Art. III. Sketch of the Mineralogy and Geology of the Vicinity of Williams' College, Williamstown, Mass.
Art. III. Sketch of the Mineralogy and Geology of the Vicinity of Williams' College, Williamstown, Mass. By Professor Dewey, of Williams' College, in a letter to the Editor.
The following sketch includes a space extending from Hoosack mountain on the east, to the State of New-York on the west, and a small distance into Vermont on the north. The accompanying map shows the relative situation of the streams, and the principal hills and mountains. The map is an enlarged copy of Carleton's map of this part of the state, with one or two corrections, which truth required. The latitude and longitude are probably not perfectly accurate.
A Geological MAP of a part of Massachusetts on
Connecticut River 1817.
Transverse Section of Rock Strata from Hoosack Mountain to Eleven Miles East of Connecticut River.
Williams' College is situated in a valley, having on the west the hills of the Taconick[48] range; on the east, Saddle Mountain, which separates it for the most part from Adams; and on the north, and northeast, two hills which belong to the southwestern part of the range of the Green Mountains. Hoosack River, rising several miles at the southeast, and passing through the northeastern part of Williamstown, winds its course northwest, to the Hudson. It is an inconsiderable stream, about six rods in width, and its current is rapid. From the south, runs Green River, a smaller stream, and enters the Hoosack one mile northeast of the college. The green colour of this stream, appears to be caused by a magnesian clay, which is washed from its banks at the south part of the town. At the west is Westbrook, rising in Williamstown, and entering the Hoosack one mile and a half northwest of the college. The soil in this whole tract is generally clayey, rather light for such a soil, and very rich. A gravelly soil appears in a few places, especially at the northern part. The interval on the Hoosack extends only a small distance from its banks, rarely exceeding, and often much less, than half a mile, and presents the common appearances of alluvial land. Rising from ten to twenty feet above this interval, the soil is in various places filled with rolled stones of quartz and limestone, as if the Hoosack had once been much above the banks which confine it at present. It is not improbable that its waters were formerly intercepted by the hills in Pownal, five miles at the northwest, forming a small lake in this valley.
The hills of the Taconick range, (A[49]) on which passes the line between Massachusetts and New-York, have generally an elevation from twelve hundred to fourteen hundred feet; Pownal Mountain (B) on the north, about fourteen hundred; and Oak hill (D) on the northeast, twelve hundred feet above the east college (C.) Saddle Mountain (EF) is an insulated mass, separated from the Taconick range by the valley of Williamstown, and from Hoosack Mountain, by the valley in Adams. It lies about south southwest, and is nearly eight miles in length, and two in breadth. It is composed of two ranges, the eastern and highest (FG) being in Adams. The mountain has its name from two of its peaks, which present at a distance the appearance of the two elevations of a saddle. The west range (E) is divided into two parts quite to its base, which with the slope of the east range encloses, on three sides, an irregular hollow, called the Hopper.(H) The northern part (E) of the west range is nearly two miles in length, and rises to the height of eighteen hundred feet; the southern (I) rises abruptly into a peak of the elevation of seventeen hundred feet. The height of the valley between the two ranges is about fourteen hundred feet. You enter the Hopper from the west, passing along a branch of Green River, and a romantic, wild, and sublime prospect opens before you. Nearly east of the entrance into the Hopper, lies the highest point of the Saddle, familiarly called Gray Lock, (F) being about twenty-eight hundred feet above the college, and probably four thousand feet above the tide-water of the Hudson at Troy. This is the highest land in Massachusetts. About two miles north northeast, is the northern peak (G) elevated twenty-three hundred feet. The valley in Adams is bounded on the east by Hoosack mountain, (K) elevated from fourteen hundred to eighteen hundred feet, and extending several miles west of south: it forms a part of the range which commences at West Rock in Connecticut.
The country included in this sketch is principally primitive; lying on the west of the summit of the primitive range, which passes southerly into Connecticut. The rocks and minerals will be mentioned in the following order.
