Mesozoic and Ccenozoic Geology and Palceontology. 103 



oceramus, aud other fossils, and in some remarks on this collection* 

 he referred this formation to the Cretaceous. The collections that 

 have since been brought in from it, in Utah, by Mr. King's and Dr. 

 Hayden's surveys, confirm the conclusion that it belongs to the 

 Cretaceous, as they contain, among other things, species of Inocer- 

 a^iiifs, Anchura and Gyrodes — genera that seem not to have survived 

 the close of the Cretaceous period. In addition to this, there is among 

 Dr. Ha3^den's collections from this rock, at Coalville, a Turritella that 

 he could not distinguish from T. martinezensis^ and a Ilodiola which 

 appeared to be specifically identical with M. pedernalis. Dr. Ha3^den 

 also had, from a little above the coal beds at Coalville, specimens of 

 03'ster that seemed much like 0. idriaensip and 0. hreweri^ of Gabb, 

 from the upper beds of the California Cretaceous. From the 

 affinities of some of these fossils to forms found in the latest of the 

 beds referred in California to the Cretaceous, and the intimate 

 relations of these marine coal bearing strata of Utah to the oldest 

 Tertiar}^ of the same region, and the apparent occurrence of equivalent 

 beds bearing the same relations to the oldest brackish-water Tertiary 

 beds at the mouth of Judith river on the Upper Missouri, he was 

 inclined to believe that these Coalville beds occupy a higher horizon 

 in the Cretaceous than even the Fox Hills beds of the Upper Missouri 

 Cretaceous series; or, in other words, that they belong to the closing 

 or latest member of the Cretaceous. 



All of the explorers of this region concur, in the statement, that the 

 above mentioned Cretaceous beds are intimately related to the suc- 

 ceeding brackish water deposits that appear to belong to the oldest 

 Tertiary; the two formations, wherever they occur together, being- 

 conformable and without any intermediate beds, so that the one seems 

 to shade into the other, without an}^ abrupt or sharply-defined line of 

 separation ; the change being mainly indicated by a gradual transi- 

 tion from beds containing Cretaceous types of only marine origin, 

 to those with brackish and fresh water tjqDcs, apparentl}" most nearly al- 

 lied to earl}^ Eocene species of the old world. 



So far as yet known, there would appear to be no strictly marine 

 Tertiar\^ deposits in all this interior region of the continent; even AhQ 

 lower parts of the surface here having been apparently gradually ele- 

 vated above the sea level, at, or very near, the close of the Cretaceous 

 period. For the same reason all of the beds hitherto referred with con- 

 fidence to the Cretaceous are of undoubted marine origin, as they con- 

 tain only marine types. 



" Proc Acad. Xat. Sci. ♦ 



