STRATIGRAPHY OF OHIO WAVERLY FORMATIONS 779 



different beds. For example, at the base of the formation from 

 central Licking County southward at least as far as western Vinton 

 County, a distance of 55 miles, there is a 30- to 40-foot bed of sandy 

 shales with no particular faunal characters noted as yet. It is 

 overlain at all points by a bed of fine-grained yellow sandstones 

 with an abundant fauna, of which one of the chief species is a 

 Productus, heretofore described as, but distinct from, Productus 

 arcuatus Hall. 



The Vinton member marks the resumption of conditions of 

 quiet, uneventful deposition, in deeper water, following the period 

 of shoaling which resulted in the formation of the Allensville mem- 

 ber. There is no transition from the one to the other. The shales 

 of the former rest abruptly on the coarse beds of the latter at all 

 points, and this contact is one of the sharp and persistent ones in 

 the Waverly series. It is suspected that its significance as a strati- 

 graphic horizon is more or less in proportion to this prominence. 



The thickness of the Vinton is determined wholly by the atti- 

 tude of the post-Waverlian erosion plane. Valleys of considerable 

 depth were cut into the Waverly following its deposition and prior to 

 the accumulation of the Pennsylvanian deposits, or Coal Measures, 

 and considerable irregularity can be detected in its upper surface 

 as a result. The greatest known thickness of the member is pre- 

 served in the northwest portion of Perry County and adjacent parts 

 of southern Licking County. Here was an area which must have 

 been uniformly high land, for the Vinton member is from 200 to 

 240 feet thick, although it does not usually much exceed 50-75 

 feet thick, and is occasionally wholly removed. On the Ohio River 

 between Sciotoville and Portsmouth the member probably attains 

 a similar thickness, but precise determination is seriously hampered 

 by the absence of the Allensville member. The Mississippian- 

 Pennsylvanian contact in central and southern Ohio has been 

 briefly described.^ 



^ J. E. Hyde, " Notes on the Absence of a Soil Bed at the Base of the Pennsylvanian 

 of Southern Ohio," Am. Jour. Sci., 4th ser., XXXI (191 1), 557-60. 



