GEOLOGICAL SURVEY OF THE TERRITORIES. 167 



resembling tertiary types as much as cretaceous. Soon we come to the 

 coal beds, which, at this locality, are nearly vertical. Above them we 

 find seams of oyster shells, but no other marine forms. And finally, 

 high up in the upper beds of the coal group, we find the greatest profu- 

 sion of brackish and fresh-water life that we have observed in the West, 

 Unio priscus, U. belliplicatus, Cyrena durkeei, Corbula pyriformis, &c. 

 So far as the Evanston coal mines are concerned, no shells have been 

 found in connection with them, so far as I know. But last year, in the 

 calcareous sandstones above the huge 26-foot bed, I discovered a mag- 

 nificent series of fossil leaves, among which, Dr. Newberry informed 

 me, he had detected species identical with those occurring in connection 

 with the coal beds of" the Laramie Plains, and on the Upper Missouri. 

 No plants have been observed in the vicinity of Bear Biver City. What 

 relation the coal beds here sustain to those at Evanston, I cannot deter- 

 mine. As yet there is no evidence of any connection whatever, except 

 proximity. • * 



The next locality where coal is exposed is at Coalville, a little town in 

 the valley of Weber Biver, five miles above the mouth of Echo Creek, 

 where it crops out in a number of places over a very restricted area. 

 The general dip of the beds is northwest, 10° to 18°. The most im- 

 portant opening of a coal vein is that of Mr. Spriggs. The coal bed 

 is fifteen feet thick, twelve feet of good coal, and the other three feet 

 somewhat impure, but useful as a fuel. The dip is 20° to 30° ; the roof 

 is composed of yellowish- gray sandstone, sometimes a pudding-stone, 

 with only about an inch or so of clay between. An air shaft sunk by 

 Mr. Spriggs passed through the sandstone sixty feet. Mr. Spriggs in- 

 formed me that there were six different seams of coal in this region. 

 Just above the third seam there is a layer of oyster shells about four 

 feet thick ; the clay under the coal varies in thickness, sometimes sixteen 

 feet, again eighteen inches ; below this is a yellowish-gray or brown 

 sandstone. Looking down the Weber Valley, the group of beds form a 

 sort of semicircle, dipping west and northwest. In the high ridge that 

 lies immediately north of Chalk Creek, we have a series of yellowish 

 and brown-gray clays and sands, with one or two beds of light, brick- 

 red, arenaceous clay, the whole extending up two hundred and fifty 

 feet above the coal, apparently. On the summit of this ridge, and in 

 different layers along the outcropping edges of the ridge, are great 

 quantities of marine shells, which are regarded as of very modern cre- 

 taceous types. A few huodred feet south of Spriggs's opening, a party 

 sunk a shaft eighty feet with the intention of cutting the bed of coal ; 

 the shaft cut through the black clays of what I regard as cretaceous 

 No. 4. In the clays that were thrown out of the shaft were great quan- 

 tities of Inoceramns, Ammonites, Ostrea, &c. The coal is evidently in close 

 proximity to these cretaceous clays, but, I think, above them. From 

 Chalk Creek to Echo City it is about four miles in a straight line ; 

 about two and a half miles of it is occupied by eight to twelve ridges 

 of the coal strata, inclining 10° to 30°, averaging 20°. There is not less 

 than one thousand feet of them exposed here, but the coal is mostly, 

 and perhaps all the workable beds are, in the lower portion. There is 

 a sort of valley which forms the line of separation between the coal 

 strata and the Wasatch Group; the remaining one and a half miles is 

 composed of the Wasatch conglomerates. In the group of coal strata, 

 all of which I suppose lie above the Coalville bed, shells of the gen- 

 era Anchura, Gyrodes, Inoceramus, and Ostrea, are found. The evi- 

 dence seems to point to the cretaceous age of the coal group in Weber 

 Valley. It is the only locality in the West that has come under my ob- 



