The Natural History of Chautauqua 



it reaches a high elevation in Cataraugus County, in western New 

 York. Beyond this, in Chautauqua County, and westward in Pennsyl- 

 vania, the plateau level again descends. 



5. On its northern face the plateau ends in an escarpment which 

 though irregular and somewhat serrated, is commonly quite pro- 

 nounced. Its position in the east is determined by the hard Helder- 

 berg Limestone; but in the extreme west it is located where hard shales 

 overlie lower fragile beds, though its condition is possibly determined 

 by a bed of conglomerate now almost completely removed. Along the 

 Erie shore, near the boundary between New York and Pennsylvania, 

 the escarpment is about two or three miles from the lake; but toward 

 the east the escarpment recedes from the lake. In some cases the slope 

 is very abrupt, and in Chautauqua County it ascends to a height of 

 500 feet in a very short distance. The escarpment is less distant in 

 Erie County, but becomes more pronounced towards the east, in Seneca 

 and Cayuga counties, while still further east it becomes sufficiently high 

 to form the " Helderberg Mountains." Therefore, for some distance, 

 the northern boundary of the Plateau province, as well as that of the 

 Catskill region, is a single deposit of limestone, which forms an escarp- 

 ment in some places rising a thousand feet above the lower plain. 



Modified from Tarr, Physical Geography of New York State. 



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