Art. I. Remarks on the Geology and Mineralogy of a Section of Massachusetts on Connecticut River.
Art. I. Remarks on the Geology and Mineralogy of a Section of Massachusetts on Connecticut River, with a Part of New-Hampshire and Vermont; by Edward Hitchcock, A. M. Principal of Deerfield Academy.
The geology of this tract, from a few miles south of Northampton in Massachusetts, to the north boundary of Brattleborough in Vermont, and of Chesterfield in New-Hampshire, is shown on the subjoined map. The primitive formation, except the argillite, is coloured vermilion; the secondary, blue; and the alluvial, gamboge yellow, according to Cleaveland. The alluvial part is elevated above the bed of Connecticut river from 10 to 100 feet, and, in most places, reposes on red sandstone. The soil in the northern part is generally argillaceous; but in the southern more siliceous. The secondary formation consists chiefly of detached eminences that rise abruptly from the plain, and are composed of red sandstone and puddingstone alternating, except the elevations A and B, (Holyoke and Tom) and a part of the range CD, passing through Deerfield and Greenfield, which are greenstone. The part coloured rose-red consists of argillite, sometimes alternating with mica slate, siliceous slate, or chlorite slate. It is thus coloured to show the extent of the argillite, and not from a belief that this rock is of the transition class; for in this region the argillite is undoubtedly primitive. Some quarries of this rock have been opened in Massachusetts; and in Vermont are extensively wrought. I have not learnt how far the argillite extends northward in Vermont and New-Hampshire. Its strata are almost perpendicular, inclining a few degrees to the west.
The primitive region on the west side of Connecticut river, included by the map, is made up of mica slate, as a prevailing rock, particularly in the northern part. Hornblende slate sometimes alternates with this, and sienite appears in various places, though its strata are generally thin. Limestone also occurs in Deerfield, Conway, Colrain, &c. of a dull brown colour. It contains so large a proportion of silex that it is often but little removed from granular quartz. Lime for building has sometimes been obtained from it. A range of granite, containing veins of lead ore, appears at Southampton, and proceeds to Hatfield. North of this, the other rocks cover it, and it does not again rise within the limits of the map.
Sienite is the prevailing rock on the east side of Connecticut river in the primitive region, more particularly in the southern part. In some places a narrow stratum of mica slate lies next to the conglomerate of the secondary formation, and a low range of graphic and common granite has been observed in Amherst and Leverett, lying next to the mica slate. Other veins of granite also traverse the sienite; and gneiss occurs in many places. The proportion of hornblende in the sienite is generally small, and mica is often present in considerable proportion. Porphyritic sienite is common in this quarter, and steatite occurs in its eastern part.
Most of the primitive region on the map is broken and mountainous, being made up of parallel ridges and detached eminences. The strata run nearly north and south, and dip to the east at angles between 20° and 60°. It would be easy to extend the map on the west to the top of Hoosack mountain, since the country is all primitive; and on the east the primitive continues, with a few exceptions, to the ocean. The map might also be extended to the boundary of Connecticut, by prolonging the primitive ranges with some divergency, and colouring the intermediate space secondary, except a narrow tract on the east side of Connecticut river, which is alluvial. These extensions were not thought necessary.
In the town of Gill, at E, there is a cataract in Connecticut river, from 30 to 40 feet in height; and it is believed that the alluvial region, and part of the secondary shown on the map from this fall to the place where the river passes between mount Holyoke and Tom, was formerly the bed of a lake: for the logs are still found undecayed in many places, from 10 to 20 feet below the surface; the river has evidently worn a passage between Holyoke and Tom: many of the hills on the northern part, and the sandstone on the plain, bear the marks of having been washed by water, and the channels of two rivers are still visible in Deerfield, the one 30, and the other 100 feet above the present bed of Connecticut river. Between mount Tom and the mountains west, there is a secondary plain of sufficient height to throw back the water over the supposed bed of the lake, before a passage was worn between Holyoke and Tom. South of these hills commences another alluvial and secondary tract, extending on both sides of the river to Haddam, in Connecticut, where the river passes between mountains, and perhaps this region also was the bed of a lake.
