70 THE ILLINOIS GLACIAL LOBE. 



ive when compared with the amount of drift on neighboring hills. On 

 some of the hills between Rockwood and Park post-office, there is scarcely 

 a trape of drift, though they are surrounded by the lowlands iu which 

 heavy deposits of drift occur. The drift continues thin on uplands as far 

 north as Richland Creek, and the boundary is located with some difficulty. 



From the narrows of Richland Creek, in sees. 8 and 9, T. 7 N., R. 4 W., 

 northeastward to Newark, there is an exceptionally large amount of drift in 

 the vicinity of the glacial boundary, both on uplands and on lowlands. 

 Several exposures were found 200 feet above the creek, .in which there is 

 not less than 50 feet of drift. The old course of Richland Creek, through 

 a lowland tract east of Newark, has been filled up to a height of nearly 100 

 feet above the creek with deposits of sandy clay, carrying a liberal admix- 

 ture of coarse rock material and an occasional bowlder. 



Siebenthal reports that in southeastern Owen County the drift is heavy 

 in the valleys, but comparatively thin on the hills, and this feature is char- 

 acteristic of the boundary in Monroe County and southern Morgan Countv, 

 as noted both by Siebenthal and by the writer. Small bowlders are present 

 in moderate number in the vicinity of the glacial boundary in all these 

 counties. 



CHARACTER OF THE OUTWASH. 



There appears to have been very little material carried out by water 

 beyond the edge of this ice sheet except along the valleys. While the 

 outer border plains and the small valleys heading in this drift margin occa- 

 sionally bear thin deposits of sand and fine gravel which seem to be an 

 outwash from the ice margin, there is nothing comparable to what is dis- 

 played along some moraines of the Wisconsin stage described below. 



The best exposure of such an outwash yet noted is found near West 

 Point, in Lee County, Iowa. About a mile northwest of the village, imme- 

 diately outside the Illinoian drift border, the following series of deposits is 

 exposed in the gradings along an east- west road : 



Section near West Point, Iowa, showing {/ravel outwash. 



Feet. 



1. Brown silt, apparently to be classed with the Iowan loess 7 



2. Fine gravel, considered an outwash from the Illinoian drift 1 to 2 



3. Ash-colored soil, representing the Yarmouth interglacial stage 11 to 2 



4. Kansan till, brown at top, becoming a yellowish gray at bottom, exposed 15 to 20 



The full extent of the gravelly outwash at this place is not known, 

 because of the silt cover, but it seems to be restricted to a strip extending 



