534 



GEOLOGICAL SUKVEY OF THE TERRITOEIES. 



eries 



as observed by us. The general divisions correspond to those 

 given, included in brackets, in the detailed sections, and 

 are indicated by the same letters. 



It is worthy of remark that, of the invertebrate fossils 

 obtained by us as far down as to the base of the series, not 

 one is of a characteristic Cretaceous genus, but all have 

 rather the aspect of a collection obtained from beds of 

 Tertiary age. It is true that Mr. Meek, and I believe 

 Mr. Emmons also, had considered that these beds might 

 be most properly referred to the Cretaceous, but this 

 was rather on account of the change in the general 

 character of the fossil fauna from purely fresh- water, as 

 in the characteristic Tertiary of this region, to brackish- 

 water marine, and the specific affinities of a few of the 

 fossils to California Cretaceous species, than from any 

 very positive evidence. As far as I know, the only 

 evidence of this kind is in the identification, by Profes- 

 sor Cope, of the saurian remains found by us at Black 

 Buttes. It seems to me highly probable, and indeed 

 almost certain, that the workable coal-seams of Wyo- 

 ming and Utah range from well- characterized Cretaceous 

 strata, as at Coalville and Bear Eiver City, through 

 these beds, which may, perhaps, be best regarded as a 

 gigantic transition series, into the purely fresh-water 

 beds, usually consideed as of Tertiary age, as observed 

 by us near Se))aration and elsewhere. 



Salt Wells. — i^ear Salt Wells a very different series 

 comes to the surface and occupies the axis of the anti- 

 clinal at this place. The rocks are first seen along the 

 railroad, about four or five miles east of the station, 

 and consist of grayish drab, thin-bedded sandstones and 

 shales, with an entire absence of the heavy-bedded butt" 

 and whitish sandstones which form so prominent a fea- 

 ture of the overlying rocks farther east. It forms the 

 high bluffs some two or three miles south of Salt Wells 

 Station, but is wanting in the immediate vicinity of the 

 railroad at that point, and for some distance to the west- 

 ward, as the station itself is situated in the valley along 

 the anticlinal axis. Two or three miles to the eastward, 

 one or two cuts show sections of the beds close to the 

 track, in which it is pretty uniformly a thinly laminated, 

 dark grayish drab sandstone or sandy shale, and, is as 

 far as we could see, entirely destitute of fossil remains. 

 Mr. Meek examined the bluffs about two or two and a 

 half miles southeast of the station, and found them to 

 consist of very much the same general character of beds, 

 with some intercalated clays, the whole, however, show- 

 ing no very abrupt variations such as are to be seen in 

 the rocks of the overlying series. jSTo fossils were found, 

 except indistinct traces of fucoids ("?) and tracks of anne- 

 lids. The thickness of the beds exposed in the bluff was 

 about 480 feet, the uppermost of which, by estimate, 

 was 250 to 300 feet below the base of the preceding sec- 

 tion, making a total from the base of the bluff to the 

 lowest member of the variegated sandstone series, of 

 over 700 feet. Add to this the probable thickness of 



