DRIFT DEPOSITS OF ILLIXolS. 13 



In regard to the boulders scattered through the drift clays of 

 this region, Dr. Bannister says: ".\ Tost of the large boulders in 

 this vicinity are of limestone; the masses of the primary or in- 

 irusive rocks are generally of comparatively small size, or when 

 of considerable size are but rarely met with." 



So much must suffice our present purpose to illustrate the 

 prevailing character of the drift in the extreme northern por- 

 tion of the State, where we might expect to encounter the most 

 unmistakable evidence of glacial action, if these superficial de- 

 posits were really due to the action of land ice. 



Coming south, within the northern boundary of the coal field, 

 we find an increased thickness of the drift deposits, and the 

 numerous artificial excavations that penetrate entirely through 

 them, afford the most satisfactory evidence of their general 

 character and extent. 



In sinking the coal shaft at Wenona, in Marshall county, the 

 following drift beds were encountered: 



Feet. 



Soil and yellow clay 10 



Blue clay (boulder clay) 46 



Sand 10 



Hard-pan 34 



Red clay 3 



Total 103 



The red clay at the base of the drift at this locality was prob- 

 ably derived from the shales of the coal measures on which it 



rests. 



At the gas well near Clinton, in DcAYitt county, the following 

 beds of drift were encountered without quite reaching the bed 

 rock : 



Feet. 



Soil and yellow clay 15 



Hard blue clay (boulder clay) 30 



Black mould with wood 2 



Dry drab colored clay 8 



Drift-wood and black mould 8 



Drab colored clay 16 



Drift-wood, etc 2 



Drab colored clay 26 



Hard-pan 12 



Drab colored clay 4 



Green copperas colored clay 10 



Total... 133 



