88 N I N KT E E XTH H E VO RT. 



A local indication of what the older strata capping the anticline over 

 this area may be holding in reserve is observable in the old Judge 

 Christiancy quarry near Dundee in Monroe County, where the Onondaga 

 (Dundee, Corniferous), beds have been heavily petrolated at some time. 



The condition thus indicated may have been, and probably was occa- 

 sioned by a sideward tilt produced by an uplift about middle Onondaga 

 time, which raised the east side of the field above the surface of the sea 

 from Sandusky Bay northward to Pelee Point and the Amherstburg 

 quarry section. From this sideward tilt the area never fully recovered, 

 a fact evidenced by the narrowness of the Onondaga surface extension 

 in southeastern Michigan and northwestern Ohio (until it changes from 

 a north and south direction) and by a comparison of elevations of the 

 lower Onondaga horizons, which are relatively lower on the Michigan 

 side of the territory in question than on the Ontario side of it. 



The west side of the field appears to have sustained local uplift at 

 about the close of Onondaga time. Of this there is evidence in the 

 Sibley neighborhood in Wayne county, where thrusting has been accom- 

 panied by crevassing in the later Onondaga beds, beds not laid down in 

 Essex County. 



Reasons might be assigned for looking to the east side of the area for 

 gas, the more volatile quantity-, and to the west side for oil, prepon- 

 deratingly. As has been stated the mid-Onondaga east side uplift and 

 westward tilt was only partly balanced up by the later west side uplift. 

 A second reason is the centuries long gradual tilting to southwestward of 

 the continental mass from the direction of James Bay and beyond, which 

 is resulting in Lake Erie waters encroaching upon the land surface 

 over the south and west shores of the lake. (See U. S. War Dept. Coast 

 Chart No. 7.) 



Wells in Monroe and Wayne Counties, at Monroe, at Dundee, Trenton, 

 Sibley, Gross Isle, River Rouge, Detroit and Windsor, do not pay, in 

 oil and gas, the cost of putting them down, and for the reason already 

 assigned in the case of the Erie township well, too far down the side, 

 or northward over the nose of the Cincinnati anticline. 



Stony Island, possibly Sugar Island and Point Mouillic, Stony Point, 

 the Raisin River Delta, and tlie islands of north Maumee Bay, together 

 mark a promiseful base-line of operations from the westward over the 

 area delimited; whereas the locality of the mouth of the Canard River 

 in Anderdon Township, Bois Blanc Island, the Detroit River shore in 

 Maiden Township, South Colchester and Pelee Island, in Essex County; 

 and the Bass Islands and west of the base of Marble Head Peninsula 

 ill Oliio. together mark an cast side limit of ])robability. 



