OF DENISON UNIVFRSri'Y. 
Sciotoville. 
( CoNGL. I, absent.) 
Shales 40 ft. 
Spirifer marionensis, 
shales and flags, 70 ft. 
Rushville, Etc. 
Conglomerate L 
Shales, Palaeoneilo atten- 
uata, etc 30 ft. 
Shales and flags 40 ft. 
Shales concretions, Spirifer 
marionensis 30 ft. 
Flags and shales 70 ft. 
Flags, unfossilif. 125 ft. 
Shales, fossils 10 ft. 
Berea grit, etc 100-175 ft. 
103 
Ashland Co. 
CoNGL I 18 in. 
Flags and shale — 10 ft. 
Siliceous flags 30 ft. 
Concretionary shales, 
Spirifer marionensis, 
30 ft. 
Flags and shales. 
Our own observations are less full and connected further north, 
and a marked lithological change accompanied by the gradual disap- 
pearance of many of the mid-Waverly horizons produces a somewhat 
peculiar habitus as we enter the Cuyahoga valley. The few feet 
of shale near the top at Cuyahoga Falls seem to extend above any of 
the southern horizons and mingle fossils like Spirifer biplicatus of the 
Waverly with coal-measure types like Entolium aviculatum. The mis- 
take has been made of regarding these shales as homogeneous. An 
almost entire change in fauna appears a mile or two below Cuyahoga 
Falls and there is little in common between the upper shales and those 
below the flags forming the second fails of the Cuyahoga. The fol- 
lowing section is given by Dr. Newberry in Summit county : 
Conglomerate. (Base of coal-measures ) 
Cuyahoga shale 
Berea grit 
Bedford shale 
Cleveland shale 
Erie Shale 
Huron shale 
The entire section, including the Erie and Cleveland shales which 
disappear further south, is less than 500 feet, and, making the neces- 
sary allowance, about 350 feet will include all of the Waverly which 
has an equivalent represented in central Ohio. 
We may now pass to a more detailed study of the recognized hori- 
zons in Ohio. 
I. J'/ie Cuyahoga shale and Logan group. 
The term Cuyahoga shale is most misleading and can serve only 
to indicate the condition of the geological column in the northern tier 
150-200 ft. 
60 ft. 
70 ft. 
50 ft. 
100-125 ft. 
