ABSTRACTS OF PAPERS 67 



the same region during the progress of the Second Geological Survey of Penn- 

 sylvania, covering the region of Cravvrforcl and Erie counties, the latter of 

 which borders Lake Erie. It was my conclusion that many of these minor 

 folds, especially tliose with steep dips, were formed by the glacial ice, the 

 iKuilders imbedded In its base creating much friction on the yielding shales. 

 The absence of erosion of these folds would be no evidence against this theory 

 of their formation, since there has been no erosion, except along the streams 

 and gullies, since the Ice Age. Of course, along the streams the removal of 

 overlying materials and the consequent release of tension would be a true 

 cause for the very small flexures observed in such locations. 



Dr. Richard R. Hice : Some at least of the faults involve a greater thick- 

 ness of strata than suggested. At least one fault on Elk Creek extends down- 

 ward a considerable depth, as is evidenced by gas flow. The folds near Mead- 

 ville are due to release of load by the eroding streams. The rocks being under 

 compress, they have "buckled up" when the stream eroded the overlying rocks. 



Mr. F. B. Taylor: Tliere are a number of folds of this type in the slides 

 along the north side of Lake Ontario between Hamilton and Toronto. Sev- 

 eral of them extend 200 or .'UK) yards. These particular folds lie in the surf- 

 wasted zone of the Iroquois beach and appear certainly to be of more recent 

 date than that beach. 



Mr. Decker replied that the area under consideration (northeastern Ohio 

 and northwestern Pennsylvania and New York) has suffered recent deforma- 

 tive movements in a manner not duplicated in adjacent glaciated areas, though 

 they contain rocks of similar composition. This suggests that glaciation is 

 not responsible for the deformation and much of it is certainly postglacial. 



Further remarks were made by Messrs. H. F. Eeid and H. M. Ami. 



QUATERNARY DEFORMATION IN SOUTHERN ILLINOIS AND SOUTHEASTERN 



MISSOURI 



BY EUGENE WESLEY SHAW 



(Abstract) 



That the Ozarks, at least the northeastern part, have suffered uplift since 

 middle or late Tertiary time, and that this deformation was not a single brief 

 movement but has proceeded, probably with interruptions, during part or all 

 of several epochs, are indicated by the following facts : 



1. Two terraces, formed by the dissection of valley flllings, rise toward the 

 Ozarks, though in most of the valleys of southern Illinois this is downstream, 

 and the form of the surface is such as to preclude the possibility that the 

 streams have been reversed. 



2. Well records show that the old valley bottoms underneath the fillings are 

 also tilted up a little toward the Ozarks. 



3. The two terraces appear to diverge slightly to the southwest, indicating 

 s(.iii(> doformation between the times of valley filling that is, between the 

 middle and late parts of the Pleistocene epoch. 



4. The valleys and terraces become narrower (<• the soutliwest towanl the 



