330 Tlie Cincinnati Rocks. — Ferity. 
the top of the Cincinnati series down into the Calciferous 
sandrock. Choosing the railroad levels at the depot as his 
hench-mark he and his class in engineering ran a line of levels 
to the spot where the stone was found — a distance of about 
five miles — and we were thus enabled to locate the horizon 
with great exactness and found it to be within a few inches of 
600 feet above the top of the Trenton limestone. In this 
estimate the 50 feet of dark shaly stone found in the gas-well 
section, supposed to be the equivalent to the Pt. Pleasant beds, 
were regarded as not belonging to the Trenton and are in- 
cluded in the figures mentioned. 
Frequent visits to this locality, known as "Smiley's Dam," 
have alwa3^s resulted in finding other specimens of raindrop 
impressions. 
Some time later, having interested Mr. David McCord of 
Oxford in my work, we visited together a locality known as 
"Little Four Mile." The stream was perfectly dry, affording 
an excellent opportunity of examining its bed. At a place 
known as Ridenour's Mills the bed consisted of a succession 
of large stony floors — often fifty feet square or more — com- 
posed of successive strata of compact limestone. Going up 
stream from Ridenour's Mills we found almost every stratum 
distinctly wave-marked. The waves were of all sizes from 
what would correspond with the gentle roll of the sea, indi- 
cating comparatively deep water, and having their ridges 
many feet apart, down to the tiniest little ripple-marks that 
could only have been formed in the shallowest and most cir- 
cumscribed pools. These wave-marks differed in direction in 
different strata, but were, with the exception to be noted, all 
in very pure limestone. Some of the strata were composed of 
the very finest and homogeneous material of a deep blue color, 
while others, equally hard and compact perhaps, were made 
up of crinoidal and shell-fragments — the limestone sand of a 
former beach. Here as elsewhere throughout the Cincinnati 
group the limestones alternate with strata of shale. I was 
much interested in finding in this shale also distinct ripple- 
marks. I have a photograph made by Mr. William McCord 
from specimens collected by his father, Mr. David McCord, on 
this same trip, which represents the ripples about three-quar- 
ters their natural size.(Fig.2)I think no one can look upon these 
and other similar specimens collected and doubt their origin. 
