STRA TIGRA PHY OF OHIO WA VERL Y FORMA TIONS 7 7 1 



doubtfully referred both to the Pocono and to the Catskill, more 

 latterly to the Catskill. So far as the writer is aware, this correla- 

 tion between the members in northern Virginia and those seen to 

 the southwestward has not before been suggested. If it is a correct 

 one, then the Purslane sandstone member, the second member in 

 northern Virginia, becomes important, not only as a very persistent 

 member along the Appalachian belt, but as the only member of the 

 Pocono along the line of the Appalachian mountains that is com- 

 parable with the coarse sandstones and sandstone conglomerates 

 of the Cuyahoga along the Waverly outcrop belt in Ohio. When 

 it is further recalled that the structure of these Cuyahoga sandstones 

 and conglomerates proves that they were derived from the south- 

 southeastward, and that the axes of the facies point in the same 

 direction, the possible correlation with the Purslane becomes doubly 

 suggestive. It remains to question whether the whole of the Cuya- 

 hoga sandstones should be correlated with the Purslane, or only 

 the upper or Black Hand member, which alone is notably con- 

 glomeratic. The question is at present too uncertain a one to 

 discuss, but if it be found that the Black Hand alone should be so 

 correlated, the broad extent of the member would be the only 

 cogent argument yet put forward for the separation of the Black 

 Hand from the remainder of the Cuyahoga sediments. 



LOGAN FORMATION 



, The simplicity of lithological structure and stratigraphy of the 

 Logan formation is in marked contrast with the extreme variability 

 which is found in the several facies of the Cuyahoga. With the 

 opening of Logan time, the localization of conditions which resulted 

 in widely different sediments in closely adjacent areas during 

 Cuyahoga time gave way to quite uniform conditions over the whole 

 of the southern Ohio Waverly belt. Extreme areal variation with 

 no very important variation in vertical succession was succeeded 

 by widespread areal uniformity and a threefold vertical subdivision 

 which can be recognized from the Ohio River to the center of the 

 state and probably well into northern Ohio. 



Subdivisions and extent. — The three subdivisions of the Logan 

 formation in descending order are as follows: Vinton member, 

 Allensville member, Byer member. 



