History of Hunterdon and Somerset counties, New Jersey : with illustrations and biographical sketches of its prominent men and pioneers, Part 45

Author: Snell, James P; Ellis, Franklin, 1828-1885
Publication date: 1881
Publisher: Philadelphia : Everts & Peck
Number of Pages: 1170

USA > New Jersey > Somerset County > History of Hunterdon and Somerset counties, New Jersey : with illustrations and biographical sketches of its prominent men and pioneers > Part 45
USA > New Jersey > Hunterdon County > History of Hunterdon and Somerset counties, New Jersey : with illustrations and biographical sketches of its prominent men and pioneers > Part 45

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" About one mile north of this locality is another exposure of a very similar rock, on the farm of Aaron Dunham. Its area is very small.

" Nearly on a line connecting these localities, and prolonged north- ward, there is a third onterop of limestone. It is on lunds of William Bonnell, and lies north of the Clinton and Perryville rond and not far froin a school-house. It has a dip of 15º N. 50 W. The rock la in very thìn heds (averaging two inches thick) and dark-colored. It resembles that at Hoffman's and Dunham's. This latter onterop is not over half a mulle south of the Mouselaughway Creek, or southern border of the CHuton tract.

" Little York and Spring Mille .- This is a narrow belt of limestone at the foot of the Musconeteong Mountain, extending from Spring Mills north- eastward to Little York. Its greatest dimensions are four miles long by half a mile in breadth. At Little York it is seen north of the village as fur na B. W. Almangh's residence. It runs thenco west by W. J. Duck- worth's and W. Vanderbilt's north of a small brook, by Vun Syekle's and Buun's quarries south of Henry Cole's, and a little north of Spring Milla to It- terminus in that direction. It appears In the road north of Spring M.Ils, aml a short distance west of this rund.

" Amsterdam and Johnson's Ferry .- The magnesian limestone appena along the base of the mountain at several intermediate points between Amsterdam and the Delaware River. It occupies the northern side of the little valley near the Presby teriun church cust of Johnson's Ferry, nud crops ont at three or four places near Amsterdam. Whether the e separate exposures are parts of one continuous belt of rock is not known. If they are, the bill south of the valley road belongs to the Triassic fur- untion, Instead of the Potsdam Samstone. The breadth of the outerup does not exceed two hundred yards. The furthest extent castorly is near the ohl store at the corner of the rond, in Amsterdam. Here a slaty lime- stone or na calcareuns alate is found in the roadside, cast of the bridge. South of west from this corner, the dark-blue, subcrystalline limestone appears in the bed of the brook, south of Elins M. Kapp's, showing itself soveral roda along in the stream. It is here in a horizontal position. Forty feet south of the stream the red shale forms the side hill next the wwwlowa.

" About one hundred and fifty yards west of this and north of the bronk Is a small quarry. Limestone of very Que grain nud HIght-colored wns formerly quarried on lands owned by Willis Vanderbilt, formerly the farm of William Snyder. A large amount of stone has been taken from this locality for lite.

REPTILIAN AGE.

Triassic Period .- The rocks belonging to this period are shales, sandstones, conglomerates, and traps, They extend from the Delaware River northeastward en- tirely across the county. As a rule, they are all strati- tied, and all slope towards the northwest. To afford a complete definition of what is meant by the terms shale, sandstone, conglomerate, trap, ete., the follow- ing, from the "theology of New Jersey, 1868," is introduced :

" Sandstone .- A rock composed of grains of quartzose sand contented together by valde of tron, carbonate of lime, sllien, or other agont, the mund constituting the largest part ; and it may be of any degree of tine- uown, from one-eighth of an inch in dinmeter downwards. It may contain fragments of mica, feldspar, or other rock, napl may be of any color,- white, drub, yellow, red, purple, blue, green, or gray.

" Conglomerate .- A rock composed of pebbles or fragments of other rocks is a conglomerate. The pebbles may be of quartz, limestone, slate, ". other rock, and they may vary tu size from a bucksbut to the lowbler id' a foot or more In diameter. The commenting nisterial may be ovide of iron, carbonato of lime, or other fine sultaners, and the color may do. jeil either upon the paste or on the pebbles.

