History of Montgomery County, Pennsylvania, Part 7

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 7

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HISTORY OF MONTGOMERY COUNTY.

sisted. The tombstones in our graveyards are con- structed of white saccharoid Italian marble. They are generally destroyed in less than a century, and very often the inscription becomes illegible inside of forty years. A walk through the cemeteries will show many examples. Granite and syenite are much used of late years.

Soils .- Soil is formed by the decomposition and erosion of the underlying rocky strata. It is always mixed more or less with vegetable monld and decom- posing woody fibre which have resulted from the crops. When rocks under the soil are exposed, so that air, as well as moisture, has free access to them, they become changed, and begin to decompose and crumble to sand or clayey earth, and begin to form soil. Gneiss and mica-schist are very durable rocks, and yet much of the gneiss and mica-schist has undergone altera- tion, so that in some localities it has rotted down and decomposed so as to form soil of earth or gravel to the depth of one hundred feet, and in the tropical regions soils of much greater depth have been formed by the wearing away of rocky masses. It must not be supposed that this erosion is the work of a few years; centuries rather have elapsed before these rocky masses have been worn down and decomposed. Gran- ite is an enduring rock, and granite hills, it might be supposed, would last forever, and yet when the oxygen and moisture commence their work, and the heat of summer and the frost of winter lend a helping hand, the erosion begins, and the hillsides and plains below derive their soil from the constituents of the granite.

Sandstone rock, in which the grains are cemented together by clay or some other hinding material, also gradually wears away, and the grains of sand do their part in forming soils. The enormous beds and cliff's of limestone also suffer erosion and form a soil un- surpassed for fertility. Limestone is readily worn away by water containing free carbonic acid gas, in which limestone is slightly soluble; pure water has no action on limestone, but when rain-water derives carbonic acid gas from the atmosphere and other sources, then its action on limestone begins, and it will begin its dissolution, however slow it may be. It must not be supposed that air and moisture are the only agents at work on the rocks to form soils. Frost and ice are actively engaged year after year in splitting and breaking up rocks. When the crevices in a rock become filled with water and the water freezes, the tendency is to split the rock into fragments which in course of time form soil ; porous rocks, such as sand- stones, loose shales and schists, which readily absorb water, are often broken apart when the water con- geals, so that fresh surfaces are exposed to weather- ing.

Heat also in a quiet way does its work in form- ing soil,-it hastens any chemical change which the rock may undergo, tending to its decomposition. During the day the rocks are exposed to the rays of the sun and become heated and expand; towards

evening when it becomes cool they contract, and this alternate expansion and contraction has a tend- ency to loosen the grains of rock, and often splits off an outer layer when the rock has become weath- ered and softened. All of the above agencies are active in forming soils ; the action may be slow, yet it is none the less sure. Thus we see how soils are formed, and how they derive their mineral constitu- ents from the rocks. The vegetable matter of soils is derived from the decay of plant life which the soil has nourished. On the Western prairies the grass grows luxuriantly and then rots, and the next spring a new crop grows. This growth and decay has been going on for years, and every year furnishes the soil a supply of vegetable matter, until in many places the soil is twenty feet deep and of great richness and fer- tility. The vegetable matter in soil generally colors it black, which is due to the carbon it contains. The soil of the prairies is of a dark color. The Eastern soils which are cultivated yearly are being exhausted of vegetable mould, and its place is supplied by barn- yard manure.

Why are some soils fertile and others barren ? All grains and vegetables require for their growth certain mineral elements in the soil ; when these elements are absent the plants cannot grow, but will wither and die ; but when the soil contains an abundance of these mineral substances, and in a soluble form so that the plants can feed on them, then the soil is fertile and will yield abundant crops. What mineral constitu- ents of soils are necessary to plants ? All plants cul- tivated as food require for their healthy growth the alkalies, potash and ammonia, and the alkaline earths, lime and magnesia, each in a certain proportion. In addition to these, cereals or grains cannot attain a healthy growth unless silica is present in a soluble form suitable for assimilation. But of all the ele- ments furnished to plants by the soil, and offering nourishment of the richest kind, phosphate of lime and the alkaline phosphates generally are the most important. A field in which phosphate of lime or the alkaline phosphates form no part of the soil is totally incapable of raising grains, peas, or beans. Wheat especially cannot flourish withont phosphates in the soil. We find these phosphates in the kernels of wheat and in the hulls surrounding the kernels. Nearly all vegetables contain phosphates to a greater or less degree, and scarcely any plants are wholly without them; and those parts of plants which ex- perience has taught us are the most nutritious con- tain the largest proportion of phosphates; for example, seeds, grain, and especially the varieties of bread- corn, peas, beans, and lentils. And if we incinerate these and analyze the ashes we can dissolve the alka- line phosphates with water, and there will remain in the ashes the insoluble phosphates of lime and magnesia which are essential to the plant. The phos- phates are as necessary to man as to the plants, and a deficiency of them in the blood is accompanied al-

