208 THE ILLINOIS GLACIAL LOBE. 



village the base of the Shelbyville drift sheet is reached at 65 or 70 feet, 

 and a few wells are obtained at this depth. A well at Harrison Harlan's, 2 

 miles south of Dunlap, at a level about 40 feet lower than the village, has 

 a depth of 117 feet. It is mainly through the older drift, which is largely 

 till, and water is obtained in sand and gravel at the bottom. 



CHARACTER OF THE OUTWASH. 



Considerable attention has been given the deposits and valley terraces 

 immediately outside this drift sheet and on its outer slope in order to ascer- 

 tain the character of the outwash. It is found that silt deposits, as well as 

 sand and gravel, cap the surface of the outer face of the moraine and 

 extend out onto the border plain. The silt deposits are loess like and fos- 

 siliferous, and suggest a feeble drainage. The sand and gravel deposits are 

 very limited in their extent, and, on the whole, favor the view of feeble 

 drainage. The amount of coarse outwash is very much less than is found 

 to characterize the Bloomington morainic system, as is shown farther on. 

 In some portions of the border the close association of silt and gravelly out- 

 wash renders the interpretation somewhat puzzling. The features can per- 

 haps best be set forth by giving attention to each valley in turn which leads 

 away from the Shelbyville sheet into the outer-border district, beginning 

 with the Wabash Valley and proceeding westward. 



In the vicinity of the Wabash Valley the Shelbyville drift sheet is 

 found to be g-enerallv coated to a depth of several feet with a yellowish 

 loess-like silt. This is especially well shown on the west side of the valley 

 in the vicinity of St. Mary's, Indiana. This silt is better developed on the 

 border of the river than at points a few miles back, there being scarcely 

 enough silt in the latter situation to conceal the bowlders which cap the till. 

 The distribution of the silt seems such as would be expected if drainage 

 conditions were inadequate to carry off the water from the melting ice. 

 There are, however, other features which seem to indicate good drainage 

 conditions. At the point where the moraine crosses the river, near Ather- 

 ton, a gravel plain is built up to a height of about 75 feet above the present 

 stream, whose surface carries basins such as occur on gravel plains or ter- 

 races leading away from a moraine, and are found only near the moraine. 

 There is at least a suggestion that this gravel plain is to be correlated with 

 the Shelbyville moraine. This view is strengthened by the fact that the 



