GEOLOGICAL SURVEY OF THE TERRITORIES. 149 



to have been elevated to some extent since that time. For some 

 distance west of Aspen the red beds fill up the irregularities of the 

 cretaceous surface, but do not conform. About half a mile west of 

 Aspen Station the road cuts through a large exposure of the lower cre- 

 taceous shaly clays of No. 2, revealing abundant fish scales and fragments 

 of Inoceramns. These cretaceous beds are well shown for about four or 

 five miles, when the coal beds make their appearance near Bear Eiver. 

 Near Sulphur Creek there is a ridge of sandstone which the road passes 

 through nearly at right angles. This ridge, which I have called Oyster 

 Eidge, trends about northeast and southwest, and the dip is west 

 northwest 20° to 25°. It is composed mostly of gray and yellow 

 gray sandstone, capped with a calcareous sandstone, filled with a small 

 species of Ostrea, and belongs, I think, to the upper portion of the 

 cretaceous group — probably No. 5. On the north side of the road there 

 is a high range of hills which are made up of the black clays of No. 4. At 

 Bear Biver City, which is not more than four miles to the west, the 

 strata are nearly vertical and trend nearly northeast and southwest, 

 with a dip northwest. There is here a series of strata, which are still 

 invested with a good deal of obscurity. On the north of Sulphur Creek, 

 for three miles before it unites with Bear Biver, the black clays of No. 

 4 are extensively exposed, and above them a series of sandstones with 

 partings of clay, gradually passing up into the strata which contain 

 coal. That a portion of these sandstones belongs to the upper cretaceous 

 group I cannot doubt, but where the line of separation should be 

 drawn between the cretaceous rocks and those of tertiary age I am 

 unable to decide. In the bed of sandstone which rests upon the well- 

 marked cretaceous clays are found a species Ostrea and a few other 

 marine species of shells, none of which are really peculiar to the creta- 

 ceous, but from their entirely marine character we regard them as such. 

 We then have from three hundred to five hundred feet of sandstones and 

 clays, with thin beds made up of marine shells, and among them a 

 species which sometimes reaches a length of twelve inches, which Mr. 

 Meek has described under the name of 0. soleniscus. In this group are 

 a few thin seams of impure coal. The dip of these beds is northwest 

 about 50°. Then comes a large thickness of arenaceous clays with thin 

 layers of sandstone, with three or four seams of impure coal and large 

 quantities of brown iron ore or limonite. The seams of coal are from 

 one to three feet thick, with the usual clays above and below. Then 

 comes the bed of coal which is well known in this region, seven feet 

 thick, nearly vertical or with a dip of 82° northwest. The inclination 

 of the entire series of rocks from the Uinta range is quite plain. 

 This coal bed has been wrought for several years, and is so convenient 

 to the railroad that it ought to be of considerable value. The coal ap- 

 pears to be of good quality. Above and below it are thick beds of clay. 

 In the clay above the coal there is a seam of oyster shells, a species dis- 

 tinct from any that occurs below it, about 4 inches thick. Above the 

 clay there is a thick bed, two hundred feet, of gray sandstone, with irreg- 

 ular layers of deposition inclining at a very high angle — 70° to 80°. 

 Then a valley intervenes to the westward, in which Bear Biver City is 

 located, one-fourth to half a mile in width, which must have once been 

 occupied with a considerable thickness of soft material, which is now 

 quite concealed by grass and other vegetation. Still further west we 

 have a wonderful series of fresh-water beds, which have been tilted and 

 flexed in a most remarkable manner. These are shown in a railroad 

 cut a little west of the city, about two hundred or three hundred feet 

 long, where nearly two hundred layers are exposed, of almost every 