ORES, MINERALS, AND GEOLOGY.

ways with some form of debility or nervous pros- tration. They are much used in medicine. If we analyze the ashes of blood we will find phosphate of soda and potash present, and also the insoluble phos- phates of lime and magnesia, the very salts we find in wheat, etc. Hence we are brought to the conclu- sion that no seed suitable to become food for man or animals can be formed in any plant without the pres- ence and co-operation of the phosphates, and man derives his supply of this nourishing element from plants he uses for food. The cereals require the alka- lies, potash and ammonia, and in addition the sili- cates of potash and soda; these silicates are derived from the rock which in a fine state of subdivision forms the soil. When the rock decomposes it yields these silicates of potash and soda, which are soluble in water and which are taken up by the plant.

Some soils contain silicates which are decomposed so easily that in every two years enough silicate or potash is set free to furnish nourishment for the leaves and straw of a crop of wheat. In Hungary there are extensive districts where wheat and tobacco are grown alternately on the same soil for centuries, and both of these plants rob the soil of immense quantities of potash, tobacco particularly; about twenty-five per cent. of the ashes of tobacco are composed of potash. But districts like this are the exception. In Virginia the tobacco-growing soils are exhausted, because tobacco cannot grow iu a soil unless there is a plentiful supply of potash, and all the potash of these soils has been withdrawn. Silica, so necessary to wheat, is not required by potatoes or turnips, since these crops do not abstract a particle of silica. From what source does the soil derive its sup- ply of potash for the nourishment of plant-life? and what rocks contain potash ? The soil derives its supply of potash from minerals, such as feldspars and micas principally, and from many other silicates. The rocks containing potash are grauite, gneiss, syenite, mica-schist, trap rock, mica-slate, and many others ; in fact, nearly all micaceous and feldspathic rocks contain this important element. The feldspars contain potash, soda, and lime, combined with alumina and silicic acid.

There are several varieties of feldspar, -- orthoclase, in which potash predominates ; alhite, iu which soda predominates ; anorthite, having a base of lime ; and oligoclase and Labradorite, having bases of soda and lime. The above bases are always combined with silica and alumina, and form what are known as sili- cates. The variety known as orthoclase contains often as high as fifteen per cent. of potaslı; a pure orthoclase will yield silica, 64.20; alumina, 18.40; potash, 16.95. Thus we see that these feldspars con- tain the very elements that the crops feed on; but these elements are in au insoluble form, and are bound up in combination in such a form that the plant cannot feed on them unless they are decom- posed and rendered soluble in water. On long ex-

posure to air, moisture, and heat these rocks become rotten and crumble and decompose; silicate of pot- ash is formed, which the rain-water dissolves, and the roots of the plants absorb as food. Silicate of alumina is also formed which will not dissolve, and forms the familiar substance known as clay. The feldspars have a pearly lustre, are scratched by quartz, and cleave very readily; this property distin- guishes them from quartz.

The other mineral mentioned as containing potash is mica. There are several varieties of mica, and in composition they are silicates of alumina and potash ; sometimes part of the alumina is replaced by mag- nesia, iron, or soda. Certain rocks, such as granite, gneiss, syenite, etc., have been mentioned as contain- ing potash. This becomes evident when we consider that granite and gneiss are composed of quartz, feld- spar, and mica ; syenite, of quartz, feldspar, and horn- blende ; and mica-schist is composed of quartz, mica, and a small proportion of feldspar. These rocks con- tain the very minerals that are necessary to form good soil. The soil derives its supply of phosphates from the rocks also. The Philadelphia and the Montgomery County granites and mica-schists contain from one- tenth to four-tenths per cent. of phosphoric acid. The syenites, gneisses, trap rocks, and even the new red sandstone contain small quantities of phosphates. In order to get a correct understanding of the soils of Montgomery County we must study the rocks that underlie the soil and from which the soil has been formed; we must know whether the minerals compos- ing the rock are such as contain plant-food. From this study we can get a most intelligent idea of the fertility of a soil. Montgomery County has a great variety of rocky strata, and hence a variety of soils. The limestone soils are generally the most fertile and productive. More wheat to the acre is raised on the limestone soils than on any other, and corn seems to attain a greater size.

