586 CHARLES S. PROSSER 
for use by the various teachers during the last five or six years. 
The writer has used them in his lectures to a succession of classes, 
while a large number of students have visited one or more of the 
localities on field trips. 
A similar disconformity was found between these formations in 
northern Ohio and an account of its occurrence at various localities 
from southwest of Cleveland eastward is contained in Bulletin No. 
15 of the Geological Survey of Ohio now passing through the press. 
A part of the evidence showing such a disconformity in northern 
and central Ohio was presented by the writer in a paper entitled the 
“Contact of the Bedford and Berea Formations in Ohio” at the 
Ohio Academy of Science meeting in Columbus on December 1, 
toirt. The part of that paper describing the disconformity in 
central Ohio makes the following portion of this article. On the 
day that the writer read this paper he received the October- 
November, to11, number of the Journal of Geology containing an 
article by Mr. Wilbur G. Burroughs describing the unconformity 
between these two formations near South Amherst, Lorain a COMER 
in northern Ohio." 
Definition of disconformity.—The stratigraphic term discon- 
formity is used in this article as defined by Dr. Grabau “to cover 
unconformable relation of strata where no discordance of dip 
exists,’ a term that was proposed by him in 1905.3 For this type 
of unconformity, which has generally been called unconformity by 
erosion, Professor Crosby has recently proposed the name para- 
unconformity.4 
DESCRIPTION OF SECTIONS 
In this article only a few of the most interesting outcrops 
showing the contact of the Bedford and Berea formations on the 
Westerville and East Columbus quadrangles in central Ohio will be 
described. 
Spruce Run sections—An excellent contact occurs on the north 
branch of Spruce Run on the Frank E. Hoover farm, 2% miles 
t Journal of Geology, XIX, 655-59. 
2 Science, N.S., XXIX (May 7, 1909), 750. 
3 [bid., XXII (October 27, 1905), 534. 
4 Journal of Geology, XX (1912), 206. 