" Shale,-Rocks which are nearly destitute of sandy particles, and con- tain a great derd of clay, which are tender and split or break with an un- wen fracture, are called shules. They are frequently but little harder than dried clayoy mud, and when exposed to the weather soon crumble down into earth. In this formation they are, in their natural state, of n red color, und these are by for most abundant. But In the vichuity of trap-rocks they are much changed, the color passing from a red to purple, dark-blue, and black. The hardness in such cases has also Increased with the change of color, till the black Is almost as hard as flint, and breaks with a smouth concholdal fracture like that of a mineral. Shales are also seen idont New Brunswick, and other places where a little copper la disseminated through the rock, which are entirely changed in color with- out any Increase in hardness. The change follows the joints of the rock, or, in some cases, the senine in the line of stratifiention, and the color passes from the red le a blue or bluish-drab. Dark-colored and black shiales are also found in some places, which owe their color to the pres- once of bltuminous mutter. They are not changed In hardness; fre- quently considerable vegetable remains; fossil fish are found In such ; and when they are heated they give off'u gus which burus with a bright blaze.

" Limestone or enlcarcons shale has been found to a limited extent In this formation.

" Basalt -U'under this name are included the trap-rocks, which are dark- colored, have a specific gravity greater than 2.9, and on their weathered surfaces are brown or dark gray, and if they have been covered by soil are of a dull, earthy, yellowish-brown color. In their fresh fractures they may be either contre or Mine-grained, crystalline or massive, and, though usually dark-colored, may vary much in shade. When powdered und tried with a magnet, they ure found to contain particles of magnetic iron ore.

" Trachyte ; White or Trachytic Trap .- This variety Is not near so com- mun as the basaltie. Its chief loenlities are about Round Valley Munn- tuin and the northern part of Hunterdon County. Rocks of this kind are light-colored by the weather to a dull, chulky white, and in or under the soil are, on their anrface, of a yellow-white color. They have n specific gravity of 2.8 or less. They are of various degrees of coursenes, and are rongher to the touch than the basaltie varieties."

The rocks of this period are remarkably uniform in dip. Having their outerops extending in lines north- cast and southwest, they verge towards the northwest at an angle of about ten degrees. Tu this rule, how- ever, there are some exceptions.

By far the greatest part of the rocks of this forma- tion are shale and sandstone. Everywhere they con- stitute the rocks of the valleys and of the sides of the ridges. Exposures of them are seen almost every- where along the roadsides, the banks of the rivulets. the railroad cuts, the escarpments of the hills, and in the bells of streams, in quarries, ete. For opportuni- ties to observe and study no Hunterdonian can go amiss, nor need he go far from his own dwelling. In color they vary, but some shade of red is quite com- mon, hence the name, red shale and red sandstone. They exist in layers that vary in quality and in thick- ness. It is not uncommon to find a layer that is at one place a perfect shale, while farther on it is a per- feet sandstone. And between these sites is seen a shading of the shale towards the sandstone so uniform that no eye can determine at what point the line of demarcation between the shale and sandstone occur -. At une place the layer may be thin-bedded, at another thick-bedtled, and farther on thin-bedded again. As a rule, that portion of a bed that is shaly is thinner in bed than that part which is -andy. But to this rule are many exceptions.

During the process of weathering, the shale first splits up into thin lamina; these lamina are often-

170

HUNTERDON COUNTY, NEW JERSEY.

times as thin as the leaves in a book. In this con- dition the rock is of short duration. It soon mould- ers into a soil that, as is found in roads in dry weather, may be worked up into an impalpable powder. In- deed, when exposed to the weather the red-shale rock is very rapid in the process of disintegration and crumbling to soil. While fresh the blocks look as if they would form a beautiful and durable wall; and so they do when immediately laid up in mortar. But, exposed to the action of the climate during the fall, winter, and spring, the exterior of each block crum- bles, the interspaces become filled with the moulder- ing fragments, and during the following summer from the surface of the mouldering heap red and white clover grows most luxuriantly.

Where better material is regarded as too expensive, the most indurated layers of the red-shale rock are sometimes quarried for building purposes. For cellar- walls the stones from these layers do very well, pro- vided that they are laid up immediately with a free use of rich mortar. But this provision is essential. Nor is the use of the red-shale stones in architecture confined to the building of cellar-walls. Within the county there are several houses the walls of which are built entirely of this material. In the village of Ringos stands an old hip-roofed house that was built out of red-shale stones which were quarried out of the layers along the south side of the road about two hun- dred yards above where the building stands by one Landis in the year 1837. The walls in this edifice are in excellent condition, and will not need rebuilding in five hundred years. Indeed, walls made of red- shale stones, with plenty of mortar rich in freshly- slacked lime, seem to grow firmer with age. However, as a building material, red shale is not in good re- pute.

