412 FLORA OF THE LARAMIE GROUP. 



range, there is no single instance of conformity between tbe coal beds 

 and tlie horizontal freshwater strata abovo them." 



Tliis cliapter also contains a list of the fossil invertebrata collected 

 in that region and named by Mr. Meek, accompanied by an interest- 

 ing letter explanatory of their geologic significance. The fact that 

 several species of Inoceramns, and some which seemed referable to 

 xVnchura, were positively credited to the coal series, led JNIr. Meek to 

 speak with the greatest caution as to the age of these rocks ; but it is 

 clear that, but for these facts, coupled with the stratigraphical consid- 

 erations urged by Mr. King, he would have scarcely hesitated to pro- 

 nounce it Tertiary. But he lays great stress upon "the fact that these 

 fossils are all marine types," and says : " From all the facts now known 

 I can, therefore, scarcely doubt that you are right in referring these 

 beds to the Cretaceous." A paragraph on page 462 gives his reasons 

 for this conclusion more in full, together with certain qualifications 

 which ho feels obliged to make, and closes with the remark that the 

 facts seem to indicate "that these beds belong to one of the very latest 

 members of the Cretaceous; or, in other words, that they were probably 

 deposited when the physical conditions favorable to the existence of 

 those forms of Molluscan life peculiarly characteristic of the Cretaceous 

 period were drawing to a close or had in part ceased to exist." 



Relative to the age of the so-called Bear River estuary beds, Mr. 

 Meek expressed himself in this communication with still greater reserve. 

 These beds had been referred by him and Mr. Henry Engelmann to the 

 Tertiary in 18G0, in a communication made by them to Capt. J. H. 

 Simpson, and published in the Proceedings of the Academy of Natural 

 Sciences of Philadelphia for April of that year (Vol. XII, p. 130). He 

 admits, however, that they may be Cretaceous, as they belong to the 

 lower disturbed system elsewhere regarded as Cretaceous. He says 

 that some of the fossils described by him from the mouth of the Judith 

 River "are identical with those found in these Bear River estuary beds," 

 exiiresses doubt that the saurian remains from there were really from 

 the same horizon, and concludes as follows: "While I am, therefore, 

 willing to admit that facts may yet bo discovered that will warrant the 

 conclusion that some of these estuary beds, so widely distributed here, 

 should be included rather in the Cretaceous thaii in the Tertiary, it 

 seenjs to me that such evidence must either come Irom included verte- 

 brate remains or from further discoveries respecting the stratigraphical 

 position of these beds with relation to other established horizons, since 

 all the molluscan remains yet known from them (my own opinions are 

 entirely based on the latter) seem to point to a later origin." 



Prof. O. C. Marsh, in giving an account, in the American Journal of 

 Science for March, 1871, of an expedition conducted by him the pre- 

 vious season through a portion of the Green River Valley and Eastern 

 Utah, describes the coal deposits met with by the party on Brush Creek 

 with special reference to their geologic age. He says (p. 195) : "As the 



