A Strati graphical Study 
143 
j shore deposits, and its thickness indicates a slowly transgressing 
sea, thus maintaining the depth of water that would assure freedom 
from the coarser terrigenous deposits (fig. 7). The nature of the 
J sediment, furthermore, indicates a sea transgressing upon a land 
! area that had long withstood erosion, a region already mantled 
with deposits of residual decay. Where, however, the Bedford 
shows some arenaceous layers inter-stratified (fig. 8), there is evi- 
dence of broad river deltas reaching out into the epi-continental 
zone. Here the irregularity of sedimentation occasioned by the 
seasonal or by longer cyclic periods of unusual water supply would 
Fig. 8. Disturbed zone at the base of the Berea along Rocky river, Franklin 
county, described by Professor Prosser {The American GeoIogist^yoX. xxxiv, 1904, 
p. 340, footnote). 
extend the coarser sediments temporarily over areas where hitherto 
only the finer muds were being deposited. 
Berea Formation. This series of thin bedded to slightly massive 
gritty layers above, below to arenaceous shales, about 37 feet in 
thickness,® illustrates rippling perhaps as no other horizon in the 
state displays the phenomenon. Along the Rocky F ork, up stream 
from the areas shown in figs. 7, 8, these sandy layers, for a verti- 
cal distance of 6 to 8 feet, consist of beautifully rippled beds aver- 
aging about two inches in thickness. Such a vertical range of 
conditions of sedimentation, usually interpreted as representing 
® C. S. Prosser: The American Geologist, \o\. xxxiv, p. 340, 1904, footnote. 
