2S0 OBSERVATIONS ON THE GEOLOGY OF THE WESTERN PENINSULA 



formations mentioned. They are the more interesting from the fact that not 

 even this much relationship prevails between the Maitland formation and any 

 of the strata lower than the Onondaga limestone. What seems chiefly con- 

 clusive of the high position of the Maitland rock is its identity with the lime- 

 stone of Sandusky, the plane of which is but little under the horizon of the 

 Marcellus shales. 



Rocks of the Detroit River, and of the Western end of Lake Erie. Having 

 become satisfied of the persistence of the pitted rock through Upper Canada, it 

 became a matter of leading interest to establish the relations of it and the over- 

 lying limestones to the strata widely developed around the head of Lake Erie; 

 regarding this as the only certain mode of ascertaining the date of the rocks 

 of Western Ohio. Combining our own observations of the dip and range of 

 the strata in Upper Canada, with the data recorded in the annual reports of 

 Dr. Houghton, the State geologist of Michigan,* we became convinced of the 

 existence of a broad, but gentle axis of elevation passing in a S. S. W. direc- 

 tion somewhere near the lower end of lake Huron. A slight but obvious 

 western dip is visible on the Maitland near Goderich, and is extensively seen 

 on the opposite or Michigan shore, southward, the whole way from near 

 Saginaw Bay to the outlet of the Detroit River. The eastern dip from this 

 axis is evidenced by the southern trend of the limestones, which cross the 

 upper end of Lake Erie, between Point Au Playe and Sandusky, where the 

 dip itself, indeed, may be detected. It is indicated by the form of the Cana- 

 dian Peninsula, and strikingly by the singular line of drainage of the River 

 Thames, which, instead of seeking a short line either to Lake Huron or 

 Lake Erie, pursues a much longer course, as if guided by the strike of the 

 rocks, and empties into Lake St. Clair. 



Persuaded of the existence of this anticlinal axis, which passes, probably, 

 somewhere between Goderich and the head of the Thames, we adverted next 

 to its probable connexion with the broad anticlinal elevation of the strata in 

 the western part of Ohio, upon which the general features of the geology of 

 that State and Indiana mainly depend. Guided by this conjecture, we fore- 

 saw that the rocks which we had been tracing from the Niagara River, in a 

 W. N. W. direction to Lake Huron, must experience an important change in 



* See second and tliird Annual Reports on the Geology of Michigan. 



