History of Montgomery County, Pennsylvania, Part 6

Author: Bean, Theodore Weber, 1833-1891, [from old catalog] ed; Buck, William J. (William Joseph), 1825-1901
Publication date: 1884
Publisher: Philadelphia, Everts & Peck
Number of Pages: 1534

USA > Pennsylvania > Montgomery County > History of Montgomery County, Pennsylvania > Part 6

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At Gwynedd, in Montgomery County, in the same formation, is found a bed of carbonaceous shale col- ored black by traces of coal which it contains, and it is also said to contain vegetable remains. Col. Bean mentions a vein of coal found in Lower Provins dence township, Montgomery Co., about one-half of a mile west of the Trooper. This vein, like the others, was found in the new red sandstone; it was from two to three inches in thickness and from eigh- teen to twenty inches in length. During the summer of 1883 hands working upon the new tunnel near Phoenixville discovered a two-inch vein of coal in the sandstone. These triassic coals yield volatile mat- ters, which burn with a non-luminous flame, but they have not the slightest tendency to form a coherent coke. They contain sometimes as high as seventy- four per cent. of fixed carbon, eighteen per cent. of volatile matter, and about two per cent. of ash.

Lignite .- Lignite, or brown coal, as it is sometimes called, has not been perfectly formed ; the lamellar or woody structure can be seen distinctly. In composi- tion it is more like wood than true coal. It yields a powdery coke in the form of the original lumps. It is brittle, burns easily, and often contains from thirty to forty per cent. of water. It is of recent geological origin, and was evidently not formed like true coal. Dr. Leidy mentions it as being found on Plymouth Creek near Norristown.

Fossils and Organic Remains .- Fossils are found in stratified rocks, such as sandstones, limestones, and slates. These rocks were evidently in a soft state at one time, like the sand, mud, and gravel which form many of our river-beds, and they were also covered with water. Corals, crinoids, shells, and other organ- isms lived in these seas, and when they died their re- mains became imbedded in the soft mud and sand which formed the bottom of these seas and oceans. In the course of time, under the influence of press-

HISTORY OF MONTGOMERY COUNTY.

ure and other forces, the mud and sand were con- verted into stratified rocks, and it is in these rocks, which have at one time been ancient ocean-beds, that we find fossils. The highest mountains have been at one time the ocean's bottom, for even their peaks con- tain fossils. On the Himalayas at the height of nearly three miles organic remains are found.

In Montgomery County there are very extensive de- posits of igneous rocks, such as granites, gneisses, mica-schists, and syenites, and iu rocks of this nature fossils are not found, because they are igneous rocks ; and their structure shows that they have at one time been subjected to an intense heat, and it may be they were in a molten state, so that any traces of organic life that might have existed would be destroyed. The red shale and sandstone formations are the only strata in which organic remains are found in this county. This rock covers the upper and middle portions of the county, and although but few fossils have been found, yet these remains are very interesting and in- structive. The reptilian relies found in Montgomery County are the teeth and bones of large lizard-like animals which lived in the ancient seas. These re- mains have been found at the Phoenixville tunnel, Montgomery County. Specimens of coprolite have also been found imbedded in the same rock. The vertebral bones of these large lizard-like reptiles are slightly concave, or hollowed out, at their articulating surfaces. Mr. Lea has named this reptile the Clep- sisaurus Pennsylvanicus.

Remains of fishes have been found in this tunnel which belong to the order known as ganoids. These are fishes which have a cartilaginous skeleton, and are covered with enameled scales or with bony plates. The sturgeons and gar-pikes are living representa- tives of this order. Batrachian remains, such as bones and teeth, are found in this locality. But few fossil plants have been found in the new red sand- stone in this county. Specimens of coniferous wood, either petrified or having the nature of coal, and still retaining the woody structure, have been found. This is termed lignite, and is mentioned by Dr. Leidy as being found on Plymouth Creek near Norristown. When the small coal vein was found at Norristown, on Elm Street, near the Stony Creek Railroad, I secured a piece of sandstone from the bottom of the vein, which bore the imprint of a fossil plant. Near Gwynedd is found a bed of carbonaceous shale which is said to contain vegetable remains. The oldest fossil yet discovered in Pennsylvania is the Scolithus linearis. This fossil is found in the Potsdam sand- stone at Edge Hill, and in the vicinity of Willow Grove and Rubicam Station. "It consists of a straight, cylindrical, stem-like impression in the sandstone, usually smooth, but sometimes grooved transversely to its axis. Its diameter varies from one-eighth to a half au inch, and its length from a few inches to two or three feet. Its position in the rock is perpendicular to the bedding, and from this

fact many think that the impression was produced by the boring of a marine worm. The end of the fossil terminates in a head, which is always found at the upper surface of the sandstone enclosing it. The im- pression looks like a large pin. These fossils are very abundant in the Potsdam sandstone in Mont- gomery County."