The plain on which the village of Deerfield stands, with the adjoining meadows, is sunk 50 or 60 feet below the general alluvial tract, and was undoubtedly the bed of a pond, or small lake, that remained after the larger one of which we have spoken had subsided. When this larger lake decreased, Deerfield river was cut off from a communication with the Connecticut by the mountain CD, and the plain extending westward from this mountain. There is a tradition, derived from the aboriginals of Deerfield, that the passage in which Deerfield river now runs through the mountain CD, was begun by a squaw with a clam-shell.
On the margin of these meadows, at considerable elevation, numerous small conical excavations appear. On digging below the surface, stones are found calcined by fire. These are probably the spots where Indian wigwams formerly stood. Many vestiges of the aboriginals are frequently found in Deerfield, such as beads, stone pots, mortars, pipes, axes, and the barbs of arrows and pikes. Near the village they had a burial-ground, where many skeletons have been uncovered. A roll of human hair was lately found here, by Mr. J. C. Hoyt of Deerfield, three-fourths of an inch in diameter, and three inches long, closely tied by a string made of the hide of some animal, which string was encircled by brass or copper clasps greatly oxidized; but the hair and string were in a good state of preservation, though they must have lain there more than a century. In the meadows, logs, leaves, butternuts, and walnuts are found undecayed, 15 feet below the surface; and stumps of trees have been observed at that depth standing yet firmly where they once grew. In the same meadows, a few years since, several toads were dug up from 15 feet below the surface, and three feet in gravel. They soon recovered from a torpid state, and hopped away.
The small range of hills beginning at the south line of Deerfield, and terminating in Gill, deserves description. At its commencement on the south, a conical hill, called Sugar Loaf, of red conglomerate, rises abruptly from the plain 500 feet. The appearance of this hill, as you come from the south, is picturesque, and it is an interesting feature of the country. The range becomes higher for three miles, where, at its greatest elevation, it is 730 feet above the bed of Deerfield river. The west side of the mountain is precipitous, and in some places naked. The ascent on the other side is gentle.
Both sides of this hill are sandstone and puddingstone, frequently alternating: though these are most extensive on the west side, and as we rise the puddingstone predominates. The strata dip to the east about 10 degrees. Near the centre of this range is a ridge of greenstone, with a mural face on the west, and amorphous masses lying at the base, half way up to its summit. This ridge does not rise so high as the puddingstone on the west of it, as may be seen in the view of strata with the map. It commences on the west bank of Connecticut river, about a mile north of the hill C, and increases in elevation nearly to the spot where it disappears at the fall of the river in Gill. This rock does not appear to rest on sandstone, but to descend through it, where there is an opportunity for observation. Deerfield river has worn a passage through the sandstone and greenstone 150 feet deep, and the greenstone passes under its bed, and the sandstone, at a few rods distant lies on each side of the greenstone. A similar fact has been noticed at the fall in Connecticut river, in Gill. Yet I have coloured this greenstone secondary on the map; for it is certain that Mount Tom rests on sandstone, and it is stated by Professor Silliman, that the same rock does in Connecticut. Could we penetrate deeper below the surface, it is probable the same would be found to be the case with this greenstone.
As stated above, this rock disappears near the cataract in Gill, and it is succeeded by puddingstone. But four miles farther north, it again emerges in Bernardstone, though it rises but little above the surface. Here its character is changed. The hornblende is more crystalline, and the rock becomes decidedly primitive, as you approach a mountain of argillite and mica slate, into which it passes, and no greenstone has been observed north of this. It terminates not far from the line of Vermont. The red sandstone and conglomerate also terminate on the opposite side of the river in Northfield.