Many of the sandstone soils are productive, but this is probably due to the fact that they often contain feldspar and sometimes mica. These rocks often con- tain little white specks, which seem to be loose and crumbling, and are decomposed feldspar. When the soil is made up of pure sand it is not fertile, as the plants cannot live on silica alone. When the under- lying rock is red shale the soil does not amount to much, and small crops are raised. Quite a number of the townships abound with this red shale, which often contains as high as seven per cent of iron. A red shale along the Stony Creek, which Ianalyzed, yielded seven per cent. of iron. The red color of this shale is due to the oxide of iron it contains. When superphosphate is applied to a red shale soil, or one containing much oxide of iron, a great deal of the phosphoric acid is wasted; it combines with the iron, forming phos- phate of iron, which is insoluble and not readily de- composed, so that it is of no use to the plant. The red shale generally accompanies the sandstone, and

HISTORY OF MONTGOMERY COUNTY.

the red soils are often derived from shale, although sometimes from sandstone. It must not be inferred that the soils in the sandstone district are not fertile, as they generally yield good crops.

Some townships contain four different kinds of soil. The following is a list of townships and the beds of rock that underlie them. The rocky strata mentioned first is the most abundant, and the others are men- tioned according to the extent of the deposit in the township. The townships not mentioned below are included in the sandstone district.

Lower Merion .- Mica-schist, garnet-schist, syenite and granitic rocks.

Upper Merion .- Limestone, sandstone, and slates.

Springfield .- Limestone, mica-schist and gneisses, syenite and granitic rocks, and sandstone.

Cheltenham .- Garnet- and mica-schist, syenite and granitic rocks, and sandstone.

Abington .- Mica- and garnet-schist, syenite and granitic rocks, sandstone and limestone.

Moreland .- Syenite and granitic rocks, sandstone and mica-schist.

Plymouth .- Limestone and new red sandstone.

White Marsh .- Limestone, sandstone, syenite and granitic rocks, mica-schist.

Upper Dublin .- Sandstone, limestone, syenite and granitic rocks.

Horsham .- Red sandstone.

Gwynedd .- Red sandstone and shale.

Whitpain .- Red sandstone. Lower Providence .- Red sandstone.

Norriton .- Red sandstone.

Worcester .- Red sandstone.

Clay and Kaolin Deposits .- The composition of kaolin is a hydrons silicate of alumina. It contains forty-five per cent. of silica, forty per cent. of alum- ina, and fifteen per cent. of water; when pure it is as infusible as sand. It is very plastic, aud can be kneaded into almost any shape when mixed with water. It is seldom found pure; it generally contains feldspar, mica, oxide of iron, or calcite, and any one of these impurities will make the clay melt. The best kinds of clay contain scarcely any of these sub- stances which tend to make the clay less refractory. The tests for a good refractory clay are : It must not effervesce when moistened with acid, as this shows the presence of carbonates which make it fusible; it must not contain more than two per cent. of iron ; it must be as frec as possible from feldspar, which contains potash and makes it fusible. As a rule, the less alkali you find the more refractory the clay, and six-tenths of one per cent. of potash is the maximum amount allowed in a good refractory fire-clay. The best way, however, to test a fire-clay is to make a brick of it, and put it in a shaft-furnace supplied with a blast and fed with anthracite coal. In a fur- nace like this steel will melt. After the brick has been in the furnace about one hour take it out and examine it; if it has melted or crumbled or fused

much on the edges it is not the kind of clay suitable for making fire-bricks. After a successful test of this kind an analysis is not necessary.

