. It has been shown that water passing from the liquid to the solid state, that is to the con- dition of ice expands in the proportion of 100 to 109. That is to say, an amount of water occupying 100 cubic inches before freezing must occupy 109 cubic inches after. The pressure exerted by this expan- sion is equal to 150 tons for each square inch of surface. Provided then the interstices of a stone are filled with water, Avhich there freezes, it is easy to see that if there is no other way of relief, the stone must be sadly disrupted. Abundant evidences of this are to be found in any sandstone quarry that has been closed during the winter months without protection. That the result is not more marked than it is, is due to the fact that relief is found in the expansion outward through the pores of the stone. It is for this reason that a coarsely porous stone will often stand a freezing test better than one that is of fine grain, the expansive force finding relief outward through the larger pores. The importance of the freezing test was early recognized, and several methods have been devised for making such in the laboratory. Obviously, the best method to pursue is that of nature, and to actually submit the samples to repeated freezings and thawings. Un- fortunately this can not at all times be readily done, and moreover nature's methods are sometimes s1oa\', so that other schemes have been proposed with a view of showing the relative rather than the actual powers of resistance of different stoues. Perhaps the best known method of determining the resisting power of stones is that pro- posed by Brard A^-hich consists in saturating the stone with a solution of sulphate of soda which on crystallizing expands as does water on passing into the condition of ice. A modification of Brard's original process was used by Mr. C. G. Page with reference to the selection of material for the Smithsonian Institution l)uilding' in Washington.' ' See Hints on Public Architecture, p. 119, by R. D. Owen, also Stones for Building and Decoration, p. 439. JIAKVI.AXD GEOI.OOIf.VI, SUKVKY 10') Tlie jirocess as carried on by [Mr. I'aoe consisted in builiiiji a carefully l)repared and weighed CTihe, for half an hour, in a saturated solution of the sulphate, and then allowing it to dry, during which process the absorbed salt crystallized and expanded. Although the results were found to be not in all cases quite reliable, and evidence was deduced to the effect that the boiling salt solution exercised a chemical as well as mechanical action, still tlicy are not without interest and may be given ill talinlar form as below. Specific 1,088 In .Malerliils. Kravlly. trrnlns. Marble, close-drained, Maryland '2.834 0. 1!) Marble, coarse "alum stone," Baltimore County, Maryland... 2.8.57 0..50 Marble, blue, Maryland 2.(113 0.34 Sandstone, coarse, Portland, Connecticut . . 14.3f> Sandstone, tine, Portland, Connecticut 2..5S3 24.93 Sandstone, red, Seneca Crceli, .Maryland 2.073 0.70 Sandstone, dove-colored, Seneca Creek, Maryland 2.4Sfi 1.78 Sandstone, Little Falls, New Jersey . . 1..58 Sandstone. Little Falls, New Jersey 2.482 0.02 Sandstone, coarse. Nova Scotia 2. .518 2.16 Sandstone, dark, coarse, Seneca Aqueduct, Peters's quarry ... . . .5.(i0 Sandstone, Acquia Creek, Virginia 2.230 18.00 Sandstone, 4 miles above Peters's quarry. Maryland . . 0..58 Sandstone, Beaver Dam quarry, Maryland . . 1.73 Granite, Port Deposit, Maryland S.CO'.I .5.05 Marble, close-grained, Montgomery County, Pennsylvania.... 3.727 0.35 Limestone, blue, Montgomery County, Pennsylvania 2.009 0.28 Granite, Great Falls of the Potomac River. Maryland . . 0.35 Soft brick 2.311 10.46 Hard brick 2.394 1.07 Marble, coarse dolomite, Monnt Pleasant, New York 3.800 0.91 The specimens operated upon, it should be stated, were cut in the form of inch cubes. Each was immersed for half an hour in the boiling solution of sulphate of soda, and then hung up to dry, this perfonnance being repeated daily throughout the four weeks which the experiment lasted. Although as above noted this process is practically abandoned, the series of tests given was productive of certain results wliich are well worth a moment's consideration. Thus the red sandstone from Seneca (^reek, [Maryland, with a spc'cific gravity of 2.672, or a weight per cubic foot of 167 pounds, lost by disintegration but 0.70 grains. This TOG THJD BUILDING AND DECOEATIVE STONES was the stone ultimately selected for the Smithsonian Institution building, and the structure as a whole is to-day probably in as good a state of preservation as any of its age in the United States. The second stone, from Acquia Creek, Virginia, with a specific gravity of 2.23, or a weight per cubic foot of but 139.37 pounds, and which lost 18.6 grains is the one in the construction of the White House and the old portions of the Capitol, Interior Department and Treasury buildings. This stone has proven so poor and disintegrates so badly that the buildings are kept in a condition anywise presentable only by repeated applications of paint and putty. The results obtained with hard and soft brick are also very striking; the one weighing at the rate of 138 pounds per cubic foot, losing 16.46 grains, while the harder brick, weighing at the rate of 143 pounds, lost but 1.07 grains. If anything can be learned from the series it is that with substances having the same composition, those which are the most dense — which are the heaviest bulk for bulk — will prove the more durable. The results obtained on coarse and fine varieties of Portland sandstone suggest at least that water would freeze out of the coarser stone, and therefore create less havoc than in that of finer grain, a probability to which I have already referred.' More recently this method has been reinvestigated by Dr. L. McI. Luquer " with a view of ascertaining what relation may exist between the sulphate of soda and the freezing methods when both are caiTied on under the same conditions. In these tests recognition is taken of the fact broiight out a generation or more ago to the effect that a hot solution of a sulphate of soda is likely to undergo decomposition and give rise to free alkali (NaaO) which exerts a powerful chemical effect and weakens the cohesive power of the granules. The method employed, as given in the paper above referred to, was as follows: The specimens, which had been carefuUy prepared, biiished, dried and weighed, were boiled in the sulphate of soda for half an hour, in order to get complete saturation, jit the end of the half hour it was noticed in every case that the solution was slightly alkaline, although at the start it had been neutral. In order to prevent any continued ' stones for I'.iiililiiig' and Decoration, :.'cl ed., p. 438. ' Trans. Am. Soc. Civil Engineers, Mar. 1895, p. 2:)"). MARYLAND GEOLOGICAL SURVEY 107 chemical action the beakers were emptied, the specimens rapidly washed with water, and the beakers immediately refilled with the neutral siilphate sohitiou. After soakins^ for several hours the speci- mens were hung up l^y threads, and left for 12 hours (during the night) in a dark room. In the morning all the specimens were covered with an efflorescence of the white sulphate of soda crystals; ihey were then allowed to soak in the solution during the day and again hung up at night. Efflores- cing for about 12 hours and soaking for about the same time constituted a period. The experiments lasted for eight periods, and were con- ducted in this way in order to make them correspond with those made with freezing water, as in the cold-storage room the specimens could only be changed night and morning. In two cases the specimens were allowed to effloresce for 36 instead of 12 hours, to insure thorough action of the salt. The experiments thus really lasted for 10 days. It was deemed that eight periods or days were sufficient, as de Thury states that if a specimen is acted on by this method of testing, the cfFect wiJl be noticed in five days. The general opinion of others seems to be also, that a week or eight days is long enough to obtain good results. During the test the solu- tion was renewed from time to time, and appeared to remain neutral. The temperature of the room varied from 60° to 70° Fahr. (18° to 21° Cent.). Those specimens most affected began to show the dis- integrating action of the solution very early in the course of the experiments. At the end of the 10 days the specimens wore sprayed with the stream from a wash bottle to remove any adhering particles, washed in water to remove the sulphate of soda, carefully dried in an air bath at about 120° Cent., and weighed again. The difference between the weights was taken as the loss due to the action of the sulphate of soda. The results are given in tabular form below. In the experiments of Prof. Bodge ' carefully prepared cubes the dry weight of which had been previously ascertained were placed in a shallow iron pan, nearly covered with water and exposed to the open air, but in a sheltered place, to freezing and thawing, for a period ' Geol. and Nat. Hist. Survey of Minnesota. Final Reports, vol. i, p. ISCi. 108 THE BUILDING AND DECORATIVE STONES of 8 weeks during February and ]Marcli. To thaw, the specimens were occasionally brought into a Avarm room for a few hours. After the exposures, the pieces were carefully examined, then dried for six days and weighed, the difference between the first and second weight indicating the loss of material by the frost action. In the freezing- experiments by Dr. Luquer, above referred to, the specimens were allowed to thaw and soak in water during the day, and were hung up and frozen at night. The experiments lasted the same number of periods as did the sulphate tests. The temperature of the cold room in which the freezing was carried on varied from 4° to 10° Fahr. and that of the room in which the soaking and thawing was done, 85° Fahr. After the freezing the specimens were allowed to soak in water for the same period as did those used in the sulphate of soda experiments, after which they were dried and weighed. During the progress of the experiments, it is stated the deterioration was so slight that the effect was scarcely noticeable, the sandstones only showing the effect of a slight residue in the bottom of the pails in which the experiments were performed. Below are given in tabular form the results obtained by both processes. It will be noted the action of the sulphate was by far the most energetic, but it cannot be learned that there is any definite relationship. Hence all things considered it seems best that the sulphate method be abandoned, and the actual freezing test always resorted to. Eesults of Experiments with Sulphate of Soda. Original Loss of Losp of ■weight in weight, in weight in No. SiJecimens tested. grams. grams. parts in lu.oOO. 1 Coarse crystaUine dolomitic marble 71.9030 0.0775 10. 7S ■2 Medium crystalline dolomitic marble !)3.8861 0.1.597 17.01 3 Fine-grained limestone 67.0964 0.1744 35.99 4 Coarse-grained red granite 71.8648 0.1115 15.51 5 Medium-grained red granite 56.4939 0.0370 6.55 6 Fine-grained gray granite 43..5910 0.0335 .5.16 7 Rather fine-grained gneiss 61.8687 0.0393 6.33 S Norite, "Au Sable" granite 3.5.1173 0.0135 3.84 9 Decomposed sandstone 39.4394 1.9010 483.13 10 Very fine-grained sandstone 37.77G0 0.1800 47.65 11 Sandstone 38.0335 0.4070 14.5.18 13 Pressed brick 37.4035 0.0930 34.86 51 Decomposed sandstone 33.9660 3.7335 1 631.31 53 Sandstone 33.9001 0.1381 57.78 MARYLAND GEOLOGICAL SURVEY 109 Results of Experiments with Frost. Orlslnal Loss of Lose In „„ _ , wclBlil In wclEht 111 wclBtit In "O. Specimens tested. craiiis. criinis. parts In lO.OCO. 1 Coarse crystalliue ilolomitic marble 63.6407 0.0197 3.10 2 Medium crystalline dolomitic marble. .. . 93.08.il 0.0316 2.30 3 Fine-i^rained limestone .55.2787 O.Oll.j 3.07 4 Coarse-grained granite .52.2787 0.0072 1.38 .5 Medium-grained red granite 03.4693 0.0113 1.70 6 Fined-grained gray granite .58.0149 Very slight, about same as No. .5. 7 Ratlu-r liue-grained gneiss .53.7260 Very slight, about same as No. .5. 8 Norite, ''Au Sable" granite 44.4665 Very slight, less than No. 5. 9 Decomposed sandstone 38.4055 0.3640 08.74 10 Very tine-grained sandstone 39.5130 0.0430 10.6:! 11 Sandstone 31.9437 0.0312 14.21 13 Pressed brick 37.1790 0.0255 6.86 51 Decomposed sandstone 34.1020 0.0610 2.5.31 53 Sandstone 20.2385 0.0180 8.89 (6) Tests to ascertain ratio of expansion and c-ontractiuii. Tests of this nature are of value for tlic purpose of (1st) making proper allow- ance for expansion in parapet walls, and similar situations, and (2nd) because through expansion the tenacity of the stone is weakened. As long ago as 1832 Col.Totten, in view of the difficulty of making perma- nently tight joints even with the strongest cements, instituted a series of experiments to ascertain the actual expansion and contraction of granite, sandstone and marble when subjected to ordinary temperature. He found the rate per inch for each degree of temperature for granito to be .000004825 inch: fnr marble .000005668 inch, and for sandstone .000009532 inch. That is to say a block of stone one foot in length raised from a temperature of freezing (02°) to that of a hot summer day, say 90°, would be expanded to the amount of .005416 inch or would be 1.005416 inches in length. The amount is apparently trifling yet it produces a weakening efl'cct wbicli is of both (■(•(.nnniii- and geologic significance. Within recent years some good work in tliis line has lieen done under the direction of the Ordnance Pepartmeut of the U. S. Army. 110 THE BUILDIKG AND DECORATIVE STONES The method of testing has consisted in placing carefully measured bars of stone in baths of cold -water (32° F.), hot water (212° F.), and back to cold water once more. It was noted that in none of the samples tested did the stone quite regain its first dimensions on cooling but showed a slight " permanent swelling." Since this can only mean that the particles composing the stone have separated though ever so slightly, it is an important matter as it necessitates a weakening which is shown by actual pressure tests. The tables given below show the amount of permanent swelling occurring in stone bars of a gauged length of 20 inches.' Oranites. Amount of Description. permanent swelling. Inch. From BracUlock quarries near Little Rock, Ark. ^Ligbt) 0048 From Braddock quarries near Little Rock, Ark, (Dark) 0034 From Millbridge, Maine, White Rock Mountain 0033 From Broad Rock quarry, Chesterfield County, Virginia 0047 From Korah Station, Virginia 0048 From Exeter, Tulare County, California 0019 From Rockville, Stearns County, Minnesota 0061 From Sioux Falls, Minnesota 00.59 From Troy, New Hampshire 0031 From Branlord, Connecticut 0043 .0033 From Milford, Massachusetts 0071 Mean 0040 MarUes. Amount of Description. permiinent swelling. Inch. Rutland, white, Vermont 01.3.5 Rutland, white, Vermont (second exposure) 0029 Mountain Dark, Vermont 0064 Sutherland Falls, Vermont 0107 From St. Joe, Searcy County, Arkansas 0196 From De Kalb, St. Lawrence County, New York 0055 From Marble Hill, Georgia 0077 Mean 0090 '■ Rep. on Tests of Metals, etc., at Watertown Arsenal, U. S. War Dept., 1895, p. 322-23. MARYLAND GEOLOGICAL SURVEY 111 Limestones. Amount of Descrlpllon. permanent (iwelUnK. Inch. From Isle La Motte, Vermont OOSl From Wasioja, Minnesota 0024 From Fort Riley, Kansas 00.">3 From Beaver, Carroll County, Arkansas 0000 From Mount Vernon, Kentucky 007."> From llarliniiton quarry, Rookwood, Illinois 01 14 From Bowling Green, Keutneky 0077 .01111 From Bedford, Washington County, Indiana OOS.i Mean 0070 Sandstones. Amount of Description. pcniinncnl swelling. Inch. From (romnell, Connecticut 00G7 From Worcester quarry. East Lougmeadow, Massachusetts 0022 From Kibbe quarry, East I.ongmeadow, Massachusetts 0020 .ooo:i From Maynard quarry. East Longmeadow, Massachusetts 0010 From Kettle River quarry. Pine County, Minnesota 0018 From Cabin Creek quarry, Johnson County, Arkansas OOIS From Sebastian County, Arkansas 001.5 From Bourbon County, Kansas, " Bandera stone " 0017 From Piedmont quarry, Alameda County, California 0174 From Olymiiia, Washington 003.5 From Clnickauut, Washington 00.52 .014S From Tenino, Thurston County, Washington 0035 Mean 004 7 (7) Tests to ascertain the fireproof qualities of stone. The expan- sive power of natural temperatures is but slight in comparison with that induced Ly the heat of a bui-ning Iniilding, which is at times so great that no natural material can be expected to remain uninjured. Several years ago H. A. Cutting ' made a small series of experiments to ascertain the relative powers of resistance of various stones to artificial temperatures. According to his results the heat resisting capacity of the various stones tested stands in the follo\ving order, the ' Weekly Underwriter. 112 THE BUILDING AND DECORATIVE STONES first mentioned being the least affected: (1) marble, (2) limestone, (3) sandstone, (4) granite, and (5) conglomerate. The tests were however scarcely sufficient to fully establish any such law. Prof. Dodge, to whose work on the Minnesota Survey reference has already been made, proceeded as follows: The prepared samples were first heated to a red heat in a muffle furnace, the temperature being raised gradually. Twice each sample was removed with tongs, and carefully inspected to note the effect of heating. After this heating test the samples, while still very hot but at a temperature below redness, were immersed in a tank of water for a few minutes. The action of the water in cavising cracking or crumb- ling was noted. Such tests are really too severe to be used in any but the most extreme cases since no stone can be expected to pass through such an ordeal unharmed. £ ^»"^ Fi<:. 15. — Cube for crushing tests. (8) Tests to ascertain resistance to crushing. This is far the most common test that is applied to stone. Concerning the utility of such tests as usually applied, the writer has expressed himself elsewhere. The first systematic and really exhaustive series of these tests made in America were those of Q. A. Gillmore, of the Engineer Depart- ment, United States Army, whose results were published in the An- nual Report of the Chief of Engineers for 1875. The size of specimens operated upon by Gillmore in the systematic part of his work was that of a two inch cube. During his preliminary experiments he found that at least within certain limits the compres- sive resistance of cubes, per square inch of surface imder pressure increases in the ratio of the culiic roots of the sides of the respective cubes expressed in inches. Thus the actual resistance of a ^ inch cube, expressed per square inch, was about 6,080 pounds, while that of a 4 inch cube, that is one bavins' S times the length of side, was JIAKVLAXD GEOLOGICAL SURVFA" 113 11,720 poTinds per square incli. The general conclusions arrived at was that having ascertained from an average of several careful trials the crushing resistance of a 1 ineli cube, an 8 inch cube of the same nature shouhl sliow twice ms much resistance per square inch of crushing surface as tlie 1 incli. This conclusion was not fully borne out by later experiments but enough was gained to show that for pur- ]K)ses of fair comparison it was necessary that all tests be made on cubes of approximately the same size. Gillmore's tests showed also that mucli il('[»ends on tlie breadth when compared with the height of the specimens tested. Thus he found that while an inch cube of Berea standstone crushed imder a weight of 9500 pounds, a block of the same stone 1 inch thick by two inches square, and which con- tained therefore only four times the amount of material sustained not merely 4x9500 or 38,000 pounds but 70,000 pounds. When the height or thickness of the specimen was doubled, so as to have the form of a two inch cube it surtained but 50,000 pounds, and when the height was increased to twice that of the width, or base, it sus- tained only 44,000 pounds. Gillmore further found that there was a great difference in the results obtained by crushing bet\veen plates of various kinds of mater- ial as wood, leather, lead and steel, in every case the tests between steel plates yielding the highest results, a fact which was shown to be due to the lateral spreading action of the other substances men- tioned. As a result of these and other trials which need not be given in detail here it seems best that jiressure tests be made on two inch cubes, the faces of which have been carefully sawn or ground so that no incipient fractures ai'e developed, and those which are to come in contact with the steel plates rubbed with a vei-y thin coating of plaster of Paris to fill in all inequalities. In the process of testing it is cus- tomary to note (1st) the number of pounds registered by the crushing machine -when the stone first begins to show signs of fracture, and (2nd) the number registered when it actually crushes. Both of these phenomena are noted in the accompanying tables (p. 145, 15G, 1G4). The result of many experiments has been to show that most lami- nated or bedded rocks will bear a greater pressure in a direction at 8 114 THE BUILDING AND DECORATIVE STONES right angles to tlieir bedding than parallel thereto. That is, a block will stand more if laid on its natural bed than if stood on edge. This result may not always appear in a small series of tests owing to sundry imperceptible differences in the specimens tested, but it is nevertheless true in a general way. Study of the results of large numbers of tests that have been made at periods extending over many years have shown that the results of recent tests are much higher than those several years ago, even on the same class of material. This residt, which is simply due to the perfection to which the methods have been brought, is so great that very unfair deductions may be drawn regarding the relative strength of materials tested at different times under perhaps dift'erent condi- tions. In fact there are few things more misleading than a tabulated statement of crushing strengths, made at intervals covering many years, on cubes of varying sizes, and under conditions which are not stated. It is interesting to note the form assumed by the fragments as a result of crushing. As a rule, a perfectly homogeneous rock gives rise to conical or pyramidal fragments according as the stone is friable, of a pronounced granular structure like sandstone, or compact as are most granites. Stones crushed on edge naturally split up into flakes or slabs. In the plate herewith given (Plate VI) are shown the shape of the fragments formed during the tests tabulated. (See p. 113.) In all this work of testing the strength of stone it is well to remem- ber that stones as a rule are apparently weaker when saturated with moisture than when dry. It is true that we have not at hand to-day sufficient data for proving this conclusively, but such data as are at hand are more than merely suggestive. Thus ]\IM. Tournaire and Michelot have shown ' that cubes of chalk three decimeters in diameter crushed wet under a pressure of but 18.6 kilograms; but when air dried under 23.5 kilograms and when stove dried under 86.3 kilo- grams. Delesse's experiments on 5 centimeter cubes of chalk and the " ealcaire grossier " found that the chalk when wet crushed under a pressure of 12.9 kilograms; Avhen air dried 23.6 kilogi-ams, and when 'American Journal of Science, 3rcl series, vol. xvi, 1S7S, p. 151. JIAKYLAND GEOI.OGICAI. SURVEY 115 stove dried 36.4 Icilogvams. The limestone (caleaire grossiei") crushed when wet under 24.35 kilogTanis, when air dried kilogi-ams, and when stove dried inider 42.7 kilogTams. Inasmuch as stones in a foundation are subject to periodic or perhaps constant saturation these facts are worthy of consideration. It is well to note here too that the effect of temperature changes upon stone is weakening. In the tests made by the Army I'^ngineers to which we have already referred ' it was found that samples which had been submitted to the hot and cold water tests to ascertain their coefficient of expansion and contraction had suffered to a remarkable degree. The average result showed that the stones from the water baths lost in strength on an average 34.9 per cent, the granites, after passing through both hot and cold water tests, poss(!ssing but 83.7 per cent their original strength; the marbles 46.2 per cent; the limestones 58.8 per cent, and the sandstones 66.9 per cent. Viv, II). — Bar f.ir expansion tests. Tests on bricks made by the United States Army Engineers showed that the wet samples had as a rule but 85 per cent the strength of the dry ones, the greatest loss in strength occurring in medium hard and hard brick. (9) Tests to ascertain elasticity of stone. Tests to ascertain the elasticity of stone when sulijccted to compressive and transverse strains, have also been made by the United States Army Engineers, and the results obtained may well be noted briefly here, though for details the reader is refeiTcd to the original publications.' The tests of elastic properties under compression were made upon prisms 4-in. by 6-in. by 24-in., the loads being applied parallel to the • Report on Tests of Metals, etc., 1S95. '•' Report of the Tests of Metals, etc., made at Watertown Aisciial. Years 1890, 1894 and 1895, Washington, T). C. 116 THE BUILDING AND DECOEATIVE STONES direction of the long sides (see Fig. 16), tlie compressibility being- measured by means of a micrometer. It was found here, as in the tests for ascertaining expansion that the stones shortly developed a permanent " set," from which they did not recover during the period of time over which the observations were extended. COMPRESSIVE ELASTIC TESTS. APPLIED LOADS. 20" IN GAUGED LENGTHS, Total nnunrii ^" square Compression o„, jn-i, '°'*' P°"°"^-inch pouudB. inch. »et men. Granite, Milford, Mass 31.5,460 0,000 0.0339 .001.5 Granite, Troy, New Hampshire 343,600 10,000 .0411 Griinite, Troy, New Hampsliire 319,340 9,000 .0S79 .0063 Marble, Cberokee, Georgia 144,960 6,000 .0133 Marble, Cberokee, Georgia 48,320 3,000 .0037 .0006 Limestone, Mount Vernon, Kentucky 59,833 3,400 .0183 Limestone, Mount Vernon, Kentucky 3,493 100 .. .0033 Sandstone, East Long Meadow, Mass 96,400 4,000 .05.54 Sandstone, East Long Meadow, Mass 3,410 100 . . .0136 Fig. 17. — Bar for elasticity tests. The transverse tests were made on similarly prepared prisms, sup- ported at the ends, tlie load being applied at the middle as shown in Fig. 17. In the table below is given the residts of a few selected tests, as determined by the authorities referred to, the term modulus of rupture signifying the weight in pounds under which the bar breaks; only the maximum results are tabulated. MARYLAND GEOLOGICAL SDKVEV 117 Xo. of tests. 203 N'o. of teetH. 204 205 TRANSVERSE TESTS. Pink Granite from Milford Pink Oranile Company, Boston, Jfasa. Dimensions. tlltlmatc strength. Distance between end supports. Inches. 19 Inches. 4.03 Ueptb. Inches. 6.03 Pounds. 0,030 Modulus of rupture. Pounds. 1,74.5 Granite from Pigeon Hill Granite Compani/, Hockport, Maxs. Dimensions. Dltimate strength. BreaUtli. Depth. Total. Inches. Inches. Pounds. Pounds, 4.03 6.03 12,320 2,404 4.01 6.06 13,450 3,416 Distance between end supports. Inches. 19 19 .Modulus of rupture. R. Fig. is. — Bar for shearing tests. (10) Tests to ascertain resistance lo shearing. The term shearinfj as used in geology includes a strain due not merely to pressure in one direction, but also those uue to pulling or thrusting in all directions up to those perpendicular to the first. It is a fonn of strain likely to be brought to bear on stone in many parts of a building, bridges, etc., and is by no means unimportant. As performed by the Army Engi- neer the test consists in subjecting prepared prisms supported at each end by blocks 6 inches apart, to pressure applied by means of a " plunger " having a face 5 inches wide, there being then a clear- ance space of half an inch between the sides of tlie plunger and the blocks on each side, below (sec Fig. 18). 138 THE BUILDING AND DECORiVTIVE STONES The results of a few experiments of this nature are given below. It is worthy of note that " before the shearing strength was reached during the tests, tension fractures were developed on the under side of the stone midway the 6-inch free span, and there were instances in which longitudinal fractures opened in the ends of the stones, cor- responding to shearing along the grain in the tests of timber." NATURAL STONES— Shearing Slonfx from Charles River Stone Company, Tests. Boston, Mass. No. of tests. Description. Shearing dimension. Transverse fracture developed on tension side. SiiearinK strengtli. Is Total. Per square inch. lbs. Indies. sq. in. lt)S. lbs. 240 Milford gmniti-, Milford, Mass 4.02x0.03x3 48.48 34,.S00 108,400 3,230 one 241 " 4.03x0.01x3 48.33 37,300 138,800 3,872 two 24a Brauford i;ranite, Brauford, Couii 4.04x0.01x3 48.50 18,900 93,500 1,925 one 243 " 4.03x0.01x3 48.44 19,600 84,400 1,743 one 244 Troy granite, Troy, New Hainpshire. . . 4.03x0.00x2 48.30 39,900 107,900 3,331 one 24.5 (1 li .t tt it 4.00 X 0.02x2 48.88 34,400 107,400 2,197 one 240 Maynard stone, E. Long .Me.idow, Mass. 3.99x6.01x2 47.90 2.5,800 53, 700 1,130 one 247 .. 4.03x6.00x3 48.34 19,900 63,100 1,287 two 248 Worcester stone, E. Long .Meadow-, •' 4.00x 6.00x3 48.00 33,900 00,400 1,383 two 249 4.00x .5.98x3 47.84 30,300 53,700 1,103 two 2.50 Klbbe stone, Ea.st Long Meadow, Mass. 4.00 X 6.00 X 3 48.00 25,100 47,600 993 two 251 1( t> a n .c 4.00 X 6.00x3 48.00 39,400 03,800 1,308 one 253 Southern marble. Marble llill, Georgia. 