188 J. D. Dana — Hocky Mountain Protaxis, etc, 



a height above tide-level of 4200 to 4600 feet. The Union Pacific 

 R. R. crosses the country from near Evanston on the east to 

 Uinta, Ogden and Corinne, and the Denver & Rio Grande R. R. 

 goes southward from Ogden, by Salt Lake City to Provo and 

 beyond. The Wasatch Mountains range from north to south 

 east of the sites of Ogden, Salt Lake City and Provo, rise to a 

 height for the most part of 10,000 to 12,000 feet, and have an 

 abrupt front to the westward, the declivity on this side occupying 

 a width of but one to two miles. The Uinta Mountains, an east- 

 west plateau-like range, lie east of the southern half of the 

 Wasatch. They have a broad slightly arched back of Carbonif- 

 erous rocks, mostly 10,000 to 13,000 feet above tide-level. But 

 only a fourth of the long range comes within the limits of 

 the map. As is observed on the map, the Uinta and Wasatch 

 Mountains are connected by a broad neck, mostly under igneous 

 rocks (lettered f, initial of fire) about 8000 feet in elevation. 

 The Oquirrh Mountains, a short range having Carboniferous 

 rocks at summit, occupy the southwest corner of the map and 

 reach a height to the south (in Lewiston Peak) of 10,623 feet. 

 The large open area on the map east of the Wasatch Mountains, 

 and north of the Uinta plateau, lettered W, and mostly 5000 to 

 7000 feet in height, is that of the Wasatch Eocene Tertiary; a 

 southward extension j^'operly of the Green River Eocene region 

 of Wyoming; and another similar area south of the Uinta Moun- 

 tains, lettered U, 9000 to 10,200 feet in elevation, is the Uinta 

 Eocene basin. On the east-middle margin of the map, there is 

 a small piece of the Bridger Eocene basin outlined and lettered B. 



Besides the large Quaternary area, lettered Q, of the Salt Lake 

 region, there are two others in the Uinta Eocene basin ; another 

 similarly lettered on the neck between the Uinta and Wasatch 

 Mountains; and another to the north by the side of a Carbonif- 

 erous area that extends north to the foot of Bear Lake. 



In the northwest quarter of the map there is another Tertiary 

 basin lettered P, which is referred to the Pliocene Tertiary ; and 

 just south, a second similar basin, in Ogden Valley, " a depressed 

 area walled in by high mountains." A small area of Quaternary 

 on the northwest corner of the neck between the Wasatch and 

 the Uinta is omitted. 



The streams of the region having canons of geological signifi- 

 cance (but with one exception not marked on the small map) 

 are: Jordan River, connecting Utah Lake and Great Salt Lake; 

 Provo River, entering Utah Lake near Provo and flowing 

 through Provo Valley from the western Uinta slopes; Little 

 Cottonwood, which flows westward and reaches the western base 

 of the Wasatch Mountains at L. C. ; Rig Cottonwood, just north 

 of the last, at B. C. ; Weber River, which rises on the northwestern 

 slopes of the Uinta Mountains and follows the railroad from Echo 

 to Ogden and reaches the lake west of Ogden ; the Ogden River, 

 which drains Ogden Valley, and flows through a canon on its 

 way to Salt Lake. 



