402 A. C. LANE 



highly probable that all of Michigan at least was covered, and the 

 freedom from land detritus makes it probable that the submergence 

 was widespread, and that whatever land existed was low, and erosion 

 mainly chemical. Elaborate subdivisions have never been made or 

 mapped of the outcrops in the Upper Peninsula. Well-records, 

 however, show toward the center facies that we may parallel with the 

 New York Clinton, Rochester (Niagaran) shale, the Lockport lime- 

 stone, and the Guelph dolomite, and besides this at least one fairly 

 persistent sandy and water-bearing horizon, the Hillsboro sandstone. 



17. Clinton. 0-130 feet. — It seems to have been well into Clinton 

 time before that part of the state where now is the Clinton outcrop 

 was submerged. While all writers recognize that the Clinton facies 

 exists in the Upper Peninsula, Rominger does not consider it worth 

 dividing, and none have tried to map it separately. A. Winchell 

 makes it but 3 feet thick. On Manitoulin Island there may be 31 

 feet. Hall gives, p. 154, Sturgeon Bay, this section: 



5 light-gray Niagaran with P. oblongus 10 



j 4 thin calcareous and siliceous beds 6-10 | 

 ^ \ ^ shaly and mixed beds Cytherina 15 \ 



( 2 heavy-bedded greenish-calcareous and argillaceous 



Possibly Medina < Hmestone with chert nodules 6 



/ I soft, brittle, greenish 20 



The Cheboygan well shows some 60 feet which may be placed 

 here. 



In the southeastern part of the state nearer New York the Clinton 

 is more surely identifiable. 



The Port Rowan, Canada, well shows 75 feet under the Rochester. 



Argillaceous dolomite seems to be the dominant rock. Water and 

 gas are often struck in it under the Rochester shale. At South Bend 

 there are argillaceous dolomites 1,180-1,300 feet. At Dowagiac a 

 brownish-red carbonaceous limestone at the bottom (1,760 feet) may 

 represent it. At Kalamazoo is an interesting section suggesting a 

 land surface near 2,230 feet. 



18. Rochester shale. — Above the Clinton a shale is generally 

 identifiable in the records; whether it is the Rochester shale or at 

 times part of the Clinton may be a question. Though persistent it is 

 never very thick — usually 30 to 20 feet. 