4.03x6.00x3 48.34 30,70(1 50,100 1,163 one 253 .c 4.03 X 0.00x2 48.34 30,300 73,400 1,501 one 254 Tuckahoe marble, Tuckalioe, New York. 4.03x6.01x3 48.33 38,8.50 7.5,100 1,.5.54 one 255 " 4.03x0.00x3 48.34 3.5,700 08,800 1,430 one No. of test;. NATURAL STONES.— 8IIEAUING Tests. PiJik Grunltt: from Mil ford Pu/k Granite Company^ Boston^ Ma»i>. Shearing; strength. Transvei'se Shearing Shearing dimensions. Inches. sq. iucli. 362 6.01x4.02x2 48.32 Transverse fracture developed on ten- sion side. Totiil. Per square inch. a- -a II Pounds. Pounds. Pounds. 38,300 88,200 1,S25 on MARYLAND GEOLOGICAL SURVEY 119 Granite from Pigeon HiU Granite Company, Rockport, Mass. Sla-arlnK strength. „ Xn Irnnpverse ^ — , *-a "of' Stiearinp! Shearing fracture g£ test ulmensions. area. developed on ten- Total. Per square Inch. n g Blon side. 5.C m « Inches. sq. inch. Pounds. Pounds. Pounds. 36.S 6.05x4.00x2 48.40 4.5,400 '.l!),10ll i,04T •2M 0.01x4.00x2 4S.0S 38,600 50,600 I,(l.-)2 (11) Tests to ascertain the specific gravity. Tlip dotcrmiiiation of the specific gravity of a stone, or its weight when compared with an eqiinl volume of water, is of interest, and sometimes of practical iinportaiicc. Of two stones of the same mineral nature, the one hav- iui;- the highest specific gravity, that is the greatest weight Imlk f. Keith, Arthur. Geology of the Catoctin Belt. 14th Ann. Rept. U. S. Geol. Surv., 1892-93, Washington, 1894, part ii, pp. 285-395, maps and plates. House Exec. Doc, 5:ird Cong-., 2ud Sess., vol. .wii, p. 285. (Rev.) Science, n. s., vol. ii, 1895, p. 97. 37. Keyes, C. R. The Origin and Relations of Central Maryland Graniles (with an introduction by G. H. Williams). 15th Ann. Rept. U. S. Geol. Surv., 1893-94, Washington, 1895, pp. 685-740, with 21 plates. 38. Secular Decay of Granite Rocks. Proc. Iowa Acad. Soi., vol. ii, Des Moines, 1895, pp. 27-31. 39. Acidic Eruptives of Northeastern Maryland. .\mer. Geol., vol. xv, 1S95, pp. 39-46. 10. Williams, G. II. The general relations of the Granitic Rocks in the Middle Atlantic Piedmont Plateau (introduction to Keyes' " Origin of Central Maryland Granites "). 15th Ann. Rept. U. S. Geol. Surv., 1893-94, Washing-ton, 1895, pp. 657-684, with jilates. 41. Keyes. C. R. Central Maryland Granites. stone, vol. xiii, ISOG, pp. 421-428 seq. 42. Maryland Geological Survey. Wm. Bullock Clark, State Geologist. Reports, vol. i, Baltimore, 1897, 539 pp., plates 17. 43. Merrill, George P. Rocks, Rock Weathering and Soils. Macralllan, New York, 1S97, 411 pp., plates 25. 136 A HISTOEY OF THE QUARRYING INDUSTRY THE QUARRIES OF MARYLAND. Granites and Gneisses. Granite is the broad family name that is applied to a large and common group of rocks, which are usually of a somewhat mottled light gray color, and almost always carry two minerals, quartz and feldspar, as essential constituents. Besides these, which make up the mass of the rock, there are dark colored iron-bearing minerals, such as black mica, or biotite, hornblende and occasionally pyroxene. Each of these may be evident to the eye without the aid of a lens. The microscope shows in addition many other minerals such as zircon, apatite or epidote which are of scientific interest, but of little eco- nomic importance as constituents of building stones, since they influ- ence neither the appearance nor the wearing qualities of the material. The foregoing minerals usually form irregular aggregates, in which the individual grains interlock in such a way that the cohesive strength of granite is relatively high. The constituent grains vary very widely in size, from individuals two or more inches in diameter to those which are scarcely separable with the unaided eye. The ar- rangement of the different mineral grains is irregular and without any prominent lines of distribution, when the granites are unmodified pro- ducts of crystallization from a molten state. Subsequent action on the rock, however, through pressure or recrystallization, generally arranges the constituent minerals in some regular order, such as in parallel or wavy interlocking lines. It is in this way that many so- called gneisses or granite gneisses originate from granites, as at Port Deposit. True gneisses, however, usually result from the recrystalli- zation of rocks laid down under water, and still retain their banded character. Since in the trade granites and gneisses compete for the same work, and since, when well sorted, there is little difference in their practicability for building purposes, they will be treated together in the present chapter, the differences between the two being shown in the order of grouping in the discussion of the principal quarries. MAKVLAND GEOLOGICAL SURVEY 137 GEOLOGIC OCCURRENCE. The granites and gneisses of Maryland are almost entirely limited to that portion of the state which has been described, in previous pai-ts of this paper, nnder the title of the Piedmont Plateau, an area wlii('h consists of masses of ancient crystalline and ])artially crystalline rocks, which are of both igneous and sedimentary origin. These rocks since their formation have been subjected to many changes and alterations, which have produced a marked foliation or schistosity, showing a general trend from the northeast to southwest, with a moderate dip or inclination toward the northwest. The topography of this area is that of a moderately high and level plateau, which has been deeply eroded into a series of rounded hills and valleys by the streams that flow across it. The granites and gneisses of the platcaii show no marked topographic features, although they are more prominent than the less resistant limestones, which occur scattered over the region. The industry based on the quarrying of the granites and gneisses is limited to a triangular area bounded on the east by the gravels and clays of the Coastal Plain and on the west by the less crystalline rocks (in the western slopes of Parr's Ridge. Within this limited area there are included other crystalline rocks such as the serpentines, gabbros and peridotites, and in a few instances certain partially metamor- phosed sedimentary rocks, such as the phyllites and roofing slates of Harford and Baltimore counties. The complex geological structure of the Piedmont zone plainly shows that the rocks have been greatly disturbed at varioiis times both prior and subsequent to the early base leveling of the region, when the crystalline rocks formed the foundations iipon which the more westerly sediments were laid down. Some of the elastics be- came involved and infolded with the massives during the process of many foldings, and both were then subjected to the more or less in- tense dynamic action of the later orographic disturbances. The in- fluence of the numerous intrusives, which are known to have broken through at variotis periods, operated still further to obliterate the original character of the rocks. The exact sequence of events has not been deciphered, altlmugh one speaking broadly may say that the gabbroic and dioritic types were the earliest to be extensively intruded. 138 A HISTORY OF THE QUAREYING INDUSTRY These in turn were followed by the more basic non-feldspathic rocks, and then at different inteiwals the granite types appeared, breaking through all of the preceding series. These granites as shown by the accompanying map (Plate VII) occupy several distinct areas along the eastern slope of the Piedmont Platean. The largest of these is that extending from Sykesville to Washington, while the most important economically is the lenticular mass extending from Rising Sun through Port Deposit to the western side of the Susquehanna river. In all there are some fifteen areas where granite is prominently developed, and in at least five of these there are quarries of considerable economic importance. DISCUSSION OF INDIVIDUAL QUARRY AREAS. GRANITE. Port Deposit. The Maryland granite which is perhaps best known outside of the limits of the state is that quarried in the vicinity of Port Deposit. This town is situated on the Susquehanna river three miles above its mouth at Havre de Grace. It is one of the principal towns of Cecil county and has good railroad connections with Philadelphia, sixty- seven miles distant, Baltimore, forty-three miles, Washington, eighty- three miles and ITarrisburg, sixty-five miles. It is possible also for light crafts to ascend the Susquehanna as far as the town and receive their loads directly from the quarry, thus furnishing water connections between the quarries and Philadcdphia eighty miles, Baltimore fifty miles, Washington two hundred and twenty-five miles and Richmond three hundred miles. The gorge of the Susquehanna is emphasized by the wall-like mass of granite which skirts the river, from which it is generally separated by a narrow belt of meadow or marsh land. A mile above Port Deposit this rock wall becomes nearly perpendicu- lar, and approaches close to the river. It was this protruding mass of the wall which first called attention to the valuable granites of the area, and it is at this point that the largest quarries are operated, the openings extending nearly to the water's edge. While some small quarrying has taken place in se^-eral spots, to gain room for buildings. MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE IX. Vir. 1 I'lIOidMlCHOGUAl'll UK r.Ii.W iri']. I'diri' IIKl'dSrr. (M.\i:xii-ii:i]Ti:x DiAMKTKUri.) Fu:. •.'.— ril()T(i.\nCIi(H;i{.M'II ok (;H.\.\1 TK. i:i.I,li:(irr cnv. (.Macmi-modTkn Diamk-iki!.-;.) MARYLAND GEOLOGICAL SURVEY 139 the industry at present is limited to the northern edge of the town, where the rock now stands exposed in an almost vertical wall measur- ing from the base to the top something over a hundred feet. The value of the granites of this area was early recognized, and the rock was used by the settlers for the foundation of some of the oldest colonial dwellings. The industry arising from the quarrying of the rock is, however, of somewhat later origin. In the years 1816- 1817 a bridge was built across the Susquehanna river at Port De- posit by the Port Deposit Bridge Company. During the process of construction the abutments for the eastern approach were made from stone quarried at the eastern end of the bridge, which is within the present corporate limits of the town of Port Deposit and not far from the site of McC'lanahan's quarries. For about ten years the opening so made was worked in a small way by Simon Freeze, who had sup- plied the materials used in the construction of the bridge. In 1829 the owners of the Maryland canal became interested in the quarry, and increased its workings. In 1830 the business passed into the hands of Samuel Megredy and Cornelius Smith, who still farther increased the scope and operations, and developed a considerable trade witli Baltimore and other coastwise towns. Two years later Ebenezer D. ilcClanahan became interested in the granite quarrying industry through his brother-in-law Daniel ilegredy, who was then a success- ful operator. McClanahan became the dominant factor in the local development and gradiially increased the l>usincss until in 1837, from data furnished by Anthony Smith, Ducatel ' estimated the annual output at from 12,000 to 1.5,000 perches. On the retirement of E. D. JfcClanahan the business was transferred to his sons, who are at present the principal owners in the Port Deposit company, which controls the local industry. The quarries at Port Deposit, as shown by Grimsley in his work on the gTanites of Cecil county, are in rocks of igneous origin, which have been variously modified by severe dynamic action. This has produced a certain degree of sehistosity which causes the Port Deposit granites to be taken at times for a gneiss rather than a granite. This foliation which is produced by the parallel arrangement of the black ' .\iiii. Kept, of the State Geolog'ist of Marvlaiid. ISliT. p. 15. 140 A HISTORY OF THE QUARRYING INDUSTRY inica flakes has a northeasterly trend nearly at right angles to the course of the river and a dip that is almost vertical. There is no marked banding in the rock, but the whole face of the quarry, which shows thousands of feet of siu-face, appears perfectly homogeneous, as though made up of a single rock. Through this mass there now pass several series of intersecting joints of which the most prominent approximately coincides with the northeast trend of the foliation, but which inclines somewhat to the dip of the foliation. A second set of joints runs almost normal to the first and is almost as sharp as those of the main series. A third set trending west of north is in- clined 60° to the principal joints, while a fourth set, approximately horizontal, serves as bedding joints. The surface of the jointing plane is usually quite smooth and even, but the direction and distance between the parallel surfaces is not always constant. This produces a slight wedging in the blocks, which increases somewhat the cost of quarrying. On the other hand the smoothness of the joint surface frequently renders the rock ready for use in building without tlie intervention of the stone cutter, and allows the extraction of enor- mous nearly rectangular blocks. The expense of preparing the rock for use in the wall is accordingly reduced. Although there are some half dozen series of jointing the rock a short distance below the surface is very compact, homogeneous, and strong, as is shown by the pressure tests of Gilhnore, who found that the compressive strength of this rock was 13,100 pounds per square inch when tested '' on edge," and still more clearly by the more re- cent tests just completed which show a crushing strength of over 80,000 pounds on two inch cubes. The incipient jointing planes, although so closely welded together as to show tliis great strength, are made use of by the quarrymen in trimming the huge monoliths and in cutting the smaller Belgian paving blocks, as the rock may be readily opened by means of wedge and " feathers." The distance between the major joints, which varies from half an inch to several feet, is sufficiently great to allow the extraction of any sized block, which can be handled advantageously by the ma- cldnery and by the transporting agencies. It is usually considered ^rAI!Y^,A^•I) geological svuvey 141 tliat the rock of the Port Deposit quarries is somewhat more easily worked than that at Frenchtown, which otherwise is indistinguish- able. This difference in working arises in part no doubt from the greater age, better facilities for quarrying and handling and also from the more convenient position of dominant lines of working in the Port Deposit quarries. The textvre of the Port Deposit granite, or granite-gneiss is highly characteristic. The rock is composed of the usual granitic constitu- ents, quartz, potassium, and lime-soda feldspai-s, l)iotite and accessory minerals. The most noticeable feature of the rock is the secondary gneissic structure, which is brought out by the arrangement of the shreds and flakes of black mica. This arrangement, which is better shown in the ledge and the hand sjipcimen ( IMate VIII) than in a tliin section, is seen on examination to b(> due to small disconnected gi'oups of mica flakes, which lie in approximately parallel lines. These lines are not straight or continuous, but are wavy and the flakes are dis- seminated or overlapping in such a way as to produce the well-known lenticular effect of gneiss. The color of the rock is a light bluish gray, which in buildings gives a bright fresh appearance at first and then gi-ndually becomes somewhat darker through an accumulation of the diist and dirt in the atmosphere. Sucli a darkening of the rock produces a mellowed pleasing effect in structures situated in most of the cities. The roughness of the surface, however, and the abundance of the black mica render the appearance of the older buildings con- structed from this rock somewhat sombre, if the atmosphere is strongly charged with dust j)articles. This is particidarly true in cities where soft coal is used extensively without smoke consumers. On the whole the appearance of this rock is unusually pleasing. The effect in a building is somewhat variable according as the rock is laid (m its bed or on its edge. The color on edge seems to be slightly brighter and more pleasing than when the stone is cut to lie parallel to the lamination. The chemical cotnposUion of the Port Deposit " granite," as shown in the following analysis ' of the specimen from McClanahan's quarry, is not normal for a granite. It is high in soda and lime and too low ' Made by Wm. Bromwell and g-iven by Grimsley. Op. cit. p. 312. 142 A HISTORY OF THE QUAERYING INDUSTRY' in potash, and the excess of soda over potash shows that the rock is really a quartz mica diorite rather than a true granite. Since the amount of potassium feldspar is greater in many of tire slides from other portions of the area, and since the rock is widely known as granite, this term is used in the present discussion in the trade-sense, rather than with the stricter scientific limitation. Analysis of Port Deponit Oranifc. SiO^ 73.69 AljOj 13.89 Fe„03 1.02 FeO . 3.58 CaO 3.74 MgO .50 Na,0 3.81 K^O : 1.48 H^O 1. 06 Total Oil. 74 From the above analysis, the results of mechanical separations by specific gravity, and estimates based on a study of thin slices, Grimsley has calculated the proportionate mineralogical composition of the rock. The following percentages are thought to be representative: Calculated percentajies, from chemical Percentajies obtained bj- speciilc gravity analyses. separation. Quartz 40.0 Sp. gr. Orthodase 9.0 3.6.5 (Quartz) 40.0 Albite molecules 35.8 3.5.5-3.04 ( p^i^i 45 q Anorthite l.'3.6 3.67-3.8 ) Biotite 9,7 | Biotite, 1 ,„„ T. .J ^ ., „ Above 3.8-,^ ... 15.0 Epidote 0.9 I Epulote, t A microscopic study of sections from the Port Deposit granite shows the presence of the usual granitic minerals, such as quartz, feldspar, dark and light micas, apatite, zircon, sphene, allanite, epidote, chlorite, hornblende, magnetite, garnets and occasionally calcite. The quartz is in relatively large sized areas, ranging from 0.5 mm. x 1.5 mm. to 3 mm. x 5 mm. With the aid of the microscope these area.-! are seen to be not single units, but composed of a great number of small quartz fragments, which have resulted from the crushing and recrystallization of the original granite during the period when the MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE X. •J 3 MARYLAND GEOLOGICAL SURVEY 143 rock received its present schistose structure. These smaller quartz fragments are aggregated together by intricat<> interlocking sutures in a way which renders the rock less rigid and at the same time capable of withstanding fully as much pressure as an individual grain. The interstitial areas between the fragments of the coarser mosaic are filled with a mosaic of still smaller grains. Occasionally the quartz shows small inclusions of iron oxide, dust-like particles and " quartz needles," although it usually appears exceptionally free from them. After a study of several sections from tlic Mc( 'lanahan quarry the present writer is inclined to think that the estimated proportion of tlie alkaline and plagioclase feldspar may better represent the char- acter of the rock of the area, and that the figures obtained from the analysis and the slides indicate a greater amount of the more soluble plagioclase feldspar than the average run of the quarry. If the in- ference is correct the stone is stronger in its resistance to decompo- sition than the above analysis wo\ild indicate. The feldspars, like the quartz, occupy well defined areas and show the shattering and recrystallization into a mosaic, as a result of the dynamic forces which have modified the rock. These mosaics arc much less frequent in the feldspars than in the quartz. The biotite occurs in aggTegates of fine shreds, showing varying degrees of orientation, and is frequently asso- ciated with irregadar grains or small crystals of epidote, sphene and allanite. The shreds and flakes are so small and so interlocked with minute gTains of quartz, that they offer little increase to the weakness due to schistosity. The other constituents are so insignificant in quantity and so stable under atmospheric conditions that they do not influence appreciably the physical or chemical stability of the rock. In any discussion or consideration of Iniilding stones, in order to appreciate the practicability of the rocks for large and permanent structures, it is necessaiy to know something of their physical proper- ties. Among these the most important, as already shown in the pre- vious chapter, are specific gravity, the ratio of absorption, tlic efi'ect of freezing and thawing, and the compression strength. The specific gravity must be known in order to compute the weight to each CTibic foot of the rock, which in turn indicates the amount of pressure im- 144 A HISTOEY OF THE QUAEEYIXG INDUSTET posed on the lower courses of the structure. Since almost all building- stones are exposed to the atmospheric agents which influence them, it is well to know also what the varying conditions of temperature have upon a given stone. For example heating, due to the rays of the sun, causes the minerals to expand. Since the rate of such expan- sion is different for different minerals and even for different directions in the same mineral, there is unequal enlargement of the grains, and hence a loss in the cohesive strength of the rock. Other things being equal this change is greater in aggregates composed of many and vari-colored constituents. Again, if the rock is porous, the expansion of included moisture may rend the rock in freezing weather, so that it becomes necessary to know the amount of moisture absorbed by the rock, and so liable to expansion through frost action. The values obtained by Gillmore ' on Port Deposit granite are as follows: Position. Cracked. strength of spec. Strength per sq. in. Sp. Kr. SVeieht oF 1 cubic tt. Ratio o( absorp- tion. Remarlcs. On bed 79,000 19,7.50 3. 730 170 Coarse, strongly dashed with black. On edge. 33,000 .53,400 13.100 3.730 170 do. On bed 66,000 16, .500 3. 730 170 do. " " 60,000 15,000 3-. 730 170 Burst suddenly. In the tests made during the search for a stone suitable to be used in the building of the Smithsonian Institution at Washington several Maryland building stones were studied, among which was included the Port Deposit granite. Dr. Chas. G. Page,' in his report on the action of frost on certain materials for building, gives as the specific gravity for the Port Dei^osit the figures 2.G0d, and as the loss by frost in grains 5.05. The method of investigation was the so-called Brard process, which consists in substituting the crystallization of sulphate of soda for the freezing of water. The tests made " for the present paper are even more creditable to 'Gillmore, Keports on the Compressive Strength, Specific Gravity and Ratio of Absorption of the Building Stones in the United States. Kept, of the Chief of Engineers for 1875, Appendix II, p. S47. Also Republished 8vo. 37 pp. Van Nostrand, New York, 1876. ■ See Bibliography No. 10. ^ The conduction of this test vfas confided to Mr. Louis K. Shellenberger, Engineer of Tests, for Eiehle Bi-os. of Philadelphia, who rank high as specialists in the construction of testing machinery. MARYLAND GEOLOGICAL SURVEY 145 tlie rock. The specimens submitted were two inch cubes, carefully prepared and subjected to tests under the most uuiforui conditions. The results are as follows: simple Crushing. Absorption. Freezing. Crushing after freezing. . percentage percentage . , Crack. Break. of gain. ofloss. Crack. Break. 07,1(10 0.2.io 0.0(10 83,000 86,000 7!),:iOO 0. ID.'i 0.0 II TS.lOO 00,800 ^... «fi,200 101,540 Tests made by Messrs. Booth, Garrett, and IJhiir, uf I'hiladelphia, on a 2-inch cube gave the crushing strength as 84,730 pounds for 2-inch cubes, which is equivalent to 21,180 pounds per .square inch.' The results of these various investigations clearly show that the Port Deposit rock is strong enough to withstand all the demands made upon it by the pressure of superimposed stone work in structures, and to resist the various deteriorating influences of frost and atmos- phere. This view of the durability of the Port Deposit granite is well sus- tained by a study of its mineralogical and chemical composition, and the evidence of disintegration shown in the quarries and in old struc- tures. The mineralogical composition indicates stability, as no min- eral is present more liable to alteration than the lime-soda feldspar, which itself is not particularly prone to decomposition, although the first of the prominent constituents to yield to atmospheric action. In- vestigation at the quarries, where a considerable depth of decomposed rock is seen to overlie the more marketable material suggests the sus- picion, that the Port- Deposit granite ■nail not withstand atmospheric agencies for any great period of time. This deceptive appearance arises from the fact that the crystalline rocks southward from Phila- delphia have not been scoured and cleaned by the action of glacial ice as in more northern latitudes. Thus the overlying waste repre- sents the decomposed products of several geological epochs, perhaps reaching back as far as Cretaceous time. The number of quarries about Port Deposit has never been very large, although now and then attempts have been made to establish ' ISth Ann. Kept. U. S. Geol. Surv.. pt. \'. ISOT. p. 0(54. 10 146 A HISTORY OF THE QUAEEYING INDUSTRY rivals to the large quarries which are at present operated by the Mc- Clanahan & Brother Granite Company. FrencMown. At the eastern end of the high suspension bridge of the Baltimore and Ohio Railroad over the Susquehanna river there is a small quarry opened in a schistose granite, which is very similar to that worked at Port Deposit. This quarry was probably first opened during the construction of the railroad bridge,' but nothing of economic import- ance was done here until the firm of Wm. Gray and Sons of Phila- delphia became interested in 1894. At this time the capital invested was about $8,000, a sum which represents but part of the present investments. No work of any particular moment was done by the present owners until the autumn of 1896, when the receipt of some moderate sized contracts encouraged the further opening of the quarry, which now bids fair to establish a well organized industry at Prenchtown. The only buildings of importance which have been built from the Frenchtown rock are the Cold Storage Warehouse and and an extension of the Baldwin Locomotive Works in Philadelphia. The location of the quarry topographically and geologically is simi- lar to that of the quarries at Port Deposit. The ground is stripped upon the side of a hill and the quarry has worked down to the level of the low bench, along which runs the Port Deposit and Columbia Eailroad. The jointing of the rock is similar to that at Port Deposit, and there are here three prominent sets of joints intersecting approxi- mately at right angles. Members of the same series are so placed as to facilitate working of the quarries and blocks containing 3,000 to 4,000 cubic feet might easily be obtained. The texture of the rock like that at Port Deposit is coarsely gran- ular, with a secondary lamination, and is adapted to all ordinary uses in general building, exterior ornamentation, curbing, paving, etc. It is possible, however, that this rock may be a little more " plucky " in working than the larger deposit farther north. This difference in the ease with which the stone is worked seems to be a temporary ' The main piers of the bridge are built of Port Deposit granite. MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE XI. GRANn E-PORI'llVRY. ELLir.OTT CITY. HOWAKD COtlNTV. MAEYLAND GEOLOGICAL SURVEY 147 feature which may have disappeared before the publication of this report. Like the rock quarried at Port Deposit, that at Frenchtown frequently appears somewhat disfigured by small black patches or basic segregations of biotite, which often render the stone unavailable for the highest grades of ornamental work. The microscopical char- acteristics of this rock as well as the color and texture are the same as those of the Port Deposit rock already described. The quarries have not been worked long enough to indicate by the product the durability of the rock or to call for discussions of its specific gravity, crushing strength and other physical features. There is no doubt, however, that the rock \vill respond readily to all the demands made upon it for ordinary building purposes, and that it will resist any pressure or atmospheric influences which it would normally encounter.' It weighs about 170 pounds to the cubic foot. ' The quarry as yet is small. At the time it was visited in 1896 the total space excavated was scarcely more than 5,000 square yards. In' 1S97 the opening was fully twice that size. The transportation facili- ties are very good, the same as those at Port Deposit. The stone may be loaded directly on the cars for Philadelphia and Baltimore or ou barges for these and other coastwise points. Ellicott City. The Ellicott City granite area consists of an irregular L-shaped mass, which has an extreme length of about five miles in an east and west direction and a breadth varying from one-half to two miles. On the north, west, and south it is bordered by a large gabbro area; on the east by gneiss. A considerable portion of the granitic area of this district is overlain by Neocene gravels (Lafayette Formation) and Cretaceous clays (Potomac Formation), thus concealing from direct observation much of the rock in question. The elastics, however, are quite thin, and consequently all the rivers and even the minor water- courses have cut their channels down to the more resistant crystalline rocks. The boundaries of the granites, gabbros, and other massive rocks are thus capable of being determined with nearly as much accu- racy as if the sedimentary deposits were not present. The quarries of Ellicott City are situated nine miles by road from 148 A HISTOEY OF THE QUARRYING INDUSTRY Baltimore and fifteen miles by railroad. They are located on either side of the Patapsco river in Baltimore and Howard counties, and tlie rock in which they occur extends on the eastern side of the Patap- sco as far east as Ilchester, but on the western side only as far as Grays. The material on the Baltimore county or eastern side is a fine grained mass, with a decided foliation or gneissic structure. On the opposite side of the river in Ellicott City itself it is more uniform and granitic. Here it also has a porphyritic structure iu consequence of the development of large flesh-colored crystals of feldspar which are disseminated somewhat irregularly through the rock, as shown in Plate XL The time of opening these quarries dates back probably into the last of the 18th century, but the details are entirely wanting. The beautiful appearance of some of the more uniformly porphyritic speci- mens early attracted attention, and in the earliest works which we have on this area, that by Dr. Hayden,' published in ISll, mention is made of these quarries. It is not certain whether the quarry on the Baltimore county side or the quarries of the Howard county side furnished the first material for Baltimore, but it is clearly evident from the character of the rock furnished for the Catholic Cathedral, that the gneiss was the more important rock at that time. Local tradition assigns the source of the stone sometimes to the Baltimore county side and sometimes to the Howard county side and tlie pub- lished infoi-mation is equally conflicting and indefinite. "When the Cathedral was constructed during the years 1806 to 1812 and subse- quently from 1815 to 1821, the material was hauled from Ellicott City to Baltimore along the old Frederick road in huge wagons drawn by nine yoke of oxen. After furnishing the rock for this building, which must have been one of the most important stone structures in the United States at the time of its construction, the quarries evidently were worked only to meet local demands. In fact they have never since been of such relatively great importance. Dr. David Dale Owen, indeed, while studying the various building stones of Mary- land at Cockeysville, Woodstock and Port Deposit, with the view of ' Geological Sketch of Baltimore, see Bruce's Amer. Min. Jour., vol. I. New York, 1814, pp. 243-248. MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE XII. _ - -* ■. ..w*. -tt'^X '*^.y'"^^y^m^^ yic. I.