1. Granite. A few pieces have been found at the foot of Oak hill, one mile northeast of the college. It consists principally of feldspar. Four miles east, are large masses of granite on both sides of the Hoosack, and on ascending Hoosack mountain they become more numerous. The principal part of this is quartz, often of a purple colour; the mica black, and the rocks exceedingly hard. I have never noticed any minerals imbedded in it. The vortex of Pownal mountain is also granitic.
2. Gneiss and Mica Slate. I connect these two, because they are not often distinct, and appear to pass into each other. They are found in large strata on Hoosack Mountain, on a hill (L) connected with Saddle Mountain, and on the east side of Saddle Mountain. The highest and the west ridge of Saddle Mountain are mica slate. The Hopper shows the inclination of the strata quite to the base of the mountain. The inclination is to the east and northeast, from ten to forty degrees. On the southwest mountain of Saddle, the strata are bare to the summit for a considerable distance, and are very fine grained mica slate, having somewhat the appearance of a soapstone slate. By this name they are called in Mr. Eaton's Index to Geology. Some of the rocks appear to be talcose. I have been able, however, to detect but a very minute quantity of magnesia in any specimens I have tried, though I obtained a considerable proportion of alumine. The higher hills of the Taconick range are composed principally of a similar slate, lying in the same direction, and with similar inclination; but it appears to have passed still farther from mica slate. At the northwest corner of the state, which is near the foot of the ridge in this place, the rock is very similar to some of that on the southwest mountain mentioned above. About a mile northwest of this corner, the rocks are cleft in several places, and in one, to such a depth, that the snow and ice remain here through the year. The Snow Hole (M) is about thirty feet long, and nearly as deep at the east end, ascends to the west, or towards the summit of the ridge, and is from ten to twenty feet wide. When I visited it in June, the snow was six feet deep on ice of unknown depth. The rock is here passing into argillaceous slate; and in many places it becomes argillaceous and chlorite slate. For the other rock, you have, I believe, proposed the name talcose slate.
3. Quartz. Though quartz is scattered through all the preceding rock in masses of different sizes, it is found in great quantity on the northeast part of Saddle Mountain, 300 or 400 feet above the college, and thence to the Hoosack along the side of the hill (L.) It is granular, often white and translucent, and often coloured with oxyd of iron. It forms Stone Hill, (N) a mile southwest of the college, on the vertex of which is argillaceous slate. This hill slopes to West Brook, where quartz often forms perpendicular banks from 50 to 100 feet high. Here also argillaceous slate rests on the quartz, as well as on the vertex, and on the east side of Stone Hill. Quartz appears again on the opposite side of West Brook, but further north, on a hill connected with the Taconick range. On these two hills, it lies in large strata, inclining, like the mica slate, to the east and northeast, often divided by veins into rhomboidal masses. On the east side of Stone Hill, it is more granular, and may perhaps be called arenaceous quartz, containing a larger proportion of iron. Near the base of Hoosack Mountain, similar quartz is found, which extends round the north side of the Hoosack to Oak Hill, (D) which is wholly composed of it. It lies in rounded fragments, called hardheads, through the northern part of the valley, and on the sides of Oak Hill in huge rocks, presenting nearly perpendicular fronts from 20 to 50 feet in height, and many rods in length. The strata are in some places horizontal, and in others nearly perpendicular. In one place it forms plates, from 2 to 5 feet on a side, and from half an inch to several inches in thickness, which are nearly perfect rhomboids, the edges never being perpendicular to the sides. Most of the quartz, except the white, yields a small portion of lime, and has been called calcareous quartz. Greasy quartz, rose quartz, hornstone, and rock crystal, are occasionally found; the last in considerable quantity south of Stone Hill. On the stream which issues from the Hopper, is arenaceous quartz of a slaty structure, which is an excellent stone for sharpening the chisels used by stonecutters.
