144 
Frank Carney 
shallow water, must imply a subsidence of the area receiving the ii 
sediments synchronous with the filling produced by the deposits. 
This conclusion is based on the assumption that such a uniform f 
condition of ripple marks persisting through a considerable verti- ) 
cal range implies a constancy of sedimentation factors. Towards i 
the upper part of the Berea, however, the beds thicken, becoming i 
more sandy, thus suggestive of littoral sedimentation. 
Sunhury Formation. This horizon of rocks consists chiefly of ! > 
shales locally arenaceous, but in the main, black in color and I :' 
bearing a considerable fauna. Both the fauna and the litholog- f‘ 
ical aspect of the formation indicate marine sedimentation. On ji . 
this principle, then, the water area in which the next older for- | c 
mation, the Berea, was laid down, continued to transgress the | ! 
land, thus maintaining a horizon of marine deposition. !| 
Cuyahoga Formation. This formation consists of shales and ii i 
sandstones, the upper boundary of which was for some time given S j 
as Conglomerate Later studies, “ however, have shown that i i 
this conglomerate horizon is not persistent, and furthermore, that ( 
even where found it overlies beds that do not have the Cuyahoga 
characteristics. So far, however, as the process of sedimentation | j 
involved in the Cuyahoga beds admit of interpretation, it is evi- I - 
dent that the quick transition frequently noted from fine to coarse ‘ 
textured layers probably indicates a somewhat static relationship • 
of land and water which would result in the coarser sediments j 
locally reaching out over mud deposits. This supposition accounts i 
for the transition from shale to an arenaceous or even a conglom- 
erate horizon. When, however, mud deposits follow, in the 
vertical succession, the sandstone or argillaceous shale, which is f 
the prevailing relationship in the Cuyahoga inasmuch as it con- | 
tains more shale than any other textured rock, it is surmised that j 
the predominating tendency of the water body was transgressive. [ 
I feel nevertheless that a closer mapping of the Cuyahoga and the 
conglomerate horizon by which the top of the formation was for- | 
merly fixed will reveal much horizontal variation, and that the || 
meaning of this inconstancy is a closely balanced relationship | 
during the early and late Cuyahoga times between the rate of 
deposition and the rate of transgression by the sea. | 
C. L. Herrick: Bull. Denison University, vol. iii, p. 26, 1888. 
C. S. Prosser: The American Geologist, vol. xxxiv, p. 359, 1904. 
il 
