390 GEOLOGICAL EXCURSION TO THE ROCKY MOUNTAINS. 



is a fragment of qnartzites and limestones to the west of the outcrop of 

 crystalline schists, which represents » portion of the overlying Paleozoic 



beds brought down by the great Wasatch fault . These lie somewhat 

 to the eastward of the line of faulting in the Pleistocene deposits of the 

 valley. 



At the head of the two Cottonwood canyons is Claytons peak, a 

 boss of granite projecting through the Paleozoic beds, and to the east 

 of this, on the east slopes of the Wasatch range, are extensive areas of 

 eruptive rocks. It is in this portion of the range alone that important 

 mines have thus far been developed. The most prominent have been 

 the Lmina mine, in Paleozoic limestones at the head of Little Cotton- 

 wood canyon, and the Ontario mine, a strong fissure vein worked to 

 a depth of over 1,000 feet (305 m.) in Middle Carboniferous qnartzites, 

 with associated porphyries, which has produced over twenty millions 

 of silver and is still paying dividends. 



From the southwestern extremity of the Lone peak granite mass a 

 low ridge of eruptive rocks, resting on altered sedimentaries of unknown 

 age, stretches across the valley from the Wasatch to the Oquirrh range. 

 This separates t lie valley of Salt Lake from that of the fresh water Utah 

 Lake. This lake is fed by four principal streams, which drain interior 

 valleys to the east of the main crest of the Wasatch, and cut deep trans- 

 verse gorges across it, which afford admirable sections of the range. 

 These are American Fork, Pro vo river, Hobble's creek, and Spanish 

 Fork. The former shows a broad anticlinal arch, and the great mass 

 of Timpanogos peak south of it, nearly 12,000 feet (.'>,<i<)7 m.) in height, 

 is formed of horizontal Paleozoic beds forming the crest of this arch. 

 The axis of this fold runs somewhat east of south and to the west of 

 the crest of this peak, following the line of a projecting shoulder; it is 

 somewhat broken, and in Provo canyon, next south, is only visible as a 

 fault line with the beds somewhat curved upward near to it. 



South of Provo canyon a second line of folding and faulting, en echelon 

 and set off a little to tin 1 west of this, is developed back of the town of 

 Provo at thebaseof Provo peak. The section seen inBock canyon, back 

 of this town, shows lower Paleozoic beds sharply upturned in an S-fold, 

 which sometimes pass the vertical in dip, but a short distance east ward 

 shallow almost to the horizontal position. Qnartzites and schists 

 occur at the base of the series. While the lines of strike continue in a 

 direction east of south the range itself assumes topographically a 

 direction more and more to the west of south. 



In Hobble's canyon, and in Spanish Fork canyon through which the 

 Rio Grande Western Railroad passes, only upper members of the Pale- 

 ozoic series are seen, dipping somewhat south of east at 25°. To the 

 south of this the range consists of mountain masses set off successively 

 more to the westward, which culminate in Mount Nebo, 12,000 feet 



