44 



GEOLOGY OF OHIO. 



contributed largely to the formation of the masses of loose material ; and 

 in Stark county the compact and tough Coal-Measure limestones have 

 supplied many of the rounded bowlders and gravel stones. In the 

 western portion of the State, the limestones that form the Cincinnati 

 arch have sometimes furnished nine-tenths of the materials composing 

 the kames. Mingled with these native rocks, however, we often find a 

 large, frequently a preponderating, number of representatives of the crys- 

 talline or palaeozoic rocks of the country north of the lakes, viz., granite, 

 greenstone, quartzite, silicious slate, crystalline limestone, and also peb- 

 bles and fossils of the Silurian and Devonian rocks of the varieties found 

 in Canada and not in Ohio. These transported masses are generally 

 small, well rounded, and never, so far as I have observed, scratched or 

 ground like the pebbles and bowlders of the Erie clay; much of which is 

 true glacial Drift. In one or two instances, native copper, evidently from 

 Lake Superior, has been found in these gravel beds. The arrangement 

 of the materials in the kames is irregular, but it generally shows plain 

 indications of the action of water. Sometimes its stratification is quite 

 distinct, and bands of gravel and sand succeed each other in nearly per- 

 fect horizontality and parallelism. In such cases the deposits are spread 

 over a large area, and where cut into hills and tables, are plainly the 

 portions of once continuous and somewhat extensive sheets. Here we 

 may conclude that the materials are rearranged, having been washed 

 down from higher levels and spread by the action of shore-waves and 

 currents. 



The " hog's-backs " and more well-defined hills of the kames usually 

 show oblique and irregular stratification ; beds of sand, gravel, and occa- 

 sionally of bowlders, alternate, but the sheets are rarely horizontal, and 

 they interlock by wedging. The sand beds are also frequently cross- 

 stratified. I give below a section of Buck Hill, Stark county, as a good 

 illustration of the structure of our kames. It is 40 feet high, and its 

 base is 560 feet above Lake Erie. 



PROFILE SECTION OF BUCK HILL, STARK COUNTY, OHIO. 



A, sand. B, gravel, sand, and bowlders. C, sheets of sand. 



