TOPOGRAPHY. 73 



CORNIFEROUS ESCARPMENT. 



This escarpment follows the north border of the outcrop of the Cornif- 

 erous limestone from the rapids at the head of the Niagara River eastward 

 past Williamsville, Akron, Indian Falls, Batavia, Fort Hill, Muinford, and 

 Garbuttsville, coming- to the Genesee River a short distance above Scotts- 

 ville. The elevation above the plain on the north seldom exceeds 100 feet, 

 but the escarpment is nearly continuous. The only noteworthy break is at 

 Batavia, where occurs a gap about 2 miles in width that was apparently the 

 old passage for a stream which drained the valley now occupied by the head- 

 water portion of Tonawanda Creek. The altitude of the escarpment is fully 

 900 feet above tide in the vicinity of Batavia, but it declines to about 600 

 feet at Buffalo, and to a level nearly as low at the Genesee River. 



There are two notable falls on the line of this escarpment, one at 

 Tonawanda Creek near the village of Indian Falls, the other on Oatka or 

 Aliens Creek near Fort Hill. Each of these falls has receded about a mile 

 from the brow of the escarpment, leaving a narrow rock gorge about 100 

 feet in depth in the line of the recession. The smaller streams which cross 

 tlie escarpment also present cascades. In some cases streams which cross 

 the Corniferous limestone disappear in fissures and caves which open 

 out into the lower plain north of the escarpment. In dry seasons the waters 

 of Aliens Creek disappear in this manner near Le Roy, as pointed out by 

 Hall ' 



PLAIN SOUTH OF CORNIFEROUS ESCARPMENT. 



The narrow plain or lowland tract which lies between the Corniferous 

 escarpment and the hilly portion of western New York extends westward 

 along the south border of Lake Erie far into Ohio, with the same width as 

 in western New York, 5 to 10 miles. It opens at the west into the great 

 plain of the interior portion of the United States; it also extends southward 

 into Grand River Basin to a distance of nearly 40 miles from Lake Erie. 

 The portion east of Buffalo is all that will be considered under the pres- 

 ent heading. It is underlain by the shales of the Marcellus and Hamilton 

 formations, while the plain along the south border of Lake Ei'ie is under- 

 lain by later formations. 



On this plain there is not a marked descent southward from the brow 



' New York Geol. Survey, Fourth Geol. District, 1843, p. 169. 



