GEOLOGICAL REPORT. 295 



red color predominates; but thence down I noticed again white sandstones, interstrat- 

 ified with gray shales, similar to those above the coal, and perhaps the same strata, 

 because there has been a disturbance and a change of the dip, which is there generally 

 toward west or northwest. Near the mouth of the creek these strata are capped "by 

 heavy beds of white sandstone with conglomeratic portions. 



Several thick beds of conglomerates occur in this district, though mostly there 

 are only single seams of pebbles within the beds of else rather fine-grained sandstones, 

 not forming separate strata, which indicates that changes in the force of the i 

 must have taken place while the single beds were deposited. The frequent < 

 of conglomeratic masses proves, besides, that a shore-line cannot have passed far from 

 the present Wahsatch Mountains, which existed probably before the Jurassic and Cre- 

 taceous era, although not in their present outlines. This is rendered still more likely 

 by the absence of Jurassic and Cretaceous strata west of these mountains, as will appear 

 from the following section V. 



From the mouth of White Clay Creek to Echo Creek, a distance of 5 miles, the 

 same formation continues, with conformable stratification and a slight dip to west and 

 northwest, so that we advance to higher strata. Part of these are brick-red, probably 

 forming the continuation of the red beds at the lower end of the White Clay Creek 

 canon. Near the mouth of Echo Canon purple conglomerates are largely developed, 

 and nearly horizontal. They form for some miles high vertical turreted bluffs on the 

 north side of the canon, while the south side generally presents steep but covered 

 slopes, with only few exposures of rocks, which dip strongly to west-northwest. I 

 was doubtful whether the red conglomerates were conformable; in some places they 

 seem to be so, in others not; but I rather think that they are a local later deposit. 

 The valley is evidently one of erosion, and not one of eruption, with anticlinal strata, 

 as has been stated by others. Some miles farther up, white, yellowish, and dull- 

 reddish, partly conglomeratic, and mostly purer siliceous sandstones form both sides 

 of the canon, probably corresponding to the lower series, which is exposed also on the 

 upper part of White Clay Creek. Their dip is still to west-northwest, but moderate, 

 although variable. Still higher up we find the divide capped by the sandstones, 

 No. 3. 



On Weber River, above the mouth of White Clay Creek, the same formation 

 continues; but the uniformity of the stratification is interrupted in consequence of the 

 proximity of the igneous rocks, which form the limits of tins section, and at several 

 points come to the water's edge. Within a short distance I observed the strata dip- 

 ping to north, west, east, and northwest. From the mouth of Silver Creek to Kamas 

 Prairie the dip is uniformly strong to northwest, and we gradually come again to 

 lower strata, although the ridge of dioritic porphyries west of the river runs nearly 

 north and south. This would rather indicate the pre-existence of the igneous rocks; 

 still, other observations show conclusively that the eruption of part of them, at least, 

 dates after the deposition of the sandstones, and at a comparatively recent period, or 

 else we would not find their tufas, in apparently horizontal position, filling portions of 

 the river valleys which are eroded in these stratified rocks. 



Near the point where the road to the Timpanogos leaves the valley of Weber 



