June, 1914.] Middle Mississippian Unconformities. 345 



of the conglomerate stratum is largely a coarse grained standstone 

 with streaks of fine pebbles. This is followed b}^ shale and fine 

 grained clayey sandstone up to the next unconfomiity. 



The lower conglomerate three miles east of Wooster lies about 

 six hundred and twenty feet above the Berea sandstone and about 

 two hundred feet below the lowest Coal Measure rock in the 

 same locality. These figures would appear to put the time of 

 these movements in the late Mississippian, but this system of 

 rocks is known to have been deeply eroded in tliis region in Missis- 

 sippian time. To double or treble the two hundred feet would 

 seem quite permissible, and it ma}^ have been much more. For 

 the above reasons, the time of the movements is assigned to mid- 

 dle Mississippian. 



At Berea, Ohio, the top of the Berea Sandstone lies at 760 feet 

 above sea, 42 miles due south at Apple Creek Village in the south- 

 ern part of the Wooster quadrangle, it lies at 300 feet above, 

 dipping 11 feet per mile. The dip of the lower conglomerate in 

 the same direction, is almost exactly the same. This would indi- 

 cate not merely a local upHft, but an uplift of considerable extent 

 so far as a north-south direction is concerned. There is reason 

 to think it extended much farther southward. 



The upper conglomerate. This bed lies, as found so far, from 

 45 to 85 feet above the base of the lower conglomerate. The 

 lesser measurement applies in the southern part of Wooster 

 quadrangle, and the interval increases northward. The dip of 

 this stratum southward is 13 feet to the mile and lies nearly 

 horizontally from east to west. It is apparent that it departs 

 somewhat from a parallel to the lower conglomerate and the 

 Berea due to differential movement. It is a remarkably uniform 

 stratum in thickness, in composition, and in tmifonnity of size of 

 pebbles. From east to west it has been observed across nearly 

 its entire belt of outcrop, and about twenty-five miles along the 

 belt. It is only one to three feet in thickness, is always largely 

 and often purely a bed of quartz pebbles ranging in size from shot 

 to pebbles three-fourths of an inch in diameter and notably even 

 in size at any one point. Cobblestones from under rock three to 

 five inches in diameter are found in places. Overlying the pebble 

 bed occurs rather soft, fine grained clayey sandstone and shale, 

 typical of the Logan shale to the southward, and carrying the same 

 fauna. 



It was marine laid as shown by brachiopods and crinoid frag- 

 ments. These occur mingled with the pebbles. The persistency 

 of the bed, the uniformity of its thickness, the assortment of its 

 pebbles, and their well rounded form, the writer ascribes to the 

 work of waves in a sea slowly advancing upon the land. The 

 character of the lower conglomerate indicates that it was laid 

 down in the same way. Both appear to be basal conglomerates. 



