CHAPTER XXXII. 



REPORT ON THE GEOLOGY OP ERIE COUNTY AND THE 



ISLANDS. 



BY J. S. NEWBBKKY. 



SURFACE FEATURES AND DEPOSITS. 



The most interesting features in the surface geology of Erie county 

 are the splendid series of glacial markings inscribed on the Corniferous 

 limestone in and about Sandusky City, the lake ridges which traverse 

 the county from east to west, and the remarkable petrifying fountains, 

 known as the Castalia Springs. The first two of these are but local exhibi- 

 tions of phenomena which are wide-spread, and are the results of causes 

 which, in their general action, are considered in a special chapter devoted 

 to Surface Geology. The features to which I refer will, therefore, be only 

 briefly described in this sketch, as the manner in which they have been 

 produced will be better understood by referring to the fuller exposition 

 of the subject given in the chapter cited. 



In its topography, Erie county is without any strongly marked features. 

 The surface, to the eye, seems nearly level, while, in fact, it forms a 

 gentle slope from the south line of the county, where it has an elevation 

 of 150i feet above the Lake to the lake level. This monotony of surface 

 has been produced by the planing action of the great glacier that exca- 

 vated the basin of Lake Erie ; not only that basin which now holds the 

 Water, but the greater one of which the southern boundary is the water- 

 shed between the Lake and the Ohio. Erie county, therefore, lies near the 

 bottom of this greater basin, and the great ice mass which filled it, moving 

 from the north-east to the south-west, ground down the underlying rocks 

 to a nearly uniform surface. The outlines of the lake shore have been 

 apparently determined by the same great cause. The general bearing of 

 the south shore of Lake Erie is essentially the same from near Buffalo to* 

 the mouth of the Huron river. There the coast line forms a large angle 

 With its former course, and stretches, with only local variations, directly 

 from Huron to the mouth of the Maumee. By a glance at this map, 

 however, it will he seen that the west end of Lake Erie is blocked up 



