OF UPPER CANADA AND THE WESTERN PART OF OHIO. 283 



tion with that of Maiden and Goderich. To this last identification we 

 attach the more importance, as the Sandusky rock, under the name of the cliff 

 limestone of Ohio, has been of late variously regarded by geologists, some 

 conceiving it to be the equivalent of the European carboniferous, or moun- 

 tain limestone. That its closest foreign relations are to the Wenlock rocks of 

 the English Silurian strata, and not to those of the carboniferous date, is obvious 

 from an inspection of its organic remains alone. But there exists in Tennessee 

 and Virginia a higher limestone not developed in either Ohio or New York, 

 much more nearly related to the mountain limestone of Europe, to which it 

 has been referred by Professor Troost. This rock, characterized by its oolitic 

 structure and the beautiful genus Pentremites, appears, as we infer from some 

 descriptions given by Troost, to be underlaid by blue limestones, identical, 

 seemingly, with the cliff rock of Ohio. 



Rocks of the Anticlinal region in Ohio. — The broad anticlinal axis which 

 we have traced from the western side of Canada into Ohio, crosses the Ohio 

 River somewhere in the neighbourhood of Louisville, and terminates probably 

 in Kentucky. It imparts a general S. S. W. strike to all the strata of western 

 Canada, eastern Michigan, Ohio, and parts of Indiana and Kentucky. The 

 lowest formation near Lake Erie which the axis brings to the surface, is the 

 pitted rock already traced. But that still lower formations are elevated by it 

 more to the S. W., is apparent from the descriptions given by Dr. Locke, and 

 other geologists, of the geology of the south-western part of Ohio.* 



The cliff limestone at the base of which we place the pitted rock is there 

 underlaid by marly shales that rest upon an extensive formation of blue lime- 

 stone, well exhibited in the region of Cincinnati. These shales probably re- 

 present the gypseous shales of New York, for it is fair to conclude that so 

 thick a mass of fine sedementary matter as they constitute on the Niagara 

 River, can hardly have thinned away at this distance westward. 



But to what formation shall we assign the blue limestones of Cincinnati? 

 Do they correspond with the Niagara limestone next under the gypseous shales, 

 or to some yet inferior formation? or do they belong to a new and interpolated 

 group not met with farther east? Influenced by a certain degree of corre- 

 spondence in the fossils, and by the known progressive thickening westward of 

 the Niagara limestone, which seems to preclude a belief of its thinning out 



* See first and second Annual Report of Geological Survey of Ohio. 

 VIII — 3 W 



