L98 /:'. M. Kindle — Stratigraphio Relations of the 



era part of the city to more than 60 feet on the southwestern 

 side of Cleveland. It lies between the sandy gray shales of 

 the Chagrin below and the gray or reddish Bedford shale 

 above. About 75 feet of the gray Chagrin shale is exposed in 

 Rocky River just west of Cleveland between the base of the 

 Cleveland and lake level. The present name of these gray 

 sandy shales which are basal to the Cleveland shale in the type 

 area of the Cleveland is derived from the Chagrin River, which 

 is located about S miles east of the City of Cleveland. The 

 name was substituted for Newberry's term Erie shale by 

 Prosser* because the latter name was preoccupied. The type 

 section is thus described by Prosser : 



"The name Chagrin formation is, therefore, proposed for this 

 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 formation 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 occurs a mile below Pleasant valley, about four miles up the 

 river southeast of Willoughby." 



The Huron or basal shale of the group was so named by 

 Newberry because of the excellent exposures along the Huron 

 River about 40 miles west of Cleveland. As originally defined 

 by Newberry, the Huron shale is "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. "f This definition of the Huron by Professor 

 Newberry appears to be hardly explicit enough for present-day 

 work because it fails to exclude definitely the uppermost beds or 

 Cleveland shale. Evidently if these two formations of the shale 

 group have any distinctive physical characteristics they should 

 be added to the original deiinitions of the Cleveland and 

 Huron shales. The writer's studies in northern Ohio have 

 shown that the two black shales of the Ohio group have certain 

 distinctive physical characteristics. 



Detailed study of a large number of sections from Lake 

 Erie to Kentucky has shown that certain lithologic features 

 characterize the upper and lower portions of the Ohio shale 

 group. and afford very important aid in identifying them. It 

 has been found in studying a considerable number of sections 

 that the lower part of the black shales above the Olentangy 



*Jonr. Geology, vol. xi, pp. 533-534, 1903. 



f Geol. Survey Ohio, Rept. Progress in 1869, pt. 1, p. 18. 



