672 JESSE E. HYDE 



even when thin. The features which characterize the member are 

 the alternating coarse sandstones and shale, the former often massive 

 and thick, and the low initial dips. At some locahties there are 

 no shales and the bedding is not always inclined. The last seems 

 particularly true in the northern part of the area. The member 

 ranges from 200 to 330 feet in thickness, but exact figures are 

 impossible. 



The Black Hand member is the principal cliff-forming member 

 of the Cuyahoga, and the beautiful scenery of Fairfield and Hock- 

 ing counties is chieHy the result of its resistance to erosion. It is 

 a massive coarse sandstone or conglomerate and is distinguished 

 from the underlying Fairfield member by the absence of shale 

 (very rarely single beds an inch or two thick may be observed) 

 and the increased prominence of its structural features, notably the 

 steeply inclined bedding {10° to 20°), the numerous erosion planes, 

 abundant cross-bedding, etc. Its thickness is usually about 100 

 feet, but may reach 150 feet over the center of the province. 



Areally, this member extends laterally beyond the lower mem- 

 bers, whenever it can be followed far enough to determine the 

 point. It persists to the eastward with complete loss of structure 

 except normal horizontal bedding into the eastern part of Fairfield 

 County until it passes below drainage, where it is frequently reported 

 in wells with "shales" below it. It is found capping the hills 

 almost as far west as Amanda (Fairfield County) and Tarleton 

 (Pickaway County) but beyond that it is removed by erosion. It 

 is not found more than three or four miles north of Lancaster, the 

 hills beyond that point falling away to lower elevations. 



In the southwest corner of Hocking County (Salt Creek Town- 

 ship) and the northeast corner of Ross, and in the western town- 

 ships of Vinton County, the horizon of the Black Hand is so low 

 in the hills that its passage westward, first into sandstones and 

 then into the shales of the Cuyahoga, can be traced with ease. 

 A marine fauna appears in the sandstones just east of where they 

 pass into shale. The transition has been traced at several points, 

 sufficient to show that the zone of transition extends a distance of 

 15 miles in a south, slightly southeasterly direction from near the 

 extreme northeast corner of Ross County to near Raysville on the 