-GAITIIKR-.S (jr.\i:iiY, KI.I.ICdTT CITY. Fig. •->.-WEHKR'S UUAHltY, KI.I.II :i lir CllY. MARYLAND GEOLOGICAL SURVm' 14!) training all the information for the Smithsonian Imilding, twice passed by these quarries and yet makes no mention of them. At the time of the Tenth Census the agent remarks that lie '' knows of no other place in the coimtry where there are so many stone hnildings in an area of the same size." Of the quarries in operation at the present day those of AVerner Bros, were opened as early as the beginning of the century. In IS72 Charles J. Werner reopened a quarry, which since his death in 1888 has been operated by his sons, who purchased in 1890 a second quarry, which liad previously been opened by Kobcrt Wilson. These (luarrios became of some importance in 1893, when one of them is spoken of as the principal Ellicott City quarry, although it is now producing little or no building stone except during the fall of the year when random rubble is quarried for local use. The output for the year 1896 did not aggregate over 200 perches. The most active quarry at the present is that operated by A. Weber (see Plate XII, Fig. 2). This quarry is situated on the Howard county side some distance below the station. The material has been furnished in recent years for some important buildings, as those of the Woman's College of Balti- more, but most of the material seems to be used for Belgian blocks, curbing and macadam. 'I'hc system of joints in the region under discussion are not regular, but intersect at varying angles and at different distances. In the Weber quarry there is one prominent series of bedding joints, which strikes in a southeasterly direction and dif)s at a low angle into tluV hill. Besides this principal series there are four or five others with more vertical dips and varying strikes, which free the rock in huge irregular blocks. The jointing is so prominent and so irregular that it modifies the manner of quarrying quite perceptibly, as the stone is first obtained in irregidar masses and then worked into desired form by hand. Such a process increases the cost of operation, but at the same time furnishes considerable random rubble of a size suitable for ballast ami rough road material. Across the river from the Weber (piarry, in the opening worked by Gaither, the jointing is more regular and the face of the quarry is seamed into innumerable rhomboids several feet in diameter (Plate XII, Fig. 1). 150 A HISTORY OF THE QUAEEYING INDUSTRY The opportunities for shipment and drainage are good. Those of the Weber quarry are seldom excelled, as the opening is in the side of a hill so close to the tracks of the Baltimore and Ohio Railroad (main stem) that cars may be loaded simply by turning the derrick boom. Probably no area of granite within the state shows as great varia- tion in the texture and the character of the rock as that about Ellicott City. In the quarries on the eastern side of the river the rock ap- pears quite schistose and homogeneous, and practically lacking in porphyritic crystals. Through it are scattered large patches or se- gregations of the darker minerals, which give to the rock the some- what sombre effect displayed by the Baltimore Cathedral. These patches do not weaken the rock, thovigh they render the stone less attractive. On the other side of the river, as has been mentioned already, the stone has a distinctly porphyritic character, which gives to it a mottled effect, well shown in Plate XL The increased amount of feldspar brightens the rock and the distribution of the crystals adds detailed variety to the structures in which it is used. The microscopic texture of the porphyritic type is shown in the re- produced photomicrograph (Plate IX, Fig. 2) where the grains are represented ten times their natural size. There is nothing particularly noticeable in the arrangement of the constituent since they unite with interlocking sutures, as already described in the discussion of the Port Deposit granites. Woodstoch. Perhaps the best granite in Maryland for general building purposes is that which is found in the small area in the southwestern corner of Baltimore county near the railroad station of Woodstock, Howard county. Woodstock is situated on the main branch of the Baltimore and Ohio Railroad in the valley of the Patapsco twenty-five miles from Baltimore. It is a small coimtry hamlet, but serves as the ship- ping point for the granites, which are quarried about one and one-half miles to the northeast. Within the area of the quarries is the small town of Granite, which was formerly known as Waltersville. Ac- cording to the account of Mr. Arnold Blunt,' " boulders first attracted • Maryland, its Resources, Industries and Institutions, Balto., 1893, p. 120. MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE XIII. GRA.NITK \V.M,1 ERSVII.LK. IIAI.'I IMORli tOl'NTV. MARYLAND GEOLOGICAL SURVEY 151 attention and were worked by several enterprising men from New Hampshire, who commenced their operations here about the years 1832-33. Among them were the names Sweatt, Riddle, Putney, Holbrook, followed by many others, among whom were the Emorys, Gaults and Eatons. The principal demand was at first by the Balti- more and Ohio Railroad for stone stringers, dressed to correspond to the flange and tread of the car wheels, and also ashlar, &c., for their bridge and culvert work." Although prospecting has been carried on ever since, only two ledge quarries have been discovered, viz. : the " Waltersville " and " Fox Rock." The former is the principal one, and was at first called the " Branch." This rock developed into a fine ledge, sur- passing all the granite around in quantity, quality and easy access, so that all the boulders in which Sweatt, Putney and Riddle were interested were at once abandoned. After working it for a year or two Putney and Riddle obtained a lease of this quarry for twenty years in August, 1835, from the owner, Captain Alexander Walters, to whose family this quarry has belonged for more than a century. It is called in the lease and is still known as the Waltersville quarry, although the name of the village of Waltersville was changed to Gran- ite about 1873-74, when the first post-office at the place was estab- lished. The lessees went to work vigorously, and besides many other improvements, built a railroad two miles long to connect with the Baltimore and Ohio at Putney and Riddle's bridge, about one mile east of Woodstock. Their first contract of importance was furnishing stone for the Baltimore Custom House. They, however, continued the business only a few years. Extravagance and mismanagement caused the failure, and they were succeeded by Edward Green and Joshua B. Sumwalt, under the firm-name of Green & Sumwalt. The senior partner dying about 1849, he was succeeded by his son Fred- erick, and the firm became Sumwalt & Green, who conducted the business until 1865, when Attwood Blunt, whose wife owned the property, took charge and continued the business until 1871, when the quarry was leased to Ansley Gill and James McMahon. After a lapse of about sixteen years, the firm was dissolved by the death of 152 A HISTOEY OF THE QUAEKYING INDUSTEY McMahon. Mr. Gill continued the business alone for a short while, when he associated with him Wm. H. Johnson, of Baltimore, and they soon after formed with George Mann, Hugh Hanna, Messrs. Grey & Sons, of Philadelphia, and Mr. Hamilton of Baltimore, a joint stock company, calling it the Guilford and Waltersville Granite Co. This company is now conducting the business. The rock from the Woodstock area was early used, as indicated in the preceding sketch, but the first published account of it which attracted attention was that by Dr. David Dale Owen.' In his report to the Building Committee of the Smithsonian Institution he says: " During the examination of structures and monuments of Baltimore marble, both in Greenmount cemetery and in the city of Baltimore, with a view to ascertain the durability and facility of working this material, I was so miich stnick with the beaiity of some of the granite vaults and fronts of buildings that I determined to visit the quarries from whence this material was prociired. . . . Accordingly I stopped at Woodstock, 16 miles beyond the Kelay House, and inspected care- fully the Waltersville branch and the Fox Eock quarries in this vicin- ity; both of which are well opened, and afford a good opportunity of judging the quality and extent of this formation. " For about a mile square at this locality is an outburst of quartzose granite of magnificent quality, both as regards beauty of appearance, compactness of structtire, and uniformity of color, texture, and com- position. I have never seen anything superior in this country; in- deed, I doubt whether it can be excelled in any country " Fidly to appreciate the quality of this granite, the quarries them- selves must be visited, and the huge blocks in mass inspected as they are removed from their original bed. There, one may see a perpen- dicular face of nineteen feet presented to view, extending twenty, thirty, and even forty or fifty feet, without a seam or fiaw, or the slightest variation in hue. A mass of forty or fifty tons weight may often be seen severed from the parent rock, by the simple but effective means of small iron wedges. . . . The Fox Eock quarry is thirty-six feet from top to bottom, where now excavated. It might be worked ' Report of the Board of Regents of the Smithsonian Institution, Jan. 6, 1848. Senate Doc. 30th Congress, 1st Session. Miscl. No. 23, pp. 31-32. MARYLAND GEOLOGICAL SURVEY VOLUME II, PLATE XIV. KS74 Fic:. 1.— WELIiER'S OUAHHY. CI! A.\'frK. HA l/l'l MnllE C.orNTY. Kic. 2— C.UJI.FOUD A\U WAl.Tlll'.SVII.I.K urAllliV. ( ; I! AXril'). IIAI.II M()I!K niirNTV. MARYLAND GKOLOGICAL SUKVEY 153 some fifteen or twenty feet lower before being incommoded by water. Jfortar adheres with such force to this granite, that, when fairly set, it requires as much force to separate the substance of the granite as to detach tlu^ mortar from the face. ■' On the whole, the inspection of these granite quarries has im- pressed me with the belief that no locality can furnish a superior qual- ity of granite, and that it cannot be surpassed for strength and dura- bility by any building-material in the world." 'J"he letters which accompany this report show that in 1847 the firm of Sum wait. Green & Co., evidently composed of Edward Green and Joshua B. Sumwalt and his son Frederick, earned on the business, and the size of the quarries, as indicated in the remarks of Dr. Owen, shows that the business had already reached a considerable import- ance. Perhaps as the result of this report by Dr. Owen, the contract was granted for furnishing the foundation stone, which was used in an extension of the Patent Office Building constmcted in 18-19, ami the Postoffice Building, in 18.55, although some of the Woodstock granite had lunni used in the general Postoffice before 1847.' The gi'anite mass as indicated by the map forms a more or less oval, isolated area of granite extending scarcely two miles northeast and .tonthwc-t and a mile imrthwcst and soutliea:it. .\lthough so small, it is one of the most important economic areas within the state. This ma.ss of granite, which is evidently intruded into the gneisses, is en- tirely enveloped by them and sends no dikes or apophyses into the surrounding rock. That the gneiss is really older than the granite is shown by the great number of inclusions found within the latter. These are chiefly of gneiss, and th'ey occur often in huge irregvilar blocks six to eight or even ten feet in size, showing narrow rims due to contact metamorphism. They are beautifully puckered and wrinkled and being much richer in ferro-mag-nesian silicates than the granite itself, their irregular outlines contrast sharply with the lighter background. (The darker portion of the large block in the center of Plate XIV, Fig. 2, is included gneiss.) The most marked feature of these quarries, especially in the Wal- tersville quarry (Plate XIV, Fig. 2), is the sharp definition of the ' Loe cit. p. 41. 3 54 A HISTORY OF THE QUAKRYIKG INDUSTRY systems of vertical and horizontal joints which are so prominent and so persistent in their horizontal extent, that they at first glance give the impression of stratification. They strike approximately north 60° east and dip at an angle of 10°-15° to the northwest. The joint faces are not planes, but ai'e curved more or less irregularly. The figures given represent the general strike and dip as seen in the Waltersville quarry, hut even these somewhat generalized values are not persistent over the entire area, for in the center of the Weller quarry, which abuts upon the Waltersville quarry on the west, the strike and dip changes com- pletely within the distance of a few feet. This irregularity in the joints has caused considerable trouble in the quarrying, although when visited the ledge worked was well exposed, and the blocks were large and easily obtained. The accompanying figure (Plate XIV) shows how large slabs and blocks may be freed at little expense. The piece in the center of the picture has been separated from the ledge at the back by a series of wedges, while it was only necessary to use a bar to pry the mass from the ledge beneath. There are fully five or six series of joints which are distributed without any marked uniformity through the mass. Besides the main horizontal joints there are others at a slight inclination, which continue for a short distance and then die out. The vertical joints show several planes oriented in different positions and showing variable dips and uneven surfaces. This jointing is sharply brought out by the weathering of the rock. " The quarry ledge has the appearance of a great wall of cyclopean masonry, layer upon layer of huge blocks rising one upon another with the regiilarity and precision of human workmanship. The sepa- rate blocks are more or less oblong in shape, and often measure 15 to 20 feet in length and from 2 to 8 feet in height. They are all more or less rounded, the spaces between the different boulders being filled with incoherent granitic sand, derived from the decomposed edges and the sides of the blocks. It is quite evident that the granitic mass was originally everywhere jointed, and that atmospheric decay took place much faster on the edges and corners than on the flat sides of the great fragments, thus quickly rounding and forming them into boul- ders like those found throughout drift areas. The sandy matrix is MARYLAND GEOLOGICAL SURVEY VOLUME II. PLATE XV. ni:rAii.i:u \ ii:w. WKi.i.Kirs urAiniY. c.ii.wni:. iMARVI.AXD nKOLOGICAI. SDEVEY 155 usually from 5 to 10 inches in tliickness. The interior of the boulders is perfectly fresh, and affords the best of rock for building purposes. As decomposition progresses the amount of interstratified sand greatly increases, and the blocks become proportionately smaller." This method of weathering facilitates the early workings in a quarry and so brings the rock into notice, but there is necessarily a great deal of waste and considerable expense in bringing these boulders into rectangular form unless there are well defined seams or a " grain " running through the rock, as is the case at these quarries. The grain (jf the rock is so marked that it cannot fail to impress any thoughtful observer who %asits the quarries.' The jointings in the Fox quarries are not as strongly brought out by weathering as they are in the Weller and Guilford and Walters- ville quarries although the different sei'ies are distributed in about the same manner. At the time of inspection, these quarries, which are operated by the Gaidts, were not in active operation, although considerable material suitable for furnishing Belgian lilocka and ran- dom rubble was scattered about the pits. The appearance of the Woodstock granite is well represented in Plate XI IT which reproduces tlie polished surface in natural size. The color of the rock is bright gray, with something of a luster imparted by the quartz and the unaltered feldspars, the latter often giving an additional faint pink tone. The mica occurs in evenly disseminated fine black flakes which emphasize the grain of the rock and only slightly subdue the bright fresh aspect of the stone. The size of the constituent grains which varies from 0.05-0.2 inches in length, and from 0.01-0.10 inches in breadth, for quartz and feldspar, is little marred by the less resistent mica wearing away and leaving small depressions, that arc scarcely discernible to the naked eye. The pol- ished surfaces, such as are represented in the plate, are darker than the rough or ashlar finished stone. The chemical composition of the I'ock, as indicated in the following analysis by Mr. Hillebrand,' shows the rock to be somewhat siliceous ■ See ante p. 152 and Plate XIV. Fig. 1. ' Report of Work done in the Div. of Chemistrj' and Physics. Bull. No. no, IT. S. Geol. Survey. (1890-91) Washington, 1892. p. 67. E. 156 A HISTORY OF THE QUAERYIXW INDUSTRY and yet particularly rich in lime. This marked increase iu the per- centage of CaO is explained by the presence of considerable allanite and epidote in the rock. It is therefore not a source of contamination, for the epidote is particularly stable under atmospheric conditions. The percentage of the alkalies is moderately high, while the iron and magnesium content is very low. The rock, accordingly, possesses great durability and power of resistance toward atmospheric decompo- sition. SiOj 71.79 AIjO., 1.5.00 Fe.Oj 0.77 FeO 1.13 CaO 2. 50 MgO 0..51 K,0 4.75 Na.,0 3.09 H.p 0.64 100.17 The tests to which sjiecimens from the Walters\'ille quarries have been subjected show the rock to be all tliat could l>e desired for strength and durability. The strength of the stone is several times that of brick, and the percentage of absorption is very low, showing that the stone can withstand both pressure and the deteriorating action of frost. The figures obtained are as follows: Simple crushinix. Absorption. Freezing. Crushing after freezing. Cracli. Break. Percentage of gain. Percentage of loss. Crack. Break. 79,700 85,700 O.S.'iS 0.011 79,400 103,200 79,200 83,430 0.333 0.039 86,800 90,300 Guilford. Perhaps the most attractive stone found within the state is that which is quarried at (hiilford in Howard county, about five miles northwest of Annapolis Junction, on the Little Patuxent river. This granite early attracted attention because of the uniformity and fineness of its grain, its light color and pleasing effect. Although the area furnishes excellent monumental and building material it is unfortu- nately situated some miles north of the Baltimore and Ohio Kailroad, a circumstance which has delayed such a development and recognition f^ ilAKVLAKD GEOLOGICAL .SIKVEV 157 of tlie rock as the material deserves. At present tli(;re is a sidetrack whicli runs from the Baltimore and Ohio Railroad to Savage Factory only two miles distant. This distance, however, with the necessary haiilinji', is sufficient to render successful competition with more favor- ably deposits soiuewhat doubtful. The quarries at Guilford were originally opened about 183-4, and were worked almost continuously from that date until the outbreak of the ci\al war in 1800. Diiring the suc(^eeding twenty-five years the operations were of little account, and little work was done until the Guilford and "Waltersville Granite Company attempted to develop the industry in 1SS7. This elfort lasted but a short time as all of the machinery was removed from the quarries in 1889. The industrial life of the district has been revived somewhat in recent years by the operations of Messrs. ^Matthew Gault and Sons, who conuuenced work in ^S[}^d, and by Messrs. Brunner and White, wIkj opeued a quan-y of superior quality in March, 1895. The Guilford granite is bordered on the north and west by the Piedmont gneiss and on the east by the gabbro. It is also in part covered by the gravels and clays of the Potomac. The jointing of the rock is sharp and usually regular, the individual planes being suffi- ciently far apart to allow the quarrying of blocks of any reasonable size; at the same time they aid materially in the freeing of the stone. The rock of this area differs from all of the other granites of the state in the persistent presence of both light and dark colored micas. Thus, according to the German classification, it is the only '" true granite " ' in the state. Other granites may have muscovite as a con- stituent, but it is not so alnmdant or typical as in the present instance. Both of the micas arc products of the original crystallization of the molten rock magma, and they are frequently in parallel growths. The biotite, which is especially rich in iron, possesses a very dark color, but shows no evident disintegration or decomposition. The feldspat ' The use of this term in i^revious papers on the granites of Maryland has led to some misunderstanding- on the part of quarrynien. In this petrosraphical sense as applied to granites " true " has not meant that all of the granites of .Maryland with this exception are " bastard " granites, but it has only meant that this gi-anite corresponds to the " zwei-glimmer " or " echte granit " of the (ierman classiflcation. 158 A HISTORY OF THE QUARRYING INDUSTRY is almost entirely microcline, which shows the cross-twanning veiy clearly, and appears clear and fresh with very few included flakes or small cystals. These microclines form the largest individual areas in the rock mass, sometimes reaching 0.15-0.2 of an inch (4-5 mm.) in diameter, while the clear transparent grains of quartz average less than 0.01 of an inch (.03 mm.). The individuals are interlocked in a mosaic, which indicates that the rock can well withstand any pressure to which it may normally be subjected. The mica flakes are small and evenly disseminated, so that they do not injure the polish which may be given to the rock in preparing it for monumental purposes. Mino7- Areas. Besides the five areas already described there are several other gran- ite masses within the state, as indicated by the map, which have been worked from time to time to supply the local demands, and occasion- ally with the hope of bringing the stone into commercial importance. Of these smaller masses which have been quarried spasmodically the most important is that of Dorsey's Run on the Baltimore and Ohio Railroad between Ellicott City and Woodstock. The stone of this area was first quarried for use on the Baltimore and Ohio Railroad to protect the roadway from the encroachments of the Patapsco. These and subsequent operations have developed two or three quarries which have furnished about 10,000 cubic feet each, since they were first opened. The proximity to the railroad has been of advantage and efforts were made in 1893 by Mr. W. B. Gray of Baltimore and Messrs. Peach and Feenay of Woodstock to develop a trade in curbing and paving blocks. The quarries at the time of writing, however, have suspended operations. The ledges furnish blocks of 40 or 50 cubic feet, but the product seems to be overshadowed by that of the neighboring quarries in Ellicott City and Woodstock. In 1888 Mr. W. F. Weller of Granite leased a quarry near Sykes- ville, and began somewhat later the quarrying of Belgian paving blocks, which was continued for some year and a half. At the present time this quarry is not in operation, and no others are at present worked in the vicinity. On the southern prolongation of the Sykesville mass near Garrett MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE XVI. FINE-GRAINEP (.RA.MTE. '■' i< i-ORI>, HOWARD COUNTY. A MAEYLAND GEOLOGICAL SURVEY 159 Park and Brookville is a quarry operated by John A. Riggs, which was probably first opened about the beginning of the century, from which time it was occasionally operated in a small way up to 1881. The total amount of stone extracted, however, does not exceed 1000 perches. INTo large stone can be obtained from the present opening, as the rock is much broken into blocks, which contain scarcely 20 cubic feet. This opening, however, is in a poor place and the best stone has apparently not yet been reached. Since the distance from the railroad renders this rock unavailable for city demands it will probably never be of more than local importance. Some twenty-five years ago a second quarry was worked at Brookville in rock which was good for local requirements. This was opened in 1850 and some 1000 perches of rock were obtained between 1850 and 1870. The granite exposures at Garrett Park embrace several small outcrops of which the best are those along Hock Creek. At several of these small exposures, quarries have been opened and worked from time to time to supply the local demand. Probably the most extensive operations carried on in Montgomery county are those near Cabin John, in a quarry operated by Mr. Gil- bert. This quarry was opened aboiit 1850 and there have been exca- vated probably 1,500,000 cubic feet. The rock is a schistose granite rather dark gray in color, and suitable for general building and road metal. In the quarry there are three prominent sets of joints, which, however, are so placed as to permit the quarrying of large blocks. Already pieces containing 1000 square feet have been obtained. The mode of transportation from the quarry to "Washington, a distance of six and one-half miles, is the Chesapeake and Ohio Canal, which has rendered the location so available that the rock has supplied some of the demand for foundation stone. At the time when the quarry was visited operations had been suspended and the machinery on the ground was unused and going to ruin. At l""ranklinville on the Little Gunpowder, three miles north of Bradshaw's Station, are exposures of a schistose granite resembling that quarried at Port Deposit although somewhat darker and even more schistose. This rock has not been quarried as much as its posi- tion and character mie,'ht warrant. It is owned and worked by the 160 A HISTORY OF THE QUAEEYING INDUSTRY Cotton Duck Factory Co. It has supplied the local demands and there have been quarried about 1000 perches a year for the last seven or eight years. Large curbing blocks might be obtained easily, as blocks 11' X 2' X 1' have been quarried. The opportunities for oper- ating are good, as freedom from water and large dumping grounds are features of the