30 GEOLOGY OF OHIO. 
The theory advanced by Prof. N. H. Winchell, in his paper on the 
Drift of the North-west, published in the Popular Science Monthly for 
June and July, 1878, viz., that the Erie clay is a mass of dust or ditt, 
which gathered on the surface of the glacier and was dropped, as it 
melted, seems to me to be quite untenable, as there were no highlands 
surrounding the great ice-sheet from which the earth could be washed or 
blown on to its surface; and all material grasped by the glacier in its 
motion tends to work out below rather than at the surface, inasmuch as 
the glacier grows from above downward, melting below, and being re- 
newed by constantly recurring snow-falls above. It may also be said 
that no existing glaciers terminate in the manner suggested by Prof. 
Winchell—. ¢., in a thin, earth-covered edge—but they always end in 
an abrupt ice-wall. 
The glaciers of the Alps and Himalayas, those of Terra del Fuego, 
described by Agassiz, and those of Alaska by Blake, all tell the same 
story. The true counterparts, however, of the great glaciers now under 
consideration, are the continental glaciers of Greenland and the Ant- 
arctic. 
, THE FOREST BED. 
Allusions have frequently been made on the preceding pages to a sheet 
of vegetable matter which overlies the Erie clay in various parts of Ohio, 
Indiana, Illinois, etc. Buried timber has frequently been found in sink- 
ing wells and in other excavations in different parts of the valley of the 
Mississippi, but the connection and significance of the phenomena were 
first pointed out in the reports of the present Geological Survey. A great 
number of instances of the occurrence of buried timber, peat, and car- 
bonaceous layers in the Drift are given by different writers on geology. 
A few only of these can be cited here: 
1. oss County, Ohio. Wood, apparently cedar, from a well in clay 30 
feet from surface, 150 to 200 feet above Scioto river. (Col. Whittlesey.) 
2. Coventry, Summit County, Ohio. Muck and branches of trees, 42 feet 
beneath surface, in a well 544 feet above Lake Erie. (Col. Whittlesey.) 
3. Cleveland, Ohio. <A carbonaceous stratum, with many trunks of 
coniferous wood on surface of Hrie clay beneath 20 feet of sand, and gravel, 
and clay (Delta deposit), 50 feet above Lake Hrie. 
4. Hamilton County, Ohio. Thirty-five wells containing muck beds, 
leaves, or timber, from 800 to 500 feet above the Ohio. (Col. Whittlesey.) 
5 Oxford, Butler County, Ohio. An upright trunk and roots of a tree 
in blue clay, at the depth of 30 feet. (David Christy.) 
6. Highland County, Ohio. In the village of Marshall, eleven wells out 
