PAPERS ON GEOLOGY 97 



RECENT CRUSTAL MOVEMENTS IN THE EASTERN 

 PART OF THE GREAT LAKES REGION 



Charles E. Decker, Allegheny College 



INTRODUCTION 



While in the region of the Great Lakes and along- the At- 

 lantic Coast, careful search has been made for even slight 

 vertical movements in recent geological time, little attention 

 has been given to recent tangential movements in either of 

 these areas. The present study has been initiated in the eastern 

 part of the Great Lakes Region to determine the age, distri- 

 bution, extent, and significance of these tangential movements. 



The rocks of northeastern Ohio and northwestern Pennsyl- 

 vania and New York for the most part appear horizontal. 

 However, a study of their distribution shows a gentle dip to- 

 ward the southwest 1 . Exceptions to this gentle dip in the way 

 of folds were noted early, and recent study is increasing the 

 number of these exceptions very materially, especially between 

 Cleveland, Ohio, and Westfield, New York. 



PREVIOUS STUDY 



Hall described and figured some folds in 1843 in north- 

 western New York 2 , and in 1910 Van Horn described some 

 small anticlines in the Chagrin shales near Cleveland, Ohio*, 

 but neither considered the edge of the folds. Gilbert* in 1886 

 recognized that some folds in northwestern New York were 

 post-glacial, and presented a paper on "Some New Geologic 

 Wrinkles." In 1903 Smallwood and Hopkins 8 described some 

 small anticlines near Meadville, Pennsylvania. While these 

 writers did not specially consider the age of the deformation, 

 recency is implied by the origin assigned for the folds, land- 

 slides on the valley walls. However, most of these folds are 

 in no way related to the landslides, and the few that are seem 

 to have no causal relation with them, so an inference of recency 

 because of such relation has little or no force. 



AGE OF THE ROCKS 



The rocks affected by the disturbances in the area under 

 consideration range in age from Middle Devonian to Lower 

 Mississippian". 



1. I. C. White: Second Geol. Surv. of Pa., Report Q4, 1881 pp. 44-49 



2. Geol. of Fourth Dist., N. "V., pp. 295-298. 



3. Bull. Geo. Soc. America, vol. 21, pp. 771-773. 



4. Proc. Amer. Assoc. Adv. Sci., vol. 35, p. 227. 



5. Bull. Syracuse Univ., Series IV. No. 1, pp. 18-24. 



6. I. C. White, Second Geol. Surv. Pa., Report Q4. pp. 93-119. 



