The altitude here is about 1200 feet, or 100 feet above the valley. In eastern Madison, altitude about 1600 feet, extensive heaps are composed wholly of pieces but few inches in size, and at least 99 per cent are from the local Hamilton. This freedom from outside material, with limited exceptions, is characteristic of the higher altitudes of the whole region. A similar estimate in Hamilton, choosing all fragments in a large heap, above one foot diameter, gave!:

Oneida and Medina were present but all smaller, likewise the Hamilton, while the larger Oriskanys from the same field, as was learned, had been buried. The cases cited represent more than the average prevalence of the Archæan in number, while in mass, the Oriskany would outrank the Archæan by many hundred per cent.

In the town of Eaton, near Hamilton, one northern piece, well-rounded, measured 9×7×6 feet. This is the largest Archæan bowlder observed by the writer south of the Mohawk River. In 90 miles traversed in the towns of Madison, Hamilton, Eaton and Lebanon, less than a dozen Archæan masses were observed having average diameters of four feet or more. From Earlville to Smyrna no Archæan was seen above 2×21 feet. At Smyrna, there is a morainic accumulation of considerable extent. A 60-foot section is exposed showing discordant beds of sand and coarse gravel, with 6 to 12 feet of till containing coarse, angular local material, at the top. 100 pieces from a heap rejected in procuring gravel, ranging from the size of one's fist to five or six inches, gave the following count:

Oneida

Clinton

Doubtful, perhaps Hudson River or Clinton
Doubtful, probably Potsdam and Medina.

Helderberg limestones

Hamilton (subjacent)

2

3

10

8

26

51

100

AM. JOUR. SCI.-THIRD SERIES, VOL. XLIX, No. 291.-MARCH, 1895.

No Archæans appear in the count. They were rare in the section. Only one seen attained a diameter of one foot. About Norwich and South New Berlin Archæans even of one foot diameter are few. Two, measuring 1 and 2 feet respectively, were the largest seen. A three foot piece, probably Archæan, was reported to me from near South New Berlin. This, however, had been broken up and removed. At Oxford the kames and terraces, rising 100 feet from the valley bottoms, contain the usual proportion of Archæan pebbles. Farther up, near the quarries of the F. G. Clarke Bluestone Company, heaps and walls containing many hundred cords of cobbles and bowlderets, do not show above one-thousandth part of material older than the Hamilton, that is, of fragments carried 40 miles or more.

The same dearth of distant material is evident on all the hillslopes about Unadilla and Bainbridge on the Susquehanna, and Greene on the Chenango. At the last named place 13 miles of fence wall above the 100 foot level, were observed without detecting a single Archæan fragment. At Binghamton, Archæan was found to the height of about 600 feet on the slopes south of the Susquehanna, but no pieces were above a few inches in diameter.

These facts regarding distribution in southern New York are fully in harmony with the facts reported from the adjacent part of Pennsylvania.*

Oneida Conglomerate. This is a mass 30 to 40 feet thick in the hills two miles south of Utica, thickening somewhat to the westward. Some layers are mainly composed of rounded quartz pebbles, while others consist of coarse sand. The altitude of the ledge is about 1000 feet near Utica, but drops with the S. W. dip to 620 feet one mile north of Clinton. The conglomerate is one of the most persistent members of the bowlder drift in central and southern New York, though the fragments are rarely numerous, or large. The exception to the latter statement is found within a few miles of the outcrop, as on the northern slope of Paris Hill, where slabs of 4 to 6 feet in length and breadth are not uncommon. In southern Oneida and Madison Counties, any large heap or wall is quite sure to yield small samples, usually not above eight inches in diameter. Only about a dozen were noted, after passing 10 miles from the outcrops, having cubic contents of more than one foot each. One 15-inch Oneida was found at Oxford. Pebbles and small cobbles occur at Binghamton. The falling off in size is much more gradual than in the case of

*See H. C. Lewis and G. F. Wright, 2d Geol. Surv. Pa., Rep. Z, p. 13.

Reckoned 100 feet thick in generalized central N. Y. section, see C. S. Prosser, Bull. G. S. A., vol. iv, p. 110.

the Oriskany sandstones. These bowlders occur at all altitudes and some have been elevated considerably within moderate distances. The Oneida fragments, at their greatest height in northeastern Madison, have been lifted 600 feet in 14 miles, if we consider them to have come from the highest point in the outcrop. It is more probable that they came from a locality which would require an elevation of 800 feet in 10 miles.

Scale 4 miles to the inch. Dotted line gives the base of main valley walls. Divides at Waterville, Bouckville and Pratts. Oriskany and Helderberg ledges at A. Altitudes of L and M approximate those of D and K.

The bowlderets are commonly more rounded to the southward, though to this there are notable exceptions, perhaps due to splitting in transit.* It was hoped that Oneida fragments north and south of the moraine would afford interesting comparisons as to amount of discoloration and disintegration since the time of deposit. No such result was realized. It is thought

*See N. S. Shaler, Bowlder Train from Iron Hill, Bull. Mus. Comp. Zool., vol. xvi, No. 11, p. 199.

