Reprinted from 

 The Journal of Geology, Vol. XXXIV, No. 2, March-April, 1926, pp. 167-174 



A NOTABLE TYPE PLEISTOCENE SECTION: THE FARM 

 CREEK EXPOSURE NEAR PEORIA, ILLINOIS 



MORRIS M. LEIGHTON 



Illinois Geological Survey 



Urbana, Illinois 



ABSTRACT 



In 1920 a detailed examination was made by the writer of the so-called "Farm 

 Creek Exposure" near Peoria, Illinois, from personal interest. It developed, how- 

 ever, that the description previously published of this very important Pleistocene 

 exposure was considerably generalized and was made prior to our present concep- 

 tions of such materials as loess and gumbotil. The following discussion gives in 

 detail the various elements in the section and offers an interpretation of them. 



INTRODUCTION 



The Peorian interglacial stage was named by Leverett 1 on the basis of 

 the relations of a body of loess to the Illinoian and Wisconsin drift sheets 

 in certain exposures east of Peoria, Illinois. One of these was a stream-cut 

 exposure along Farm Creek, 7 miles east of Peoria, and another a railway 

 cut along the Toledo, Peoria & Western Railway, about half a mile farther 

 east. Photographs of these cuts, taken by Dr. Calvin in 1897, are shown on 

 Plate XI of Monograph XXXVIII, opposite page 128, and general descrip- 

 tions are given in the legends and on pages 128 and 187 ; but, to the writer's 

 knowledge, no detailed description has been published, such as is desirable 

 for type cuts. 



In connection with his investigations of the Pleistocene for the Illinois 

 State Geological Survey, the writer had occasion to visit these exposures 

 during the field season of 1920. He was accompanied by Messrs. Ben 

 Herzberg and E. W. Ahern, students of the University of Chicago, who 

 aided materially in the examination. The railway cut was too badly slumped 

 and grassed over for study, but the Farm Creek exposure was in exception- 



1 Frank Leverett, "The Illinois Glacial Lobe," 17. S. Geol. Survey, Monograph 

 XXXVIII (1899), p. 1ST. 



