CHAPTER VII. 



(continued.) 

 THE ATTENUATED BORDER. 



So far it has been thought best to adhere closely to the 

 delineation of the glacial margin through New Jersey and Penn- 

 sylvania as given in the report of Lewis and Wright in Vol. 

 Z of the Pennsylvania Survey. But in the preparation of 

 that report we were laboring under the false impression that 

 the extreme glacial margin was always marked by a distinct 

 moraine. This error was partially recognized by us in speaking 

 as Professor Lewis, especially, did, of a bordering ''fringe' ' 

 of sporadic glacial deposits extending some distance farther 

 south than the line as marked on our map. The study of 

 this was taken up later by Professor Edward H. Williams and 

 carried on across the state with the result that the boundary 

 of the "fringe" or "attenuated border" was found to extend 

 on an average, about twenty miles farther south than our 

 "terminal moraine." Similar results were found to prevail 

 in New Jersey by Professor Salisbury, Professor A. A. Wright, 

 and myself. 



To be specific: The extreme glacial limit in New Jersey 

 reached to an irregular line running from Bound Brook, a 

 little south of Plainfield, to Riegelsville, on the Delaware, a 

 few miles south of Easton, Pa. So far, land-ice evidently 

 extended at one time. The striated bowlders found by Profes- 

 sor Salisbury and others still farther south were doubtless 

 carried by floating ice when the land was depressed to the 

 extent of about 200 feet, of which evidence will be given in 

 a later chapter. 



