white.] DISCUSSION OF LARAMIE FOSSILS. 247 



mie strata that have already been discussed in this report ? Too much 

 yet remains to be done in the investigation of these beds and their fauna 

 to admit of definite replies to these questions, but the following already 

 ascertained facts have an important bearing upon them. In the section 

 published by Mr. Meek in the An. Bep. U."S. Geol. Sur. Terr, for 1872, 

 p. 451, these brackish-water Laramie beds are seen to come in the series 

 above the Fox Hill Cretaceous strata. In the neighborhood extending 

 from three to seven miles north from Evanston the coal series is seen to 

 rest upon the brackish-water beds, and in turn to be overlaid by the 

 Wasatch Group. This warrants their general reference to the Laramie 

 Group, but whether they may not be older than any of the other Laramie 

 strata that have been discussed in this report remains for further inves- 

 tigation to decide. The fact that some of the invertebrate types of 

 these brackish- water beds are apparently extinct, while none of those of 

 the other Laramie beds are now known to be so, suggests their greater 

 antiquity, but does not necessarily prove it ; especially so as those types 

 are not known in older strata. On the other hand some of the species 

 in the upper beds at the Almy coal mines, some 100 or 500 feet above 

 the range of the brackish- water species, are regarded as identical with 

 forms that have been found both in the Fort Union and the Lignitic beds 

 of the Laramie Group east of the Eocky Mountains in Colorado. It 

 should furthermore be remarked that the conditions of the strata at the 

 junction of the Fox Hills Group with the brackish-water Laramie beds 

 in this region are not accurately known; and also that I am not sure of 

 the exact conformity of the coal-bearing upper beds upon the latter ; 

 while the unconformity of the Wasatch, upon the Laramie in this region, 

 is well known to be general. It therefore seems not improbable that the 

 displacements which took place in this region were not confined to the 

 immediate close of the Laramie period, but that other lesser movements 

 took place at different times between the close of the Fox Hills epoch 

 and the earlier part of that of the Wasatch. 



The displacements that took place at or near the close of the Laramie 

 period, in what is now the vicinity of Bear Eiver Valley, were very great, 

 and they are doubtless of considerable extent in this region, although 

 not at ail apparent in a large part of the Green Eiver Basin. They in- 

 volved not only the Laramie strata, but the older groups also ; at least 

 those of the Fox Hills and Colorado Groups, which are seen to be so in- 

 volved in this immediate neighborhood, if the latter have been correctly 

 identified. This is shown in Mr. Meek's section of the strata in the val- 

 ley of Sulphur Creek at its confluence with Bear Eiver, which has already 

 been referred to. That section shows not only abrupt and deep foldings 

 of those strata, but certain slips or faults also. The portion of it which 

 is numbered 28 consists of the brackish- water Laramie beds as they are 

 seen at Mellis Station on the east side of Bear Eiver, and which there 

 appear to occupy the east side of an abrupt synclinal fold. No strata 

 above those of the Laramie Group appear to be involved in this sharp 

 fold, against the upturned strata of which those of the Wasatch Group 

 appear to abut unconformably. The whole group is probably thus in- 

 volved, but the upper beds, as seen at the Evanston coal-mines, have not 

 been discovered there, the waters and scattered shingle of Bear Eiver 

 covering the surface they would otherwise occupy if present. The Lar- 

 amie strata that occupy the western side of the fold appear upon the 

 western side of Bear Eiver, a couple of miles southwestwardly from 

 Mellis Station, those of both sides of the fold being nearly perpendic- 

 ular. 



Flanking these upturned Laramie strata upon their west side, and in 