SANGERFIELD

that the variable amount of iron pyrites in the Oneida beds, occasioned the breaking up, or discoloration of some pieces, while others, shaped and deposited at an earlier date, show no signs of change.*

Lower Helderberg.-The limestones are deeply cut by the several valleys at about the position of the moraine belt in each, though not in all cases does the terrane outcrop above the glacial debris, except farther to the north on the hill sides and summits. At Oriskany Falls, 120 feet of these beds are exposed on the west side of the valley, in quarries and natural ledges. 40 feet are massive beds, the rest thin, two to six inches in thickness. The limestone is found not infrequently in slabs and rounded masses up to four feet in breadth or diameter. This is true for only six to eight miles from the outcrop; and it is only for this distance that the limestone occurs at high levels. From Hamilton southward, the fragments are small and almost confined to the gravel trains, terraces and kames of the valleys, rarely occurring above 100 feet from the valley bottoms. The possible causes of this distribution will receive further inquiry after an account of the Oriskany sandstone has been given.

Oriskany Sandstone. The outcrop, from which the New York geologists named this terrane, is found one half mile north of Oriskany Falls, near the town line of Augusta and Marshall, Oneida County. It appears in a continuous ledge, three fourths of a mile long and 125 feet above the Oriskany Creek, the valley wall rising still 400 feet to the westward. Below it lie 120 feet of Lower Helderberg, and above are 50 feet or more of Corniferous. The hill range is capped with Marcellus and Hamilton. The general trend of the ledge is S. 23° W. The sandstone stands out to its full thickness, 12 feet at the north, thinning to 7 or 8 feet at the south, and dipping southward about 47 feet per mile. Below the sandstone on the valley side, is a broad shelf of Lower Helderberg. The sandstone forms a shelf about 5 rods wide, quite bare except where disintegration has taken place, making a slight cover of soil and vegetation. The rock is a coarse grained, grayish white sandstone, weathering to yellowish brown, with certain zones full of pockets from which the characteristic fossils have disappeared by solution. There are two sets of joints, S. 38°-48° E. and S. 33°-38° W. The joint blocks average 10 to 20 feet in breadth and length, and are often set off, from a few inches to several feet. There is no distinct bedding plane except at the top and bottom of the mass. The passage from the limestone below, and to the limestone above, is sharp, and the

*Suggested to the writer by Professor C. H. Smyth, Jr.

abundant springs issuing on these planes suggest the setting off of the blocks by freezing. But some lie in positions in which only glacial plucking could have placed them.

The shelf of Lower Helderberg, varying from 40 to 80 rods. in width and sloping gently to the eastward, has been swept clear of the overlying Oriskany. Evidently the power to pluck ceased more abruptly than the power to transport. But the outmost blocks of the ledge were considerably pared off by grinding action after their neighbors had been carried away. The general movement of the ice was slightly off the ledge to the eastward. The lower ice, which accomplished the plucking, may have swerved to the east locally on this rather steep valley wall, thus increasing the otherwise slight angle between the line of movement and the line of the ledge. Doubtless by weathering along the joint planes, and by solution of the upper surface of the subjacent limestone, as seen under the present ledge, the blocks had been loosened and plucking thus facilitated. Even with this assistance it is puzzling to understand how blocks of some scores of tons weight could be handled, with so little purchase as seems to have been possible.*

The Oriskany valley runs N. 60° E. from the divide to Oriskany Falls, and thence N. N. E. toward the Mohawk. We have here ideal conditions for seeing how ice behaves in crossing a valley diagonally. Our best data are afforded by the transport of large blocks from the above described ledge. The striæ so far as found, and certain glacial flutings on the hills, support the evidence furnished by the travelled blocks. These bowlders were noted by Vanuxem :†

"The Oriskany sandstone first appears out of place and at a higher level in Grout's quarry, amongst the drift, or alluvion on the top of the Onondaga limestone, the thickness of the Cauda-galli Grit and Onondaga Limestone being the difference of its original position and the top of the quarry. The sandstone showed characters of a local origin. The same sandstone is found in great abundance and immense blocks, scattered over the hills in the towns of Madison, Eaton, Hamilton and Lebanon, being more numerous toward the valley of the Chenango canal. They appear on the side-hills, but few hav ing been noticed toward the middle of the valleys. All the blocks there seen were the counterpart of the mass at Oriskany Falls, being readily recognized from local differences in the rock, prevailing at all its points of outcrop." At page 127, Vanuxem speaks again of the frequency of the bowlders in the towns named and adds,-" In smaller masses it has been

*See however T. C. Chamberlin, Rock Scorings of the great Ice Invasions, 7th Ann. Rep. U. S. G. S., p. 193.

† Geol. 3d Distr., N. Y., pp. 127, 222–223.