448 GEOLOGICAL SURVEY OF THE TERRITORIES. 



As I liave, howev^er, luentionetl faulrs and lateral displacements of 

 the strata here, it iiuiy be thought by some who are yet incredulous. in 

 regard to the Cretaceous age of these coals that these disturbances of 

 the strata may have given origin to erroneous (;onclusions respecting 

 the positions of the beds containing the Cretaceous types with' relation 

 to the coals. This, however, is simply impossible, because these fossils 

 occur, as elsewhere stated, both above and below the coal-beds, even in 

 local exposures, where ail the strata, and included coal-beds, can be 

 clearly seen conformable and in their natural positions with relation 

 to each other. Consequently it would not, in the slightest degree, weaken 

 the force of the evidence, even if we should admit any conceivable 

 amount of disturbance of the beds, or even if we were to suppose the 

 whole vast series of beds had been bodily tilted up and completely in- 

 verted, (of which condition of things there is no evidence,) because, even 

 in that case, we would still have unquestionable Cretaceous types both 

 above and below the coal-beds. 



In the reports above cited, I stated some reasons for supposing this 

 whole group of Cretaceous rocks to belong to a more recent member of 

 that system than any of the recognized subdivisions of the Upper Mis- 

 souri Cretaceous. The facts observed at the locality last season, how- 

 ever, seem to demonstrate that this is not the case. For instance, m'c found 

 toward the lower part of the section, both above and below the main 

 coal-bed, Inoceramus prohlematicus^ a widely distributed species that is 

 very characteristic of the Niobrara and Benton groups of the Upper 

 Missouri, which there occupy positions below the middle of the series; 

 and, so far as I know, this species never occurs in this country above 

 this horizon.* Again we found, far above this, in division 2o of the sec- 

 tion, numerous specimens of a larger Inoceramus, which, if not really 

 identical with one of those forms, is scarcely distinguishable from I. 

 Sagensis and I. Nehrascensis of Owen, which occur in the later members 

 of the Upper Missouri series. From these facts, it is more probable 

 that we have here, at and near Coalville, representatives of the whole 

 Upper Missouri series, with possibly even lower members, farther up 

 Weber River, than any of the known Upper Missouri subdivisions of the 

 Cretaceous. If this is so — and there seems to be little reason to doubt it — 

 the marked diflerence observed between almost the whole group of fossils 

 found here, and those of the Upper Missouri Cretaceous, would seem to 

 indicate that there was no direct communication between the Cretaceous 

 seas or gulfs of that region and those in which these Utah beds were 

 deposited. Difiereuces of physical conditions, however, probably also 

 played an important part in the production of this diversity of life, 

 since it is evident from the great predominance of clays and other fine 

 materials in the Cretaceous beds of the Upper Missouri, that they were 

 deposited in comparatively deeper and more quiet waters than those in 

 Utah, in which coarse sandstones, with occasional pebbly beds, predom- 

 inate. 



Although the Coalville coals, and indeed all of those of this entire 

 region of country, belong, (as might be expected from their compara- 

 tively modern age,) chemically speaking, to the brown-coal series, they 

 are of unusally good quality, being geherally as hard, black, compact, 

 and shining as the far older Carboniferous coals. They burn much like 

 bituminous coal, being, in fact, semi-bituminous. As they contain more 



*For the information of European geologists, not familiar with the details of our 

 geology, it should bo stated that the entire Upper Missouri Cretaceous series belongs to 

 the upper part of that system. 



