147 



in the limits of the Wisconsin glaciation, includes but small 

 areas of the glacial flood-plain, and these are not especially 

 sandy, although it is stated (Leverett, '99, -p. 207) that there are 

 some dunes capping the eastern bluff-line near the upper end. 

 The lower section, extending from Meredosia to the mouth of 

 the river, about sixty-five miles long, is also narrow, and- al- 

 though the strips of glacial flood-plain are often quite sandy, 

 they are, so far as I know, destitute of blow-sand. 



In the Mississippi River valley also, well-developed sand 

 areas of the same general character as the large Illinois River 

 area are similarly present a little farther northward. Large 

 tracts of sand lie on the sag over the supposed preglacial con- 

 nection between the two rivers, and a similar very sandy glacial 

 flood-plain extends interruptedly along the east side of the 

 valley of the Mississippi, with small dunes capping some of the 

 bordering uplands, from near Burlington, Iowa, up to the 

 vicinity of Savanna, 111. Blow-sand is known to be present, 

 with all its attendant phenomena, in considerable quantities. 

 The glacial flood-plain along this river is also quite sandy be- 

 low Burlington over considerable distances, as far as the mouth 

 of the Illinois, but so far as known without true blow-sand de- 

 velopment. The blow-sand areas of these two rivers are ap- 

 parently very similar also in organic life, and evidently should 

 be grouped together. 



East of the Illinois River, along the Wisconsin morainic 

 border, especially in eastern Illinois and in adjacent Indiana 

 counties, there is considerable sandy outwash along the rivers, 

 but no definite development of blow-sand is known to me. 

 These sandy strips appear in the Sangamon valley near Niantic, 

 along the Embarras in Cumberland and Jasper counties, and in 

 the Wabash valley near Covington, Ind., and fromTerre Haute, 

 Ind., to the mouth of the river, the sand at Covington resulting 

 from the Bloomington glacial substage. 



There is an important sand area in northeastern Illinois, 

 with considerable development of blow-sand, derived from the 

 glacial outwash and sand beaches of the upper Kankakee val- 