The greenstone in the above described range, is of a finer texture than the same rock in Connecticut; and the feldspar, in some specimens, is scarcely discernible with a microscope. Indeed, in many instances, the eye would decide the rock to be basalt. Much of it is fissile, the laminæ varying from half an inch to a foot in thickness. This is most perceptible among the loose masses; but it exists also in that in place. Whether this circumstance be accidental, I will not attempt to decide.
A large proportion of the greenstone of our vicinity constitutes the base of amygdaloid. The imbedded substances are calcareous spar, quartz, chalcedony, analcime, prehnite, &c. as will be more particularly mentioned hereafter. Globular concretions of greenstone are common in this amygdaloid, several inches in diameter, and of greater specific gravity than the other parts of the rock. A great number of columns occur in the same range, having from three to six sides. Some of them are quite regular, and are well articulated, exhibiting at their joints considerable concavities and convexities. They are from one to thirty feet long, and, in their natural position, incline a few degrees to the east, as may be seen in the view of strata with the map; A few have been noticed that make lateral curves. One of these hexagonal columns measures at one end as follows:—Diagonals, 27, 29, and 29½ inches; sides, 16½, 13¼, 11½, 17, 11½, and 16½ inches. The convexity of this column is a little more than an inch. The best instances of these prisms occur one mile east from the village of Deerfield.
Masses of greenstone are found at considerable distance from the range, among the puddingstone. One has been noticed weighing many tons, a hundred rods from the range of greenstone, and on much higher ground. Some of these scattered fragments contain chalcedony. A specimen of petrosiliceous porphyry has been found among the same puddingstone, and also a mass of singular, though not well defined, amygdaloid, whose base is similar to wacke, and imbedded substances are calcareous spar, chlorite, and green earth.
The elevation in the north part of Sunderland, called Toby, from 800 to 900 feet high, is chiefly conglomerate, red, brown, or greenish, which, in some parts, alternates with chlorite slate, secondary argillite, and a sandstone that seems to be passing into gray wacke slate. Some of the imbedded masses in this puddingstone are quite large, its cement is frequently calcareous, its aspect is singular, and it is very different from the puddingstone before described, On the opposite side of the river. At the foot of this mountain, in the bottom of Connecticut river, distinct impressions of fish are found on a schistose rock, like the one above mentioned as passing into gray wacke slate. This same species of slate occurs in several other places at the bottom of Connecticut river, as at the fall in Gill. In this last place bituminous shale has been noticed.
In Mount Toby, in Sunderland, is a cave nearly 150 feet above the bed of Connecticut river. It opens to the north and west, forming a quarter of a circle, is 130 feet in extent, 60 feet deep, and from 3 to 20 wide. A little to the south of it, is a fissure in the puddingstone, formed by a separation of the rock, ten feet wide, and as deep as the cave. So perfect is this division, that it appears as if cloven down by the sword of some Titan. Perhaps this cave and fissure were formed by the washing of the waters of the lake we have mentioned on the sandstone and conglomerate beneath; thus causing the superincumbent rock to fall and separate. There is no appearance of any other convulsion. Imperfect, calcareous stalactites are found in this cave.
The falls in Connecticut river, at E, are not unworthy of notice. The river here is about 40 rods wide, and the height of the main cataract, raised considerably by an artificial dam, is 30 feet. The fall continues two miles. On the north bank you view the cataract from elevated ground, and can see the river nearly a mile above and below—above, perfectly smooth and calm, below, forming a quarter of a circle, and tumbling among the broken rocks. On the opposite side of the river are a few buildings, the commencement of a canal, and, behind these, moderately elevated hills, covered with woods. Two rocky islands near the middle of the descending sheet, and another thirty rods below, add much to the beauty of the view. Looking from the southeast shore, you have a partial prospect of the falls, and a view of an amphitheatre of greenstone hills, through which a small river empties. The pleasure derived from the view proceeds more from its wildness than its sublimity.
