STRATIGRAPHY OF OHIO WAVERLY FORMATIONS 775 



central Ohio, into Wayne County.^ This is to within 40 miles 

 of Lake Erie. 



The Allensville member. — The quiet conditions of Byer time were 

 terminated by general shoaling of the region which resulted in the 

 formation of the Allensville bed, whose chief characteristic is its 

 coarse sandstones. Over much of the area this was brought about 

 gradually, since there is a transition from one to the other; in fact, 

 the typical sandstones of the Byer type are found almost to the 

 top of the Allensville. 



The name Allensville is given from numerous outcrops near that 

 village in the western part of Vinton County, although the bed is 

 not especially well developed there nor any better exposed than at 

 other points. As is shown on the map (see Part I), it is found 

 from the Ohio River as far north as the work has been pushed. 

 In Scioto County along the river it is known certainly that it 

 disappears westward, thus demonstrating that the source of its 

 material lay to the eastward. In Pike and Ross counties this 

 westward disappearance has not been completely demonstrated 

 because of poor outcrops, but it is almost certain. 



The greatest thickness yet observed is 39 feet, reported by Mr. 

 Schroyer in Pike County, but this is exceptional. Commonly 

 it is from 15 to 25 feet throughout the whole area but not infre- 

 quently it is less. It is least on the Ohio River near its extreme 

 western limit where it diminishes rapidly from 6 feet to as many 

 inches just before its final disappearance. The bed is apparently 

 present at every point within the area of its occurrence indicated 

 on the map. 



As just noted, its chief characteristic is the occurrence of very 

 coarse, excellently assorted, and usually well-rounded quartz grains. 

 South of Fairfield County the material of the coarse beds is really 

 a fine conglomerate of excellently assorted pebbles from one- 

 sixteenth to one-eighth of an inch in diameter. The coarse beds 

 there first appear in the section as thin layers, often only an inch 

 or less in thickness, between much thicker beds of the typical, 

 Byer-like sandstones. It is very difficult exactly to locate the base 

 if the outcrops are poor. Much of the lower part of the member 



^ Bull. Sci. Lab. Dennison Univ., V (1890), 24-32. 



