534 CHARLES S. PROSSER 



mass of argillaceous and arenaceous shales and calcareous 

 layers on account of the excellent exposures on the banks of 

 this river extending from Willoughby to the south of Pleasant 

 valley. With perhaps the exception of the cliffs on the shore 

 of Lake Erie, there are probably no finer outcrops of the for- 

 mation to be found than those forming the steep banks of the 

 Chagrin River. One and one-half miles south of Willoughby is 

 a cliff nearly a hundred feet high, and a magnificent one more 

 than a hundred feet high occurs a mile below Pleasant valley, 

 about four miles up the river southeast of Willoughby. 



i6. The term "Huron shale" was proposed by Dr. Newberry 

 in 1870 for "the great mass of black, bituminous shale, desig- 

 nated by the former Geological Board as the 'Black Slate.' "^ 

 Its outcrop was described as forming "a belt from ten to 

 twenty miles in width, reaching from the Lake shore [Erie] at 

 the mouth of the Huron River, almost directly south to the 

 mouth of the Scioto." Its outcrop on the shore of Lake Erie 

 was given as extending from east of Sandusky to Avon Point. 

 The higher black shale outcropping near Cleveland was named 

 the "Cleveland shale," which was separated from the lower 

 black shale or Huron by the Erie shale. It is generally sup- 

 posed that Newberry's "Huron shale" in northern Ohio, 

 although represented on the Prelimmary Geological Map of Ohio, 

 accompanying this report, as extending across the state from 

 Lake Erie to the Ohio River and in the southern part 

 apparently comprising all of the black shale which Andrews, 

 later in the same report, named the "Ohio black slate," rep- 

 resented only the lower mass of black shale which occurs in the 

 northern part of the state. It was not until much later that it 

 was known that the top of the Ohio shale in southern Ohio corre- 

 sponds with the top of the Cleveland shale and that Andrews's 

 "Ohio Shale" is equivalent to the Huron, Erie, and Cleveland 

 shales of Dr. Newberry in northern Ohio. 



In 1 861 Professor Alexander Winchell gave the name 

 "Huron group" to a division of the Michigan rocks, which 

 included all the deposits between the top of his Hamilton group 



'Geol. Surv. Ohio, Rept. Progress hi i86q, Part I, p. 18. 