location. The distance, however, from the rail- road might be a serious drawback. In the town of Benson, Harford county, there is a small opening for granite, where quarrying was first carried on in 18S5. The out- put is small, not reaching 1000 perches a year, and yet from this lo- cality was furnished the material for one of the churches in Bel Air. The quarry, which is owned by Mr. L. Amoss, is situated near Win- ter's Kun on the Harford pike and was never opened %vith the inten- tion of operating it extensively. The stone is in boulders and is easily worked by hand. On exposure it becomes lighter and more pleasing in color. Near Baldwin's Station, Cecil county, is a small quarry of schist- ose granite, which supplies some of the local demands of Elkton, Maryland, and IS^'cwark, Delaware. This quarry is on the farm of Levi L. Hammond and was opened in the year 1842. The opera- tions are small, the' average yearly output reaching perhaps 2000 cubic feet. Blocks containing 1200 feet have been obtained, and even larger might be quarried, if the facilities for handling were at hand. The quarry is only worked occasionally for building stone, which is sold by the perch. GNEISSES. Certain of the more uniform and compact gneisses furnish first- class building material and many quarries have been opened in the areas where the demand is great and the expense of handling and transportation is fairly low. These quarries are especially noticeable in the vicinity of Baltimore where all of the conditions are fulfilled. The gneisses of the area, represented on the map, show great constancy in their mineralogical and textural composition. They are composed of alternating bands of fibrous to micaceous hornblende, biotite and chlorite schist between lighter colored more or less feldspathic quartz- MARYLAND GEOLOGICAL SURVEY 161 schist. Tlie dark ferruginous bands break down readily and are not used at all as structural material, but are discarded as waste. The best material comes from those portions of the lighter bands which are composed almost wholly of quartz, the prepared blocks differing but little from those made of a well characterized quartzite. The rocks are rather strongly bedded in slabs from one quarter to three feet in thickness, and are thus more easily worked than the hardness of the rock might at first suggest. The areal distribution of the gneisses, as represented by the accompanying map, clearly shows that the structure of the area is intricate and complex. The general trend of the formation is north-northeast and south-southwest, with a similar strike for the foliation, which usually dips to the northwest at a high angle. In the region adjoining Baltimore the structure, as indicated by the contacts and the position of the foliation, is still more compli- cated by sharp folds, faxilts and intrusive masses. Beginning east of Catonsville the strike of the foliation (probably nearly the same as the original bedding) becomes more and more northerly, until at "Woodberry it turns quite rapidly to the east and southeast crossing Jones' Falls south of Hampden with a trend somewhat north of east. The strike about Lake Montebello (Baltimore city) seems to radiate in a fanlike manner to the northwest, north and northeast. About Lake Roland and the Bare Hills this structure becomes even more confused, and yet preseiwes a general parallelism with the gabbro- gneiss boundary. The quai'ries about Baltimore are grouped around two centers, Jones' Falls and Gwynn's Falls, on the northern and western sides of the city, the location being determined by the facilities afforded by the shape of the country for opening and working the quarries on a hori- zontal plane. This method of working decreases the cost of handling the stone, avoids any expense or difficulties because of water and often furnishes a convenient and cheap dumping ground away from the rock bed which may be worked in the future. Jones' Falls. The quarries on Jones' Falls were originally opened at some distance from the city, as they were in operation probably before the beginning 11 Ifi2 A HISTORY OF THE QUAREYING INDUSTRY' of the i^rescnt centnrv. The first mention of them is found in a rare jonmal' published in Baltimore in 1811, where the following words occur in a description of the geology of Jones' Falls: " Imme- diately above this [a pegmatite dike] it [the gneiss] assumes nearly the texture of the first mentioned, being fine, hard and compact, and gradually passing through the above transitions, until, at one mile and a half from Baltimore, it acquires a texture, siich as to render it highly valuable and useful in various branches of masonry, and as such, is here quarried on both sides of .Tones' Falls, to considerable advantage to the proprietors." The first quarries opened were probably situated on the right bank of the Falls about where the Mount Vernon shops now stand, and wei-e operated more or less continuously until the building of the Northern Central Railroad, about 1830. The (piarries on the left bank of the stream have been in almost continuous operation from the time of their opening until now. It has been difiicult, however, to gather any information regarding the various oi^erators who have been interested here. The occurrence of the quarries is all that could be desired. The rock is clearly bedded in sheets, ranging in thickness from four or five inches to five or six feet. These sheets extend with almost no break for considerable distances, as is shown in the accompanying view of the quarries leased by Messrs. John F. Curley and John G. Sehwind. The sharp light lines extending diagonally across the main sheet from left to right are small faults with a throw of a few inches. These sheets are rendered workable by two series of joints at right angles to each other, situated at favorable intervals. These are also supplemented by a '" grain " in the rock, which is at right angles to the bedding and nearly parallel to one of the planes of jointing. From this distribution of the lines of weakness, it is possible to free large blocks from the bed and then, if desired, the slabs may lie sepa- rated readily into smaller blocks. The angles of inclination between the planes of jointing, bedding and grain do not vary widely (usually 10°-15°) from 90°, so that the stone may be squared without great cost. No dynamite is used in the qimrrving, but oeeasionally charges ' Loc. cit. pp. 255-271. MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE XVII. Ki.;. l.-lMIOTOMlCliOcniAIMI OF CKAXn'K, (iK.WI riO. (MACNrFiKi) Ti-:x DrAMirriais.) Fig. S.-l'HOTOMliJHOGHAlMI OF GXKISS. ISAl.Tl.MORK. ( M.VG.MKiEn Tkx 111 ametehs.) MARYLAND GEOLOGICAL SURVEY 163 of powder are employed to loosen the rock and thus render it easily separable along its joints and grain with the " ping and feather " wedges. The inclination or dip of the beds also facilitates the quarrying. It is usually about 45° to the northwest, so that the freed blocks may be easily handled. There are two methods of utilizing this dip. In the Pcddicord quarry on the Falls road the operations are carried in horizontally aJoiig the strike, and then the vai-ious beds are worked from the top and side. In the Curley-Schwind quarry, where the same beds are exposed, the " head " is first driven in across the strike, and then the beds are worked along the strike. The texture of the different sheets varies considerably, Imt tli(> first quality rock runs quite uniformly. It always shows a huninatinn parallel to the original sheeting and should therefore be laid on its bed in structures. The quartz and feldspar grains are of approxi- mately the same size and unite with the small mica plates to form a uniformly textured rock of dark gray color. The different beds vary somewhat among themselves in the size of the grain, in the relative amount of quartz and feldspar and in the amount of lamination. As is true of many sedimentary gneisses, this difference in the dark and light bands is so well defined that the quarrymen by a little sorting may furnish niaterial wliieli will run uniforuUy for individual ship- ments. There will, however, be some difference between different shipments, unless considerable care is exercised by the quarry master. The color of the roek has been given already as dark gray, but from this there are uuuiy \ariations, with a range from very light gray to a dark sombre, vitreous blue-black. The variation depends upon the amount of feldspar and mica present. If the rock is composed almost entirely of clear, vitreous and pellucid quartz grains the rock is usually dark and cold whether there is much mica present or not. AVhen felds])ai' is ]iresent or tlie gi'ain of the rock lieeouies fin(^ or saccha- roidal the color of the rock is brighter and more pleasing. The amount of mica present in the feldspathic fine grained rock seems to have a greater eft'ect on the color than is the case in the more quartz- ose varieties. This constant blue-iirav tone in tlie color of the rock 164 A IIISTOEV OF THE QUARRYING INDUSTRY has led to the application of the local term " blue stone," which is current among the qiiarrymen and is often introduced into contracts." The chemical composition of the gneiss is so variable that single analyses cannot represent the character of the whole mass. A fair representation of the composition of the lighter colored gneiss would show the silica rather higher than the average. A microscopical study of these same lighter bands, which are used the more extensively, show that the constituents do not always interlock, although there has been considerable growth of the quartz grains since the rock was formed. These are indicated by the light veins about many of the grains in Plate XVII, Fig. 2. Most of the grains are somewhat rounded, suggesting that the gneiss is of sedimentary origin, and the interstitial spaces are filled with more finely comminuted fragments of quartz, feldspar and secondary minerals. Among the last are epi- dote, garnets and occasionally fibrolite, cyanite and staurolite.' The chemical and mineralogical composition of the Jones' Falls rock show that the individual constituents are not liable to decom- pose readily and that there are few minerals occurring as accessory constituents which really vitiate the rock. On the other hand, the crnshing tests show that there is a much more marked tendency to physical disintegration in certain directions. The rock to be service- able must, therefore, be placed in the wall in certain positions only. The results of the tests are as follows: Crushing. Absorption. Freezing. Percentage of Percentage of Crusiiintr CracU Break. gain. loss. after freezing, yuartzose layers ( 66,700 70,140 0.197 0.038 80,118 118,000 ("Blue Stone.") f 85,940 96,300 _ Feklspathic layer ) 94,300 ' l.lli; 0.0.53 (;3,060 84,830 ("B. granite.") j" 78,000 103,500 ' This term " blue stone " is a iJOiiular one which is applied to different rocks in different localities; e. g. in the District of Columbia it signifies a mica schist; in Pennsylvania and New York a blue-gray sandstone; in Ohio a gray sandstone. This last tisage has become so common in the trade that it is hardly proper to call the Baltimore gneiss a " blue stone." - On the faces of the joints where there has been a little space after the movement of the rock there are often found haydenite (chabazite), laumon- ito, harmotome (or phillipsite?), stilbite, beaumontite (heulandite), siderite, pyrite, barite, haloysite, epidote, garnet, and tourmaline. See Notes on the Minerals occurring in the neighborhood of Baltimore by George H. Wil- liams. 17 pp. Baltimore, 1887. .MAHVI.AXl) GEOLOGICAL SURVEY 165 The quarries show that the rate of decomposition and disintegra- tion is really very slight for gneisses standing at so steep an angle that the surface waters may saturate the rock with great freedom. There is, of course, considerable stripping required in some places, but when it is remembei-ed that these rocks, unlike the rocks farther north, retain the evidences of exposure to the destructive agents of the soil and atmosphere since Cretaceous time, certainly several mil- lion years, the amount of weathering seems insignificant. The most serious drawl)ack is not in any possible line of weakness, l)ut in the color. AVheu pieces of gneiss from different layers are intcrniinglcd willuMit any t-aro or arrangement, the effect is not pleas- ing, but qiiite the reverse. There is ciirrent an impression that the material for the Cathedral in Baltimore came from the Jones' Falls quarries, a view which is scarcely in harmony with the statement of Mr. Robert (!ilmor, Jr.,' in which lie describes how the material was brought from the Falls of the Patapsco about ten miles out on the Frederick pike. Part of the material may have been furnished from the nearer source, but Tmder these circumstances it would probably have been from the quarry on the right bank and not from any of those on the left bank, since the former was then the more important source of material, ^loreover, certain buildings such as the old Court House, portions of the Jail and some of the buildings at the Woman's College show that the rock may give a pleasing effect in structures. The demands at the present time are satisfied by higher grade material, such as the Port Deposit or Woodstock granite, and a large part of the gneiss quarried is employed either for foundations and pa^dng or as a backing for the more pleasing stone. The quarries in operation at the time of inspection by the writer were the Peddicord, the Curley-Schwind, and the Atkinson.^ Of these the Peddicord is the largest, showing an excavation of over seventeen million cubic feet; the Curley-Schwind shows about three million, and tlic Atkinson something over a niillinii cubic feet. ' Bruce"s Anier. Miii. .lour., vol. i, .New York, 1S14, p. 2.12. See p. 126. ■The ".\tkiiisoii " of the topograpliiu map is now the Peddicord and At- kinson is working- a smaller quarry a little farther northeast beyond the Curley-Schwind quarry. 166 A JIlSTOltY OF THE QUAKEYING INDUSTRT Gwyn7i's Falls. The woi-k in tlio area west of Baltimore along the Gwynn's Falls and Gwynn's Run did not begin for some fifty years after that along the Jones' Falls, since the product lay to the west of the growing town and was sejoa rated from it by a series of ridges which increased the ci:ist of transportation. As the city extended westward, the supply from Jones' Falls became more expensive, and that from the small openings along Gwynn's Falls cheaper. The real work of the area began about 1850 and has continued without any marked abatement to the present time. The largest quarries in this part of Baltimore are operated by John G. Schwind, lessee and part owner of the large quarries on Edmondson Avenue, which are perhaps the largest and best equipped of any of the openings about the city. As shown upon Plate XYIII, Fig. 2, the rock of this quan-y is a gneiss, inclined at an angle of 30° and dipping to the northwestward. The general strike of the beds conforms to that of the area, which is north 45° east. As is the ca.se of the Jones' Falls quarries, the rock exposed in the quarries varies considerably, and furnishes two marked grades of material, one which is almost pure quartz resembling a quartzite and the other a much more feldspathic and micaceous aggre- gate very similar to the granite, but showing a greater or less per- fection in its bedding. In the qiiarry face the individual l)eds range in thickness from two to four feet, each showing great uniformity. The workable ones are clearly separated from each other, either by well defined bedding joints or by beds of inferior quality. Across each sheet are at least three sets of joints nearly at right angles to each other, which greatly increase the ease with which the material is extracted. The joints are separated from each other by distances ranging from a few inches to several feet, so that while facilitating the work they do not render the rock inferior, because of too great frequency. It is possible to obtain blocks of any size within the range of economical handling. This limit seems to be reached in blocks of seven or eight tons. The hoist in use, however, is capable of handling ten ton blocks. The pro- duct of these quarries is scarcely distinguishable from that already des- scribcd as characteristic for those of Jones' Falls. I-ike the latter the MARYLAND GEOLOGICAL SURVEY VOLUME II, PLATE XVIII. Fk;. 1.-CUKI.KY-SCH\VIND (HJAUKY. HALTIMOHK Fiu. -'.-"EllMMMISiiX a\1:M K' HI AlUtV. HAI.l'I.Mi Hil':. MARYLAND GEOLOGICAL SURVEY 167 range in material is very wirle. All of the product furnished is un- affected by any considerable amount of deleterious minerals. The worst blemish arises from an occasional concentration of the feldspar individuals and nocnsioiially disseminated Innght pyrite crystals. The minerals, such as laumontite, stilbite, etc., for which the quarry is well known, do not occur within the body of the rock, but are secon- dary products distributed along the jointing planes. They accord- ingly are not injui'ious to its strength or weathering properties. Ma- terial has been furnished from these quarries for a good many well known buildings, especially in the city of Haltimore. Some material has also been shipped to Virginia. Peidiaps the most prominent structures which liave used this stone are the Traction Power House, a portion of the new Penitentiary and the Bolton Synagogue. In these buildings the stone is used chieflj' as a foundation stone, the superstructure being constructed in part of Port Deposit granite and in part of other domestic stone. Besides furnishing first-class founda- tion material the quarries utilize their waste by means of crushers in the preparation of crushed stone suitable for the construction of roads and gravel walks. The openings somewhat farther west, owned and operated by David Leonard, produce some of the best stone from this region. They were opened sometime prior to 1850 and have been worked more or less continuously ever since. The stone is very similar to that of the Edmondson Avenue quarry possessing the same marked bedding and several sets of joints, which allow the extraction of the stones in rectangular blocks of convenient size. It is probable that in this quarry the jointing is a little more irregular and the material fur- nished a little less satisfactory for the production of large blocks of foundation stone. This slight difference in the character of the ma- terial extracted has led the present owner to work a considerable por- tion of his stock into paving blocks. The distance of the luud and the sharp hill, which limits somewhat the load, increases a little the expense of furnishing the stone in the center of the city. The quality of the stone, however, which when cut is fully equal to that of any of the quarries about Baltimore, together with the uniform faithful- 108 A HISTOKY OF THE QUAREYIKG INDUSTRY ness in fulfilling contracts causes a steady demand for the product of the quarry. In addition to these two quarries, there are others in the imme- diate vicinity, which are worked in a small way, furnishing a little material now and then for various local demands. These, however, change hands so frequently and are worked so irregularly that they do not seriovisly affect the market for stone of this general character. Besides the larger quarries of the area just considered there are scattered in various directions about Baltimore, especially to the east and north of the city, several others which have been worked to some extent to supply the local demand for building stone. Such openings are worked occasionally along various portions of Herring Run, near Hall Spring, and Ivy, and along the upper course of Gwynn's Falls, near McDonogh. These quarries furnish material similar to that obtained from those on Jones' Falls and Gwynn's Falls and help to supply the demand for paving blocks, sills, steps and curbings in their local areas. The chief sale for this product, however, arises from its use as a road ballast in the construction of many of the pikes which radiate from Baltimore. The material is crushed and furnishes a very fair road metal. GABBEO. Although the gahbro or " niggerhead rock " of Harford, Baltimore, and Howard counties is sharply separated from the granites and gneisses scientifically, when used as a foundation and building stone it competes with the granites and gneisses, so that it is proper to con- sider this material under the general title of the present division. The stone is so hard to work and so sombre in its effect, that little or no demand has ever been developed for it. There are, however, a few buildings such as the railroad station at Arlington, a church and some of the mills at Woodberry and a few scattered structures in the valley of the Patapsco which have been made of it. The stone is generally used in natural boulders, as the drift materials of the ISTew England states is used in the construction of higher grade of Queen Anne houses. The slight demand for dressed gabbro, the use of boulders and its plucky character have practically precluded the sue- MARYLAND GEOLOGICAL SURVEY 169 cessfiil exploiting of this rock for building-stone purposes. There is, however, a strong and ever increasing demand for materials of this character in the construction of macadamized roads, since as a road metal there is no substance in the state better adapted for this pur- pose. AMPHIBOLE SCHIST. Carroll county, about Westminster, and Montgomery county, north- west of Washington, possess a finely crinkled, compact rock which has been used in a few instances as a building stone with good effect. The material qiiite probably is a metamorphosed amygdaloid, in which most of tlio minerals have been changed to very stable forms. It is of a pleasing grayish green color and even texture, and when freshly furnished it is very easily worked, being carved in almost any form with ordinary tools. On exposure it hardens through a secon- dary deposit of silica, and becomes a very serviceable stone. It has been used in the Iveyscr Memorial (^Imi'ch at Reistei'Stown, in the residence of the president of the Wcslei'ii Maryland College, and in the foundations of many of the more prominent buildings in West- minster. Some of the stone, which was used as a base of the build- ings constructed there at the beginning of the century, shows that it suffers little or no disintegration from exposure to the atmosphere. This material will never be used extensively as a building stone, since it is very imeven in its appearance and limited in its local occurrence. The porosity of its texture causes it to collect dirt rapidly and so it becomes unsightlj- if used in the large cities. Marbles and Limestones. The marbles and limestones of Maryland are the most uniformly distributed of all the building stones in the state, for larger or smaller areas may be found in Baltimore, Carroll, Howard, Frederick, Mont- gomery, AVashington, Allegany and Garrett counties. These differ widely however, in character, mode of occurrence and geological age. Unlike the granites, gneisses and serpentines, they are not confined to the central portion of the state, called the Piedmont Plateau, since they are found well developed in the broad Hagerstown and Frederick 170 A HISTOEY OF THE QUAEEYING INDUSTEY" valleys and in the more mountainous areas of the AUeghanies. The exposures are almost always poor on account of the relative readiness with which these rocks break down under atmospheric agencies, and from the same cause they always occur in valleys and never along ridges or the crests of mountains, as the sandstones do. Moreover, whenever there occur sufhcient bodies the valleys are characteris- tically broad, ilat and very fertile. According to their geological age the marbles and limestones have midergone various degrees of change, since the time of their forma- tion. There is a progressive increase in their crystalline character and freedom from fossils, from the little changed fossiliferous Gi-reen- brier limestones of Garrett county to the crystalline, non-fossiliferous marbles of Baltimore county. This increased alteration, which they have imdergone, is accompanied by a change in color from the dark limestones of the Carboniferous and Lewistown formations through the lighter Shenandoah liiuestones to the variegated marbles of the Phyllite formation and the clear white or blue marbles of unknown age which are so extensively worked in Baltimore county. The a'coloaical frirmations which furnish either limestones or marbles are the Triassic (ISTewark), running as a narrow belt across Montgomery, Frederick and Carroll counties; Permian (Frostbiu-g), occurring in a few hills about Frostburg; Cai'boniferous (Bayard and Gi-eenbrier), forming several bands of limestone in Garrett and Allegany counties; Silurian (Lewistown), with its heavy beds of limestone in several belts confined to the western and eastern portions of the Central Ap- palachian district, in Allegany and Washington counties; Cambro-Silurian (Shenandoah), blue and gray limestones, dolo- mites and marbles, forming the broad and fertile Hagerstown and Frederick valleys in Washington and Frederick counties; Undetermined, interlocated in the phyllites of Frederick and Car- roll counties, and the Airhean (Algonkian '.) marbles of Baltimore and Howard counties. According to their character, their occurrence and the uses to MARYLAND rscni nniCAi ciirvfv vol IIMC M PI 4TF XIX. JlAUILA.Mi fiEOLOGICAL SURVEA' 171 which these various stones are put they may be p-rouped for discus- sion in the following- snlidivisinns: The Marbles, includino- the hijihly crystalline dolomites and niariiles of "Baltimore, Howard and Carroll counties. " Potomac Marble " or breccia which is found locally in the " Tied beds" of the Newark Formation (Triassic) in Montponiory, Frederick and Carroll counties. Serpentines or ''Verde Avtiqve." of irart'ni'il. Italtiuidrc and Montgomery counties. The Limestones, including the crystalline blue and gray limestones, magnesian limestones and " dolomites " of Frederick, Washington, Allegany and (larrcft counties. MARBLES. The marbles of oMaryland have been known for their excellent eifect in building and nionumental work since the beginning of the century. They are all confined to that portion of ^Maryland com- posed of the highly crystalline rocks of the Piedmont Plateau, while those of economic importance at the present time are confined to a small valley known as the Green Spring Valley extending east and west at a distance of 12 to 20 miles north of Baltimore. This broad and beautiful valley sends off several large arms into the surrounding hills of gneiss and granite in such a way that the areal distribution is so anomalous and ii-regular as to render any ex- planation of the structure unsatisfactory. The same irregularity in distribiition is noticeable in the marble ai'eas between Glyndon and Glencoe and west of Ellicott City. This complexity of structure has led to \ai'i<>us views regarding the age of these deposits. Ducatel ' and Alexander from their study of the formation in 1833 regard them as " primitive." Tyson ' in his first i-eport classes them with the " metamorphic rocks " and evidently regards them as Silurian since they are placed on his map and in his list of " Geological For- mations " ° between the Chazy-Black River and Trenton. Tu the ' Re])ni-t. on the Projt'<-ti'(l Survey of the State of .\Iaryl;ind. Annapolis, 1834, p. lit. = First Report of Philii) T. Tyson. State Aui-icultnral Chemist [1800], p. :iO. " Same, pp. .iO, :io-.)G. I i'2 A HISTOKY OF THE QUAEEYING INDUSTBY " Eeport on the Building Stones " of the Tenth Census Mr. Hunt- ington ' describes the area as " a small isolated area of Lower Silu- rian limestone bounded by rocks of Archean Age," and calls atten- tion to the fact " that almost all of the marbles of commerce so ex- tensively quarried east of the AUeghanies are from strata of Lower Silurian Age." Somewhat later Dr. G. H. Williams who made a detailed study of the area expressed the conclusion that ' " The posi- tion to be assigned to this complex [gneiss, marble, quartz-schist] in the geological column is a matter deserving careful consideration, although data for a perfectly satisfactory conclusion are not at hand. It is believed that these rocks are demonstrably older than the altered lower Paleozoics of the western Piedmont region; and yet that they themselves contain in their chemical composition, stratigraphy and the presence of certain obscure conglomeratic beds near Washington, evidence of a clastic origin. For these reasons, as an expression of our present knowledge, the complex is pi-ovisionally assigned . . . to the Algonkian horizon." This view was subsequently restated ' and held by the author imtil his death. The marbles of this eastern area are throughout much coarser than the lenses of fine compact crystalline marble found intercalated in the phyllites of Carroll and Frederick counties. " Another striking con- trast between the marbles of these two regions is, that, while the latter contain tlieir impurities in the fonu of thin argillaceous bands, the former have theirs represented by layers of perfectly crystallized sili- cates." The western marbles also seem to be much more shattered and more difficidt to work than the somewhat uniformly jointed mar- bles of the Cockeysville area. Cockeysville and Texas. These two towns are located on the j^^orthern Central Railway about fifteen miles north of Baltimore, and are separated from each other by a distance of a mile and a half. Although situated so close to- gether, and representing but parts of a single formation in a common ' Building- Stones and the Quarry Industry. Tenth Census, p. 177. ■ Guide to Baltimore, p. 89. ' Jfaryland. its Resources, Industries and Institutions, Baltimore, 1893. MAUYLAND GEOLOCJICAL SUKVEY 173 valley, the quarries expose rocks showing many ditferenees in compo- sition, purity, coarseness of grain and texture, which have developed different industries in the two places. The rock at Texas is a coarse- grained marble of nearly pure carbonate of lime suitable for use as a flux or fertilizer, while that at Cockeysville is a finer-grained dolo- mitic marble, rich in magnesium and well adapted to l)nilding and decorative purposes. It is not known when the stone of this area was first used or first recognized as of economic importance. The first recorded description is that in a letter by Dr. II. H. Hayden ' to Dr. Nathaniel Potter in which he writes: "Immediately to the northward, as well as to the eastward of the Hare Hills the limestone commences. This, I believe, is its first appearance in the vicinity of Baltimore, which is distant six miles. From this to the distance of twenty miles to the northward, and how much farther I am unacquainted, the limestone tracts discover a variety of transitions. In many places it approaches so near to a marble, as to render it not only useful, but highly valuable in almost every branch of civil architecture; and the prospect is favor- able to a supply of such as will answer every purpose of statuary and sculpture in all their variety." That Dr. Hayden's view of the adaptability was correct was soon shown by .