340 CHARLES S. PROSSER 
Dr. Kindle states: 
The lower part of the black shales above the Olentangy shale is everywhere 
characterized in Ohio by spherical concretions often of large size. Concretions 
of this type are entirely unknown in the Cleveland shale both in its typical area 
and outside of it. On the other hand, in the region where the Cleveland is 
typically developed the thin limy bands with cone-in-cone structure are 
common. ‘This type of rock has never been found associated with the spherical 
CONEKEHIONS.. 490 It is proposed, therefore, to limit the term Huron shale to 
Fic. 5.—Huron shale on East Fork of Huron River, below Jacobsburg. Uppet 
part of cliff (15+ ft.), all black shale containing spherical concretion near its base 
with vertical diameter of 5 ft. Blue to bluish-black shale alternating with black 
from 3+ in. below base of concretion for 9 ft. to river level. 
those beds of the Ohio shale exposed on the Huron River, at Rye Beach and 
elsewhere, in which the spherical concretions occur and the Cleveland shale to 
the higher beds in which they do not occur and in which the cone-in-cone 
structure does occur.? 
In northern Ohio the writer has not seen any spherical concre- 
tions in the Cleveland shale or cone-in-cone layers in the Huron 
shale. In central Ohio, however, thin, limy, lenticular layers with 
t American Journal of Science, 4th ser., XXXIV (August, 1912), 198, 199. 
