380 GEOLOGICAL EXCURSION TO THE ROCKY MOUNTAINS. 



the great Wasatch fault. They have a maximum temperature of 1300 

 (58° 0.) and leave a ferruginous deposit. 



At Ogden, an important Mormon town of .15,000 inhabitants, the road 

 crosses the Union Pacific railroad, the pioneer transcontinental line, 

 which reached here in I860, crossing the "Wasatch range through the 

 deep gorge of Weber river. In Bonneville time this river built an 

 immense delta of sand and gravel on the margin of the plain. 



From Ogden the road makes a detour to the westward around this 

 delta and follows the lower level of the valley, near the lake, past the 

 Mormon towns of Kaysville, Farmington, and Centerville. Fault scarps 

 are continuously visible along the base of the mountains, being espe- 

 cially conspicuous near Farmington. 



l''i(i. 17. — Shore lines and fault scarps near Farmington. 



The load now passes around another low promontory of the Wasatch, 

 Opposite the southern end of the lake, to Salt Lake city, which lies to 

 the south of the promontory. Near Salt Lake city are both warm and 

 hot springs, also issuing from the great fault, with a maximum tem- 

 perature of 12: P V. (53° 0.). 