BONE CAVE OF PORT KENNEDY .- The following account of the cave is taken from the American Journal of Science and Arts, vol. i. 1871, p. 235:

MESOZOIC RED SHALE.

20 FT

LIME STONE

40 FEET

43 FT.

LIMESTONE

ללתי

LIMITY

IOFT

" Before the discovery of remains in the Port Ken- nedy Cave nearly the whole of the walls had been removed in quarrying. A tooth of a mastodon hav- ing been found by one of the workmen, Dr. Quick, of Phoenixville, showed it to Mr. Charles Wheatley, and these two gentlemen immediately visited the cave and commenced the search for remains. They found one end of the cave still remaining, and having the form in transverse section shown by the figure. The width at the top is about twenty feet ; below it grad- ually expands to thirty feet, and then there is a rapid contraction downward until, at a depth of about forty feet, it is ten feet wide. The whole of the space above this level is filled with the débris of the ad- joining mesozoic red shale, with occasional angular fragments of auroral limestone, without any trace of organic remains. Where the cave narrows to ten feet the floor is composed entirely of a black clay eighteen inches thick, filled with leaves, stems, and seed-vessels of post-tertiary plants. Scattered all through this mass of vegetable remains, and also in a red tough clay underneath for six to eight inches in depthi, are found the fossils. The vertebrate remains are as follows ( taken from the proceedings of the Amer- ican Philosophical Society for April 7, 1871, where Professor Cope describes the remains so far identified) : " Mammalia .- Megalonyx lorodon, Cope ; M. Wheat- leyi, C .; M. dissimilis, Leidy ; M. sphenodon, C .; M.

ORES, MINERALS, AND GEOLOGY.

tortulus, C .; Mylodon (?) Harlani, Owen ; Sciurus caly- cinus, C .; Jaculus (?) Hudsonius, Zimm .; Hcsperomys, Waterhouse; Arvicola speothen, C .; A. tetradelta, C .; A. didelta, C .; A. involuta, C .; A. sigmoides, C .; A. hiatidens, C .; Erethizon cloacinum, C .; Lepus sylvat- icus, Bachm .; Praotherium palatinum, C .; Scalops ; Verpertilio (?) ; Mastodon Americanus, Cuv .; Tupirus Americanus, Auct .; T. Haysii, Leidy ; Equus ; Bos; Ursus pristinus, Leidy ; Canis (?) ; Felis.

" Aves .- Meleagris ; Scolopax.

" Reptilia .- Crotalus (?); Coluber (?); Tropidonotus (?) ; Cistudo (?) ; Emys (?).

" Batrachia,-Rana (?).

"Dr. Horn has examined the insects, and gives a preliminary list of the coleoptera, as follows (orthop- tera were also found) :

"Curabidc .- Cychrus Wheatleyi ; C. minor ; Cymindis aurora ; Chlænius punctatissimus ; Plerostichus leviga- tus ; Pt. longipennis ; Dicclus alutaceus.

" Scarabæide .- Aphodius scutellaris ; A. micans ; Pha- nœus antiquus ; Copris punctulatus.

" Ilisteridre .- Saprimis (?) ebeninus.

"The remains of mylodon, ursus, and tapirus have been mostly obtained from the tough red clay di- rectly under the plant-bed, but the remains of rodents, snakes, tortoises, birds, plants, and insects are mostly confined to the plant-bed."

Minerals .- Minerals and fossils seldom ocenr to- gether, becanse many minerals are the result of fusion which would burn out any traces of organic remains, 1

hut occasionally remains of plants are preserved in rocks which contain minerals ; for example, mica-schist sometimes contains a mineral called macle and the fos- sils orthis and spiriferes, but in this case the mica-schist is not an ancient igneous rock, but is of sedimentary origin, and has been formed of rocks of recent origin which contain fossils. Many minerals in nature have crystallized out of water which held them in solu- tion at a high temperature. Of recent years science has so imitated nature that many minerals are made artificially by fusion, and by the action of water at a high temperature. Marble has been made from limestone experimentally. A Frenchman, operating with the aid of water at a temperature of from one hundred and thirty to three hundred degrees centi- grade, succeeded in producing in a crystallized state the principal minerals found in metallic veins, among others quartz, spathic iron, carbonates of manganese and zinc, heavy spar, sulphide of antimony, mispickel, and red silver. He also produced some of the copper minerals found at Shannonville in the same way. Facts like these show how nature has formed these metallic veins. In France, during the last century, nearly all the mineral species have been reproduced artificially by various methods. When fusion was resorted to the apparatus was simple, consisting of a furnace, heated by a blow-pipe, supplied with illu- minating gas, and driven by a blast. The substances to be fused were put in platinum crucibles encased

in fire-clay. Not only were minerals formed, but also lavas and trap-rocks. All attempts to make rocks containing quartz, feldspar, and mica, or hornblende (such as granite and syenite), by fusion, proved un- successful.

