ERIE COUNTY. 187 



GEOLOGICAL STBUCTUEE. 



The section of the rocks underlying Erie county is, in descending 

 order, as follows : 



Thickness. 



1. Bere&grit 60 feet. 



2. Bedford shale 75 



3. Cleveland shale 50-60 



4. Erieshale , 50?' 



5. Huron shale 300 



6. Hamilton limestone 20 



7. Corniferous limestone 100?' 



8. Oriskany sandstone 0-5 



9. Waterlime group 100 ? ' 



10. Onondaga salt group 30-40 



In the oil well bored at the mouth of the Vermilion river, the Niagara 

 limestone, the Clinton group, and Medina sandstone were penetrated, 

 but they nowhere come to the surface within the limits of the county. 

 Of the foregoing strata, the first is the sandstone quarried at Amherst 

 and Brownhelm, of which the outcrop crosses the east line of the county 

 within less than a half mile of the lake shore ; thence it sweeps round 

 to the south and west, passing through Berlinville, and a little east of 

 Norwalk, in Huron county. Within the area lying to the south and east 

 of this line the Berea grit underlies most of the surface, but it is very 

 generally covered and concealed by the Drift materials ; and it is only 

 where its more compact and massive portions have resisted the action of 

 erosive agents, and these have been left in relief, that it projects above 

 the surface. The hills in which the Amherst and Brownhelm quarries 

 are located, and the elevation known as Berlin Heights, are all masses of 

 this character. They were once bluffs upon the shore of the Lake, and 

 every where show marks of the action of water and ice. Along the out- 

 crop of the Berea grit its softer portions have undoubtedly been most ex- 

 tensively eroded, and are now deeply covered by Drift deposits, so that 

 probably little of this portion of the area it occupies will furnish valu- 

 able quarries of building stone ; but as the surface rises and the rocks 

 dip toward the south and east it soon passes below the surface, and there 

 is every probability that within the townships of Berlinville, Lawrence, 

 $nd Vermilion, the Berea grit will hereafter be quarried in many local- 

 ities precisely as it now is at Berea. 



So far as we can judge from the exposures of this rock in Erie and 

 Huron counties, it becomes more shaly toward the south, passing gradu- 

 ally into the soft ochery sandstone which represents it at Ashland, Mans- 

 field, and further south. 