Prall's Quarry .- On a farm owned by A. J. Prall, in the township of East Amwell, is a quarry from which have been taken a great many perches of stones, mainly for building bridges. The quarry is in the side of Bleak Ridge, along the west bank of Mountain Brook ; it is well drained and easy to work. In it the layers range in thickness from eight to twenty inches. They are divided by two systems of joints that meet very nearly at right angles. They dip towards the northwest at an angle of twelve de- grees. The stones from this quarry dress well, "take mortar" quickly, are very sightly, make a strong wall, and resist the disintegrating effects of the climate ex- traordinarily. From this quarry may be taken stones that are three feet wide, a foot or more thick, and from six to twelve feet long.

Wyckoff's Quarry .- About a mile southwest of Rea- ville, in the bank on the west side of the Neshanic, is a quarry which has been occasionally worked for stones to build bridges. The abutments of the bridge over the Neshanic near this site were here obtained.

Nevius' Quarry .- Along the east bank of the Ne- shanic, near Nevius' mill, is an outerop of indurated

shale that has at some time been worked for building- stones.

An analysis of the red shale shows it to contain all of the ingredients to form a productive soil :

Silicic acid and quartz. 73.00

Peroxide of iron. 10,00

Alumina 3,20

Lime .. 4.93

Magnesia. 0,90

Potash

0,73

Soda.

0.97

Sulphuric acid

trace

Carbonic acid ...

Water. 1.00

Altered Shale .- In some places the shale presents an appearance that leads the geologist to believe that it has been exposed to intense heat, and to a very great degree by this agency altered in its appearance, in its physical qualities, and in its chemieal composi- tion. Such is the case with those layers found adja- cent to the trap-rocks hereafter to be described. For instance, as we ascend the Sourland Ridge from Van Lieu's Corner, all along the roadsides, at and near the base of the hill, the rock exhibits the appearance of ordinary shale; but as we ascend, the appearance of the rock becomes such that one believes it to have been altered by igneous agencies. Near the base it is easily broken, easily impressed with the ham- mer; on its exposed outcrop it exhibits its lami- nated structure, and is covered with a deep soil, made from its disintegrated laminæ. About midway up the ascent we notice that the layers of rock are harder, broken with more difficulty, show less of the laminar structure along the outerop, and are covered with a less depth of soil. Farther up the layers are still harder, and the weathered surfaces present less of the lamination ; the soil over the layers is also less deep. Near to and at the brow of the ridge the layers are well defined, are of almost flinty hardness, break with difficulty, and to the blow of the hammer yield a con- choidal fracture. Many of the specimens found along the brow, if suspended when struck with the hammer, ring like pot-metal or like the blacksmith's anvil. Here and there specimens may be found that present an appearance that leads one to believe that, at some distant time, they have been in a state of fusion, their seams being obliterated by that coalescence of the sides of continuous layers that much resembles the union of contiguous bricks and stones that have been heated up to the melting-point. "This feature is well exhibited in the altered shale north of Pero Hill. Here, in place, is seen a great succession of strata completely fused together ; so that, if quarried, the beds would divide up into blocks from one foot to five feet thick, and, in proportion, as long and as wide. Indeed, upon the surface and imbedded into the soil are fragments of indurated shale, three feet thick, four feet wide, and six feet long, that are almost as hard as flint.

The shale north of Cedar Summit exhibits the same phenomena very boldly. Upon the surface here are huge blocks of altered shale of flinty hardness. Upon

171

PHYSICAL GEOGRAPHY AND GEOLOGY OF HUNTERDON COUNTY.

the bank that skirts the castern side of the road that extends from Wertsville to Cedar Summit rests a block of this material that is four and a half feet wide, four and a half feet deep, and eight feet long. The layers of this stone seem to be completely and very firmly joined by fusion.

At many other places similar appearances are pres- ent to one ascending the northern slope of the Sour- land Ridge,-for instance, along the road from Rin- gos to Rocktown, from Wertsville to Cedar Summit, from Unionville to Bihl's Corner, and from Wyckoff's Corner to Cedar Summit.

The indurated rock above described doubtless is but ordinary shale altered by the agency of heat com- municated to it from the basaltie trap over which it lies. There can be but little doubt that the trap that underlies this indurated rock was injected, in a mol- ten condition, into the bed in which it now exists. In the process of cooling it must have imparted to the contiguous shale an enormous amount of heat,- enough to fuse the layers contiguous to it,-while those farther distant must have suffered a less eleva- tion of temperature. Hence the gradation in the amount of alteration that we find in the successive layers of the shale which is found along the northern słope of this ridge.