Montgomery County contains a variety of minerals. But few specimens are found in the new red sandstone, except in the localities where metallic veins of copper are found. Here we not only find copper minerals but ores of zinc and lead. The copper-mines near Shannonville have yielded many mineral species, such as copper, mispickel, iron pyrites, covellite, cuprite, melaconite, hematite, quartz, chrysocolla, brennnerite, libethenite, malachite, copper pyrites, azurite, wulfenite, galenite, zincblende, calamine, pyromorphite, anglesite, cerussite. These species were found when the mines were in operation, and even at the present time many of them can be secured. At the copper-mine in Upper Salford township native copper and several copper minerals are found. At Henderson's marble-quarry, near Bridgeport, graphite and crystals of dolomite which are finely striated are found, and occasionally small pieces of malachite. At Conshohocken, quartz, flint, chalcedony, chlori- toid, and cacoxenite are found ; at Bullock's quarry, fibrolite, calcite, and occasionally a small seam of iron pyrites are found. At O'Brien's quarry beautiful crystals of calcite, sometimes nearly transparent, are found. At the iron-ore mines near Conshohocken the hematite is sometimes coated with a manganese mineral called pyrolusite. Edge Hill furnishes speci- mens of hematite, braunite, pyrolusite, turgite, and gothite. The soapstone-quarries at Lafayette have yielded many mineral species. The following copper minerals have been found there, bornite and chalcopy- rite. Iron minerals found there are magnetite, pyrrho- tite, and titanium iron ore. The silicates found there are asbestos, hornblende, garnet, zoisite, albite, talc, serpentine, staurolite, jefferisite, enstatite. The sul- phates found there are epsomite and calcanthite. Phosphate of lime (apatite) and carbonate of lime and magnesia (dolomite) are found.

On the other side of the river, at the abandoned soapstone-quarry, talc, asbestos, and very fine octa- hedral crystals of magnetite are found. At Hitner's marble-quarry calcite, strontianite, dolomite, heavy spar, and iron pyrites are found.

Quartz .- Quartz is known under the names of silica, silex, sand, silicic acid, flint, etc. It crystal- lizes in the hexagonal system, mostly in the form of hexagonal prisms, terminated with hexagonal pyra- mids. It is one of the hardest of minerals, the point of a knife-blade or edge of a file making no im- pression on it. The highest heat of a furnace will not melt it; the common acids have no action on it. It readily scratches glass. Its hardness is 7. Quartz occurs of various colors, -white, brown, yellow, blue, gray, green, black, violet, and often color- less. These colors are generally due to some mineral

HISTORY OF MONTGOMERY COUNTY.

oxide which the quartz has taken up. The lustre is vitreous, the fracture is conchoidal and uneven. The composition of quartz when pure is silicic acid = Sio.2. The mineral quartz occurs in many varieties. Rock crystal, smoky quartz, milky quartz, aventurine quartz, ferruginous quartz, and amethyst are the crystallized varieties. Chalcedony, carnelian, prase, agate, flint, hornstone, jasper, and opal are the varieties of quartz which do not exhibit a crystalline structure. The colorless variety known as rock crys- tal is found in many localities. I have noticed very fine crystals on Eastburn's Hill, Bridgeport. They have been found in abundance here, but the best specimens have been secured. Very large crystals, having a pyramid on each end, have been found at King of Prussia, and from this place to the Schuyl- kill River very fine crystals are found. I have no- ticed a peculiar variety of quartz crystals in Shain- line's marble-quarry, near Bridgeport. The crystals are three-quarters of an inch long, and taper from the base to the apex of the crystal. Quartz crystals are found in the limestone-quarries near by. Aventurine quartz has been found in Conshohocken. Ferruginous quartz, colored brown, red, or yellow by oxide of iron, I have noticed in the vicinity of Bridgeport. Chal- cedony has often been found as a coating ou other rocks near Conshohocken and Bridgeport. The arrow- heads found in many localities are generally com- posed of jasper. There is a valuable deposit of sand near Valley Forge, which is used as a lining or covering for the bottom of the heating-furnaces in the pipe- mill, Reading, Pa. Most linings would not stand the heat of these furnaces, but this sand is infusible. was requested to examine it, and found on analysis that it is composed of fine grains of very pure quartz, free from iron, and not a trace of feldspar or any mate- rial that would flux with it was found.

