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, 1873, viz., that the Erie clay is a mass of dust or dirt, 

 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 — i. e., 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. Ross 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 Erie clay beneath 20 feet of sand, and gravel, 

 and clay (Delta deposit), 50 feet above Lake Erie. 



4. Hamilton County, Ohio. Thirty-five wells containing muck beds, 

 leaves, or timber, from 300 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 