\[r. Mills in the construction of the Washington Monii- ment in Baltimore, the cornerstone of which was laid on the Fourth of July, ISl."). A lack of funds delayed tlio completion of the monu- ment for nearly fifteen years, and it was not until the 25th of No- vember, 18:29, that the last piece of the statue, comprising the bust, etc., was raised to the summit. The three blocks constituting the figure of Washington wei-e origi- nally quarried as a single piece over seventeen feet long at the Taylor quarry, about a quarter of a mile west of the railroad at Cockeysville, and presented by F. T. D. Taylor of Baltimore county. The marble used in the moniuueut, which came in part from tlie Taylor ([uarry and in part from the Scott quarries five miles fartlici- north, was ' Hayden's Geological Sketch of Baltimore. Jour. Balto. Med. & I'hil. Lye. vol. i, ISll, pp. 255-271. Repub. Bruce's .Xmer. Min. Jour., vol. i, New York, 1S14, pp. 243-248. 1 I 4 A HISTORY OF THE QUAEEYIXG I>-DUSTEY donated by General Charles Ridgely of Hampton, and the stonc- eutting was perfoi-med by General William Stenart.' After this increased demand for marble as a building stone, it is doubtful if much material was taken out for \ise in structural work during the succeeding iifteen years; the trade in lime for agi*ieultural purposes, however, increased rapidly diu'ing the years following the war of 1812, until it was estimated that fully 200,000 bushels were produced annually. This trade was so extensive, that in 1S39 there were fears expressed that the old cpiarries were nearly exhausted. The popular apprehensions became so great that the State Geologist, J. T. Ducatel, made an investigation which showed the practically inexhaustible character of the deposits. The same year (1839) Mr. Gilmore ' offered to furnish stone to the Federal Government at 90 cents per cubic foot. From this same rejDort (1830) we gain the first information con- cerning the operators in this region in the statement that " the quarry on the lands of Mr. "\Vm. Bosley has been worked for many years past by Messrs. Baker and Connolly." The senior member of this firm was one of the first owners of this marble property and he did much to develo]) the industr\\ Sometime in the early forties !Mr. Baker associated with him in the business his son-in-law James B. Connolly, who succeeded to the business on the death of Mr. Baker. The fullest accoimt we have of the early woi'kings of the area is that given by Dr. David D. Owen ' to the Building Committee of the Smithsonian Institution after his visit to the quarries in the early part of 1847. He foiind at the time some thirteen quarries in moder- ately active operation, the product being used for both building and agricultural piu'poses. Five operators, Messrs. Samuel Worthington, Griscom and Bur- roughs, Fell and Robinson, E. J. Cooper and Thos. Symington, made bids for furnishing the stone for the Smithsonian Building without success The stone at that time was offered at $1.87 to $2.20 per ' Scharf's History of Baltimore City and County, Maryland. Phila., 1881, pp. 265-267. -Ex. Sen. Doo.. 3.ith Cong., vol. v. >'o. :i21. = Sen. Doc. .KiTli Cong-.. 1 Sess., lYo. 2.3, pp. 25-30. -MAIiVLAXD IIEOLOCKAL .SliaKY ll O porch of 3000 pounds for niLlilo delivcrpcl free on board tlie c-ai's at (.'ockeysville. Of the qnarries inspected \>\ Dr. Owen uiAy a few arc still (IS'J.SJ in operation, most of them liavinu- Ijecome exhausted. Scott's qnarrv, which is located about five miles ndiib nf ('ockeys- ville, has nt)t been worked dnrinji' the last forty years, as the openini>- was abandoned as soou as the good stock was exhausted, it was from this quarry that part of the marble for the Wa.shing-ton monument was obtained. An old quarry formerly on the jiroperty of Mrs. Chisilla Owings, about 200 yards from the present Beaver Dam quarries, was opened in 1840 and worked till 1873. It was then ai)andoned on account of the poor ciuality of the stone, and is now filled with water. This quarry was operated for a time by the Sherwood Marble Co. The old quarry of Thos. Worthington from which the stone was obtained for the City Hall in Baltimore is situated about a mile west of the railroad at Cockeysville Station. It was opened some years prior to 1845 and was abandoned in 1873, when the white stone was exhausted. It is now the property of Mr. William Wight. Samuel Worthington's old quarry is located about half a mile southwest of the one just mentioned, aud is now owned by ^Ir. E. Gittings Men-yman. It was abandoned in 1873 on account 1 Analf/ses of Ma, Mr. I. 11. 111. IV. IllSoI. h.'tl 2. 33 2.00 SiO, 0.44 A 1,0, Fe,0, FeO I ) .40 tr. C:iO 29. OS 30.73 29.30 .52.08 MtrO 20. SO 20.87 20.81 2.38 HO 1.22 0.08 CO., 44.26 45.85 100.33 4.5.31 43.54 itO.Ol 99.38 100.00 Specimen. Analyst. Ueferenceg. I. Cookeysvi lie. SclnieHler. Bull., 148, . p. 25.5. II. „ Whittiehl. " 60, p. 2.55. , p. 159. " " (iiiide to Baltimore, p. 08. III. Hiffgins. (n ( reralculated.) IV. Texas. estimated averaire. The exact limits of the arcal distribution of the marble and the dolo- mite have never been determined because of the lack of exposures and the high state of cultivation throughoiuit the area underlain by the two rocks. It seems probable, from the data at hand that the distri- bution presents an intricate interweaving of the two types which may yield much information on the subject of dolomitization if the work- ings ever present sufficiently continuous exposures of the rock surface. ' Mai_vlam.l, its Kesources, Industries, and Institutions, p. 135. 180 A HISTORY OF THE QUAKRYING INDUSTRY The microscopical texture of the Cockeysville and Texas rocks dif- fers but slightly from that presented to the unaided eye. The grains interlock in about the same Avay and the interstitial areas left between them seem very small. The two rocks differ from each other, when seen with polarized light, since sections of the Cockeysville rock show fewer vari-colored bands than that from Texas, due to the secondary twinning of the small individuals of the carbonate of lime which is more susceptible to twinning through pressure than the magnesian carbonate. The two minerals are intimately mixed in their distribu- tion, and only occasionally show any marked variation in the size of the grains. Accessory minerals are present, but they show no differ- ences in texture beyond those evident to the naked eye. Few American building stones have been as thoroughly investigated with reference to their crushing strength as the marbles of Baltimore county. From the time that Mr. Kobt. Mills became interested in the properties of the Baltimore marbles, which he used in the con- struction of the Washington monument in Baltimore, the engineers and architects charged with the construction of the Public Buildings in Washington have watched with interest the behavior of this stone in structures. The use of these marbles in public buildings has also led to extended experiments on the part of government officials. Prior to 1837 all of the important public buildings at Washington were constructed of Aquia Creek (Va.) sandstone, which was so treacherous and unsightly after exposure that as early as 1839 an inquiry was instituted by Congress as to the availability and cost of marble and granite. At this time Mr. Gilmore offered to furnish marble from the Baltimore county quarries at 90 cents a cubic foot, and Mr. Mills, the government architect, highly endorsed the rock. The iirst published results of crushing strength tests on Maryland marbles were obtained before 1851, as stated in Professor W. R. Johnson's paper on American and Foreign Building Stones (pp. 6, 7),' by Mr. Eobert Mills and Dr. Charles G. Page. These tests were made on two-inch cubes of coarse '' alum stone " from Texas and ' Comparison of E.xperiment.s on American and Foreign Building- Stones to determine their relative strength and durability; by Professor \Valter R. Johnson, Amer. Jour. Sci., 2 ser., vol. xi, 1S51, pp. 6-7. MARYLAND GEOLOGICAL SURVEY 181 showed considerable range in values. Similar tests were also made on two-inch cubes of fine grained marble from Symington's quarry (now abandoned), which show much greater uniformity. Other ex- periments on Maryland marbles were made by Mr. Dougherty, Su- perintendent of the Washington monument in Washington, which gave still other results. Prof. Johnson noted the wide discrepancies in the figures obtained from these different experiments on material from the same localities, and concluded that the variations miist be explained either on one or the other of three suppositions; 1st, that the strength of the different specimens of the rock is thus variable, and that consequently no certain reliance can be placed on its powers of resistance; 2nd, that the experimenting or the machine^ with which the testings were conducted were faulty; or 3rd, that the re- sistance to crushing for a imit of area at the ba?e, increases in some ratio with the number of units composing that area, that is, with the actual area of the base.' Johnson favored the third explanation, but the second seems to be as much in accord with later results. Since these early experiments were conducted, great advances have been made in the manner, uniformity and accuracy of the testings, so that residts obtained now are not to be compared or averaged with those of earlier M'orkers. The conditions under which the testings are carried on cause the results to vary within wide limits. The experiments conducted in the preparation of the present re- port were made with the greatest care and under the same conditions. All of the specimens were two inch cubes, placed between two quarter-inch thick soft pine blocks in exactly the same position, and the testing machine was run at the same speed in each case. Almost all of the blocks were cut from the average stock of a well-known stone-yard. Some were crushed just as they were received from the stone cutter, while others were crushed after they had been submitted to absorption, freezing and thawing tests. The results are as follows: Crack. Bresk. L CockeysviUe iiuirhli', unoricnted without immersion .57,740 •i. •• ■• •• •• " SI. .580 3. - •■ .. .Ufter absorption j ( and freezinir. ) 4. •• " " •• •■ ■ -ir.rM) (i'.i.soo • Loc. eit., p. 17. ]82 A HISTORY OF THE QUARRYING INDUSTRY' Somewhat higher ligures have been obtained at other times, as is shown by the accompanying letter, but the conditions of the testing are mjt known. [Hugh Sisson, Esq., Baltimore, Md., giy ■ 1 Washington, D. C. [ ] The compressive strength of the six 3" cubes of Beaver Dam Marble, which you furnished, was as follows: No. 1. 84,000 lbs. 3. 90,000 3. 90,000 i. 84,000 .5, 0.5,000 6. 94,000 89,066 Average. Strength per square inch, 33,416 lbs. The strength of the large crystal marble is about 13 600 lbs. per sq. inch. The 1" cubes have not yet been crushed, but I feel satisfied the result will not show a greater strength per square inch than those obtained in crushing 3" cubes. Very respectfully, Your Obt. Servt., Geo. W. Davies, ^ „ , „ „„ Cifpt. Axxixt. EM/ineer. By direction of Col. Casey. i" It is therefore clearly shown that the rock from the Beaver Dam quarries at CockeysviUe, as usually furnished, can well sustain any weight which the exigencies of structures may demand. Many crushing tests were made on the coarse-grained " alum stone " from Texas in earlier years and the results have been brought to- gether by Johnson. The most satisfactory test, however, is furnished by the Washington National Monument itself, which shows the Texas rock (Griscom's lime riuarries) subjected to increasing pressure from top to bottom as given in the following table from the report made bv Col. Thomas L. Casey, Corps of Engineers, Fnited States Army, engineer in charge of the construction of the monument, to W. W. Corcoran, Esq., chairman of the joint ^commission lur the completion of this structure dated July 37, 1878.' ^Quoted in Tenth Census, vol. x, Report on Building Stones, p. 359. MARYLAND GEOLOGICAL SURVEY. VOLUME II. PLATE XXII. Vu:. l.-TIIlin'Y-KK'.irr T(l\ MdXnl.rni. cncHKYSVILLK. I'u;. L'.-lHnoMAG .M.VKlil.K (jr.MMIY. I'nlXT OF HOCKS. ilAKVLAXD GEOLOGICAL SURVEY 183 Distance of Joint from top. tn feet. 2.5 .50 Contents In cutilc feet. Average wetglit per cubic foot of masonry in severai divisions. 13 555 100 34 719 First Division, 169.5 lounds. 150 63,957 171.00 79 239 200 101,674 250 300 148 204 298 373 Second division, 167.8 pounds. 343.00 261 291 3.50 272 369 400 450 360.268 470,495 Tliird division, 16.5.8 pounds. .500 585 476 Weight In pounds. Pressure In tc squB n re (2210 lbs.) per foot. Distance of Stability line of under resistance from action of axis in feet. the wind. Least. .M etin. Greatest. 0.603 29.4.54 2,297,630 2.67 2 90 3.26 1.0.52 17.378 5,8.S4,973 4.41 5 23 0.04 1.670 11. .539 10,840,728 5.85 7 24 S.04 2.087 9.7.58 13,431,081 6.44 s.os 9, 72 2.224 9.360 17,195,713 7.14 9 12 11.09 2.383 8.983 2.5,019,140 8.35 0.90 13.44 2.007 8.610 34,411,997 9.54 2 63 1.5.73 2.779 8.4.52 43,963,6.55 10.. 56 -1 11 17.60 2.899 8.417 4.5,816,912 8.28 1 51 14.73 2.892 8.481 61,38.5,397 10.09 3.. 84 17.60 2.869 8.902 78,666,278 11.76 0.03 20.30 2.889 9.190 97,264,244 13.38 8.02 22.6.58 2.928 9,413 The fact that tlie coarse-grained marble without crushing actually withstands a prcf^ure of 28,790 ' pounds to the square inch when this pressure is applied evenly and slowly would seem to indicate that stone like that from Cockeysville might withstand under similar cir- cumstances a pressure of fully twice as iniicli as tlie figures given, since the earlier tests by Mills and by Dougherty place the strength of the " Symington " stone at twice that of the Texas rock. The freezing tests which were conducted by Dr. Charles G. Page according to the Brard method described on page 104 gave the fol- lowino- results: " ' Computed on tlie assumption that the value of the crnshing weight varies as the third power of the side of the areas compared. 'Report of the Board of Regents of the Smithsonian Institution. Sen. Doc. No. 2.'!, 30th Conoress. 1st Session, p. 21. 184 A HISTOKY OF THE QUAKRYING INDUSTRY Spec, marked. s. G. Weight cubic ft. Loss frost in grains. l-er- cent. of loss. 'i. bymington's close-grained marble (similar to Worthington's.) 3.834 177.1 0.20 (I.02B 4. " large crystal marble, 2.8.57 178. .5 0. .50 0.069 o. •' blue limestone, 2.613 163.3 0.34 s. Port Deposit granite, 2.000 103.0 5. 0.5 Since the cubes vised were but one inch in diameter they did not weigh over 720 grains and the percentage approximates the values given in the fourth column. During the preparation of the present report Mr. Shellenberger tested the rock by depositing two-inch cubes in a freezing chamber for forty-eight hours and subsequently drying them at 212° F. The percentage loss from freezing and thawing, calculated on the differ- ence between the original weights before immersion and after drying, was obtained as follows: Weight after freezing 48 hours ata° F. Per cen t "iVi-ight Weiglit and then of loss alter l)efore dried at by drying freezing 312° F. treezing Mark on Kind of 24 iiours 48 hours for 24 Loss in and cube. stone. at iVi" F. at 2^ F. hours. weight. thawing Grams. Grams, Grams. Grs. 3. Marble 367.15 367.93 367.13 0.02 0.005 4. .' 3li7.07 367.86 367.03 0. 04 0.11 These figures and practical experiments show that a cubic foot of the Cockeysville rock weighs about 175 pounds per cubic foot or 4,375 pounds per perch of twenty-five cubic feet.' They also indi- cate that the close-grained marble (now the only one in general use for buildings) is exceptionally non-absorbent and resistant to the dis- integrating effect of frost. This is well borne out by a study of the oldest structures standing, which show little or no " spalling " as the result of frost action, and the character of the weathering shown in the quarries. The " dry seams " which have caused occasional loss, as in the case of the Baltimore Court House monoliths, seldom prove troublesome in the material furnished for ordinar\' buildings, since they may ' When sold by weight it has been customary to figure 3,000 lbs. to a perch. i, SIAEYLAXD GEOLOGICAL SUKVEV 185 usually be avoided in the smaller blocks. The strain which cause them to open after dressing is also more evenly di^tribnled in struc- tures using smaller pieces of stone. The mineralogical and chemical composition of carefully selected blocks of marble from Cockeysville show that little more can be de- sired to assure the stability and consequent durability of the stone. When care is taken to avoid the few bands and pockets of pyrite and mica there is nothing in this rock which will render its decomposition rapid, as all the accidental or accessory constituents are in the form of stable compounds such as tremolite, tourmaline, or quartz. These in the first-class stock are seldom in any abundance, with 'occasional exception of finely fibrous and disseminated colorless tremolite. The outcrops, though decayed from ten to twenty feet below the surface, show the rock to be very durable for a carbonate, especially as the cn- tii'e area of its occurrence has been exposed more or less continuously to disintegrating influences since at least late Tertiary time without any period of scouring by glaciers. Old tombstones, said to have been cut as early as 1829, show their lines as sharp and their surface as smooth as pieces which have been exposed to the atmosphere for only a few years. Little discoloration has developed beyond the darkening due to dust or nearby brick or iron. The other areas of marble, similar to that of the Green Spring Valley, are not worked for building stone, but the whole product is burnt for lime, which is generally applied to the land of the imme- diately adjacent country. The centers of distribution arc Rutler in Baltimore county; Marriottsville and Highland in Howard county. Both Butler and Highland are so far from railroads and so lacking in transportation facilities, that they will never compete with tiic Cockeysville product so long as conditions remain as at present. Marbles of Carroll County. Intermediate between the clear white, fine grained saccharoidal marbles of Baltimore and Howard counties and the crystalline dark blue and gray limestones of the Hagerstown and Frederick valleys are the variegated marbles of Carroll county, which have fui-nishcd samples imsurpasscd in beauty and variety by those of other states. ISCl A HISTORY OF THE QUAEKYING INDUSTRY At the Centennial Exposition in Philadelphia in 1876 there were ex- hibited specimens of " deep red," '' dark red veined with white," " salmon colored," " lavender veined," " undulate pink and white " and " rnhy " marbles which came from ( 'arroU and Frederick counties. Besides these many others might have been supplied. Some samples of tlie stone resemble the deeper colored Tennessee marbles, while others suggest the yellow Sienna, but lack its bright, clear tone. All of these varieties occur in lenses in the phyllites which in cer- tain localities have been shown by Mr. Keith to be of Cambrian age. The lenses do not occupy any considerable extent or present large exposures, but instead are confined to valleys which are long and nar- row and arc the direct result of the readier removal of the calcareous rocks than of the adjacent shales and sandstones. The marbles thus occupy the bottom lauds and seldom outcroj) high above the level of the streams. All of the valleys fonned in this way trend parallel to the longer axes of the lenses in a X. E.-S. W. direction, as is well rep- resented in the valley east nf the road from T^ew Windsor to Union- ville and in the smaller valleys at the south of Spring ]\Iills P. O. Up to the present time the method of extracting the stone has been very crude, since the only desire has been to obtain the rock in pieces small enough for foundations and ordinary buildings. According to information furnished by Prof. Uhler, there has been a marked de- terioration in the method of (luarrying these marbles since he first began to study these rocks. Formerly considerable attention was paid to the extraction of the stone without explosives, while at the present almost all of the quarries use powder or dynamite to loosen the rock and render its extraction easy. During the earlier workings beautiful slabs were taken out for altar fronts and interior decorations. From a study of the walls of the small quarries it seems probable that no blocks can now be obtained in size, shape and quantity for first-class building purposes. The jointing is not trustworthy and the rock tends to break down into thick angular blocks varying in size from eight cubic feet to small fragments. Careful work with channelling- niachines or diamond drills and a discontinuance of explosives might allow the quarrying of blocks which would be valuable for interior decoration in the form of mosaics and mantels. MARYLAND GEOLOCIC AI. Sri;\-KV 187 Another serious drawliiu-k in working these rocks, wliicli iqipear so beautiful in samples, is the iircfiiilar distrii)utioii of the ^Milurs, which seem to oliev no nile and to follow no definite eonrse. Tlie white may be i-i'iihii-i'(l by red uv the red may be nqihiccd by liluc and sn dm. There seems, iidwevcr, to be a greater amount of red and white or clear white tiian anyfliinf>- else. The variations in color are so fre- ([uent and uncertain, that it seems doubtful, if any quarry now opened could fultill any niodcnitcly biri;c (irdrr wilb niatiTial like a ijiven sample. I'bai llurc arc beautiful uiarbb's within these lenses is be- yond doubt, but a suitalde ]ilace for tiic d('\ilii]iniont of a jn'ofitable inthistry in I hem has yet to be found. Amoui;- the o]ienin,4i's in tiiesc marbles in Carroll county, wliiidi are used quite iicncrally for lime, are the following: Jonas Batdiman, Bachman's Mills; "Wm. H. Eberhart, Bachman's .Mills; .Terenu'ah Ih'own. Xew AA'indsor; Samucd Harris, Lessee, Xew Windsor: V.\>\\. Stoufl'cr, Xi'w Windsor: John T. Dutterer, Silver Run: W'ni. A. Leppo, Silver Hun; J. C. Robertson, Warfieldsburg I'. ().; E. J. Gorsuch, AVestminsfer; Wm. A. Boop, Westminster: Henry B. Rigle, Westminster. At various points around the northern end of the Blue Bidge and occasionally along the course of the Shenandoah river Mr. Keith has found a local development of white marble, which is often pure white, with an exceptionally even grain, resend>ling a high grade statuary marble. .Mention of such material may be found in the reports of the earlier state geologists, and the exposures have been met with in several places, hut in no instance have they been free from stain or jointing in masses which offer a reasonable return for investment. Such, however, may .sometime be found, although Keith eonsidei-s that this marble is not of sufficient body to be valuable. Small quar- ries have been opened near Keedysville and just below the station at Edgemont, but these have not been adequately developed. POTOMAC MAKBLE. The most interesting building material in the entire state of ^Fary- land is the " Potomac marble,"' " calico rock " or '" Potomac breccia," wliicli has bi'cu used occasionally for the greater portion of the cen- 188 A HISTOKY OF THE QUAERYI>-G INDUSTRY tnry. The chief interest in this rock arises from the fact that it is " the only tnie conglomerate or Ijreccia marble that has ever been utilized to any extent in the United States." ' This conglomerate is fonnd in several places along the eastern slope of the Bine Eidge and is most extensively quarried in the vicinity of Point of Eocks, Frederick conntv near Washington Junction on the Baltimore and Ohio Railroad. The quarries are small affairs, which have been operated spasmodically. The one in operation at the pres- ent time is located about a mile east of the Washington Junction sta- tion on a spur which runs northeasterly from the Metropolitan Branch. This rock was first brought into notice by Mr. B. H. Latrobe, Su- perintending Architect in the construction and repair of the Capitol and White House before and after the war of 1812. In his report on the piiblic buildings, read February 14, 1817,' Mr. Latrobe gives the first account of the use of this marble as a building stone, as fol- lows: " For the columns, and for various other parts of the Hoiise of Representatives, no free-stone that could be at all admitted has been discovered. Other resources, therefore, were sought after. A stone hitherto considered only as an enciimberance to agriculture, which exists in inexhaustible quantity at the foot of the most south- easterly range of our Atlantic mountains — probably along the great- est part of their extent, but certainly from the Roanoke to the Schuyl- kill, and which the present surveyor of the capitol, and probably oth- ers, had many years ago discovered to be a very hard, but beautiful marble — this stone was examined, and, after much labor and perse- verance, has been proved to answer every expectation that was formed, not only of its beauty, but of its capacity to furnish columns of any length, and to be applicable to every purpose to which colored marble can be applied. ■■ The present commissioner of public buildings has, therefore, en- tered intii a contract for all the columns, and pi-ogress has been made in quarrying them. They may be procured each in a single block sliould the transportation be found convenient. ' Merrill, " Stones for Building- and Decoration," New York, John Wiley and Sons, 1S91. p. 92. -Senate Documents, 14th Congress, 2nd Session, Xo. 101, pp. ?, and G. MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE XXlll. r-OTOMAC MARHl.E. rolNl OF RUCKS. KKKDERU K lOL'NTV. ^t.\RYLA^D GEOLOGICAL SURVEY' ISO " A block of one of the pilasters lies ready to be brought down to Washiiiiiton, and will, probably, arrive in a few days. The quarries are situated in Loudoun county, Virginia, and Montgomery eountj', Maryland." The columns which were then procured are still standing in the old House of Rpjjresentatives, now iised for the sittings of the Supreme Court. The quarries whence they were obtained have never been fully developed, although Mr. Latrobe thought that he had found in the newly discovered marble of the Potomac an inexhaustible I'esource of the most beautifid building materials situated easily accessible by water. There is some doubt as to the exact location of the particttlar source of these blocks used in the capitol, although they were mono- liths of considerable size for the lime and tiie primitive means of trans- portation. Plate .\.\I1, Fig. -2, represents tlie opening reported to be the source. It is situated in the woods north of the Metropolitan Branch of the Baltimore and Ohio Railroad about half way from "Wash- ington Junction to the quames now in active operation. A few yeai'^ later in his paper on the geology of the Southern States the Rev. Elias Cornelius ' gives the following account of this brecciated limestone: " It is also in the valley of this river [Potomac], and not far from its famous passage through the Blue Ridge, that immense quarries of beautiful breccia have been opened. This rock was first brought into use by Mr. Latrobe, for some years employed liy the government as principal architect. It is composed of pebbles, and fragments of siliceous and calcareous stones of almost every size, from a grain, to several inches in diameter, strongly and perfectly cemented. Some are angular, others rounded. Their colors are very various, and often bright. Red, white, brown, gray, and green, are alternately conspicti- ous with every intermediate shade. Owing to the silicious stones which are frequently imbedded through the mass, it is wrought with ' Ou the Geology, Mineralogy, Scenerj', and Curiosities of I'arts o£ \'ir- g-inia, Tennessee, and the Alabama and ilississippi Territories, &c., with Miscellaneous Eemarks, in a letter to the Editor, vol. i, Amer. Jour. Sci., New Haven, 1819, p. 216. 