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.