46 THE ILLINOIS GLACIAL LOBE. 



The surface of the Kansan appears to have been subjected to some 

 erosion, for it drops down about 15 feet in a distance of 20 rods in passing 

 toward the river valley. This sloping - surface of the Kansan is leached and 

 humus stained, and the Illinoian till mantles it with a bed of nearly uniform 

 thickness, thus presenting an upper surface nearly parallel with that of the 

 eroded Kansan. 



In the autumn of 1894 the writer observed several exposures of a soil 

 and weathered zone in ravines in western Scott and eastern Muscatine 

 counties, between what are interpreted to be the Kansan and Illinoian till 

 sheets. They are not conspicuous in eastern Muscatine County, but may 

 be seen both north and south of Blue Grass, in Scott County. The 

 exposures noted are not sufficiently deep to show the lower till sheet to 

 good advantage, but the upper is well displayed and has the characteristic 

 appearance of the Illinoian. Its thickness is but a few feet — in some places 

 only 6 or 8 feet, and seldom more than 15 feet. The Yarmouth soil and 

 weathered zone is represented by a gummy black or gray clay, changing 

 below to a reddish-brown till. The Sangamon soil and weathered zone is 

 represented by a similar dark gummy clay and a leached and reddened 

 till surface. The Iowan loess in this locality is only about 8 feet in depth, 

 and is more compact than the bluff loess found in Davenport. 



At Muscatine the party of geologists above mentioned examined 

 exposures in the east part of the city, in the east bluff of Mad Creek, and 

 east from there on or near Second street and on Park avenue. These all 

 occur in a lowland tract bordering the lower course of the creek and 

 occupying the interval between the creek and Mississippi tliver. Its 

 general elevation is about 80 feet, and the highest points barely reach 100 

 feet above the low water in the river. The latter are found in a low ridge 

 following the bluff of the Mississippi. This lowland carries on its surface 

 a nearly pebbleless silt several feet in depth, at the bottom of which there 

 are occasional thin deposits of sand resting on till. The tliickness of silt 

 and sand is scarcely 10 feet, or less than one-half of the thickness of the 

 Iowan loess on neighboring uplands. It seems doubtful whether the 

 deposit is of Iowan age or is to be correlated with the loess. The view 

 that it is alluvial seemed to us more probable. The till beneath this silt 

 and sand was found to carry numerous large bowlders, some of them being 1 



