594 CHARLES S. PROSSER 
Rocky Fork section.—This stream enters Big Walnut Creek not 
far below Gahanna, and various sections on its banks have been 
more or less fully described by the writer in former papers.* There 
has been some uncertainty where the line of division between the 
Bedford and Berea formations should be drawn and in his later 
papers the base of a concretionary sandstone has been considered 
as marking this horizon.?_ Later studies appear to support this con- 
clusion and a very brief statement of these additional data will now 
be given. In former papers a section at the lower end of the gorge, 
where the basal part of the Berea is shown, and another one farther 
up the creek on the opposite and eastern bank, where the entire 
Berea formation occurs, have generally been described. On the 
western side of the stream, between the two cliffs mentioned above, 
is another one which will now be described. 
SECTION ON WESTERN BANK OF ROCKY FORK 
Total 
No. ; Thickness Thickness 
Feet Feet 
4. Berea sandstone.—Buff, quartz sandstone which 
forms upper part of cliff. Some of the layers are 
fairly thick; but more of them are thin-bedded.... 26 425 
3. Arenaceous shale changing to thin sandstone at top 
of zone. ‘This shale is more sandy than that in zone 
No. 1 of the Bedford. The measurements for this 
zone have varied from 6 ft. 2 in: up to 7 ft. 8 in., 
depending upon the amount of thin-bedded sand- 
stone at the top which has been included.......... 62= 163 
2. Concretionary sandstone stratum composed largely 
of rather fine-grained, quartz sand. Varies in 
thickness fromien ity roms to;2-| ate. ceva en nein 2 "OF 
1. Bedford formation.—The surface is somewhat irregu- 
lar, indicating a line of disconformity between the 
two formations. Mainly blue, argillaceous shale 
with occasional thin layers of compact, blue, cal- 
careous sandstone, which weather to a brown, rotten 
SEOME R aray olla ikes corey ate eee shecmapre ches gel RAL rail aa acts cane p aire ceo EAS 7 
Ico 
7 
leo 
Samples were taken from a thin sandstone a few inches below the 
top of zone No. 1 and from the lower part of the concretionary 
t Journal of Geology, TX (1901), 216-18; ibid., X (1902), 274-78; American 
Geologist, XXXIV (1904), 340, 341. 
2 Journal of Geology, X, 278; American Geologist, XXXIV, 340, footnote. 
