35 



with the fossil relics of marine life ; then an uninterrupted passage of con- 

 formable beds through the brackish period up, till the whole Green River 

 basin became a single sheet of fresh water.'' He regards the line of the 

 upper bed of oysters as the summit of the Cretaceous, and the superimposed 

 beds as Tertiary, in the following language (page 453): "while the fresh- 

 water species which are found in connection with the uppermost coal-beds 

 seem to belong to the early Tertiary period." He thus places the line some 

 distance within what I have regarded as the Cretaceous boundary. 



Mr. Lesquereux, as is known, regards these beds as Tertiary, not only 

 on account of their vegetable fossils, but also on account of the stratigraphic 

 relations of the formation. His conclusion to this effect is consistent through- 

 out, and is a fact of the highest importance in this connection. 



Mr. Meek has fully discussed the age of this series in his interesting 

 article in Hayden's Annual Report for 1872, the general tenor of which is 

 indicated by the passage I have quoted from the opening of his remarks, in the 

 beginning of the present notice of the -Bitter Creek beds. His opinions may 

 be cited as follows: In the Annual Report for 1870, he determined the same 

 beds visible at Hallville as Tertiary; in that of 1871, three species of oysters 

 from other parts of the Bitter Creek beds are placed in the Cretaceous list, 

 each one with question as to the identification of species, a point, in the case 

 of oysters, of first importance in the determination of the age of the deposit. 

 The remarks in this report, as well as those in Mr. King's report, refer either 

 to the much lower Weber River coal or to the different area of the Bear River 

 group, and are consequently noticed under that head. 



In a paper on the age of these beds, published August 12, 1872, the writer 

 asserted the Cretaceous age of the series. On this, Dr. Bannister, the com- 

 panion of Mr. Meek, writes 1 " that Mr. Meek, and, I believe, Mr. Emmons also, 

 had considered that these beds might be Cretaceous ; but this was rather on 

 account of the change in the fossil fauna from purely fresh-water, as in the 

 characteristic Tertiary of this region, to brackish-water marine, and the spec- 

 ific affinities of a few of the fossils to California Cretaceous species, than from 

 any very positive evidence. As far a.s I know, the only evidence of this kind 

 is in the identification by Professor Cope of the saurian remains found by us 

 at Black Butte." 



It only remains to observe that the strata and coal of the Bitter Creek 



1 Annual Report for 1872, p. 534. 



