In the lower beds fossil shells of various kinds occur (See specimens). Those observed not far below the sandstones occurred in large concretionary hardening of which the matrix was yellowish. They appeared to include Faludinas [?]. Small lamellibranchs were the most common however. In the lower layers large Unio like shells were found, in some places (as already mentioned) in connection with vertebrate remains. A small Ostrea is also very common. If the greater number of the shells are as I suppose fresh water they must be mingled with those (Ostrea) of salt water origin. No clearly separating line can be found between different parts of the section. Probably estuarine conditions.

From the appearance of the formation one would put it under the name of Lignite Tertiary, which it closely resembles in every respect. I believe it is the lower part of that formation. The appearance of oysters is anomalous, but agrees with Hayden's accounts of marine or semi-marine in the base of the Western Tertiary. The exposures along the line to the E. being few however & the dips so moderate & undefined it is impossible to be stratigraphically sure that the formation in question overlies the Sonbre Clays. No junction observed. The section observed near the East Fork renders it possible that these beds may underlie the Sombre Clays. It seems far from probable that two formations so exactly alike...... [?] should occur one below & one above the Sombre Clays, & that fresh water (? see fossils) conditions should prevail in the middle of the Cretaceous.

The two methods of arrangement may be shown as below but the first seems in every way the most probable, the second only requiring consideration from the section near E. Fork showing to all appearance such beds underlying the Sombre Clays.