340 DESCRIPTIVE GEOLOGY 



SECTION III. 



WAHSATCH EANGE. 



BY S. F. EMMONS. 



The Walisatcli Eange forms one of the most important featni'es topo- 

 graphically of the Cordilleran system, in the fact that it marks the central 

 line of elevation of this great mountain region, and forms the divide between 

 the arid interior basins of Nevada, and the high, relatively well-watered 

 plateau country that drains into the Gulf of California. It is even more 

 important from a geological point of view, inasmuch as there are found rep- 

 resented here all the principal formations, from the early Archaean to the 

 latest Tertiaries, developed on a scale of unusual magnitude, while in its 

 structure are seen the effects of dynamical forces, which have folded and 

 twisted thousands of feet of solid rock as if they were as 3d elding as so 

 many sheets of paper. - 



To the westward, it presents always a bold, abrupt escarpment, rising 

 suddenly out of the broad, flat plains of the Utah Basin, and attains its 

 greatest elevation within one or two miles of its western base. 



To the eastward it slopes off very gradually, forming a region of broad 

 ridges and mountain-valleys, from 15 to 20 miles in width, whose waters 

 all drain into the Great Salt Lake, through canons and gorges cut through 

 its main western ridge. Its higher peaks attain altitudes of 11,000 to 12,000 

 feet, and the general mass of the main ridge has an average height of nearly 

 10,000 feet above the level of the sea, so that as late as midsummer the 

 winter's snows remain unmelted along its summits, and the plentiful con- 

 densation of the eastward-moving atmospheric currents, produced by so 

 high a mass, furnishes a continuous supply of water to the mountain-streams, 

 from which the valleys along its western base derive their exceptional fer- 

 tility. The view of the range, as seen, for instance, from one of the islands 

 of Salt Lake, presenting a mountain- wall of over 100 miles in length, of 

 delicately-varied outHne, the upper portion slightly covered by a thin 

 mantle of snow, its slopes, wdiile dotted with patches of pine, revealing all 