Quartz is one of the most abundant minerals in nature, and the most common constituent of rocks. The granites and gneisses, which are composed of quartz, feldspar, and mica, often contain as high as forty per cent. of quartz. The mica-schists, garnetifer- ous schists, syenites, and granitic rocks, which com- prise the southern end of Montgomery County, from Philadelphia to the limestone belt, are made up to a great extent of quartz. Mica-schist contains from forty to seventy per cent. of quartz, and sometimes a still higher percentage of quartz is found in certain varieties; the other constituent is mica. The large belt of new red sandstone which is found north of the Montgomery County line stone belt, extending from the Delaware River as far westward as Valley Forge, is made up almost entirely of quartz colored red by oxide of iron. While existing in rocks abun- dantly as quartz, it also makes, on an average, a third of many other minerals; that is, it is chemically com- bined with other substances making various common minerals. These minerals are known as silicates. Of recent years quartz has a new use in the arts :

when fonnd pure and white and free from impurities it is mined and made into sand-paper, and is used as a polisher of metals softer than steel. It has been mined at Bridgeport and Valley Forge for this pur- pose. The purest rock crystals are made into lenses. Amethysts of fine quality are used in jewelry.

Building Stones of the County .- The best and most desirable building stones are those which are compact and yet can be readily cut into any desired shape. The stone must not be soluble in water, or must not be acted on or altered by the impurities which are found in the atmosphere. Building stones which meet the above requirements are exceedingly lasting. The most durable building stones now employed are granite, gneiss, basalt, porphyry, ser- pentine and compact sandstones. All of these rocks are highly silicious, and but little acted on by the weather. The hardness of the first four of these rocks is so great that it is difficult to dress them, but even this obstacle does not prevent their general use. Besides the silicious building stones we have the calcareous stones, which are carbonate of lime principally. The different colored varieties of marble and limestone come under this class; they are much softer than the silicious stones. Of late years grauite is much used, especially for public buildings ; the Masonic Temple and the new post-office building at Philadelphia are built of a variety of granite. The granites have been employed for too short a time as a building stone to measure approximately its rate of weathering. The feldspar in granite begins to weather first, while the quartz and mica are not so readily at- tacked. It has been found that a polished surface of granite will weather more rapidly than a rough one, but the decay of a polished granite surface is not ap- parent after exposure for twenty years or more; there is no doubt but that the polish will finally dis- appear and the surface roughen when the weather begins to act on the crystals of feldspar. The pol- ished columns and surfaces of granite, syenite, etc., in the new Public Buildings at Philadelphia will fur- nish points of observation for the future study of the weathering qualities of these stones.

We have extensive beds of syenite and granitic rocks in Montgomery County, which have been little used as yet for building stones. They are very hard and compact, and are not the fine-grade building stone. The new red sandstone, which covers the greater portion of Montgomery County, is much used as a building stone, and nearly all the stone houses in the upper portion of the county are built of this rock. The finest silicious sandstones are more durable than granite. The best varieties are those which are nearly a pure, fine, silicious sand, as free as possible from iron or lime. Sandstones are composed of grains of sand, which are bound together by a cement. This cement, or matrix, may be clay, lime, oxide of iron, feldspar, or even gelatinous silica. The grains of sand in sandstone are not affected by weathering, but

ORES, MINERALS, AND GEOLOGY.

