of Lake Erie. Through the interest aroused in them by an excursion of the American Association for the Advancement of Science, while meeting in Cleveland, Ohio, in 1888, the Kelly Island Lime and Transport Company, of which Mr. M. C. Younglove is the president, has been induced to deed to the Western Reserve Historical Society for preservation a portion of one of the most remarkable of the grooves still remaining.

The portion of the groove preserved is thirty-three feet across, and the depth of the cut in the rock is seventeen feet below the line, extending from rim to rim. Originally there was probably here a small depression formed by preglacial water erosion, into which the ice crowded the material, which became its graving-tool, and so the rasping and polishing went on in increasing degree until this enormous furrow is the result. The groove, however, is by no means simple, but presents a series of corrugations merging into each other by beautiful curves. When exposed for a considerable length it will resemble nothing else so much as a collection of prostrate Corinthian columns lying side by side on a concave surface.

The direction of these grooves is a little south of west, corresponding to that of the axis of the lake. This is nearly at right angles to the course of the ice-scratches on the summit of the water-shed south of this, between the lake and the Ohio River. The reason for this change of direction can readily be seen by a little attention to the physical geography. The highlands to the south of the lake rise about seven hundred feet above it. When the Ice period was at its climax and overran these highlands, the ice took its natural course at right angles to the terminal moraine and flowed southeast according to the direction indicated by the scratches on the summit; but when the supply of ice was not sufficient to overrun the highlands, the obstruction in front turned the course and the resultant was a motion towards Toledo and the Maumee

FIG. 35.-Same as the preceding. (Courtesy of M. C. Younglove.)

Valley, where in the vicinity of Fort Wayne an extensive terminal moraine was formed.

The much-mooted question of a succession of glacial epochs finds the most of its supporting facts in the portion of the glaciated area lying west of Pennsylvania. That there have been frequent oscillations of the glacial front over this area is certain. But it is a question whether the glacial deposits south of this distinct line of moraine hills are so different from those to the north of it as to necessitate the supposition of two entirely distinct glacial epochs. This can be considered most profitably here.

The following are among the points with reference to which the phenomena south of the moraine just delineated differ from those north of the line:

1. The glacial deposits to the south appear to be distributed more uniformly than those to the north. To the north the drift is often accumulated in hills, and is dotted over with kettle-holes, while to the south these are pretty generally absent. Any one travelling upon a line of railroad which traverses these two portions of the glaciated area as indicated upon our map can easily verify these statements.

2. The amount of glacial erosion seems to be much less south of the line of moraine hills delineated thar north of them. Still, glacial striæ are found, almost everywhere, close down to the extreme margin of the glaciated

area.

3. The gravel deposits connected with the drainage of the Glacial period are much less abundant south of the so-called "terminal moraine of the second Glacial period" than they are north of it. South of this moraine the water deposits attributed to the Glacial period are of such fine silt as to indicate slow-moving currents over a gentle low slope of the surface.

4. The glacial deposits to the south are more deeply

coloured than those to the north, showing that they have been longer exposed to oxidising agencies. Even the granitic boulders show the marks of greater age south of this line, being disintegrated to a greater extent than those to the north.

5. And, finally, there occur, over a wide belt bordering the so-called moraine hills of the second Glacial epoch, extensive intercalated beds of vegetal deposits. Among the earliest of these to be discovered were those of Montgomery County, Ohio, where, in 1870, Professor Orton, of the Ohio Survey, found at Germantown a deposit of peat fourteen feet thick underneath ninety-five feet of till, and there seem also to be glacial deposits underneath the peat as well as over it. The upper portion of the peat contains "much undecomposed sphagnous mosses, grasses, and sedges, and both the peat and the clayey till above it" contain many fragments of coniferous wood which can be identified as red cedar (Juniperus Virginianus). In numerous other places in that portion of Ohio fresh-appearing logs, branches, and twigs of wood are found underneath the till, or mingled with it, much as boulders are. Near Darrtown, in Butler County, Ohio, red cedar logs were found under a covering of sixty-five feet of till, and so fresh that the perfume of the wood is apparently as strong as ever. Similar facts occur in several other counties in the glaciated area of southern Ohio and southern Indiana. Professor Collett reports that all over southwestern Indiana peat, muck, rotted stumps, branches, and leaves of trees are found from sixty to one hundred and twenty feet below the surface, and that these accumulations sometimes occur to a thickness of from two to twenty feet.

Farther to the northwest similar phenomena occur. Professor N. H. Winchell has described them most particularly in Fillmore and Mower Counties, Minnesota, from which they extend through a considerable portion of

Iowa. In the above counties of Minnesota a stratum of peat from eighteen inches to six or eight feet in thickness, with much wood, is pretty uniformly encountered in dig

FIG. 36.-Section of till near Germantown, Ohio, overlying thick bed of peat. The man in the picture stands upon a shelf of peat from which the till has been eroded by the stream. The dark spot at the right hand of the picture, just above the water, is an exposure of the peat. The thickness of the till is ninety-five feet. The partial stratification spoken of in the text can be seen about the middle of the picture. The furrows up and down had been made by recent rains. (United States Geological Survey.) (Wright.)