The Structural and Economic Geology of Erie County. 



By Irving P. Bishop. 



Physiography. 



Erie county, in central-western New York, is bounded on the north by 

 Niagara county, on the east by Genesee and Wyoming counties, and on the 

 south by Cattaraugus and Chautauqua counties. The w estern limit is the 

 international boundary from the lower end of Grand Island, to a point where 

 the boundary line makes a right angle with a line drawn to the mouth of 

 Cattaraugus creek. It is separated from Niagara county by Tonawanda 

 creek and the west branch of Niagara river; and from Cattaraugus and 

 Chautauqua counties by Cattaraugus creek. 



The extreme length of the county, north and south, is forty-three and 

 one-half miles, and its greatest width is about thirty-nine miles, The land 

 surface contains 1,071, and the lake portion about 160 square miles, giving 

 it a total area of about 1,230 square miles. 



Topographically, the county comprises three provinces. They are — -jwst, 

 a low and nearly level plain on the north, extending from the Niagara river 

 and Tonawanda creek to the limestone terrace ; second, a slightly higher plain 

 having the limestone escarpment for its northern boundary and extending 

 southward to a line drawn through Bay View, Spring Brook and Marilla ; and 

 third, a region of rolling hills rising gradually to the height of 1,500 feet or 

 more above tide, and occupying almost all of the southern half of the county. 



The Northern Plain.. This plain includes nearly the whole of the town- 

 ships of Grand Island, Tonawanda, Amherst and Clarence and the northern 

 half of Newstead. Along the Niagara river the banks form clay escarpments 

 averaging about twenty feet in height and dropping abruptly to the edge of 

 the water. From the top of the bank the county extends southward in an 

 almost level plain, unbroken by hills or ridges, to the foot of the limestone 

 escarpment. . 



The Middle Plain, The middle plain rises abruptly from the northern 

 plain, presenting throughout the greater part of the northern boundary an 

 escarpment of limestone varying from twenty to one hundred feet in height. 

 South of this, the surface is gently undulating with a few lower hills, gener- 

 ally presenting smooth surfaces. On this plain, Murder creek, Hansom creek 



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