190 A HISTORY OF THE QUAEEYISG ISDUSTRY much (lifficnlty; bnt Avlien finished, shows a fine polish, and is unques- tionably one of the most beautifully variegated marbles, that ever ornamented any place. It would be difiicult to conceive of anything more grand than the Hall of the Representatives, in the Capitol, sup- ported as it is by twenty or thirty pillars formed of the solid rock, and l^laced in an amphitheatrical range; each pillar about three feet in diameter, and twenty in height. Some idea of the labor which is em- ployed in working the marble may be formed from the fact, tliat the expense of each pillar is estimated at five thousand dollars. The speci- mens in your possession, are good examples of its general structure, but convey no adequate idea of its beauty." The words of commendation and the beauty of the columns of the Capitol led the regents of the Smithsonian Institution to investigate the locality and to consider the availability of this rock for the build- ing of the Smithsonian Institution. Accordingly in the spring of 1847 Dr. David Dale Owen visited these quarries which, on the whole, he found were worthless for the pixi-pose in hand. At the present time the work in the Potomac marbles is earned on almost exclusively by the AVashington Junction Stone Co., which quai-ries both sandstone and Potnmac marble. The former is obtained in good sized blocks but the latter is wrought almost entirely in small slabs. The marble is taken from a small opening about half a mile southwest of the quarry buildings. The conglomerates under discus- sion belong in the Xewark fcmnation, which extends along the western border of the Piedmont Plateau from Connecticut and JSTew York southward. The development of the Potomac marble within the Newark is not great and there are Init few exposures within the state. It is sparingly developed north of Frederick, a mile south of Thur- mont and only barely represented at Point of Rocks on the eastern slopes of the Catoctin Momitain. According to Mr. Keith' this lime- stone conglomerate occurs in lenses or wedges in the sandstone ranging from 1 foot to 500 feet in thickness, or possil)ly even greater. They disappear through complete replacement by sandstone at the same horizon. The wedge may tliin out to a feather edge or may be bodily ' Keith, Geology of the Catoctin Belt, 14th Ann. Kept. U. S. Geol. Snrv., \V:ishington, 1894, p,art ii, p. 34(). MARYLAND GEOLOGICAL !>l]iVF.Y 11)1 replaced upon its strike by sandstone; one method is perhaps as eoni- iTion as the other. The conglomerate is made up of pebbh's of limestone of varving size whieh sometimes reach a foot in diameter, although usually aver- aging- aboTit two or three inches. The fragments, which are both well rounded and angular, range in color from gray to blue and dark bhie, and occasionally 7)ebblcs of quartz, ehloritic schists and white crystalline niai'ble occur. All are embedded in a red calcareous matrix mixed with a greater or less amount of sand. The pebbles are very similar to the magncsian limestones of the Shenandoah formation, developed in the Frederick and llagerstown valleys and to the rocks of the com])lex which forms the Catoctin Mountain. Occasionally ])ebbles show evidences of having been decayed even before they became a j)art of the conglomeritic nuuss, but this may be due to their greater solubility, since the uiatrix does not show a corresponding de- gree of decomposition. The bedding so far as it has been observed is irregular and of little importance in the quarrying of the rock, the lenticular character of the beds having far more importance than the position of the indi- vidual pebbles within the mass. In the same way the jointing is also a relatively subordinate feature since the different degrees of cohesion between the i)arts of the pebbles and that between the pebbles and the matrix i>lay an important part in deternuning along what planes a rupture will take place. The texture shows a wide variation in the size of the grains, in the chai'acter of the material composing them, and in the relative amount of matrix between the grains and pebbles. This wide range in the size of the particles and in their abundance leads to many difticidties in polishing the rocks, but the difference between the hardness of the limestone and that of the quartz pebbles is particularly a source of expense and annoyance, since the hard quartz pebbles break away from the softer parts in which they lie, leaving numerous cavities to be filled with colored wax or shellac. This differ- ence in the hardness and nuiterial of the pebbles, together with the conglomeritic character of the mass excludes the use of hammers and chisels. Any satisfactory quarrying of the blocks must b(> done with 192 A HISTOEY OF THE QUARRYING INDUSTRY saw and abrasive materials. It is this difBculty in the working, to- gether with the fragile nature of the stone itself, which has kept it from the conspicuous place in the market, which its oddity and beauty deserve. The chemical composition of breccia can scarcely be determined from a single analysis, and the figures obtained from an average of several analyses may be of little account. The values obtained de- pend A-cry largely on the accuracy of the analyst, the fineness of the grain, the homogeneity of the specimens and the number of samples taken to make an average test. Higgins ' gives the following as " the average of various analyses made of the Breccia marble, or Calico limestone, found in Montgomery, from which the pillars in the House of Representatives at Washington are made: " Sand 12.3.5 per cent. Iron and clay 1.00 Lime, as carbonate 70. .50 Magnesia 1.5.00 Otlier constituents not wortliy of estimation 0.2.5 Total ilil.OO This is probably of little value in itself and should have no weight in estimating the value of the marble. The stone is particularly suited to mosaic work and interior decorations, and should not attempt any competition as a structural material with the stones now in com- mon use. The influence of microscopic structures in a stone like this breccia is more than over-balanced by the variations in the larger structural features of the rock. If the microscope or hand lens shows that the stone is sufficiently fine and homogeneous to take a good polish with few minute irregularities on the surface that is sufficient, still experi- ence clearly shows that this rock will take a good polish and that it will withstand any pressure to which it may be subjected as an orna- mental or decoi-ative stone. This unique material deserves to be fully exploited and pushed as a novelty in the highest class of interior furnishings. It is believed that a demand might be created for this stone in some of the best ' Second Kept. Ju.s. Higgins, State Agr. Cliemist, Annapolis, 1852, p. .39. MARYLAND GEOLOGICAL SURVEY. VOLUME II. PLATE XXIV. Fir.. I.-WIIITEFURI) QUARRY, GAXIHKI.A. IIAIU'OHU ilOUXTY. l-'Ui. -J.-SLATK ijr.VUliV. I.I.\MS\ li.LK. i'iiKUKUli.K (.ul.MV. JLAKVI.A.ND GEOLOGICAL SURVEY 193 work which is done in New York, Philadelphia, Washington and other large cities, where tliere is a call for materials which are suitable fi)r floors and other interior decorations, striking in color and texture and of pleasing contrasts. SERPENTINE. Serpentine or " Verde Antitjiie " has been (pi.initd in Maryland for many years, but the annnal production has always remained small. As this rock enters into competition with some of the marble for in- terior decoration it has frequently been classed as a marble, although so far as the Maryland deposits are concerned it is in no wise related to the marble, however intimately interwoven with calcite veins it may be. The deposits of the state are found in Cecil, Harford, Balti- more, Howard and Montgomery counties, where they have been worked to a greater or less extent in the hope of obtaining good ma- terial for general building or interior decoration. The most thor- oughly exploited are those about Baltimore, at the Bare Hills, those on the banks of Broad Creek in the eastern part of Harford county, and a small area near Cambria in the northern part of the same county. That the stone is capable of furnishing beautifid slabs for decorative purposes is readily seen from the accompanying illustration (Plate XXV). The deposits on Broad Creek are situated in the midst of a large serpentine area, which extends from the Susquehanna south- westerly into Baltimore county. The nearest town is the small vil- lage of Dublin some three miles to the south, which is lacking in both railroad and canal cl(' (listiirliiiiice, as shown Viy the liands of fibrous serpentine wliicli arc often faulted to tlic distance of i or f of an inch (Plate XXV). This seaming and faulting cause considerable \va.ling wiliiamsite, and shows sometimes a slightly slaty structure. Tt occurs in various shades of green, from a pale leek- green to a deep blackish-green, and from a small admixture of mag- netic iron, more or less clouded; vavdy with thin veins of dolomite passing througli the mass. Tt is translucent to semi-transparent; it is exceedingly tough, and its hardness is considerably greater than that of marble, scratching the latter with great ease." 'I'lie analyses of the deep green translucent and lihick mottled varie- ties gave tlie fallowing results: Silieio acid 40.06 4il.::!i Alumina 1.37 l.lll Chromic oxide 0.20 trace. Niccolous oxide 0.71 0.3:! Ferrous " 3.43 0.!)7 Mauiranous ■• O.Oil trace. Magnesia 39.02 38.32 Water 12.10 12.86 .Magnetic iron .3.02 fi.22 100.00 100.00 Hardness 4.00 4.00 Specilic gravity 2.068 2.660 ' I.oc. fit. ]). 7. 196 A HISTORY OF THE QUAERYING INDUSTRY Merrill states in his " Stones for Building and Decoration " that the " spociiic gravity is 2.6G8, which denotes a weight of IfifiiJ- pounds per cubic foot, or practically the same as granite. Specimens of this stone received at the National Miiseum admitted of a very high liis- trons polish, the colors being qnite nniformly green, slightly mottled with lighter and darker shades. It is not a true verde antique in the sense in which this name was originally employed. So far as can be judged from appearances, this is a most excellent stone, and admirably suited for interior decorative work." Since the rock has Ijeen formed under conditions not far different from those existing at the surface, it is probable that no considerable degree of chemical decomposition will take place; the source of danger, however, lies in the tendency toward physical disintegration, brought about by pressure and frost action. The beauty of the rock, when polished, fits it pre-eminently for service as an ornamental stone, and, when used in the interior for ornamental veneering, the rock is not subjected either to harsh atmospheric action or to any detrimental amount of pressure. What has been said of the Broad Creek quarries may equally well be said of the smaller opening operated by W. Scott Whiteford about three quarters of a mile southwest of Cambria, a small station on the Baltimore and Lehigh Railroad not far from Cardiff. This is the only quarry which has made any shipments during the last year. The opening whence the material is obtained is now filled with water and does not appear at first sight very favorable. As represented in iho accompanying figure (Plate XXIV, Fig. 1), it is still small and there is considerable opportunity for expansion. The transportation facilities are good and the supply of material is sufficient to permit successful competition with other serpentine areas. The rock worked seems more suitable than in many of the aban- doned openings of serpentine, since it is fii'uicr and somewhat more schistose. If the sawing is done parallel to the schistosity the expense is less and the slabs are relatively stronger. Cutting in this direction does not give quite as pleasing a texture to the surface, liut the general effect is good. The stone from the Whiteford quarry is MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE XXV. srriM':ntink. IIROAI) t REKK, H^KIORO . MARVLAXD OEOLOOICAL SUUVEY 107 lighter aiul iimre mottled tlmn that IVdiii BniaJ Crceh. In its mot- tling it rc.-^cnibles i\w \n-odnct from abandoncil openings near White Hall, Baltimore county. The plant includes maehinei'v for sawing, grinding and polishing the rock by steam power and the operators have shown that in spite of the difhcnlties to be overcome lieantiful slabs of polished stock 8' x 4' X 2" may be obtained. LI.MES-I'OXES. The blue and gray limestones of Paleozoic age have never been (juarried in ^Maryland as building stones except for local use. The most important and in fact the only one which has been used in promi- nent buildings is that from the Shenandoah formation of the Hagers- town and Frederick valleys. According to the Report of the 10th Census this rock is a magnesian limestone containing alumina and graphite, while earlier analyses made by Dr. James Higgins ' show a wide range in the composition of specimens from different portions of the Plagerstown valley. Analyses of /Jniestonc. SiO, 5. 80 0.:.'.5 2.40 3.00 0.70 2.00 0.60 0.00 0.20 2.00 Al,()3 1 Fe,0, i 0. 10 0.«0 0.27 0.04 0.00 .20 0.10 0.30 CaO* 50. TO .■>G. 18 .5;i07 B0.2] oO. 70 ol.frt .'•).'>. 18 .i0.7'.l .54.32 53.20 Mj;0* 1..-.7 l.:U LOT 20. 3T 21.12 14.(10 0.41 1.43 1.1(1 1.24 CO.j 41..=iS -14.01 42. ST 46.00 47.40 41.113 43.81 41.48 43.00 43.16 Undt. 0.13 .25 tr. tr. tr. 0.00 0.00 0.00 0.30 0.10 * Computed from CaCO, and .MgCO,. The quarries, according to Prof. Chas. E. Monroe, are on a belt locally called Cedar stone, a few hundred feet in width extending for a distance of several miles, and believed to be peculiar in the fact that the upper layers furnish the most desirable stone. This stone is of a deep blue color when freshly quarried, but u[)<>n exposure there is slowly formed a thin white coating over the face of the rock, which brightens the color to a dove-gray, thereby greatly improving the appearance of the buildings. This change goes on uni- formly and accordingly does not pass through the unsightly mottled stage. ' 3r(l Report, p. 135. 198 A ni.STOliV OF THE quareyixg ixdustky There is no doubt that this rock might become of considerable im- portance economically as a building stone. At present, however, the residual soil, with which it is covered, lends itself so readily to brick making tliat there is little demand for stone except in heavy structures or for foundations. Many other areas in the Hagerstown valley offer limestones which may ultimately prove of importance as building stones. Openings in the rock are made only for lime at the present time, and the methods of quarrying, which sliatter the rock by heavy charges, make the exposvu'es look less favorable for the production of building stone than is actually the case. If proper care in extraction were exercised, there is no doubt but that large blocks of limestone could be quarried in many places throughout the entire valley, which would in some in- stances work into a good grade of " black marble." In the Frederick valley little has ever been done towards quarry- ing the blue limestone for building purposes, as almost all of the stone which has been taken oiit has been burned for lime which finds a ready market. The buildings in Frederick show that there has l^een some quarrying for building material, since se\'eral of them are built of limestone and almost all of them have limestone foundations or sills. "West of the Hagerstown valley in Washington, Allegany and Gar- rett counties there are three Paleozoic limestones, namely the Lewis- town, Rockwood and Greenbrier. Of these the first is the only one which oft'ers reasonable grounds for expecting good building material within its limits. The upper massive beds of the Lewistown which outcrop in five or six small bodies along the Potomac from Hancock to Cumberland, and form a continuous belt from the latter point to Keyser, West Virginia, afford every indication that satisfactory build- ing material may be obtained. Little if any work has been done in this formation because there have been no local demands.' Of the two remaining formations the Rockwood is of such a nature that it cannot be iised at all, and the Greenbrier is scarcely any better adapted to building purposes. Both formations occur in \-alleys with " It is a matter of interest in tliis connection to note that outside of Cum- berland and Frostburg there is scarcely a stone building in either Alle- aany or Garrett counties. MARYLAND GEOLOGICAL SURVEY VOLUMF II Dl «TF X«VI. < to I ilAKYLAMJ llEULOlilCAL SURVEY IDD very few outcrops. The latter division has a single exposure on the Potomac between Keyser and Piedmont, West Virginia, and is im- perfectly shown on Jennings Hun and Bradchu-k's linn. It is also iiijiin'd fur sti-m-lural |iiir|)nscs liy the pyvite which (ic('Ui"s scattered tluMlHgh it. S.VNDSTONES. Although there is but one sandstone within the state which has attained any considerable rc])utation as a building stone, there are many formations in different parts of the area which furnish suitable sandstones for local construction. As is the case with all building stones the factor of transportation facilities is so im[)ortant that only those deposits can come into general use which are situated adja- cent to prominent lines of travel either by railroad m- boat. The sandstones of the state range in geological age from those which are sup])osed to 1)0 Archean to those which l)elong to the Triassic period. According to their age and im])ortance they may be considered under the following heads: tiie Triassic sandstones, the Paleozoic sandstones of the Pocono, Monterey and Tuscarora formations, the Camhrian or Mountain sandsfoncs, and the Micaceous sandstones of the eastern Piedmont area. Their distribution is shown cm Plate XXX. THE TRIASSIC SANDSTONES. The Triassic or " Seneca Red " sandstones are the only ones quar- ried in Maryland which possess a recognized reputation in the market, or which furnish materials for more than local work. The formation in which they occur is extensively developed along the eastern edge of the United States from Connecticut southward through iN'ew York, N'ew Jersey, Pennsylvania, and Virginia, and in scattered areas into Xorth and South Carolina. It is from rocks of the same age that the well-known building stones from Portland, Connecticut; Pralls- ville, Xew Jerecy, and Hummelstown, Pennsylvania, are qnarried. This formation enters Maryland from the north near Emmitsburg, and continues with varying width through Carroll, Frederick and ]\rontg()mery counties to the Potomac river. Between these limits there is an almost edUtinudHs licit le and Vincent seem to have been the most prominent opei'ators in the aica. Ill 1807 Mr. Peter sold his quarry to Mr. II. TT. Dodge, \v]\n ciroanized the oriiiinal Potomac Med Sandstone ('(Jinpany, a com- pany wliich ui'carly dcvclopt'd the quarries and marketed a large amunnt of the stone, principally in Washington. In 1874 the com- pany became involved in litigation, and the quarries were closed for nine years. In 1883, the company was reorganized, and the work pushed rapidly forward until June, 1889, when the canal, iipon which the company depended for transportation, was washed out and the quarries lay idle for a period of two years. In 1891 Mr. George Mann, of Baltimore, purchased the property and foiuided the present organization, " The Seneca Stone ( 'ompany,'' which has worked the quarries during the last seven years. The beds from which the building stones are now obtained lie west of Seneca Creek, on the left bank of the Potomac river, where the dip is some 1.5 to 20 degrees to the southwest. This inclination of the lieds allows the quarrying to be carried on from the south and south- west without very much stripping and little or no binding from over- lying strata. The openings show that the available material is dis- tributed in workable bods, varying in thickness from eighteen inches to six or seven feet. These are separated from each other by bands of inferior material of different color and texture. The sandstone beds themselves differ very mvich, not only in color but also in hardness and texture. Some are fine-grained and can be wrought to a sharp arris; others are coarse-grained and may assume the character of a conglomerate. Interstratificd with these grits are argillaceous shaly beds, wliich, together with some of the conglomeritic beds, are entirely 202 A IIISTOKV OF THE QUAKRYING INDUSTRY initit for the lietter grades of work, and cannot compete with local sti)ni' for rongli foundation work on account of the cost of transporta- tion. In strata showing as wide variation as these do it is natural that only a portion i)f the material excavated is available, and there must necessarily be a considerable waste. Occasional clay holes in the lower grades, which produce unsightly holes on exposure, increase the \vaste, but these do not affect the character of the better grade of stone, since they may be avoided by a careful selection of the ma- terial. The bedding of the rock determines the direction and manner of operating the quarry, while the presence of two series of joints greatly facilitates the extraction of the material. These joints run normal and parallel to the strike of the bedding. The first stands perpendicular to the dip and the second is practically vertical, so that the blocks obtained are more or less rectangular. The distance be- tween the joints varies from a few inches to se\'eral feet, liut average satisfactorily for economical quarrying. The texture of the stone which is placed upon the market is ex- ceptionally good. It is very fine-grained and uniform and is not at all shaly, and shows little or no disposition to scale when exposed to the weather. The particles of quartz are e\'idently distributed through a fine, scarcely perceptible cement, and over the entire face there are very minute flakes of muscovite which brighten the general appear- ance of the rock. Occasionally in larger lilocks there are seen small bands of coarser grain which indicate the bedding, and in a few in- stances this alternation in texture is emphasized by variations in the color of the cement. One of the most valuable features of the Seneca sandstone is the extreme readiness with which the stone may be carved and chiseled when it is first quarried. It is then soft enough to be easily cut and the textTire is suificiently uniform to render the stone satisfactory for delicate carving. As is frequently the case with all building stones the rock after exposure loses the readiness with which it may be worked and becomes hard enough to turn the edge of well tempered tools. It is this hardening on exposure which protects and preserves the delicate tracery sometimes seen in the finer examples of dressing in l)locks from these quarries. I .\rARVi.AM) (iKoi.OGKAi. sujtVEV 2();5 Tlic cdlnr (if tlic Seneca Creek sandstone as furnished l>y the Stnieca Stone ( 'iiiii|i;niv varies from a liomnpeneous lig'lit reddisli lirown or einnamdii In a cdiocolatc or dvv\) [lurpU^brown. When freshly ([uar- ricil tlie colors arc c\cii hrighter than after the rock has been ex- posed sonH> time, the rock presenting tones of a light reddish fawn color. The color changes with the composition. With an increase in quartz the histre of the rock becomes brighter and with an increase in feldspar the tone of the rock becomes grayer, while an increase in the amount ot cement deejiens the color. The rock under discussion when studied microscopically is found to be composed of angular grains of quartz, micro<'linc, plagioclase and muscovite. The first three of these minerals occur in more or less clearly detined polygons, which al)Ut each other without interlocking. They show no uniform direction in the position of their longer axes. The same is true of the muscovite which occurs in long narrow shreds. This lack of interlocking lietween the grains causes large interstitial spaces which render the rock friable, porous and absorbent tuiless they arc tilled with some cement. In the Seneca stone the spaces are almost entirely occupied by a natural ferruginous cement which in- creases the strength of the rock. The relations between color, cement and porosity are indicated in the first two determinations by Page, given Ix'low. The individual grains are covereil with films of iron oxide and there seems to be no evidence of enlargements due to the secondary deposition of silica. The plagioclase grains show some alter- ation, but those of the luicrocline are usually fresh and unclouded by decomposition products. Since the plagioclase is present in very sub- ordinate amounts its alteration does not materially decrease the strength of the rock. A cin-sory examination of some of the old litiildiugs made of stone fr(nn Seneca Creek leaves the iui|ir(ssion that at least part of the rock from this loc-ality is unsuitalile for fine buildings liecause of its low crushing strength and its tendency to scale. This apparent defect in the rock arises from two causes, the lack of care in the selection of material, and in the cutting of the blocks so that they will rest par- allel to their beddinc when set in the buildinas. Material where such iJ04 A HISTORY OF THE QITARKYING INDUSTRY scaling appears does not represent the better grade of Seneca stone but is coarser, showing more evidences of cross-bedding, and it is also much richer in mica and poorer in cement. There seems to have been a constant tendency among the earlier builders and stone cutters to place the rock, not on "' bed," but on " edge." Many of the promi- nent structures which now give evidences of flaldng or spalliug clearly show all of the defective blocks to be on " edge." In all rock like the poorer grades of sandstone, such a position speedily brings out the inherent weakness of the rock. The only determinations of crushing strength available, prior to the present study, were made many years ago by Dr. Chas. G. Page and published by Walter R. Johnson ' in the American Journal of Science. These give the aver- age crushing weigiit per square inch as 2691 pounds. This value was obtained on two separate specimens, one of which was from the Smith- sonian Institution. The fact that both rocks give the same values indicates a marked uniformity in the strength of the better grades of rock. The tests recently made show the strength per inch as high as 18,625 pounds per square inch (see below). The weight and disintegrating effects of frost upon the Seneca sandstone Avere carefully studied by the Brard method before the stone was accepted for the Smithsonian Institution, and we have as a result of Dr. Page's " investigation the following determinations: Specific Lost l)y frofet gravity. in grains. D.ark red Seueca saudstoue (similar to Peter's) 2.672 0.70 Liglit Seueca sandstone, dove-colored 2.486 1.78 Dark coarse sandstone, of Seneca aqueduct, Peter's quarry not ascertained. 5.60 Sandstone four miles above No. 3 D, Peter's ue.xt vpest Beaver Dam quarry not ascertained. L.'iS Dark sandstone, from quarry near Woods' resi- dence not ascertained. o. ',14 The specific gravity of these rocks indicates that the weight per cubic foot of the stone is l.j-t to 165 pounds. These figures seem to ' Comparison of Experiments on American and Foreign Building- Stones to Determine their Relative Streng-th and Durability. Amer. .lour. Sci., 2 ser., vol. .xi, 1851, p. 7. -Report of the Board of Regents Smithsonian Institntion, Senate Doc., .30th Congress, 1st Session, No. 23, pp. 21-22. MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE XXVIII. Vic. l.-SA\DSTO.\K IJlAlMtY. KM M ITSIill'.r.. FltKllKlUGK GOUN'TY. ^53^'. Fig. -'.-SA.XU.STUXI:; ULAUKY. SKXKGA. .MU.XTUU.MKHY COUXTY. MARYLAND GEOLOCilCAL SURVEY 205 indicate that the Seneca rock is slightly heavier than the usual run of brownstones, which, according- to the table given by Hopkins/ range from 127.5 to 100. 1, with an average of 161.4 pounds. In structures the Maryland and Pennsylvania stones will range between apjiro.ximately the same limits. The various tests recently conducted bv the Survey are very favor- able to the Seneca rock. The specimens examined were in two-inch eul)es cut from stock furnished to one of the stone yards of Baltimore. The figiires below thiis represent the average run of the quarry and not especially selected stock. Simple crushing. Absorption. Freezing. Crushing after freezing. Craclc. Breaii. 2,368 0.000 73,700 74,. 