324 DESCRIPTIVE GEOLOGY. 



lying the upturned quartzites, in the main canon, is an obscure develop- 

 ment of limestone, which is, however, so well covered with glacial debris 

 and the Tertiary conglomerates that its position and relations are unknown. 

 The conglomerates here have a dip of 8^ from the range, and are composed 

 of remarkably coarse gravel, hardly showing the lines of deposition. West 

 of Bear River, on the heights directly north of Weber Caiion, these con- 

 glomerates are exposed to a depth of 3,000 feet by sharply-eroded glacial 

 canons. They are there seen to have a dip of 5° from the range, and to be 

 composed of the very coarsest and most' loosely-compacted conglomerate, 

 quite devoid of distinct bedding. Their dip is only gotten by certain zones 

 of finer material and shale, which may be traced through them. It is impos- 

 sible here to draw the line between the Wyoming Conglomerates, which 

 doubtless form the upper part of the series, and the Vermillion Creek series, 

 which, in the vicinity of the Wahsatch and Uinta Ranges, develop such a 

 great amount of conglomerate. 



At La Motte Peak, to the east of the canon of Bear River, the quartz- 

 ites dip 16° to the north. The rock is here a reddish-purple quartzitc, 

 containing some fragments of decomposed feldspar, together with rounded 

 grains of quartz, and a few broken fragments of crypto-crystalline quartz. 

 Chemical analysis of this rock by Mr. B. E. Brewster gave the following: 



Silica-- 87.47 



Alumina - 7.47 



Ferric oxide 0.26 



Magnesia 0.20 



Soda 1.30 



Potassa : 2.53 



Ignition : 0.56 



99.79 



To the north of La Motte Peak, the dip of the rocks, forming the spur of 

 which it is the culminating point, steepens more gradually and continuously 

 than in the main canon, and at the point of the spur the Carboniferous lime- 

 stones are found dipping 52° to the northward. On the face of one of these 

 spurs is found a conglomerate, made up of boulders, mostly as large as a man's 



