78 REPORT OP THE 



The black bituminous slate of Michigan has generally been 

 regarded as equivalent to the "black slate" of Ohio and Indi- 

 ana, which is reputed to occupy the horizon of the Marcellus 

 shale or perhaps the Genesee slate of New York. The Marce 1 .- 

 lus shale, however, lies below those New York rocks whose 

 equivalents are found at Partridge Point, while our black slate 

 lies above, more nearly in Ihe position of the Genesee slate, or 

 some of the shales of the Hamilton Group. The lithographical 

 resemblances, as inferred from the New York Reports, seem to 

 give color to this identification. 



With reference to the setttlement of this and similar geolog- 

 ical questions, I paid a visit to several localities in the vicinity 

 of Cleveland, where observations have been made by Dr. New- 

 berry, Prof. Hall and others. Dr. Newberry accompanied me 

 to several points and rendered me every possible assistance. 

 About 3 miles east-south-east from Cleveland is an outcrop of 

 sandstone dipping south-east. This is at top, coarse, glistening 

 and somewhat mottled. Below, it becomes light colored, then 

 dirty reddish gray, and then highly ferruginous, with ironstone 

 partings. On the whole it closely resembles the sandstone of 

 the upper part of the Marshall Group. It is said by Dr. New- 

 berry to be 150 to 200 feet below the conglomerate. At Mecca, 

 in Trumbull county, it is completely saturated withjoil. 



At a lower level I observed chocolate colored or reddish 

 shales with interlaminations of light blue, argillo-calcareous 

 slate. From the equivalent of these shales on the west side of 

 the Cuyahoga river,>is manufactured the mineral paint of 

 Ohio 



Still lower, were noticed beds of concretionary shale, cr flag- 

 stones, underlain by fissile shale. The under surfaces of the 

 former are marked by the appearance of flowing mud, a phe- 

 nomenon described as occurring in the Portage sandstones of 

 New York. 



At a still lower level occurs a large stone quarry, showing a 

 section through a series of bluish, fine-grained sandstones with 

 ahaly partings from half an inch to a foot thick. These beds 



