294 EXPLORATIONS ACROSS THE GREAT BASIN OF UTAH. 



sider it as such. It may be an equivalent of those strata which Dr. Hayden, on Lieu- 

 tenant Warren's expedition, observed at the mouth of Judith River (see Proceedings 

 of the Academy of Philadelphia, May, 1857), which are likewise in close connection 

 witli an estuary formation, but appear to be developed on a much smaller scale. They 

 are also strongly tilted, contain coal and Ostrea glabra besides other fossils, and were 

 regarded by Dr. Hayden as probably on a parallel with the lowest portion of No. 1 of 

 his section of the Cretaceous rocks of Nebraska, though he suspected from the presence 

 of a Ilctfauf/ia that they might be older. 



From the crossing of Sulphur Creek these strata, forming ;i ridge in the direction 

 of their trend, extend southwest to the East Fork of Bear River, striking it about 1.5 

 miles below Captain Simpson's road, where the coal must again crop out. They also 

 continue in the opposite direction, forming considerable mountains north of Sulphur 

 Creek, when their trend changes more to north and finally to north-northwest, and 

 they strike Hear River a second time near the mouth of Yellow Creek. In conse- 

 quence of another disturbance, they crop out again east from there on Muddy Creek 

 below the crossing of the Salt Lake road, where Colonel Fremont found the coal. 

 Captain Simpson discovered it also on White Clay Creek, below the mouth of Porter's 

 Fork, when- I observed again, in connection with it, heavy beds of white sandstone 

 witli the same Ostmt. The latter occur likewise on Weber River, about 1.5 miles 

 above the mouth of White Clay Creek, and again 1 mile below the point where the 

 road, turning westward, leaves Weber River; but I did not find there any coal with them. 

 Strata of a similar character are exposed at numerous other points. Nine miles 

 west of Hear River they form the Needles, on Yellow Creek, composed of strongly- 

 tilted white and gray, compact, siliceous sandstones, which are partly fine-grained, 

 partly coarse-grit stones, and conglomeratic, and interstratified with mostly reddish 

 shaly strata, arenaceous shales, and shaly sandstones. Most prominent there, is a 

 heavy mass of light-colored conglomerate, composed of rounded siliceous pebbles of 

 the size of hen's and pigeon's eggs with only a few larger ones, thickly disseminated, 

 together with gravel, in a mortar-like matrix. It forms the rugged crest of the hills 

 from which they have received their name. This elevation trends toward the head of 

 \\ Into Clay Creek, on which the same rocks were observed near the upper forks, also 

 standing on the edge and partly even tilted beyond the vertical. The dip of the strata 

 along that creek is not uniform, and the slopes are partly covered, so that I.was pre- 

 vented troin obtaining a section; but as the dip generally varies between southwest 

 and west we may presume that we come to higher strata the farther we descend the 

 creek, and that those at the upper fork and at the Needles probably correspond to those 

 on the east fork of Weber River near the point where I obtained Jurassic fossils. 

 Some miles below the upper forks, in high mountains on the south side of the creek, 

 yellowish conglomeratic sandstones crop out, also one of a dull reddish color, strongly 

 dipping to west-southwest, and lower down a considerable thickness of alternations of 

 impure whitish sandstones and light-colored argillaceous shales, conformable to the 

 former and likewise containing conglomeratic seams. Near the mouth of Porter s Fork 

 we reach the coal-bearing sandstone mentioned above, and then white sandstones, al- 

 ternating with red arenaceous slate and red shales. At the lower end of the canon, the 



