48 THE ILLINOIS GLACIAL LOBE. 



Section on Mississipjri bluff west of Green street, Muscatine, Iowa — Continued. 



Feet. 

 Disturbed beds of sand with folds that appear to have a prevailing east- west trend, as if 



shoved from the north 4 to 12 



Blue-black till with fragments of wood, very thickly set also with small stones and very 

 calcareous, not characterized by weathered seams, possibly pre-Kansan, exposed only a few 



rods to 8 



Peaty bed, exposed only for a few feet i to 1 



Sand, perhaps from decomposed Coal Measure Sandstone 1 to 2 



Coal Measure Sandstone exposed at bottom of pit at level probably 50 feet above river. 



Total 60 



The blue-black till at the base of this exposure is thought by Bain to 

 be very similar in physical texture to some of the supposed pre-Kansan 

 deposits of southern Iowa. The writer has observed several instances of 

 similar material near the bottom of the drift series in southeastern Iowa. It 

 is thought best not to include it in the Kansan unless these suspicions are 

 removed. 



In the Muscatine cemetery, on the bluff back of the exposures just 

 described, at an altitude about 200 feet above the river, a well passed 

 through 215 feet of glacial deposits, including loess and sand. The drift is 

 mainly blue till, but beds of sand such as outcrop in the exposures near 

 Green street were passed through. 



For a few miles in the portion of the Illinoian drift border adjacent to 

 the southwestern flowing portion of Cedar River, in Muscatine County, 

 sand dunes and a general coating of sand, drifted probably by wind from 

 the plains bordering the Cedar River, form a mautle of considerable depth 

 on the crest of the terminal ridge, and conceal the structure of the ridge, so 

 that wells afford the only means for obtaining information concerning it. 

 Several deep wells have been made which penetrate from 120 to 300 feet 

 of drift, the least depth at which rock was found being 120 feet. These 

 wells usually penetrate a large amount of till, but there are thin beds of 

 sand associated with the till at various levels. In some cases a hard till is 

 found at considerable depth, which, it is probable, is as old as the Kansan, 

 and possibly is pre-Kansan in age. The following list of wells in Musca- 

 tine County will serve to set forth the variations in structure and the great 

 depth of drift. The list begins at the northeast part of the county and pro- 

 ceeds southwestward along the ridge. For several of the sections the writer 

 is indebted to Prof. J. A. Udden. 



