134 THE JOURNAL OF GEOLOGY. 



bed and soil are terms which are used interchangeably in the Ohio 

 Geological Reports. It ought also to be stated in this connec- 

 tion that a few miles to the north a buried soil occurs beneath 

 the till, but it lies within the district covered by a later invasion 

 of the ice, and the horizon is, I am convinced, above that of the 

 one in question. There is also a soil above the yellow till of 

 this earlier drift sheet which is buried by a silt deposit, as 

 described below. I feel, therefore, that it is necessary to refer 

 to different horizons the instances that have been reported from 

 south-western Ohio. 



Deglaciation interval zvith developmoit of a soil attended by 

 oxidation, leaching and erosion of the earlier drift sheet. 

 Except where erosion has removed it a capping of silt several 

 feet in thickness is found upon the surface of this till sheet. It 

 is clearly of much later age than the till, being separated from 

 it by a sufficient interval for the development of a soil, and for 

 a large amount of oxidization and leaching and erosion. This 

 silt is discussed below. 



The soil which was developed on this till sheet does not 

 commonly show a black color, though exposures of such a soil 

 color are met with in all parts of the district outside the outer 

 moraine. The evidence of a land surface is more generally 

 found in the deep brown color, and weathering or soil-producing 

 disintegration of the upper part of the till. The deep brown 

 changes gradually below to the ordinary yellow color of oxidized 

 till, but at top it terminates abruptly at the base of the over- 

 lying silt. The color of the silt being much lighter than that of 

 this brown soil the contrast is very marked. The deep brown 

 color extends usually to a depth of two feet or more, while dis- 

 coloration extends to six or eight feet. The amount of discolora- 

 tion is somewhat greater than is commonly found at the present 

 surface of the newer drift. Repeated comparisons of the soil in 

 the two districts lead to the conviction that this older drift sheet 

 had been exposed as a land surface for a longer time before the 

 silt was laid upon it than has the outer moraine of the newer 

 drift up to the present date. The same conclusion is reached 



