128 THE ILLINOIS GLACIAL LOBE. 



west part of Davenport, Iowa, the following beds are exposed, as reported 

 by Mr. Pratt, who examined the exposure while the excavation was fresh : 



Section in railway cutting near Davenport, Iowa. 



Feet. 



1. Ordinary prairie soil, altitude 167 feet above Mississippi River 1 



2. Loess, iron stained and distinctly laminated with lamina; curved and in places interbedded 



with thin layers of sand; the deposit also contains small calcareous nodules and shells of 

 the genera Succinea, Heiicina, and Pupa 20 



3. Bluish-gray clay, containing a few shells like those of No. 2; a tusk, several teeth, and other 



portions of Elephas primigenius ( ?) were found just at the junction between Nos. 2 and 3 . . . 3-5 



4. Bed of brown peat in which the peat moss, Hypnum aduncum, was sufficiently well preserved 



to be identified; quantities of much decomposed coniferous wood were also distributed 

 through this bed 1 



5. Dark-brown soil, resembling the peat, but more decomposed 2 



6. Blue clay, very tenacious, coutaining sand, gravel, and small bowlders, many of them 



distinctly glacier scratched, extending beneath base of cutting. 



The peat bed, with its associated soil and silts, is reported to have been 

 exposed for a distance of 30 or 40 rods. Concerning it Dr. C. A. White 

 remarks: 2 " This deposit is quite remarkable in many respects ; in none 

 more so perhaps than in the fact that the bed of peat rests upon a bed of 

 clayey silt and is in turn covered by a similar but much deeper one, these 

 varying conditions evidently having been produced by the shiftings of the 

 adjacent and then sluggish river in that very early period of its postglacial 

 history." 



The Sangamon soil has been exposed by some of the streams within 

 the limits of the Wisconsin drift, notably on the Embarras and Kaskaskia 

 rivers and tributaries of the Illinois. It is found below loess or white clay, 

 which in turn lies beneath the till of the Wisconsin drift. Two excellent 

 exposures on Farm Creek, east of Peoria, Illinois, are shown in PI. XI, 

 figs. A and B. In the first (A) the soil is not shown, but there is a deeply 

 leached and weathered zone at the top of the Illinoian. In the second (B) 

 there is a bed of peat resting upon silt which bears some resemblance to the 

 overlying Iowan loess in texture, but is not so calcareous and is of a deeper 

 brown color. Whether it is similar in origin to the loess can scarcely be 

 decided. The writer also is inclined to question whether the silt below peat 

 in the Davenport section just described should be referred to the Iowan 

 loess. Beneath the silt which underlies the peat shown in fig. B there is 

 Illinoian till, and this is leached to a depth of 3 to 4 feet. This section 



1 Op. cit., p. 120. 