The clay-beds of Montgomery County are found in the limestone belt, generally in the vicinity of the mica-slates and schists, and it is in these deposits of clay that we find the extensive deposits of brown hematite ore. The principal clay-beds are fonnd in Upper Merion, Plymouth, White Marsh, and Spring- field townships. The clay in all of these townships is found in the limestone. There seems to be a de- pression in the limestone, which may have been the former bed of a stream, and the clay is found resting on the limestone and filling up this depression or bed. Most of the clay, however, has been derived from the mica-slates and schists, and the beds are parallel to the limestone, and occupy the position of those rocks from which they have been derived. These are the old clays, while the clay which is found occupying the depressions of the limestone and is not parallel to it is said to be a more recent clay. The most im- portant bed of kaolin now worked in Montgomery County is found at Lynch's Kaolin Pit, situated in Plymouth township, on the Ridge pike, about two and a half miles from the borough of Conshohocken. This pit was opened in 1877, and Mr. Lynch informs me that over seven thousand tons of kaolin and clay have been mined; the average yield at present is about fifteen hundred tons per year. This deposit is of local importance, as it supplies clay for the terra- cotta works at Spring Mill, owned by Mr. Morehead, and also the works owned by Mr. Scharff. At these works terra-cotta pipes of all sizes are made. Various clay ornaments and chimneys are manufactured here. There are several different kinds of clay at this pit : First a beautiful white kaolin, which is free from iron and is quite coherent ; this variety is used for making pottery and also for lining blast-furnaces and pud- dling-furnaces, where it has to stand a very high tem- perature without melting. This kaolin contains ex- ceedingly minute scales of mica, which are scarcely visible to the eye. The next clay is the red clay used in the manufacture of terra-cotta and also for lining and fixing puddling-furnaces. This clay contains a little oxide of iron. The next variety is a blue clay, and is known as the new clay, and makes most excel- lent fire-bricks. It is more coherent and plastic than any of the others. Formerly the clay used for making the large cylindrical pots in which glass is melted was imported from Germany, but recently this blue clay was tried, and served the purpose very well, standing the high temperature without crumbling or fusing. This clay is now used by J. M. Albertson & Sons at the Star Glass-Works, Norristown. The extent of this deposit is not known ; the bed is about seventy fect in thickness and extends over the entire field. The clay is shipped to Philadelphia, Norris- town, Pottstown, and Conshohocken. Near the clay is found a bed of fine white sand.

ORES, MINERALS, AND GEOLOGY.

Limestone Valley of Montgomery County .- The great limestone belt of Montgomery County, which has furnished such immense quantities of marble and lime, commences in Abington township, about a mile and a half north of Abington ; at this point it is quite a narrow belt, but it widens as it extends westward, entering the northern corner of Cheltenham town- ship, aud becoming a broad belt of limestone as it extends through White Marsh, Plymouth, and Upper Merion townships. In Montgomery County it extends as far south as Conshohocken and Spring Mill, and it extends to within a short distance of the towns of Barren Hill and Edge Hill. It extends along the Schuylkill River from Conshohocken to Norristown, are in a nearly vertical position or inverted. It is chiefly within these limits that the blue and yellow limestone has been altered by heat and changed into crystalline and granular marble of different colors. Nearly all the marble-quarries opened are included within this steeply upturned or overturned outcrop. It is likewise along this convulsed and metamorphosed side of the trough that nearly all of the largest, deep- est, and richest deposits of brown hematite have been met with." The color of the limestone varies in dif- ferent localities,-pale grayish-blue, white, pale straw- yellow, and bluish-white. The marble is of various colors,-white, black, and often mottled. The thick- ness of the limestone belt is not known. Professor and crosses the river, extending into Chester County, ' Hall says, "The probability is that it is not far from and forming the beautiful Chester Valley. But this two thousand feet thick, but it may be much less." I have noticed that from Potts' Landing to Consho- hocken the prevailing color of the limestone is blue, and from Potts' to Norristown we have a variety of colors,-gray, white, yellow, and blue. Gray is the prevailing color. Between these two points there are two small veins of mica-schist which are very narrow. The limestone directly in contact with these I have found has been metamorphosed into a white marble. limestone belt does not end here, it passes entirely through Chester County, and extends into Lancaster County as far as the source of the Big Beaver Creek. The total length of this immense limestone belt from near Abington, Montgomery Co., its eastern ex- tremity, to the Big Beaver Creek, in Lancaster County, its western extremity, is fifty-eight miles. The widest portion of the belt is three miles, while the average width of limestone is two and a half miles. In Chester County, at Downingtown, the belt is not so wide, being only three-fourths of a mile in width. The greatest width of the limestone in Lancaster County is not much more than half a mile. The general struc- ture of this first main belt of limestone is that of a long slender basin or synclinal trough, the southern side of which is much steeper than the northern. From the neighborhood of the Gulf Mills, a little west of the Schuylkill, to its western end this oblique symmetry prevails with scarcely any interruption.