The position of the hills, boundaries, and rivers, on the accompanying map, may not, in all cases, be precisely correct. The general outlines were enlarged by a pentegraph from Carleton's map of Massachusetts, and the intermediate objects were placed chiefly by the eye; their relative situations being determined by travelling over the ground, and viewing them from different elevations. The boundaries of the several formations have not been so carefully noticed near the angles of the map as in the central parts. Of their correctness generally, however, I am confident. The latitude and longitude of Deerfield, from which those on the map were marked, were obtained by taking a mean of the observations given by Gen. E. Hoyt, in the Transactions of the American Academy of Arts and Sciences, and of twelve lunar observations since made. The result is, Lat. 42° 32' 32". Long. 72° 39' from Greenwich.
With the map is given a view of the strata of rocks from Hoosack mountain to eleven miles east of Connecticut river, on a line nearly east and west, passing through Deerfield. The horizontal distances are laid down from a scale: the elevations are assumed. The principal rocks only are coloured; for it is very difficult to determine the breadth of many, since they frequently alternate with one another. I have not examined the country on the east side of Connecticut river with sufficient care to be able to extend the section on that side more than a few miles.
It may not be amiss to mention, that Mount Holyoke, so much celebrated for the delightful view from its top, has been found, with a sextant, to be 830 feet above Connecticut river. Its height has been frequently overrated.
The mineralogy of this section of the country has been but imperfectly explored. I shall mention those minerals only of which I have obtained specimens, and whose localities have not been noticed by mineralogists.
Quartz—several varieties.
1. Rock Crystal—abundant. Some good specimens are found in Conway, on feldspar, with the usual hexagonal, prismatic crystals, and these crystals cross each other in all directions.
2. Irised Quartz—found in Leyden.
3. Granular Quartz—in Deerfield.
4. Radiated Quartz—in Whately and Shelburne.
5. Blue Quartz—in rolled masses on the banks of Deerfield river.
6. Greasy Quartz—in same place.
7. Pseudomorphous Quartz—in greenstone, Deerfield.
8. Lamellar Quartz—in same place. The laminæ sometimes penetrate crystals of common quartz.
9. Tubular, or Pectinated Quartz—in same place.
10. Quartz Geodes—in same place.
Prase—in the north part of Sunderland. (Not good specimens.)
Amethyst—in Greenstone, Deerfield: the colour is not deep, but delicate.
Chalcedony—in same place—considerably abundant, but generally in small masses.
Carnelian—in same place, not plenty. The chalcedony, in some specimens, seems to be passing into cacholong, and the carnelian into sardonyx.
Agate—in same place. It is made up of chalcedony, carnelian, and quartz. They are generally small, but some are elegant.
Jasper, red, and yellow—found in rolled masses on the banks of Deerfield river and in Leyden. Some have been found imperfectly striped. It occurs frequently as it was formed by the aboriginals into barbs for pikes and arrows.
Petrosilex—on the banks of Deerfield river—not good specimens.
Feldspar—the red variety occurs in puddingstone, Deerfield. It is not necessary to mention any other locality of a mineral so common.
Hornblende—very abundant—mostly black in this vicinity.
Mica—this is very abundant on the east side of Connecticut river. Some crystals of it have been found in Amherst.
Talc—in Shutesbury.
Steatite. The localities of this are seen on the section. The aboriginals formed many articles from this mineral, as pots, pipes, &c.
Chlorite—in Shutesbury: also in amygdaloid, Deerfield. In Deerfield academy there are some Indian pipes of this mineral, well wrought.
Green Earth—in small quantities, in amygdaloid, Deerfield.
Schorl—the black variety occurs in Pelham, Shutesbury, and Orange, Mass., and in Brattleborough, Vermont.
Epidote—in Deerfield, Shutesbury, Leyden, and Pelham, and in Athol, Worcester county. The specimens poor.
Tremolite—in the west part of Leyden, near Green river. The rock in this region is chiefly mica slate, and the quantity of tremolite is very great. Tons of it might be easily collected.
