106 GEOLOGY OF ILLINOIS. 



At McCann's ford the same limestone apparently that was left at 

 Ryan's ford just below the north line of Cumberland county, appears 

 in a bench on the west side of the river, where it is underlaid by ten or 

 twelve feet of sandy, micaceous shale. The full thickness of the lime- 

 stone was not seen here, the upper part having been cut away in the 

 erosion of the river valley. The limestone is said to outcrop again a 

 mile above McCann's, but I did not find the exposure. No rocks are 

 seen on the east side of the river above the ford for two or three miles, 

 and the hills, which are from a hundred to a hundred and twenty-five 

 feet in hight, were mainly composed of drift material. The followiug 

 section shows the relative position of the rocks found in the south 

 part of this county : 



Ft. 

 Soft, brown, micaceous, slialy sandstone, passing dov/n into an nnstratified concretionary mass. 30 to 40 



Sandy and argillaceous shales 15 to 20 



Rough, gray, unevenly bedded limestone ; 8 to 10 



Dark- gray micaceous shale 10 to 12 



The coal which is found beneath the limestone higher up the river 

 seems to be undeveloped here, as it is also in Cumberland, and no indi- 

 cations of it were seen south of the road running east from Charleston. 



Three miles a little south of east from Charleston, near the bridge on 

 the road to Westfield, the sandstone which forms the upper division of 

 the foregoing section crops out at the foot of the bluff on the west side, 

 where quarries have been open'ed in it for building stone. This sand- 

 stone is considerably harder here than at Hanging Rock, and affords a 

 very good material for bridge abutments, foundation walls, etc. The 

 lower twenty feet of the bed here is but partially stratified, but the 

 upper portion is evenly bedded, and as it hardens on exposure it affords 

 a very good building material. Near the bridge there is an exposure 

 of about fifteen feet of argillaceous shales with bands of carbonate of 

 iron, and just at the water's edge below the bridge there is a partial out 

 crop of the upper part of the limestone. The outcrop of sandstone at 

 the quarry measures thirty-three feet in thickness including some shaly 

 layers at the top of the exposure. 



A half mile below the Westfield road on the river, Prof. Cos reports 

 the following detailed section, but whether above or below the main 

 sandstone is not stated, though they are probably above that rock : 



Ft. In. 



" Gray, friable shale, vrith several bands of iron stone 20 



Fossiliferous iron stone 6 



Friable shale 1 



Black shale 8 



Gray clay shale J 5 



Impnre coal - 2 



Sandstone V" 



. He also reports the following beds. as occurring above the sandstone 

 on the river three miles east of Charleston : 



