start 3066 end brier fauna. These shales maybe 10 feet thick followed by mac shales interbedded with red shales. for fully 60 foot more before the Potterville comes in. Therefore the brieferina is here in the low Mancul Chert. It abounds in genuine Chester fossils as Lemnula cutguadata, Spirifera leidgi, Productus chesterensis etc. In the brieferina zone are also red beds abounding in bivalves of many species and Ostr- acodidea. Therefore these red-beds are marine but those below and above identical in color have no fossils. It seems to me that much if not all of the Mancul Chert is here marine. It is a cycle of deposition like the marine ones of the Pennsylvanian beginning with marine deposits and ending in a filled sea and continental deposits. At the eastern end of this cut about one mile west of Briclion may be seen a fine example of marked unconformity of the Lower Potte- sville on the Mancul Chert. The sketch of it is on the next page and a photo (Film 1-12).