32 THE ILLINOIS GLACIAL LOBE. 



They consist of rootlets about 2 cm. in length and 2 ram. in diameter. 

 They are, therefore, too small to afford good sections of the wood cells. 

 The locality where these specimens were obtained is now a prairie region 

 and the spruce tree is not native in the forests which border the streams, 

 the only conifer present being the red cedar. Several instances of the 

 occurrence of logs at the base of the loess in western Illinois have been 

 reported to the writer by well drillers, but no specimens have been obtained. 

 The evidence is, however, considered good that much of this region was 

 forest-covered prior to the deposition of the loess. Whether this emergence 

 and forest growth occupied a long period has not been satisfactorily deter- 

 mined. 



Last season (1897) the writer found a fine exposure of muck and peat 

 and wood, associated with silt, at the base of the loess in a cutting on the 

 Toledo, Peoria and Western Railway, 4 miles west of Washington, Illinois, a 

 photograph of which is presented in PI. XI, B. It is several miles inside 

 the border of the Wisconsin drift, and the loess is here covered by a bed of 

 till of Wisconsin age. At this cutting the Wisconsin drift is only 15 feet in 

 thickness, the upper portion having been removed by erosion. The section 

 at the cutting is as follows: 



Section at a cutting on the Toledo, Peoria and Western Railway, 4 miles icest of Wash- 

 ington, Illinois. 



Feet. 



Gravel 6 



Blue till (Wisconsin) 8 



Gray clay, laminated, pebbleless, very calcareous 1 



Brown loess, probably of lowau age, calcareous, and containing helix shells 6 



Pea^y silt of brownish black color, containing a large amount of wood (Sangamon) 5 



Drab colored loess-like silt, becoming brown toward bottom, filled with mats of fibrous roots. . 4-5 



Reddish-brown leached till (Illinoian) 4 



Brown nnleached till (Illinoian) exposed 8 



Total 42 



Specimens of the shells in the loess, of the wood in the peat, and of the 

 roots under the peat have been collected, but have not been specifically 

 identified. The silt under the peat is somewhat similar to the deposit which 

 overlies it, though it may prove to be of different origin. This series of 

 beds seems to indicate that a land surface, which had been exposed to 

 atmospheric action favorable for leaching of the till, was transformed into 

 a swamp favorable to the growth of peat, and that this swampy condition 

 was followed by the deposition of the loess. As the gummy clay just dis- 