Another evidence that the rock here described has been subjected to a high degree of heat is the occur- renee in it of mineral in a crystalline form. At many places along the slope of the ridge are found, in the indurated rocks, crystals of quartz, tourmaline, epi- dote, and those of kindred minerals. In many places, too, the rock is shivered or broken up into very small, regular or irregular, fragments, which are sometimes cuboidal, more frequently lozenge-shaped,-a fractur- ing that is easily explainable on the hypothesis that the layers now formed out of these pieces were once layers of ordinary shale that have been subjected to intense heat and very great lateral pressure.

To the rock modified or altered by the intluence of heat is given the term "altered shale." To show that in chemical composition, as well as in physical ap- pearance, it differs from ordinary shale, the following tahle is given, being the results of the analysis of three specimens of altered shale,-one from Hunter- don County, the others from Mercer County. No. t is a specimen from along the Lockatong Creek ; No. 2, from the farm of Spencer S. Wearts; No. 3, from Moore's mills, upon Stony brook :

No. 1.

No. 2.

No.3.

Silica .... ...........

51.00

51.2

AM (0)

Alumnino ...

22 .. 15

40,60

Protovido of Iron ....

1.12

8.1

0,80)

Manganese ....

.93

3 8

4.76

Magnesin ....

3.37

.6.3

Potash. .....

1.38

.....

6.48

Sulphuric acid

......

Curbonic ach ..

2.30

5.0

.80

Water ..

1.7

.65

09.03

.....

The above table shows that the altered shales con- tain in considerable quantities the elements for mak- ing a valuable soil.

At many places altered shale is used for architec- tural purposes. Upon the Sourland Ridge and along the brow of the table-land are many houses built of the surface-stones which are but the fragments of altered shale. In color these stones are generally purple or dark blue. They are very hard, and very durable : a wall made of them is very beautiful. But since, under the hammer, the fracture is conchoidal, they are difficult to shape and are much hated by masons. They do not "take mortar" well, and, as a consequence, they make a wall that is less strong than one made of common shale-stones.

From strata farther away from the trap-rock, where the layers have been less altered by heat, stones may be quarried that work well under the hammer, "take mortar" middling well, and are comparatively durable. Of this character are the stones obtained from the quarry on the farm owned by Joseph G. Quick, also from the one on the farm owned by Ashur Iliggins, and from the quarry at the factory near Ringos, from Dr. G. HI. Larison's quarry, at the western terminus of Anastomosing Ridge in Lambertville, and at Patrick Hunt's quarry, on the northern slope of the Sourland, in the same city,

The altered shale along the northern slope of the Sourland Ridge and along Bleak Ridge abounds in the minerals epidote, tourmaline, steatite, pyrites, and mica.

Epidote is found in abundance in the altered shale along Swan Rill, in the city of Lambertville. More sparingly, it is found in the shale of the quarries within the city limits. Near Basaltic Cliff is another site at which are found in considerable numbers no- dules of epidote. From this locality there is at the Academy of Science and Art a block of altered shale containing nodules of this mineral from an inch and a half to two inches in diameter.

Tourmaline oceurs in the "sandy shale" on the "high grounds" southeast of Lambertville. Gener- ally, the crystals are small. In color they are dark brown or black.

Steatite occurs in the joints of the quarry worked by Patrick Hunt at Lambertville. Its color is light red or reddish-gray.

Cavities lined with quartz crystals often occur in the strata of altered shale. In these, sometimes, the crystals are almost acicular and long; in others. columnar and short.

Crystals of iron pyrites occur in the sandy layer- of altered shale.

Flakes of mica occur in the arenaceous strata of shale. At some places pieces of shaly sand-tone are picked up that, from the presence of the mineral, glitter as if set with scales of burnished silver.

All along the brow of the table-land, from the Delaware River to the Cakepoulin Rivulet, occur

......

2.63

1.41

Soda

0.18

172

HUNTERDON COUNTY, NEW JERSEY.

outcrops of altered shale. Indeed, from river to rivulet there are two lines of outerops that are ap- proximately parallel.

The altered shale along these lines is very similar to that found upon the northern slope of the Sourland Ridge. At some places it is flinty, rings when struck with the hammer, and breaks with a conchoidal frac- ture; at others it is less indurated and breaks with more regularity. In it exist the same kind of min- erals found in the altered shale of the Sourland.

The shale forming Raven Rock is a part of the most southerly of these lines,

Sandstone .- That part of a layer of a sedimentary Triassic rock that consists largely of grains of quartz- ose sand is known as sandstone,-sometimes called " freestone." As above intimated, sandstones do not constitute entire layers, but the same layer is called a shale in that part which is largely made up of clay and is nearly destitute of sandy particles ; while that part of it that is made up chiefly of sand-grains, with an absence of clay, is called a sandstone.

