June, 1914.] Middle Mississippian Unconformities. 
345 
of the conglomerate stratum is largely a coarse grained standstone 
with streaks of fine pebbles. This is followed by shale and fine 
grained clayey sandstone up to the next unconformity. 
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 this region in Missis¬ 
sippian time. To double or treble the two hundred feet would 
seem quite permissible, and it may 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 uplift, 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 stratiun 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 uniformity 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 tinder 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. 