Cyanite, or Sappare—in Deerfield, in mica slate; discovered by Dr. S. W. Williams.
Actynolite—rare, found in Shutesbury.
Serpentine—found in Leyden in rolled masses. Some of the specimens admit a fine polish, and the ground is handsomely variegated. It has not been noticed in situ.
Asbestus—compact, in Pelham.
Garnets—very plenty in Conway, Deerfield, Shelburne, &c. Good specimens of the melanite occur in Conway.
Native Alum—in Leyden, in small quantities, efflorescing on argillaceous slate.
Sulphur—in Conway, Shelburne, and Warwick, efflorescing on mica slate.
Prehnite—in greenstone, Deerfield, encrusting the columns and in radiated masses, but rarely crystallized. The veins of it, when in place, are nearly perpendicular.
Zeolite—in same place, not abundant. Some good specimens of the radiated variety are found.
Chabasie—in same place, considerably abundant. No crystals have yet been found whose sides exceed a quarter of an inch. It occurs in the veins of the greenstone, in geodes, on balls of zeolite, on chalcedony, on lamellar quartz, &c.
Stilbite—in same place, not abundant. It is commonly associated with chabasie, and the crystals, though small, are well defined.
Analcime—in same place, very abundant, and is associated with quartz and amethyst, which are sometimes enclosed by analcime. It generally occurs in cylindrical, reniform, and radiated masses. A few perfect crystals only have been observed.
Laminated Calcareous Spar—in the same place, not uncommon.
Chalcedony, carnelian, agate, amethyst, prehnite, zeolite, chabasie, stilbite, and analcime, have been found nearly in the same place; and it may not be amiss to observe, that this spot is distant from Deerfield Academy about one mile, and bears from the same, by a true meridian, E. 2°, 15′ S.
Iron Sand—found in considerable quantity near the falls in Connecticut river, on the Montague shore.
Sulphate of Iron—in Conway, in small quantities, efflorescing on mica slate.
Sulphuret of Iron—in Halifax, Vermont, in abundance; also in Charlemont, Mass., Deerfield, &c.
Magnetic Oxide of Iron—very common in the region west of Connecticut river. I have observed it in Athol, Worcester county.
Specular Oxide of Iron—some veins of this ore occur in Hawley, Bernardstown, and Warwick, and have been wrought to a small extent.
Micaceous Oxide of Iron—in the iron mine in Hawley.
Green Carbonate of Copper—in greenstone, in Greenfield. This ore constitutes a vein on the bank of Connecticut river, passing into the hill on one side, and under the river on the other. It has never been wrought, nor, indeed, is its locality publicly known.
Copper Pyrites—in the same vein, not abundant, at the surface.
Sulphate of Barytes—in the same place, constituting the immediate walls of the vein. Its breadth on the wall varies from an inch to a foot, and the breadth of the vein is 6 or 8 feet.
Galena—in Whately. This is probably from a continuation of the vein of this ore that appears at Montgomery, Southampton, and Hatfield. A single crystal has been found in the same range, in Greenfield, twelve miles north of Whately; but it was not in place.
Red Oxyde of Titanium—in Leyden, crystallized on quartz and tremolite, chiefly on the latter; colour brownish red—specific gravity 4.232; scratches glass, handsomely geniculated, and sometimes several geniculations in the same specimen; in one as many as six could be perceived.
Eagle Stone, or Nodular argillaceous Oxide of Iron—one specimen on the banks of Deerfield river.
Rose-red Quartz—a loose mass in alluvial soil, Deerfield.
Red Oxide of Titanium—in Shelburne.
I would acknowledge my peculiar obligations to Professor Silliman, of New-Haven, and to Dr. David Hunt, of Northampton, Mass. for the very generous assistance they have given me in a commencement of the study of mineralogy, and for their liberal aid in this particular communication. Their kindness, it is believed, will not soon be forgotten. To several others, also, I am indebted for communicating facts of importance.
Deerfield, October, 1817.