PAPERS OX GEOGRAPHY AND GEOLOGY 351 



gravel may be found sand, and over all the lower por- 

 tions, above the sand, is silt. In places the sand has been 

 piled up into dimes by the wind, and the higher parts of 

 the lowland and the adjoining parts of the upland are 

 covered with loess. The position of the Wisconsin Ice 

 Sheet leads one to believe with scarcely a doubt that it 

 was the source of supply for the thick lowland deposits. 



The source of the "Wabash is far north of the southern 

 limit of the Wisconsin Ice Sheet. The source of the Em- 

 barrass is also north of the this same position, bnt it is 

 not very far north. It rises just south of the Champaign 

 moraine, the first stopping place of the Wisconsin Ice 

 edge as it retreated towards the northeast. Its stop at 

 this place was brief. The tributaries of the Embarrass, 

 Muddy, Brushy Fork, Indian and Eaccoon creeks had 

 their sources far to the south of the Wisconsin Ice edge. 



When the ice edge stood along the line which crosses 

 the state near Shelbyville, Mattoon. Charleston and 

 Paris, the rivers that flowed southward from it were 

 much larger and much more heavily laden with rock ma- 

 terial than at present. Throughout the long ages during 

 which the ice advanced, retreated, halted, readvanced and 

 retreated again, until its final disappearance from the 

 region, great torrents of water were borne away by the 

 Mississippi, Illinois, Wabash and Embarrass rivers. It 

 was chiefly by means of the gravel, sand, and silt which 

 the Wabash and Embarrass carried that the low lands of 

 Lawrence County were built up from 50 to 175 feet higher 

 than they were in pre-glacial times. Since the Wabash 

 was a much larger river at the ice edge than the Embar- 

 rass and since it had a number of tributaries that also 

 flowed from the ice edge, it- contributed much more mater- 

 ial toward the building up of the lowland than did the 

 Embarrass; and since its source lies far to the north of 

 the southern edge of the Wisconsin Drift sheet, it and 

 its tributaries continued to furnish gravel, sand, and silt 

 long after the ice edge had retreated north of the source 

 of the Embarrass. 



Under the circumstances described above, from the 

 time of the farthest advance of the Wisconsin Ice sheet 

 the Embarrass and Wabash began building up their val- 



