4o6 A. C. LANE 



the Traverse and Monroe (Milwaukee and Waubakee of Alden) 

 represented, and not the Dundee or Corniferous, it is more natural 

 to suppose the Dundee absent here also. The irregular red and 

 rusty character of the Dundee samples at Manistee and the way 

 it varies in the wells also suggests a deposit near shore frequently 

 interrupted by disconformities. 



Of the Frankfort well no samples have been kept, but I am told that 

 the wells were put down deep enough to have reached the Niagara 

 (1,800-2,200 feet) without striking rock salt and without reaching a 

 very strong brine. So that it is likely that this was just outside the 

 Salina sea like Milwaukee, while Ludington and Manistee were just 

 inside. 



St. Ignace and Cheboygan wells showed the New York Salina 

 red and blue shale facies. We have therefore good reason to believe 

 that at the close of the Niagara or Guelph the sea-level fell so that all 

 of the southeastern portion of Michigan was above it. This begins 

 the emergence between the Silurian and Devonian. If the salt 

 deposits were laid down as a non-oceanic Caspian sea, we may 

 suppose red shales like those of St. Ignace were deltas of a stream 

 that fed it, and that the inland sea extended to the New York Salina 

 where were other deltas from Appalachian streams. The bottom of 

 the Salina sea should, however, have been below sea-level, like the 

 Dead Sea at present, for we find just after Sylvania time, and at the 

 beginning of the Devonian, incursions of ocean water and animals. 

 Now, the top of the Niagara below this is not less than 1,200 feet at 

 Wyandotte, and below the top of the Salina 700 or 800 feet. If then 

 the top of the Niagara at Wyandotte was above sea-level after the 

 Guelph, either the continent was raised something like a thousand 

 feet, or there was warping of the crust during Salina. There was 

 warping of the crust during the Upper Monroe, and since, but not, I 

 think, enough to alter the fact that Lower Michigan has been perma- 

 nently a basin. Any such emergence of the continent should have left 

 traces in the sediments derived therefrom, sandstone or red shales 

 derived from residual clays. No such beds are known to me. The 

 Salina appears to me rather the result of but slight emergence, which 

 grew more marked but irregular during the time of formation of the 

 top of the Monroe. 