500 72,380 2, .530 0.013 0.5, S40 R!),500 (i'.i.onn .... (i7,.5(i0 0.5,240 The mineralogical and chemical composition leave nothing lack- ing as to the promise of permanency in the Seneca sandstone imder the action of atmospheric agents. There are no deleterious minerals in rlie carefully selected stone which may injure its wearing power, and the chemical analyses show that the constituents arc in stable combi- nations. The microscopical exauiinations also show (Fig. 14, p. 97) iliat the cement firmly binds the interlocking gi-ains without lea^^ng any considerable interstitial spaces in which moisture may lodge to destroy the integrity of the rock. This lack of porosity is shown also in the slight loss by freezing, as given in the above tables. The best e\'idence of durability is foiind in the structures which have been made of this material. Owen reports (1847) that " Ijy close inspection of slabs exposed now 20 years to atmospheric agencies and severe mechanical friction, the mark of the dressing-chisel is still sharply imprinted in the surface. On the perpendicular wall of the aqueduct, where the water has been oozing through the joints and trickling down its face, forming an incrustation of carbonate of lime, ' The Building Materials of Pennsylvania, No. 1 IBrownstone. Appendix to the Ann. Rept. of renii. State College, Official Doctimeiit Xo. 22 for 1S90, pp. :;o-3i. 20G A HISTORY OF THE QUAEE.YIXG INDUSTRY one may observe, wliere this calcareous cnist lias scaled off, the grooves and ridges of the surface still nearly as distinct as when the block first came from the hand of the stonecutter. '' The angles and edges of the keystcnics of tlic arch, placed under these must unfavorable circumstances, are sharp and entire. Only one or two lilocks of this work of 20 years' standing show sign of decay; but these seem to lie such as either have not been well selected, or have been placed on the edge in the wall. " Even the tow-path of this aqueduct, over which the horses pull and mules have been traveling 20 years, is still unimpaired. Even the corners around which the heavy lock-gates swing, show no signs of chipping." ^Merrill later (1891) corroborates these observations and says: '' On blocks of the stone in the aqueduct of the Chesapeake and Ohio Canal which have been constantly permeated by water every season for fifty years, the tool-marks are still fresh and no signs of sealing are visible other than are produced by too close contact at the joints. . . . The Smithsonian Institution erected in 1S48 to 1S.54 from this stone, shows few defects from weathering alone, and these only in those cases where they might have been avoided by judicious selection." Xo discoloration has been noticed in the rock beyond the darken- ing which gradually and uniformly takes place on exposui'e. Minor Areas. Throughout the entire extent of the Triassic as exposed in Mary- land there are small local quarries developed to supply the demands for foundations and occasionally for more pretentious building. The general demand, however, is more than overcome by the cost of trans- portation in all but the most favorably situated localities. There are many occurrences which will prove of value as the country becomes developed and improves its facilities for distributing its resources. Among the most promising of these smaller openings is one located near Taneytown and owned by John Yingling. This quarry is sit- uated on the western side of a little hill on the road leading from the Emmitsbui'g pike to Harney, not far fnmi the former. The rock exposed is more feldspathic than any iif the Triassic sandstones now MAKYI.AM) GEOLOGICAL SURVEY 207 worked in the state. It is bright gray and gives a pleasing impres- sion, which is in accord with the present demands for light and cheer- ful trimmings. The stone has been tested and the crushing streiigtii and absorption for two-inch cnlics is as below. I. II. Absorption. Crack (iT/.tOO jjoiincls. il4,0{l(> pounds. 0.004 Break !I4,000 •■ 109,400 The rock is, therefore, strong and when niMnipulalcd ])r(iiK'vly may be extracted in blocks of snfheient size to meet ordinary demands. The means of drainage and the (>])])ortnnitv for dumping waste are favorable, wliilc the distance from the (piarrv ti) the railroad is not far enough to render competition iinsuccessfid. The smaller quarries which have been worked spasmodically include the cpiarries just north iif Emmit.sburg, and several ojR'nings about Taneytown, Thtirmonf and Union Mills. It is not improbable that suitable rock might be found in tin- vicinity of Bruceville, where the railroad facilities are esjiecially favoral)le. "Washington Junction. — The oidy other source of red aiiar AVashington Junction in Frederick county. Here the AVashington Junction fStone Company, capitalized at $30,000, carries on considerable work in extracting and dressing the red, brown and variegated sandstones. The present operators began work in 1892, and have continued quarrying almost continuously ever since, furnishing much stom! for such Imildings as the l'"ort McHenry Hospital, Baltimore, churches at Forest Glen, Maryland, and Winchester, A^irginia, and many houses in the l)ettcr part of AVashington. The beds from which this sandstone is obtained di]) gently to the west, and thus afford opportunity for the economical extraction of the stone. Blocks 20 x 6 x 4 feet may be obtained if the demand and the machinery warrant. The stone does not differ noticeably from that furnished at Seneca but shows the same pleasing color and tex- ture already noticed in the latter jilace. The (piarries are well eqni])- ped with saws, rubi)ing beds, polishing machines, etc. The chief 208 A HISTORY OF THE yUAEBYIXG INDUSTKY drawback in the location of tliis opening, which is a mile and a half from the railway station, is removed by a small spur track which ex- tends from the quarry to the station and to the wharf on the Chesa- peake and Ohio Canal. The general mode of working the quarry is shown in the accom- panying figure (Plate XXIX, Fig. 2), which inadequately represents the ledge whence the material is obtained. PALEOZOIC SANDSTONE. Among the various later Paleozoic formations there are four which develop well marked sandstone series. These are the Pottsville, the Pocono, the Monterey and the Tuscarora. Xone of these have been worked to any considerable c-xtent as liuilding stones, because of the lack of demand and transportation facilities. The Pottsville Formation. — The Pottsville is the lowest division of the coal measiires and forms the mountain ridges which border the coal basins. It consists of sandstone and conglomerates interstrati- fied with sandy shales in which thin beds of coal are locally developed. The sandstones are usually coarse-grained and conglomeritic, with marked evidences of cross-bedding which are irregular in extent and disti'ibution. The individual pebbles, frequently very small, are held together by a siliceous cement, which indicates great durability for the rock. ITnfortiuiately such a cement renders the working of the stone l)oth difficult and expensive. It is probable that this material will never become of economic importance except in the supply of local demands for foundations, steps and occasional door sills. The Pocono Formation. — The Pocono formation is very similar to the Potts\'ille and consists mainly of hard, thin-bedded flaggy sand- stones which occasionally become sufficiently conglomeritic tn produce confusion between the two formations. The sandstones of the former have received but little attention and have been used only occasion- ally as a supply for flagging. It seems quite probable that as the demand for building stones increases the flags, which are well devel- oped in places, may come to be of some importance. The Monterey and Tuscarora Formations. — These two forma- tions have a considerable development in Allegany and Washington MARYLAND GEOLOGICAL SURVEY. VOLUME II, PLATE XXIX. HitrmiPrf^, Fv:. l.-MOXOCACY AUTKlIt CT. WliriK (JT AHT/lTl': I'ltuM liKI.T'S (ilAJiHY. I'l.;. V.-SA\liMii\K ijl \|;i;Y. I'nl\r i IF imrKS. I'HKUERlClv COLWXV. MAKYL.VXD GEOLOGICAL SCKVEY 209 counties, where the stone lias been used to supply the local demands. This is especially true of the area about Cumberland. Here the Mon- terey sandstone, which is of a buff-brown to yellow color, was the first to be introduced. It is the source of all of the sills, foundations and lintels for the older buildings. The most important structure in which it is exclusively employed is the Episcopal church. Time has shown that the very property for which the stone was first chosen, viz., the ease Avith which it is cut, is detrimental and that it, together with the clay holes which seem to be developed frequently, leads to the ready disintegration of the rock, so that many of the steps, sills and foundations of the older buildings are in quite a dilapidated state. Where this stone was used in curbing the blocks have become rounded, or broken or deeply worn. The stone itself when dressed presents a very pleasing appearance, especially in trimmings, where it coin cides with the present tastes in architectural work. It is quite pos- sible that by careful selection good material might be obtained from one of the several quarries in Cumberland to supply the .demands foi' a light gray or yellow trimming stone. As a clew in the choice of material it may be stated that as the number of fossils decreases the rock becomes harder. Although the Monterey has not proved altogether satisfactory about Cumberland there are other points in the distribution of this forma- tion where it seems probable that good material may be obtained. The best of these is the quarry owned by Mr. B. S. Randolph of Frost- burg, which is located in Washington county near Dam jSTo. 6 of the Chesapeake and Ohio Canal. The opening, which was made for glass sand and not for building stone, is in the form of a timnel from thirty to forty feet deep, and is situated about SOO yards back from the canal and from 400 to 500 feet above it. The stone is of clear creamy-white color and would make a bright trimming or structural material. At first sight the rock looks as though it is too friable and not strong enough to endure pressure, but the experiments show that in two-inch cubes it has a crushing strength of 73,780 poimds on edge and 75,600 normal. This indicates that the first impressions are incorrect and that the rock is capable of withstanding any ordi- 14 210 A HISTORY OF THE QUARRYING INDUSTRY nary pressure. The purity of tlie rock is attested by the following analyses made by O. ( 'reath of Pottsville, Pa. : 1. 2. 3. 4. SiO,, 99.255 99.5.58 99.398 97.55 AljOs 610 .341 .47.3 3.44 CaO 110 0.81 .103-1 .01 MgO tr. tr. tr. j FeO .037 tr. FeO 025 0.20 100.000 100.000 100.000 100.00 When it was found that the Monterey sandstones were not as durable as expected and that they soon became disfio-ured by exposure, attention was directed to the harder white sandstones of the Tusca- rora which are exposed in Wills Mountain just west of Cumberland. The ledge here exposed has a thickness of some 300 feet, but the solid rock has not yet been quarried, since the demand is more readily sup- plied by utilizing the many detached blocks which cover the slopes of the mountain. At the present time this stone is used for foun- dations and trimmings in all of the better class of buildings in Cum- berland, and its character is well shown in the Presbyterian church. The rock varies somewhat in texture and firmness according to the different beds, but on the whole shows unusual uniformity. It is bright gray in color and is composed entirely of fragments of quartz, which are themselves cemented by a siliceous cement, causing the rock to be in reality a quartzite rather than a sandstone. Feldspar and mica are also found in the rock. Few imperfections were noticed and for one of such siliceous character the rock seems to be very free working. The chemical composition, as might be inferred from the mineral contents, is largely silica. Professor C. F. Chandler ' in his report on the mineral resources of Cumberland gives the following analysis: Silica 98.35 Sesquioxide of iron 0.43 98.77 ' See Tenth Census, vol. x. Report on Building- Stones, p. 178. MARYLAND GEOLOGICAL SURVEY 211 while a more complete one furnished by the present operators is as follows: Silica 98.00 AI3O3 65 Fe,03 15 CaO 40 MgO .21 Alkali tr. Water and organic 50 !)9.!)1 'i'li(' Tuscarora sandstone unlike that of the Monterey shows great dnraliility in whatever position it may he placed, and it is accordingly nsed in almost all of the local work on the embankments of the Chesa- peake and Ohio Canal and in foundations wherever there is a con- siderable superstructure. It is also used to great advantage for pav- ing, curb-stones, steps and trimmings. Besides the prominent sandstone formations of the Paleozoic al- ready mentioned and that of the Cambrian considered below, there are scattered throughout the series numerous small beds of sandstone which arc sometimes utilized to supply local requirements. The quar- ries which have l)een opened are scarcely worthy of the name and the product from all of them is insignificant. Cambrian ok Moixtaix Sandstone. — There extend across the state two parall(>l bauds of dense quartzites which form the Blue Ridge and Catoctin mountains. These quartzites were originally porous sandstones, which have subsequently been thoroughly consolidated by a dense siliceous cement. Similar rocks also occur in the small de- tached area of Cambrian .sandstones which forms Sugar Loaf Moun- tain. The rock has never been brought prominently into the market, altliough it lias been used quite extensively for railroads, canals, roads and a few individual buildings. It is not known when the first work was done here, but according to Schai-f the quarries at Sugar Loaf were operated quite extensively prior to 1830 to furnish stone for the old canal. At this time there was a traniroad several miles long ex- tending from the quames to the canal. The rails were .stnplings and the tram cars were hauled by horses. This little railroad ante- dated the Baltimore and Ohio and has practically disappeared, road 212 A HISTORY OF THE QUAEEVING INDUSTRY bed and all. During the succeeding decade the Sugar Loaf stone was used in the Baltimore and Ohio Railroad, which has continued its use occasionally ever since. Other quarries have been opened in a small way along the Western Maryland Railroad to supply the demands for good road metal and small quarries have been operated l;iy the Mount St. Mary's authorities at Emmitsburg. The latter furnish a stone of dense, even texture in which there can be little absorption and little consequent loss by the action of frost. The crushing tests show that its strength is ex- ceptionally great as a two-inch cube sustained a weight of 93,900 pounds before cracking and 104,200 pounds before breaking. In buildings the rock appears of a bright fresh gray color which darkens but little on exposure. Its general appearance is well shown in the recent additions to the Imildings at Mount St. Mary's. The siliceous character of the rock renders it difficult to work in other than the natural face, but its durability, strength and compactness render it unsurpassed where great permanence is desired. There are within the area of Cambrian sandstone above enumerated many exposures of rock which deserve more careful investigation and which no doubt would prove of service if the transportation facilities were at hand. At present the demand is not enough to warrant any workings beyond the occasional operations carried on at the McGill Belt Quarry at the base of Sugar Loaf Mountain and the incidental quarrying at Mount St. Mary's, near Emmitsburg. MICACEOUS SANDSTONES OF EASTERN MARYLAND. Scattered over the northeastern portion of ^Maryland in Baltimore and Harford coimties are several exposures of highly micaceous quartz- ose rocks, which were originally sandstones, but which have now imdergone considerable change through dynamic metamorphism. These are most characteristically developed in Setter's Ridge along the Green Spring Valley, ten miles north of Baltimore, and on the Balti- more and Lehigh Railroad near Pylesville, and eight or ten miles south of the Mason and Dixon line where the railroad crosses Deer Creek. MARYLAND GEOLOGICAL SURVEY. MARYLAND GEOLOGICAL SURVEY WM Q. CLARK STATE QEOLOQIST 1898 LEGEND TUSCARORA S. S. | tV \ POTTSVILLE CONG (_ CAMBRIAN S. S POCONO S. S. : QUARTZ SCHIST | 9 | ORISKANY S. S. TBIASSIO S. S. I N i SLATE VOLUME !!. PLATE XXX. urn BV A MOen A CO. BAITO. .MARYLAND GEOLOGICAL SURVEY 213 Beer Creek Sandsiones. At the station known as " The Rocks," the Baltimore and Lehigh Railroad and the Deer Creek pass throngh a ridge of highly metamor- phosed hard mioaceons sandstones in a gorge 350 feet below the sum- mit. This ridge extends in a northeasterly and southwesterly direc- tion for a distance of ten to twelve miles and forms a part of the folded phyllite series wliich arc probal)ly of Cambrian age. The sand- stone of wliich it is cnuijiosed lies geologically some distance above the base of the series and below the bottom of the Peach Bottom slates. The stone is a micaceous sandstone rich in quai-tz wliich locally becomes clearly conglomeritic. It contains more or less white mica, rjddritc and bluish kyanite which are the product of secondary crystal- lization due to the metamorphism. The schistosity is well marked and in many instances minute flutings and crinklings are noticeable, producing in a cross section of the rock a somewhat pleasing figure and lustre. This stone has long been used in the surrounding country for foundations, sills, steps, and hearthstones, and its fire-proof char- acter was early appreciated by Dr. Thomas Johnson of the U. S. Army. In 1891 a company known as the " Maryland Cranite' Com- pany " was organized to develop the material as a building stone. T'ables were strung to deliver the stone on board the cars and con- siderable work was accomplished in preparing for quarrying. The company soon ceased operations, either beca\ise satisfactoiy rates were not made with the railroads or because there was no demand for the stone, which was nosition of the beds, which furnish the slates of the Peach Bottom district, is in either the Hudson River or Quebec 222 A HISTORY OF THE QUARRYING INDUSTRY' series, probably the latter as determined by Professor James Hall in 1883 from fossils submitted to him by Dr. Persifor Frazer.' The productive beds are thought to lie the axis of a narrow over- turned synclinal fold which is included within the phyllite forma- tion, extending in a northeast-southwest direction across eastern Mary- land. The stratigraphic position of the band is still in some doubt, since no detailed mapping of the area has ever been completed. Just below the slates, which form the top of the well-defined topographic features called the " Slate Ridge," is a band of talcose chlorite slate which runs parallel to the roofing slates on either side of the ridge. These talcose slates are in turn underlain by a metamorphosed quartz conglomerate which resembles that of the exposures at the Rocks of Deer Creek. This quartzitic conglomerate wraps about the end of the slate formation some fifty feet below the exposure of the slate. To the southward the bands of conglomerate from either side coalesce and form a continuation of the slate ridge, which extends outhwest- erly across the Broad Creek at Pylesville, where Broad Creek has cut a well-defined gorge. While few, if any, observations have been made upon the true bedding of the slates and while no satsifactory contacts have been found in recent studies in the area, the workings along the ridge seem to point conclusively to the fact that this syncline is somewhat overturned to the east, so that the dip of the westerly side is practically coincident with the cleavage, as is claimed by the quarrymen. The slate ])elt itself forms a narrow zone beginning a short distance southwest of the road running from Cambria to Pros- pect and extends in a northerly direction more or less parallel to the " Slate Ridge " through Maryland and York county, Pennsylvania, to the Susquehanna river, which it crosses. There is a short exten- sion of the formation east of the Susquehanna in Lancaster county, which at times has lieen the most productive portion of the belt. Throughout all of that j^art of the area Avhich has furnished good slates the bedding is not clearly defined and the ledges of first-class material do not seem to present any continuous arrangement, suggest- ing valuable beds separated by non-productive ones. This lack of definition in the bedding of the stone renders it impossible to com- ' Tran.s. Amer. Inst. Miii. Eng., vol. xii. 1SS4, p. 3.JS. -MAUVI.AM) (GEOLOGICAL SURVEY 223 piite with any degree of .iceuvacy the thickness of beds or '' veins." Some of the quarries produce good slate over a distance of a least 150 feet across the strike and their operations are limited not by the quality I if tlic stone but by a short-sightedness during early operations which allowed the rubbish to be dumped upon the workable beds. All of the quarries along the line show a great many series of joints which both aid and hinder the working of the quarries. The principal or bedding joints, as observed in the Proctor Brothers' opening (shown in Plate XXXI, Fig. 1) strike cross the cleavage and dip at an angle of 42° to the southwest. Similar bedding joints were observed in the I'each Bottom and York and Peach Bottom quarries (Plate XXXlPj. In addition to this most clearly marked jointing, there is a second series of joints dipping at an angle of 26° with the same strike and another set of joints which dip at abo\it 80° to the northeast with their strike normal to the cleavage. These three systems free the rock in large rhomboidal slabs and they, if they existed alone, would be very valuable aids in quarrying the rock. Unfortunately besides these somewhat uniformly inclined joints there are a great many other jointing planes developed through the beds which do not seem to- be conformable to any system of arrangement. They cut each other at all angles and intersect the plane of cleavage either acutely or with considerable obtuseness. In the York and Peach Bottom quarries there are sharply defined uneven jointing planes which leave the rock protruding like a series of folds whose axes lie parallel and separate from each other at a distance of one to three feet. The ma- terial on each side of the curved jointing planes (see Plate XXX 11, Fig. 1) is of the same character and there is no evidence to warrant rlic assumption that there has been a direct bending into small folds either prior or subsequent to the development of the cleavage and the other jointing planes. The great number of joints and their intersection with each other at varying angles renders much of the material ex- tracted \inavailable for the manufacture of roofing slates or mill stock. While this is so and the amount of rubbish about the quarries is very great it is doubtful if there has been a greater portion of waste ma- terial than is common in slate quarries the world over. Another fac- 22-4 A HISTORY OF THE QUAEEYING INDUSTRY tor wliicli must be regarded by practical o[)eratijrs working in the Peach Bottom area, is the presence of " flint seams " and " blue joints " which modify the manner of working the stone and fre- quently render much of the material worthless. The " flint seams " are of at least two classes; those of the first occur in long thin layers along the jointing planes where the two sides of the joint have been separated sufliciently to allow the deposition of quartz. The second class includes much more irregular deposits which occur in irregular masses varying from a fraction of an inch to several feet in diameter. These apparently represent zones of more intense crushing and subse- qvient deposition of quartz since it is a common saying among the quaiTvmen that the seams cleanse the rock and make the cleavage finer and truer. The " blue joints " referred to are really closed joint- ing planes in which chlorite has been deposited in more or less com- plete orientation with the chlorite of the body of the slates. The seams are not evident at first, but during the splitting and trimming of the slates develop as lines of weakness which render the pieces ob- tained of no value. The most prominent feature in the texture of the Peach Bottom slates is the coarse fibrous arrangement of the particles which give to the stone an appearance somewhat suggestive of the fibre of petri- fied wood. This texture renders the slates much stronger in certain directions than they might otherwise be, but precludes the method of breaking the slates by sharp blows applied normal to the cleavage and makes the stock unavailable for luilling purposes. The peculiar " fibrous " texture of the slate is indistinctly shown in Plate XXXI, Fig. 1, which represents the combined opening of the Peerless, Peach Bottom and Excelsior quarries. This also renders the use of the " plugging machines " and similar instruments of doubtful value. It has also been found more economical and feasible to saw the slates across their grain. The material prepared for market shows little or no variation in the nature of the stone employed, but the character of the finished product seems to vary somewhat in different quarries. Xot only is there a difl'erence in the skill with which the work is done, but the quarrymen seem to differ in the amount of care which they HAKYLAXD GEOLOGICAL SURVEY 225 exercise in sorting the first and second qualities. Wliilc different beds and different portions of the quarry furnish stock that differs in the ease with which it is worked and in the character of the finished pro- duct, the qiiarrymen say that good material may he obtained from all portions of the opening and at all depths below the zone of superficial weathering. In company with qiiarrymen from all regions the men hold to the Ix'lief that the rock improves indefinitely with the depth. The color of the Peach Bottom slates is a deep blue-black which is absolutely unfading, as is shown by the color of slates which have been exposed since the beginning of the century. This fact alone places the product of the area among the best slates of the world. From this color there seems to be no variation in any of the well pre- pared material. It should be borne in mind, however, that slates, like broadcloths, when placed side by side with their texture in differ- ent positions show differences in their sheen and that these differences may l>ecome so marked that an impression of a variation in color is often given. Care must be exercised accordingly not only in the selection but also in the laying of the slates if the most desirable effect is to be obtained. The imfading quality of the Peach Bottom slates allies them ^\^th the products of the Maine and certain of the Ver- mont quarries and sepai-ates them from the less unifoi-mly colored slates of the Lehigh and Slatington districts which are not always able to retain their color unmodified by exposure. The only influ- ence of exposure in the Peach Bottom slates which has been noticed, is a slight increase in the gloss or sheen in those pieces which have been longest exposed to the sun and atmosphere. The bulk composition of any building stone may be very misleading, since it does not show in what state the chemical constituents are com- bined. This is especially true with slates. It, however, is of consider- able advantage in showing the lack of injurious elements and the presence of advantageous components. The valuable constituents in the slates are the silicates of iron and alumina, while the injurious constituents are sulphur and the carbonates of lime and magnesia. Three analyses of the Peach Bottom slates are given below, one by the Pennsylvania Geological Survey made in 1 877,' one by Booth, Garrett ' Second Keport Laboratory of the Survey, bj- .\ndrevv S. JlcCreath, Har- risburg-, 1879, p. 370. 15 226 A HISTOEY OF THE QUARRYING INDUSTRY and Blair of Philadelphia in 1885, and one by George P. Merrill.' They are as follows: Analyses i>f Slates. Pa. Geol. Sur. B. G. & B. Meriill. SiO, 5.5.880 .58.370 44.15 TiO,, 1.370 tr. tr. AljOg 31.849 31.985 30.84 ^«=0 \ 9 034 10.661 14.87 Fe,03 J MnO 0..586 tr. tr. CaO 0.155 0..300 0.48 MgO 1.495 1.303 0.27 CoO tr. K^O \ 4 ;^oo 1.933 4.36 Na,Oj H.,0 3.385 4.030 J 0.51 CO,^ 0.390 (. 4.49 C ' 1.974 0.930) S 0.107 wanting. SO, 0.33 FeS, 0.051 99,801 99.909 99.97 These analyses show the percentage of deleterious and advantageous minerals as follows: Geol. Surv. B. G. & B. Merrill. Silicates of iron and alumina 86.763 91.016 89.86 Sulphur 0.039 0.107 wanting. Carbonates of lime and magnesia 3.319 3.066 1.435 The source of the material for the first analysis was the " J. Hum- phrey (fc Co.'s quarry," now the Peach Bottom, and the second was also from the same opening. The material for the third analysis was taken from the opening of the Peerless quarry about one hundred feet west of the limits of the pit of the Peach Bottom. In describing the source of the materials Merrill gives the following description of the mode of weathering of the slates: " In the fresh cuts made dur- ing the work of stripping, to open new quarries, the sound rock is overlain by a variable thickness of ferruginous residual clay. Joint blocks and splinters of the slate scattered through this clay, in all stages of decomposition leave no doubt as to its origin. Blocks, deep velvety black on the interior, are surrounded by a crust of ocherous » Rock, Kock Weathering- and Soils, 1897, p. 229. MARYLAND GEOLOGICAL SURVEY VOLUME II, PLATE XXXII FiG. i.-YoUK .\.\]l I'KAGilliuT'ruM UL:A1:UY, CAMBltlA. I'lu. -J. XuXlii A\U rKACllHUTTOM QUARRY. CAMBRIA. MAKYLA.ND GEOLOGICAL SURVEY 227 brown-red decomposition product, the decay penetrating irregidarly like the processes of oxidation into a piece of metal. The first physical indication of decay is shown by a softening of the slate, so that it may be readily scratched by the thumb nail, and an assumption of a soapy or gi'easy feeling, the entire mass finally passing over to the deep red-brown unctuous clay, sufficiently rich in iron to serve as a low-grade ochre, for paints. .The incidental chemical changes are sur- prisingly large, as shown by the analysis below, column T 1 icing an average of two analyses of one of the blocks, and II that of the resi- dual clav. In III. IV, and V are siven the calculated losses of con- ^tituents." i. n. 1)1. IV. V. Conetitncnijj. Fresh Aritllllln. Kesidiial clay Pcrcentftsc of loss for c!ntlre block. VorcentHgc of cachconstltucnl saved. rercentago of each eunstltu- enl lost. .SiO, 44. Li^ •■ii.n% 'ir,.Z4% 42.4:5^ .