4. Granular Limestone is abundant at the Cave or Falls, in Adams, and on both sides of the Hoosack. The Cave or Falls, (O) is a singular chasm between limestone rocks. A small stream, which appears once to have run on the surface of the hollow between two small elevations, has now worn a passage many feet in depth through the limestone. The chasm is narrow, winding in its course several rods long, and its opposite sides were connected, till four years ago, by a natural bridge of limestone. From the bridge to the water is 70 feet. There is a dark cavern of several feet diameter, and some passages into the rocks. The white marble walls, the foaming of the water below, the piles and irregularity of the rocks, and the thick overhanging trees, make the scene very wild and interesting. The limestone rests on mica slate. On the west bank of the Hoosack, and east base of the hill, (L) the same coarse-grained and white limestone is found, resting on the mica slate at the west of it.
At the north and west base of Saddle Mountain, (E) and at a less elevation than the quartz, are extensive strata of limestone, inclining the same way as the mica slate of the mountain. It is less distinctly granular, and less white than the other, but belongs to the same rock. It forms tolerably good marble. Between the strata are crystals of carbonate of lime, rhomboidal, and tending to the lenticular form. Some of these strata appear to be composed of blended crystals of this kind. In one place are strata of several rods in length and breadth, which are inclined to the southwest, and thus lie against the mica slate of the mountain. The inclination is about forty-five degrees. Unless this limestone be connected with that on the east of Saddle Mountain, (and no connexion has yet been traced,) it must be considered as lying on both sides of the mica slate, or alternating with it.
5. Argillaceous Slate rests on quartz on Stone Hill, and is also found low down in the valley connected with limestone. It constitutes the hill (P) connected with the Taconick range, and also Northwest hill, (Q) whose base is compact limestone. A few miles north, this slate is distinctly marked, and in about 12 miles, forms hills of roof slate in Hosack, New-York. It is annually carried in large quantities to Albany. On the first-mentioned hill, it contains some talc.
6. Aluminous slate. This is found in argillaceous slate, in Pownal, 5 miles north, at the base of a hill east of the Hoosack. It is used to set colours.
7. Chlorite. In rounded masses, generally with quartz, scattered through the valley in Williamstown, and found at an elevation of some hundred feet on the hills of the Taconick range. Chlorite slate has already been mentioned as occurring on the same range.
8. Rubble Stone. In rounded masses through the valley.
9. Compact Limestone. In several places low in the valley. Near the college it is white and deep gray. In the veins of the latter, talc is diffused in all directions. It contains silex, often from 3 to 15 per cent., and sometimes gives fire with steel. In some cases it is earthy. On Green River, one and a half mile south of the college, it lies in thin strata, which are divided by seams into very regular rhomboidal plates of various sizes. On some scattered fragments on this river, are found carbonate of lime in crystals, with pieces of white feldspar. On West Brook, this gray limestone is traversed by a vein of quartz, containing sulphuret of iron. The strata of this rock are almost invariably inclined to the east. A coarse soapstone is found in the limestone near the college, and a vein made up of brown argillaceous slate, soapstone, quartz, and sulphuret of iron, passes through it. This limestone appears to be very different from that at the base of Saddle Mountain, and from that which yields the marble of Berkshire county. It may still be primitive, but primitive compact limestone.
10. Granitell of Kirwan, Quartz, and Feldspar. This aggregate forms extensive strata at the east base of Stone Hill. The feldspar is diffused in grains through the quartz, and sometimes crystalline, forming porphyritic quartz. This aggregate is often compact and very hard, but frequently it is porous and hard, forming good millstones. Sometimes the quartz appears in such fragments, that the stone resembles breccia.
11. Black Tourmaline. In beautiful small six-sided prisms, in scattered pieces of mica slate at the base of Stone Hill.
12. Amianthus. Only a small specimen, attached to argillaceous slate.
13. Bitter Spar. On compact limestone at West Brook. Some of the crystals are rhomboids, and some appear to be the half of rhomboids split through their longer diagonal.
14. Jasper. The common brown or red, and black, in small rounded masses, and also a piece of variegated or striped jasper.