it is the weathering of the cement which binds the grains that causes sandstones to crumble. If the cement be at all soluble in water then the weather- ing commences. When a sandstone is composed of thin layers or planes of stratification, then it is very apt to split up along these planes under the action of the weather. This fact is well known to builders, who are always careful to lay the stone on its bed. The Potsdam sandstone, which is found in Moreland, Upper Dublin, Springfield, White Marsh, and Plym- outh townships, is a fine-grained white or gray sand- stone, with scales of a light-colored mica. It occurs in narrow belts, and is composed of thin layers as mentioned above. This fact unfits it for a good build- ing stone, and it is used but very little. It is the new red sandstone which is in such general use as a building stone in this county, particularly in the country. Quarries of this stone are worked in nearly every township in the northern aud central portions of the county. In some localities the stoue is white, and makes a beautiful building stone. This white stone is extensively quarried on Main Street, near the eastern limits of Norristown. The red and the white sandstones are found in these quarries; the lower strata are white and the upper red, with an occasional layer of red shale. The white contains a pink feldspar and scales of a pearly mica, and is free from iron. This stone makes a very handsome building stone, and is much used. Although it con- tains the constituents of granite, it is not granite, but sandstone with a matrix of feldspar. Stoue of the same nature is found in Bridgeport. In the northern part of Upper Dublin township there is a sandstone containing a feldspar, which weathers rap- idly and soon disintegrates. One of the best stones for bridge-building and foundations and heavy ma- sonry of all kinds is extensively quarried at Consho- hocken, on both sides of the river. The West Con- shohocken quarries were worked sixteen years ago, and now they daily average over one hundred tons of rock for shipment. The rock is blasted out in huge pieces, which are cut by steaul drills, and after- wards dressed. The shipment of stone from this quarry on Sept. 6, 1883, was one hundred and seventy- seven tons. Boyd, Stintson & O'Brien's quarry, in East Conshohocken, yields the same kind of stone, and is a continuation of the strata. This rock is a tougli quartzose mica-schist, composed of quartz and mica mostly, and extends from the county line, in the southern portion of Upper Merion township, across the Schuylkill in a narrow belt and extends into White Marsh township. The handsome new railroad bridge across the Wissahickon was built of this Con- shohocken stone. The blasting at these quarries is done by dynamite.

The most important building stone Montgomery County furnishes is marble. The many valuable marble-quarries in the county are described under limestone in the geology. Hitner's, Potts', Hender-

son's, and Derr's marble-quarries are the principal ones in the county, and they furnish not only the county with marble but also Philadelphia. Nearly all the marble used in Philadelphia, with the excep- tion of the imported, is brought from these quarries. It is used principally in building. The handsome county court-house at Norristown is built of Mont- gomery County marble, and many handsome private residences are built of like marble. Notwithstanding the general use of marble as a building stone, it is more acted ou by the weather than any stone in general use in large cities. When marble is used for building pur- poses it has, at first, a fine polished surface ; exposure of two years in a large city suffices to remove this polish, and to give the surface a rough granular char- acter. The grains which have been bruised in pol- ishing are first attacked, and soon drop out of the stone. If the marble be not cared for it soon be- comes covered with a dirty crust, beneath which the stone seems to be a mass of loose, crumbling calcite granules. When this crust is broken the decay is rapid. The crust varies from the thickness of writ- ing paper to a millimetre, and is of a dirty gray or brownish-black color. When examined under the microscope it is found to consist of particles of coal and soot, grains of quartz sand, fragments of red brick or tile, and organic fibres, which are held to- gether by an amorphous cement of sulphate of lime. This decay and disintegration of marble in large cities is due to several causes. The most active de- stroyer is rain-water containing carbonic acid gas, which dissolves marble. Rain-water always con- tains carbonic acid, and in large cities, where com- bustion produces an extra amount of this gas, rain-water will have an extra amount in solution. When rain falls on marble it begins to dissolve very slowly, and the grains of marble lose their cohe- sion. Marble exposed to rain always weathers more rapidly than marble that is sheltered. Another very active destroying agent is the sulphuric acid that is always present in the air of cities where much coal is burned. All coal contains sulphur, mostly in the form of iron pyrites, and when it is burnt it is con- verted finally on oxidation into sulphuric acid. This acid is extremely corrosive. Sulphuric acid is present in the air in a considerable quantity in large cities, where thousands of chimneys and furnaces send forth their smoke. It acts ou marble by dissolving it and forming sulphate of lime, which is the cement which binds the dirty outer crust together. Marble in the country, free from this destroyer, lasts much longer. The marble columns of the Philadelphia Mint had become so corroded and rotten that they were recently replaced by granite columns. The marble columns of the Custom-House show plainly the action of the weather. It is very evident that white marble in large cities is utterly unsnited for out-of-door use, and its employment for works of art which are meant to stand in the open air ought to be strenuously re-

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History of Montgomery County, Pennsylvania, Part 6

Author: Bean, Theodore Weber, 1833-1891, [from old catalog] ed; Buck, William J. (William Joseph), 1825-1901 Publication date: 1884 Publisher: Philadelphia, Everts & Peck Number of Pages: 1534

Author: Bean, Theodore Weber, 1833-1891, [from old catalog] ed; Buck, William J. (William Joseph), 1825-1901
Publication date: 1884
Publisher: Philadelphia, Everts & Peck
Number of Pages: 1534