GEOLOGICAL SURVEY OF THE TEERITOPJES. 339 



another, and tliough well preserved by a thin incrustation of coal upon 

 their surface, they are rarely isolated, and their nervation, too, being 

 scarcely distinct, their determination is diiSicult and somewhat uncer- 

 tain, i did not find at Evanston any fucoidal remains. The specimens 

 obtained by Dr. Peale, however, have, in a hard, gray sandstone, two 

 branches of a fucoid, (Halimenites major^) labeled from that locality. 



§ 10. Coalville, Utah. 



This place is known to me only from descriptions given by Dr. Haydeu, 

 Mr. Hodge, and other explorers. ]^o fossil remains of land-plants have 

 as yet been obtained from strata in connection with the Lignitic beds. 

 Judging from the relative disposition of the coal-beds, their thickness 

 and their chemical compounds,* I have been disposed to consider 

 them as equivalent to those of Evanston. Professor B. F. Meek's ob- 

 servations, however, as published in this report, indicate for the geology 

 of Coalville a series of Lignitic strata with intermediate beds, clay and 

 sandstone, bearing remains of evidently Cretaceous animal species, there- 

 fore tending to refer the whole series to Cretaceous. Except the fucoid 

 species, abundantly found at Coalville by the same observer, we have no 

 botanical evidence to bear upon the question of the age of these strata. I 

 believe, nevertheless, that this case is of the same nature as that of Black 

 Butte, where Cretaceous animal fossils are found hundreds of feet higher 

 in the measures than thick beds of lignite, immediately overlaid by shale- 

 bearing remains of plants positively of Tertiary age. Facts of this 

 kind have to be judged from a general point of view, in considering the 

 evidence of general relation. For, indeed, in a formation like the Lig- 

 nitic, which may be called a formation of transition, the evidence 

 given by vegetable and animal paleontology, or by land and marine 

 remains, can but disagree sometimes. 



THE Tv^ESTEEN LIG-NITIC FORMATION COWSIDEEED AS EOCENE. 



Dr. Hayden in his reports has constantly alluded to the Lignitic group, 

 especially to the barren sandstone underlying it, as to beds of passage 

 or of transition between the Cretaceous and the Tertiary, often men- 

 tioning them as Eocene. No formation is exclusively limited in its char- 

 acters, at least not in those which are supplied by fossil remains. On 

 this account, every geological division might be considered as being a 

 transition, and this is especially the case for the strata intermediate be- 

 tween a marine and a land formation ; as, for examx^le, in the Carbon- 

 iferous epoch, to which our Lignitic has so many points of similarity. 

 Devonian animal fossils ascend to the Subcarboniferous, or even to 

 the true Carboniferous measures, which have also species of inverte- 

 brate animals characteristic of the Permian ; and the plants which have 

 entered into the composition of the coal are found already, some of 

 them at least, in the Middle Devonian, the Hamilton period ; while the 

 most common sfjecies of ferns, even of Sigillaria of the Carboniferous, 

 have left traces of their presence high up in the Permian. The same 

 might be remarked on every other artificial group, which geologists 

 have to fix for convenience and better understanding. The discussion, 

 therefore, on the age of the formation called Eocene, and now under con- 

 sideration, should not admit as evidence isolated facts in contradiction 

 to the persistence of general characters observed over wide areas, 

 in great thickness of strata, and which give to the whole a kind of 



'^ Mr. Hodge's paper in Dr. Hayden's Report, 1870, p. 321. - 