As above stated, as a rule that part of a layer which is sandy is thicker than that part which is shaly. This condition of the layer gives a clue to the solution of the problem concerning the origin of the strata com- posing the Triassic Period, as found in New Jersey, Pennsylvania, and Maryland.

As to the origin of the Triassic rock, the most plansihle theory is that at the close of the Carbon- iferous Age there existed a lagoon that extended from the Hudson River southwestward through Penn- sylvania and Maryland into Virginia. This lagoon was flanked upon the northwest and upon the south- east by rock belonging to the Archæan Age. Along the northwest the land rose up abruptly into the Archæan highlands, as at present. Here was a short slope to contribute of its detritus to the filling up of this ancient lagoon. But towards the southeast rose up a plain of Archaan rocks that extended away from the shore of the lagoon far back into a region which is now covered by the waters of the Atlantic, From this extended slope the streams transported the de- tritus and deposited, as silt, the clayey elements of their freight to form the red-shale rock, and the coarse and sandy elements to form the sandstones and con- glomerates.

As the streams were transporting to this lagoon their freight of detritus, to be spread out to form the layers of trias, those particles which were coarser and heavier-such as sand-grains and the like-would be first deposited, while the finer-grained-and conse- quently the more easily transportable-would be car- ried farther on and spread more extensively over the bottom of the lagoon. Hence, we infer that those por- tions of a layer, or of a succession of layers, that are sandy are at the bottom of what once was an estuary of an ancient stream, and in consequence was the recipient of the heavier particles of the freight brought down by each successive freshet of the stream ; while

the lighter particles of the same freight were carried beyond these gritty beds, to be spread out to form laminæ of shale.

Every observer must have noticed that the shale-rock consists of laminæ; that the sandstones are destitute of laminæ. At some places it is possible to trace a thin layer of sandstone as it thins ont into a lamina of shale, Perhaps every layer of sandstone, no mat- ter how thick, is but a swell of gritty material in a lamina of a Triassic layer that at the time of its deposition extended over the bottom of the whole lagoon. If this be so, we see that the estuaries of streams must have filled up more rapidly than those parts of the lagoon that were farther away. This must have caused frequent changes in the course of the streams as they flowed through those estuaries.

Of this we have abundant evidence in any quarry that we may visit. However, in some it is more noticeable than iu others. At Stockton we see a suc- cession of layers of sandstone superimposed by a suc- cession of laminæ of shale. These laminæ in turn are superimposed by a succession of layers of sandstone. These sandstone are again superimposed hy layers of shale ; and so on to the end of the layers that consti- tute the quarry. This happened, no doubt, by the filling in of the bed of the stream with sand; while the elements to form shale were carried farther away, Nor is it difficult to determine in what direction the current of the estuary moved. Upon the surface of freshly-exposed layers in the quarries at Stockton is seen the arrangement of the particles of sand forming the stones. This arrangement is marvelously similar to that of the grains in a bar of sand deposited in any of our mill-ponds at the time of a freshest from a heavy shower. Further, the largest stones of this justly-famous quarry may be broken to pieces, and every piece reveals the same structure. Nor is this quarry the only site that offers testimony to this hypothesis. The whole hed of sand forming Sandy Ridge everywhere exhibits the same structure. In- deed, so boldly is this fact exhibited in the structure of this ridge that, when a boy, I used to hear the men working in the sand-pits of this deposit remark, "This sand looks as if it had been washed here by some great freshet of an enormous river."

The arrangement of the particles of sand forming the stones of the quarry at Stockton and the huge deposit of sand known as Sandy Ridge are such as to show that the current, at the time these beds were formed, moved from southwest to northeast, or, in other words, moved from the site at which these quar- ries appear in the direction of the line of Sandy Ridge. Hence, we may infer that the stones of the quarry at Stockton, Brookville, and Prallsville are composed of the sand-grains and pebbles first depos- ited in the bed of the stream in the ancient estuary, that the sands of Sandy Ridge and those of the de- posit at Sand Brook were the sediments of the current under less rapid movement, and that the fine-grained

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History of Hunterdon and Somerset counties, New Jersey : with illustrations and biographical sketches of its prominent men and pioneers, Part 45

Author: Snell, James P; Ellis, Franklin, 1828-1885 Publication date: 1881 Publisher: Philadelphia : Everts & Peck Number of Pages: 1170

Author: Snell, James P; Ellis, Franklin, 1828-1885
Publication date: 1881
Publisher: Philadelphia : Everts & Peck
Number of Pages: 1170