BUFFALO SOCIETY OF NATURAI, SCIENCES 5 



The Unconsolidated Deposits. 



Owing to the long period of time during which erosive 

 agencies were at work upon the rocks of Erie county and to the 

 effects of the great glacier which overrode this area, planing the 

 surface, transporting, depositing and mingling the detritus, 

 the rock formations of the county have been in most places buried 

 from view by their overburden of earth. The problems presented 

 by the unconsolidated detritus are extremely complex. 



Topography of Erie County. 



Topographically the county is divided into three rather 

 distinct areas, the lines dividing which are more or less well 

 marked. Its topography depends primarily upon the underlying 

 rock formations, partly upon the erosion which these have 

 undergone, partly also upon the modifying action of the great 

 glacier which at one time covered them. 



The first area comprises the northern part of the county. It 

 is limited at its southern edge by the "Ledge," an escarpment 

 marking the outcrop of the Onondaga limestone. This "Ledge" 

 extends from the Niagara river at Buffalo to Akron, and beyond 

 into Genesee county. Northward from the "Ledge" to 

 Tonawanda creek, the boundary of the county, the land is low 

 and flat and is a portion of the southern part of the valley of 

 Tonawanda creek. 



The second area lies south of the "Ledge" and is bounded 

 on the south and east by the ranges of hills. which constitute the 

 southeastern corner of the county. It slopes gently upward 

 towards the south. Along the eastern border of the county it 

 extends approximately from Akron to Wales. On the western 

 edge it contracts to a narrow plain lying between the hills and 

 Lake Erie. 



The third area comprises the hills of southeastern Erie 

 county. These rise slowly from the low-lying plain and reach 

 at Concord the altitude of 1500 feet. Through these high lands 

 numerous streams have cut deep valleys. 



The Rock Formations. 



All the rocks of Erie county are sedimentary, that is, they 

 were laid down in water, either as detritus derived from the 

 erosion of some land, or the minerals abstracted by living 



