100 ILLINOIS ACADEMY OF SCIENCE 



eastward to Westfield, New York. While distinct folds of 

 considerable size were found particularly along the Vermilion 

 and Black rivers in northern Ohio, no evidence of recency was 

 found in connection with any of the folds until in the vicinity 

 of Cleveland. From there eastward through northeastern 

 Ohio and northwestern Pennsylvania and New York the rocks 

 have suffered recent deformation in a manner not duplicated 

 in those in adjacent glaciated areas. 



Though these movements have not been studied eastward, 

 there is evidence that they extend much farther in that direc- 

 tion, and some of them have been noted on the north side of 

 the lakes as well. 



THE LOESS IN ILLINOIS : ITS ORIGIN AND AGE 

 T. E. Savage, University of Illinois 



INTRODUCTION 



In spite of the fear that it might appear presumptive to pre- 

 sent a paper on the much discussed problem of the loess be- 

 fore this Academy, it seemed to the writer that there is need at 

 this time of a more extended statement than can be made in 

 the ordinary geologic reports of the main facts of the loess 

 deposits and of the interpretation which those facts reasonably 

 support. 



The name loess is applied to the fine-grained silt-like deposit 

 that, over portions of Illinois and elsewhere in the Upper Mis- 

 sissippi Valley, lies at and immediately beneath the surface 

 to a variable depth of from 2 or 3 to 50 or more feet. On the 

 hills it is generally yellow, but over the more level, poorly 

 drained areas the soil developed at the top of the loess is 

 colored dark with organic matter to a depth of 1 to 3 feet, be- 

 low which the color grades through shades of gray to yellow- 

 ish brown. The deposits rarely show any trace of stratifi- 

 cation or lamination, and where cut by streams or excavations 

 it tends to stand for a long time in nearly vertical cliffs. In 

 the dryer places, especially in the thicker deposits on the hills, 

 the loess contains numerous shells of species of air breathing 

 gastropods that now inhabit forest-covered slopes. In its 

 typical development the loess is practically limited to the 

 Mississippi basin and in this region it sustains peculiar rela- 

 tions to certain topographic features and to certain beds o! 

 glacial drift. 