15. Galena. Only a specimen in the limestone on West Brook.
16. Iron Ore. Bog ore on the Hoosack, a mile northeast of the college. Yellow earth, from which yellow ochre is obtained in great quantity, in a hill (R) on the bank of Green River, 2 miles south of the college.
At the north end of Saddle Mountain, but low down, yellow earth is connected with reddle, or a substance much resembling it. It is less hard than the common reddle, but is composed of the same ingredients.
Magnetic Oxyd of Iron, regular octahedrons, in mica slate at the base of Stone Hill.
Supersulphuret of Iron, massive and crystallized, in argillaceous slate, mica slate, compact limestone, and quartz.
17. Prase. Beautiful, and containing sulphuret of iron; lately found by Mr. Eaton, a little east of the summit of Hoosack Mountain, in Florida.
18. Puddingstone. Where Pownal Mountain reaches the Hoosack, (T) 3 miles north of the college, are some hills of this aggregate. It is composed of rounded masses of quartz, chlorite, and limestone, of various sizes, connected by an argillaceous cement.
19. Potters' Clay. Excellent for vessels of common pottery.
The minerals of this section, it is obvious, are not very important; but as connected with a transverse section of the country, they possess considerable interest. For this reason they have been particularly mentioned.
In the north part of Williamstown is a mineral spring, familiarly called the Sand Spring (S.) The water rises from several places in a reservoir of about a rod in diameter, and from one to three feet deep. It is very soft and warm, but contains very little saline or earthy matter. Gas continually rises in it. It appears much to resemble the spring at New Lebanon, New-York, and has proved useful in the cure particularly of some cutaneous diseases.
The transverse section, connected with the map, passes over Stone Hill, and the north part of Saddle Mountain. The different rocks are shown in the section, directly below their places on the map, by drawing lines from the several strata parallel to the sides of the map. This section is connected with that given by Mr. Hitchcock, in the 2d number of this Journal. It ought perhaps to be mentioned, that according to Mr. Eaton's account, the granite of this section sinks under gneiss to the east, and rises again in Hampshire County, "supporting the same rock of gneiss;" but where it reappears, the granite contains "many imbedded minerals." This section corresponds generally to the place and character of the minerals in any section across Berkshire county. There are, however, some peculiarities which may be mentioned at a future day. The colouring corresponds to that on the geological map in Cleaveland's Mineralogy.
C. DEWEY.
Williams' College, Jan. 27, 1819.
P.S. I have a part of a rock crystal, which contains, in a hollow, a liquid and a little air, and some black or brown particles, which just sink in the liquid. It was found several years since at Diamond Hill in Catskill. This hill is only a small eminence on the bank of the creek at that place, composed of limestone, (if I have been correctly informed,) between the strata of which, and on the side next the creek, this and other rock crystals were found. I believe, Sir, you have one like the above, obtained from the same place. The crystal, which was generously given me by Mr. Van Loon, who found it, is only a part of two crystals connected at their bases. Partly under one of the solid angles formed by the united pyramids, is the hollow, about ⅝ inch long, about ⅜ filled with the air, and about ¼ inch wide. The principal curiosity about it is the liquid. It has never been known to freeze. It was exposed yesterday morning an hour to an atmosphere 4 and 5 degrees below zero. It became less fluid, for the bubble of air moved with less ease and rapidity. Still the liquid was fluid. Its colour, which is naturally white, had a slight tinge of yellow. The Rev. Mr. Schaeffer of New-York supposes the black particles are bitumen. Is it possible the liquid is naptha? This oil is sometimes colourless, and does not congeal at zero, and that which I distilled from the Seneca oil, does congeal at some degrees below zero. It can hardly be salt water, unless it be very salt, and even then, it would have congealed at the temperature of the air yesterday. What way can be devised to ascertain what it is?
Jan. 30, 1819.
After seeing the notice of the crystals found at Hudson by Mr. Schaeffer, I wrote to a member of the Lyceum of Natural History, New-York, rather more full an account than the above, of my crystal, &c. I hope to ascertain, whether the liquid will congeal at 10 or 20° below 0, but have some fear lest the crystal should be injured.
C. D.