The strata of the north side of the valley, or from the synclinal axis northward, dip at an average incli- nation of about 45° southward, or more strictly S. 20° E. But this inclination is not constant east of the Schuylkill River. There are two well-defined synelinal basins, flanked by the Potsdam sandstone. West of the river a synelinal basin extends to the northwestward between Bridgeport and Henderson Station, and is also flanked on both sides by the Potsdam sandstone. The south side of the limestone belt between Spring Mill and its eastern extremity is bounded by the Potsdam sandstone. But from Spring Mill west to the Chester County line the South Valley Hill quartzose mica-schists form the remainder of the sonthern boundary in Montgomery County. The limestone belt is bounded on the north by the Pots- dam sandstone and by the new red sandstone. Folds of Potsdam sandstone extend in a diagonal direction across the main belt of limestone at Oreland, Cold Point, and Henderson. Here we find the Potsdam sandstone extending into the limestone. According to Professor Rogers, "The southern steeply upturned outcrop has been more metamorphosed by heat than the northern, and this alteration is greater when they

The color of limestones is generally dne to organic matter which they contain, although not always ; the black marbles are colored by graphite or carbona- ceons matter; the yellow or brown limestones gen- erally contain iron as oxide or carbonate. Very often in the same quarry will be found several veins, each vein having a different color. The limestones of Montgomery County are highly magnesian ; many veins contain enough carbonate of magnesia to form what is knowu as dolomite. Dolomite contains about 45 per cent. of carbonate of magnesia and 55 per cent. of carbonate of lime when pure, although the percentage of lime and magnesia may be less and still be dolomite. Dolomites are harder and tougher than limestone, and usually present a finer grain ; a true dolomite will not effervesce with acetic or hydro- chloric acid in the cold, while limestone, composed of carbonate of lime only, will effervesee at once with either of these acids. The hardness of limestone is about 2, while that of dolomite is about 3.5. The more magnesia carbonate enters into combination with carbonate of lime the more the nature changes ; it will not effervesce so freely. From an examination of a large number of limestones from quarries in the county, I find that the more carbonate of magnesia enters into their composition the less readily will they effervesce with hydrochloric acid in the cold; and when the percentage of carbonate of magnesia is small they will effervesce quite freely with hydro- chloric acid. This might be an approximate method of determining whether a limestone be highly mag- nesian. Most of the county limestones are highly magnesian, containing trom 10 to 35 per eent. of car- bonate of magnesia, although many veins contain very little, if any, maguesia, and are mostly carbonate

HISTORY OF MONTGOMERY COUNTY.

of lime. The limestones of Port Kennedy are highly magnesian, containing as high as 42 per cent. car- bonate of magnesia. Another sample yielded 38.40 per cent. of carbonate of magnesia. The first sample might be called a dolomite. The limestone near Con- shohocken does not contain so much carbonate of magnesia. A sample from O'Brien's quarry yielded 17 per cent. carbonate of magnesia. The limestones from Norristown to Potts' Landing along the river are highly silicious, at least some veins are more so than in the vicinity of Conshohocken. No rule, however, can be laid down about this, for very often in the same quarry one vein will contain 3 per cent. of silica and the next vein 9 per cent. of silica. The variation is so great that it is a source of much trouble and in- convenience when the limestone is used as a flux in the blast-furnace. When so used it is advantageous to secure limestone as free from silica as possible, because the object of the limestone is to combine with the silica and clay in the iron ore and form a slag, and if the limestone used contain a high percentage of silica it will necessitate the use of an extra amount of lime- stone. Marble is simply limestone which is changed in structure and rendered crystalline and granular; by this metamorphosis the organic matter of the lime- stone is burnt out and it becomes white, and changes from a morphous to a crystalline form.

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History of Montgomery County, Pennsylvania, Part 7

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