^)7. .')7 AljOj 30. S4 .S!1.90 0.00 100.00 0.00 KeO 1 Fe,0, , 14.ST 17.(11 1.2:! 01.22 8.78 CilO 0.48 None. 0.48 0.00 100.00 MifO o.a- 0.25 0.08 71. S4 2X.ir, K,0 4.a6 1.'.'4 :i.:^H 22. 04 77.9.5 Na,() 0..5I 0.2:5 0.:« 0.30 O'.I.IU C 11,0 4.4!) 16.62 0.00 lS7.:n None. 0<).07<5; 100.02'? 40.8:!(s; .Microscopical and physical examinations are even more important tlian chemical analyses in determining the stal)ility of roofing slates wliicli cx]iosc such a relatively large surface^ to the action of frost and solution. Merrill has based his discussion of the stability of slates upon the amount of crystallization as shown by the microscope and the presence or absence of free carbonates of lime and magnesia, sulphides of iron or of carbonaceous material. The most characteristic features of the microscopic structure of the Peach Bottom slates are as follows: The most evident constituents ai"e quartz, feldspar and chlorite. These are very small and indistinctly outlined against each other, as is usual in fine-grained slates. In the preparation of the slide the fibrous character of tlie stone which is evident upon larger pieces is especially prominent, and this is not wlidlly lost in even the thinnest parts of the slide. The material seems to be completely recrystallized 228 A HISTORY OF THE QUARRYING INDUSTRY and no constituent is present in large areas which is at all untrust- worthy. As the color seems to come from the chlorite and not from the finely comminuted particles of non-crystalline material, it should be permanent and unfading. Professor Mansfield Merriman," who has made a long series of ex- periments on the best methods of determining the durability of slates, regards physical and impact tests as most expressive of their perma- nency. An account of his experiments on the Peach Bottom slates is as follows : " During the present year the writer has made tests for strength, toughness, density, softness, porosity and corrodibility on twelve specimens of Peach Bottom slate, following the same methods as described in the former paper for the old Bangor and Albion slates. The specimens were 12 x 24 ins. in size, varying in thickness from 0.21 to 0.29 in. For the test of strength they were laid on supports 22 ins. apart and broken by a load slowly applied at the middle. The modulus of rupture for each case was then computed from the formula : ,, , , 3 X breaking load x length Modulus = " ? 3 X width X square or thickness " For instance, the specimen marked Qi was 12.04 ins. wide, 22 ins. between supports, 0.26 in. thick, and it broke under a load of 283^ lbs. ; hence its modulus of rupture is 11,490 lbs. per square inch. The deflection, measured at the moment of rupture, was also noted as an index of toughness. " The density of the specimens was determined by finding the spe- cific gravity of each. The degree of softness was found by the weight aliraded by 50 turns of a small grindstone under a constant pressure of 10 lbs. The porosity was determined by finding the percentage of water absorbed in 24 hours, after being dried for the same length of time at a temperature of 135° Fahr. The test for corrodibility was the percentage of loss in weight after immersion for 63 hours in a solution consisting of 98 parts by weight of water, 1 part of hydro- chloric, and 1 part of sulphuric acid. " The color of the slate was a dark bluish gray, or bluish black, and the texture of the surface was slightly scaly and soapy, being less 'Trans. Amer. Soc. Civil Eng., vol. xxvii, 1893. pp. 3.S1-349; vol. xxxii, 1894, pp. 529-539. MARYLAND GEOLOGICAL SURVEY 229 smooth than the jSTorthampton varieties. AVhen ruptured by flexure, the specimens broke square across the grain without splitting or lami- nation. The tests for density, softness, porosity and corrodibility were made on pieces of the ruptured specimens. " The table below gives the results of all the tests for each of the 12 specimens and also the mean values. " An examination of these results tends to confirm the conclusions announced in the previous jiaper that in general the strongest speci- mens are the heaviest and softest, as also the least porous and cor- rodible, although exceptions occur in the case of Q7 and P2, and the Q specimens seem more corrodible than the P's, although greater in strength. The tests for strength and corrodibility are probably those of greatest importance in forming an opinion regarding the value of the slate under actual conditions of service. The test for softness, althoiigh a good one for a single lot of specimens, may not serve to fairly compare lots tested at different times on accoimt of the varying conditions of the grindstone. Mark of 'pecimen. MoUuliiB Of rui"- lure tn Ibti. per sq. in. rilimiile deflection in incties on sun- portsSslns apart. Sped lie Gravity. Grains abraded by 50 turns of small Krindstone. Percent, of water absorbed inv*4 hours. Percent, of welfiiitlost 68 hours In acid solution, Q, 11,.590 0.32 2.886 69 0.265 0.347 Q, 13,.58.5 0.30 2.907 115 0.197 0.197 Q, S,400 0.30 2.900 110 0.304 0.291 Q. i;^,43() 0.32 2.893 177 0.228 0.194 Q. s,:«o 0.28 2.900 75 0. 264 11.237 Qo 12,010 0.32 2.918 67 0.209 0.300 Q, 14,210 2.890 111 0.278 0.341 Q. 13,0I!0 0.34 2.902 t;7 0.261 0.240 P. 10,.520 0.24 2.912 69 0.171 0.150 P, 9,300 0.20 3.88.5 .53 0.143 0.336 P, 10,470 0.34 3.858 87 0.316 0.161 P. 11,2.55 0.26 2.873 80 0.155 .... Means. 11,260 0.293 2.894 0.224 0.226 .... While the preceding methods of testing are readily carried on in the laboratory, they are not easily made under conditions of actual practice on account of the absence of precise weighing apparatus, and the lack of time and skill. It seems desirable that a test for slate should be devised which can be quickly applied by an architect or builder, and be used with confidence. An impact test, made by simply 230 A HISTORY OF THE QUARRYING INDCSTRY" dropping a ball, appeared one likely to yield good results, and accord- ingly a series of experiments has been carried on to determine what can be done in this direction. In connection with these, a series of severe acid tests has been made on the same specimens The pieces of slate used in the impact test were 6 x 7f ins. Each piece was placed with the ends loosely clamped in grooved supports, so that it was approximately in the condition of a beam with fixed ends, the length between edges of supports being about 7|- ins. and the width 6 ins. A wooden ball weighing 15.7 oz. was dropped upon the middle of the slate from a height of 9 ins., and the number of blows required to produce rupture was noted. The number of foot-pounds of work per pound of slate, expended in causing rupture, is a measure of the ultimate resilience of the material or of its capacity to resist shock, and thus is an index, both of its strength and toughness. Five speci- mens of each kind of slate were thus tested, and the table below gives the indi^adual results and means. ... As the resiilt of the investi- SpeciniL'u. Thickness inches. Weight ounces. No. of blows. Foot-pounds of worii per pound of slate. p. 0.36 17.3 9 0.13 p> 0.36 17.3 15 10.39 Ps Q.31 20.4 5.5 31.74 p< 0.38 18.4 53 .33.35 pp. 0.39 20.4 68 39.33 Means 0.3S 18.7 39.8 34.17 Q, 0.36 17.3 11- 7. .54 Q. 0.27 17.8 30 13.35 Qs 0.3'.l 19.3 17 10.39 Q. 0.38 18.3 6 3. 89 QQ, 0.37 17.6 11 7.37 .Means 0.37 IS.O 13.0 8.49 Percentages ofloss of weight. Foot-pounds of worl; per pound ot slate. Spec. After lao hours. After 240 hours. After .%fl hours. Specific gravity. Q, 0.4.5 0.90 1.37 Qa II. +11 0.99 1.33 Mean 0.43 0.94 1.39 8.5 3.90 ■ Ps 0.33 0.81 1.13 P. 0.38 0.9S 1.10 Mean 0.30 0.87 1.11 3.89 MARYLAND GEOLOGICAL SURVEY 231 gations thus far made, it may be concluded tLat the tests for density and softness, although of importance for slates of the same locality, are not good indications of the strength and weathering qualities of those of different regions; that the tests for porosity, corrodibility and flexural strength give good indications of these properties; that the results found for strength and corrodibility when mentally combined give on the whole an excellent idea of the value of the slate; ami that an impact test with a wooden ball shows both strength and tough- ness, while it at the same time indicates the capacity for resistance to corrosion." LTAMSVILLE. At the present time no slate is quarried at Tjamsville, although this locality has been known as a source of slate for nearly, if not quite, a iiundred years. Parrish in his brief history of the slate trade in Ainerica states' that quarries " near Frederick " were opened about 1812. This may be a reference to the small openings at Linganore, but it seems more in harmony with local traditions to infer that the quarries about Ijamsville were in mind. When Tyson prepared his report there were two slate quarries in operation. One was situated just west of the railroad station, beside the tracks, and the other was about a half mile south of the town. They were evidently quite small, for they had not reached the best mateiial. Little work was done during the time of the Civil War, and the more prominent quarry, shown in Plate XXIV, Fig. 2, was permanently abandoned about 1870, when the " pit " commenced to undermine the roadbed of the Baltimore and Ohio Railroad. The smaller opening, lying south of the town, never attained any con- siderable importance, although efforts were made as late as 1892 to bring the product of this quarrs' into the market. The method of working followed was that of the Germans, who mine rather than quarry their slate. A shaft was sunk to a depth of about sixty feet, but the enterprise was not successful. The slates from Ijamsville formerly brought nearly as good prices '.•\nier. Jour, iliniug-, ii, 1S66-T. 232 A HISTOEY OF THE QUAREYING INDUSTRY' as those from Hai-ford county,' but at the present time they are almost imsaleable. This is not due to the poor or unstable character of the stone so much as it is to the relatively poor workmanship displayed in recent years and the popiilar demand for a slate which will ring when tapped with a finger or pencil. Because of the hard and com- pact character of the better siliceous slates from Pennsylvania and the northern states, it has become customary to regard all dull or soft slates as untrustworthy. In many instances this view is correct, but in the case of the Ijamsville slates it is not warranted by the facts. The slates from this locality show microscopically that they are well crystallized, and that they do not owe their softness to a partial change from a shale to a slate, but to an admixture of the relatively stable and soft mineral talc, which is usually wanting in the better known slates. If the stone were unstable the blue-black color would change upon exposure. This it does not do, since roofs on which the slates have been exposed to the atmosphere for fully fifty yeai-s do not indicate any change in color as a result of this exposure. In spite of their permanency in color and their strength the slates have yet to prove themselves a basis for a profitable industry. ' The price per ton for the Harford county slates, as given by Tysou, ranged in 1860 from $12 to $23, whicli would be approximately from $1 to $6.50 per square. The prices for the Ijamsville slates were: " First quality, $5 for 560 lbs., which cover 100 square feet; second quality, $4 for 620 lbs., which cover 100 feet." The quality of the slates furnished was probably about equal to that of the Lehigh slates of to-day. jrARYLAKD GEOLOGICAL SIRVEY 233 THE BUILDl^^G-STONE TJLVDE. Collection of Statistics. Any discussion of the statistics concerning the building-stone in- dustry in Maryland or any other state must be limited to conditions obtaining during the last ten or fifteen years, and even within these limits the figures obtained ai-e far from satisfactory. There is prob- ably no line of statistical work which offers a greater number of dis- couraging features in proportion to the problems involved than that connected with the quaiTying industries. These difficulties arise from several causes. Prior to the inauguration of statistical work by the U. S. Geological Sun-ey there seems to have been no attempt at the uniform collection of annual figures regarding the output of building stone within the limits of tlie United States. The only exceptions to this statement are found in the tables presented in the Eighth, Xinth and Tenth Census Keports made in the yeai-s 18G0, '70 and '80 respectively. Earlier rejxirts of this nature either made no enumera- tion of the industry based on actually gathered statistics, or their classification is such as to render comparison with later data of little value. The work of the U. S. (Jeological Survey in the collection of sta- tistics has been noteworthy, and a marked increase in the amount of information concerning the building-stone industry is evident from year to year. The fii-st repoi-tri of this organization were based upon the Tenth Census, atid it was not until the yeai- ISSi that any con- siderable amount of material was collected concerning the granite industiy of the different states. At the beginning of their work the agents of the Federal Survey met with many discouragements which have been encountered anew in the prosecution of the present work. The greatest source of dtday and lack of details arises from the atti- tude of the quarrj'men themselves, who disregard written communi- cations and even refuse to impart information to membere of the Sur\'ey. The grounds for this attitude among the quarry-men arc 234 A HISTOKY OF THE QUARRYING INDUSTRY due to various reasons. Sometimes no record lias been kept of the amount of the product which has been shipped, and in other instances the record preserved is in such shape that little of a statistical nature can be gathered. Among those operators who preserve a careful record of their output, expenses and wage list, there are many who refuse to give information because they have been so annoyed by the importunities of unauthorized gatherers of statistics, who make un- warranted requests on the time and information of the quarrymen, that they fail to make a discrimination between demands which are legitimate and those beyond all reasonable bounds. Many of the trade journals and similar organs have gathered statistics from year to year and published them in such a way that trouble has arisen between the employers and the employees, until the operators are almost afraid to give even the most commonplace information. Other statistics gathered from various soiirces have been utilized by the tax collectors and other petty officials as a basis for exorbitant demands, imtil the quarrymen feel that information may be used against them in almost any conceivable way. Before satisfactory statistics can be gathered concerning the various phases of the quarrying and marketing of stone, it will be necessary to overcome all of these misunderstandings and prejudicial notions held by the quarrymen. Annual Production in Maryland. Considering all of the available sources of information, of which the most trustworthy are the reports of the U. S. Geological Survey, it has been possible to construct the following table which approxi- mately represents the annual output of the quarries within the state during the years 1860 to 1897 inclusive. A study of these columns gives only an inadequate conception con- cerning the fluctuations of trade which have occurred during the last half century. So much depends upon the conditions under which the statistics were gathered and the minimum limit of output recorded that it is of little use to make a detailed study of the individual indiis- tries. There are, however, a few facts concerning the statistics obtained in different years as recorded by the various statistical bureaus which are of interest. MARYLAND GEOLOGICAL SURVEY 235 VAI.IE l)F ANNUAL I'UODL CTION IN MARVLANI). Gkanite. Sandstone. Si.ate. Mahiu.e. Limestone. Total. LS60 40, 900 20,000 30,000 324,030 1870 8^,229 80,8.53 275,000 234,199 1S80 224,000 .50,700 05,929 1881 1S82 1883 1884 4.5,000 iss.-, 65,250 ISSG 54,000 1887 90,000 10(1.110(1 429,(1(10 1888 2(;:!,9.52 [1.5, 000 1 85,500 175,000 [175,000] 1 8sil 447,489 10,60.5 110,008 119,675 164,800 872,778 1890 447,489 10,00.5 110,008 139,810 1G4,.800 872,778 1801 4r.0,000 10,000 12,5,425 100,000 1.50,000 83.5,425 1892 4;>0,0(I0 ,5,000 116,.500 105,000 200,000 807,-500 1893 2r.o,s.i.T 300 37,884 130,000 1894 308,9Cili 3,450 153,068 175,000 350,000 990,484 189.5 370, 020 10,830 00,357 145,000 20(»,000 608,214 1S9G1 2.51,108 10,713 72,142 11((,000 204,278 708,241 1897 188,33.5 [10,000] .53,939 100,000 249,809 608,083 Granite. — Since the war the granite industry has shown a slight bnt steady increase in the amount of its output, which is not fully brought out by the increasing values of the annual product. The reason for sucli nn increase in volume seems to lie in the growing demand for granite in all sorts of structures and in the slight cheap- ening in the cost of extraction and dressing. These conditions are accentuated by the gradual change in public taste respecting the use of triuiiiiiiig stones, which demands gray sandstones and granites in place of the broAvnstones. The latter now hold a far less important position ill the market than in the years inmicdiatcly succeeding the Civil War. During these years there has also developed a consider- able trade in paving stones and road iiidals which has allowed the utilization of the angular blocks and waste of the quarries, thereby decreasing largely the ex[)ensc of operation. The trade seems to be moderately uniform and somewhat similar to the oscillations in the general demand, as, for examjile, in June, 1893, there was a marked falling off ill tbc output, the only shi])iii('iits being in fulfilluiciit of ' See note p. 241. 236 A HISTORY OF THE QUARRYING INDUSTRY I orders alreach^ presented. The trade recovered temporarily in 1894, but has since then been in even a more discouraging condition than at any time during the last decade. Sandstone. — The sandstone industry is the most variable among all of the quarrying industries carried on in the state. During the years 1875 to 1884, no work was carried on at the Seneca. This stagnation in business was due to the strong reaction against brown- stone and other sandstones which swept over the country about 15 or 20 years ago. During the years 1888 to 1891 there was consider- able activity, but the sandstone industry felt the general depression of '93 so strongly that the reports indicate almost no output. Later, as tlie companies became active, the product increased somewhat and is at the present time about normal. In fact, there seems to be a slightly grcwing demand for high grade brownstone which may in time supersede the lighter colored stone as trimming. Marble.- — The marble industry has been almost constant through- out the last ten years, showing only slight relative changes in the value of the product, which averages about $140,000 annually. This is the only industry which did not seem to feel the depression of '93, a fact which is due no doubt to the uniform product and uniform demand for the Cockeysville marble, A\'hich furnishes most of the material within the state. Some of the fluctuations between the different years may be accounted for by the oscillations in the serpentine output, since this is included among the marbles. Slate. — The nearest complete details concerning the actual output of the quarries are available respecting the slates. This no doubt arises from the peculiar nature of the manufacture and the high skill and intelligence required in the preparation of slate stock for the market. Unlike that of the other bviilding stones, the manufacture of slate requires a special skill which is usually acquired by practice from childhood. This fact influences greatly the product of the vari- ous quarries, for it is regarded by the operator as more disastrous to discontinue operations than to be left with a surplus of stock. The labor, because of its peculiar skill, cannot be replaced at will, and the quarrymen throAvn out of their customary employment are unfitted to MARYLAND GEOLOGICAL SURVEY 237 enijage in othrr linos of indnstrv. This method of procedure requires an increased capital, which in turn has rendered the profits much less during periods of depression,' since there is no compensating reduction in the wages of the quarrvmen. Prices, Wages, ktc. 'Die facts which have heen gathered from personal conversation witli (luarivuicn and contractoi"s over the entire state are so at vari- ance with one another, especially concerning the price, that it has heen impossible to obtain any mean values which satisfactorily repre- sent the average price per foot for the different products throughout the state. AVith the exception of the highest grade work, and the product of one or two of the larger operators, there is no systematic regularity in the price charged for products of the same kind and quality, the prices even var\-ing 20 to 40 per cent on opposite sides of a hill connected by a deeply cut valley which eliminates variations due to differences in the price of hauling. The same fact is true concerning the gneisses quarried about the city of Baltimore, where the figures given for different quarries show a variation in the price of random rubble, for example, of fully l.')0 to 200 per cent. The prices for the different products are given in subjoined tables, from which it u)ay be seen that the same material when sold by different standards is really sold at quite different prices, as, for example, when rul)ble-gneiss is sold at the rate of $2 a cubic yard ($1.38 per jwreh), $1 per long ton ($.74 per perch) and $1 per perch. The figures gathered likewise do not show a uniform difference in price between the labor and the product in the counties and those in the vicinity of Baltimore, although the price is usually lower in the country districts for both, except among the skilled laborers belonging to unions which regulate the wages. Even here at times tliere seems to be an unfair- ness toward the city artisan, since he is compelled to pay somewhat more for living expenses than his competitor outside nf urban in- fluences. The actual information in these tables is limited by the confidential nature of the facts given and the unwillingness in certain instances to impart any sort of statistics because of previous breaches in con- 238 A HISTORY OF THE QUAKKYING INDUSTRY fiflenee by unofficial agencies. The wages are generally fixed l)y the unions to which most of the skilled workmen belong. Considerinc: the capital invested, the wear of machinery and the valnc of the stone in the ledge, the margin between the cost of extraction and the price of the finished product is not excessive. GRANITE AND <4XEISS. Undressed Stone. Cost Wages. Prices at Quarry. Per foot. Koyaltyper DreSS- S- L- Per Per Per Per " '""'•• percli. perch. vd. cu. Ir. ton M I «(i. Rubble $3..50 $1.00 ... .«l.on 1.80 Flagging W . . 35 . . Curbing ... .30 . , Paving ... .2.5 ., .30 Belgian blocks $10 peril Dimension .60-1.3.5 Monumental .70-1.35 Rubble 05 3.00 1.00 .80 3.00 1.35 1.50 Flagging .3] 28 56 Curbing 6-10 35 60 Coiling S 45 3.00 Dimension .... 3.50 1.50 Pointed .... 3.00 1.35 65 . 75 . Ax bammered 13-15 65 . 1,50 . Bush liammered 33-33 1.03 . Belgian bloeks .^lOper M 1.80 30 $i, 5 TRIASSIC SANDSTONE. Cost of Undressed Stone. IVages. Cu. ft. Royalty per percli. Rubble 00— $1.50 .35 $3.50 $1.35 .3.00 1.35 -MAKYLAXD GEOLOGICAL SVKVEV ^JJU PALEOZOIC SANDSTONE. Cost hf Lndhkssed Stone. Waues. ^ . I.. Rubble .$1.00— .$3.00 per cu. yd. .$l.:i.T— .$1.4.-> *l.w'.5 Flaggiug 1.4.5 per sq. yd .... Macadam .70 per percli .... Tlie wages in Alli'nanv and Garrett counties are lower than in IMontgomery and Frederick since the industry in the latter localities is more firmly established and the product of a higher grade. 'J'lie variations in price for the same material according to the units of measurement are noticeable in the sandstone reports, but they are not so extreme as in the gneiss and granites. All of the product of the Peach Bottom area is used for roofing slates, since the grain of the rock is rather against its being used for milling purposes. Thus the above prices represent the figures for almost the entire output of the region. The slate trade maintains the price of stock more uniformly than almost any other of the stone quarrying industries, for the prices obtained to-day are nearly tlu; same as those obtained seventy-five or eighty years ago. The method of reckoning has changed from weight to area of roof, and the " lap " of the upper courses of the latter has during the years increased from two to three inches in the higher grade materials. The manner of estimating the number of pieces per square is based on the practice in laying slates. The slates are laid so that the first course is over- lain by the second course and by two or three inches of the third. The overlapping of the first third coui'ses is known as the " lap," and it is not unusual for the roofer to buy his stock with a " three-inch lap " and lay it with only a " two-inch lap," thereby saving for him- self a small margin which does not appear to the consumer. More- over, the workmanship and uniformity in the product has greatly improved so that, although the apparent price remains the same, there has been a steady improvement in the material furnished to the consumei'. The following list of prices does not repi'esent anj' except the standard thickness of three-sixteenilis inches. That is, the stock runs about four pieces to the inch " in ilic rick."' When the speci- 240 A HISTOEY OF THE QUAEEYING INDUSTEY Mu. & Pa. Slates. SLATES. Pa. Slates. Maine Slates. Vermont Slates. 9x7 686 3.. 50 3.. 50 lOx.5 833 3.05 3.35 10x6 686 3. .50 3.. 50 7.00 lOxT 596 3. .50 3. .50 7.00 10x8 514 3.50 3. .50 4.00 3.00 7.00 11x5 730 3.35 3.50 11x6 600 3.65 3.75 11x7 514 3.65 3.75 11x8 450 3.65 3.75 4. .50 3.. 50 13x6 534 4.50 4.75 3.30 3.10 3. .55 4.80 3.80 4.00 9.00 13x7 458 4.60 4.75 3.35 3.20 3. .55 .5.00 4.00 4.00 9. .50 13x8 400 4.60 4.75 3.35 3.25 3.55 .5. .50 4. .50 4.00 9. .50 12x9 356 4.60 4.75 5.60 4.60 4.00 9.50 12x10 330 4.60 4.75 .5.80 4.80 4.00 14x7 374 4.85 5.35 3. .50 3.40 3.95 6.40 5.40 4. .50 11. 3.60 UxS 338 4.85 5.25 3.75 O.40 3.95 6.60 5. .50 4. .50 11. 3.60 14x9 391 4.85 .5.25 3.75 6. .50 5.. 50 4. 25 11. 3.60 14x10 362 5.00 .5.25 6.60 .5.60 4.25 11. 3.60 14x13 219 6.50 .5. .50 14x14 187 7.00 6.00 16x8 377 .5.10 5.(iO 4.40 3.75 4.25 3.00 7.30 6.30 4. .50 11. 4.00 16x9 247 5.10 5.60 4.40 3.75 4.35 7.00 6.00 4. .50 11. 4.00 16x10 233 .5.00 .5.50 4.40 3.75 4.25 7.10 6.10 4.50 11. 4.00 16x11 302 .5.00 5.50 6.90 .5.90 4.35 16x13 ISO 6.80 .5.80 4.00 16x16 1 39 7.00 6.00 18x9 314 .5.10 5.60 4.30 3.75 4.25 3.00 7.10 6.10 4. .50 11. 4.00 18x10 192 5.10 5.60 4.30 3.75 4.35 7.30 6.20 4.50 11. 4.00 18x11 175 .5.00 .5, .50 7.00 6.00 4.25 18x13 160 5.00 .5. 50 6.80 5.80 4.00 3.60 18x14 137 6. .50 .5. .50 30x10 170 .5.10 5.60 4.30 3.75 4.25 3.00 6.80 .5.80 4. 50 11. 4.00 20x11 1.54 .5.00 .5. .50 4.30 0.80 5.80 4.35 30x13 143 .5.00 5.50 4.30 3.. 50 4.25 fi.90 .5.90 4.35 3.60 20x13 130 5.00 5.50 20x14 131 4.00 22x11 138 5.00 5.. 50 4.00 3.35 3.80 3.00 6.50 .5. .50 4.35 3.60 22x12 137 5.50 4.00 3.35 3.80 6.60 5.60 4.00 3.60 22x13 116 5. .50 32x14 108 .5.50 4.00 34x13 115 .5.00 .5.50 3.80 3.25 3.50 3.00 (;.60 .5.60 4.00 3.60 34x13 105 4.85 .5.35 3.80 34x14 98 4.85 .5.35 3.80 3.45 6.10 5.10 4.00 3.60 24x15 91 4.75 .5.15 34x16 85 4.75 5.15 MAEYLAND GEOLOGICAL SURVEY L'41 tications call for one-quarter inch stock, sawed edges, polished sur- faces or boring and countersinking, the price increases somewhat per square according to the character of the work required. The Peach Bottom slates do not need to be drilled and countersunk as much as some of the more brittle slates from the northern states, since when punched, the hammer goes through, making a clean hole without any injurious flaking or spalling on the underside. The figures in the foregoing table show that there has been a de- crease in the prices obtained for the Maryland slates since 1895, and that the material from the New England quarries demand higher prices than that for Maryland, while the prices of the Virginia and Lehigh slates are lower. Note. — The figures indicating- tlie annual i)i-oduot for IH'.m are tliose pub- lished by the U. S. Geolog-ical Sui-veJ-. .\lthough tliey are different from the results obtained in the exhaustive investigations carried on by the State Geological Survey, they are more valuable for a comparative .study, since the conditions governing their collection and tabulation are more in accord with those existing in previous years. 16 itFe 06 MARYLAND GEOLOGICAL SURVEY/ WM. BULLOCK CLARK, St*te GeoiO(.ist. THE BUILDING AND DECORATIVE STONES OF MARYLAND Containingf an Account of their Properties and Distribution* BY GEORGE P. MERRILL AND EDWARD B. MATHEWS. (Special Publication, Volume II. Part H.) THE JOHNS HOPKINS PRESS. Baltimore, October, I89S. .^' ''^^' G^^ .^ -rr,. S^ -^c^. -S- c"' o. xS^'" .N*"^