GENERAL FEATURES OF ILLINOIAN DRIFT SHEET. 275 



At a few places near Sardinia a dark band, apparently a soil, occurs 

 between Nos. 1 and 2, but in the majority of sections observed it is not 

 present. The deep-brown color of No. 2 marks the weathered zone and is 

 striking-ly in contrast with the pale color of Nos. 1 and 3. Its color more 

 nearly resembles the residuary' clay that rests on the subjacent limestones 

 than that of any members of the drift series. It is fully as significant as a 

 black soil in denoting- atmos|)heric action. At Sardinia wells are 30 feet in 

 depth, but none reach the rock, and rock is not exposed in valleys near 

 there whose depth is 30 to 40 feet. Between Sardinia and Mount Oreb, 

 near Whiteoak Creek, two exposures were observed of a soil or black band 

 between the silt and the underlying- till at a depth of 2 or 3 feet. 



Near Mount Oreb station a gas well, in a depression on slightly lower 

 ground than the station, strikes rock at 49 feet A well at J. F. Jenning's 

 residence, on ground slightly higher than the station, penetrates 68 feet of 

 di'ift and unconsolidated beds, of which the following is the section: 



Section of Pleistocene beds in Jenning's well at Mount Oi^eh, Ohio. 



Feet. 



1. Yellow clay, pebbly - 14 



2. Sand and gravel 6 



3. Blue till , 20 



4. Bluck mucky clay (preglaoial?) 15 



5. Sand 3 



6. Alternations of bluish clay and black muck extending to the limestone 10 



Total :...* 68 



On the uplands in Mount Oreb, near the Christian Union Church, is a 

 gas well which has 106 feet of drive pipe, but the rock was struck at slightly 

 less than 100 feet, there being a few feet of rotten rock below the drift. At 

 the Jennings well the drive pipe is 76 feet in length, but it extends a few 

 feet into the rotten surface of the limestone. The difference in thickness of 

 drift is not due to knolls or ridges, but to inequalities of the underlying rock 

 surface, the uplands in the vicinity of Mount Oreb having now a very flat 

 surface. 



Between Mount Oreb and Williamsburg there are rock exposures in 

 shallow ravines, the altitude of the rock surface being somewhat higher than 

 at Mount Oreb. A soil was frequently- observed between the silt and under- 

 lying till, at about 3 feet below the surface. At Williamsburg' the East 

 Fork of Little Miami River has rock bluffs rising on each side of the creek 

 to a height of about 20 feet, above which there is about 50 feet of drift, 



