1869.] 



51 



[Hayden. 



feet thick ; instead of which, it makes a bend and cuts its way throagh a 

 massive gneissic ridge. 



Extensive deposits of wliitisli, fine blue and rusty yellow sandstones, 

 hard enough for building purposes, with flesh colored marls, probably of 

 pliocene age, and resembling very closely in many respects the more 

 recent tertiary beds along the Platte, occur in this valley. These recent 

 beds dip east or south-east. We thus learn that some of the later move- 

 ments in the elevation of these mountain ranges have been of compara- 

 tively modern date. Terraces continue to show themselves the entire 

 length of the Weber river, and they are probably synchronous with those 

 which surround the basin of Salt Lake valley.* 



Fig, 5. 



After emerging from the Wasatch Kanyon of the Weber valley, we pur- 

 sued a southerly course along the base of the Wasatch range to Salt Lake 

 city. For 20 miles or more, all the unchanged rocks have been worn 

 away from the flanks of the mountains or completely concealed by debris. 

 All over the gentle slopes at the foot of the mountains are strewn masses 

 of rocks ; all gneissic and evidently from the central parts of the moun- 

 tains. Terraces distinctly suiTOund this basin everywhere. There is one 

 large one, with two or three smaller ones, on the sides of the mountains, 

 and from the lowest one downwards, the surface slopes gently to the lake. 

 I was informed that the lake had risen 9 feet vertically since 1868, and of 

 course the water has aggressed upon the land to a great distance. I have 

 heard no explanation of this phenomenon. All the lakes in the west are 

 said to be rising more or less. 



* This Illustration from a sketch by Mr. F. W. Meek of the terraces along the Missouri river be- 

 tween Council Bluffs and Sioux City, will apply equally well to Helena or Salt Lake valley ; and 

 they are doubtless synchronous in age. In the sketch, the distant high hills are composed of yellow 

 marl or " loess," the terraces the same, and the bottom of ricli vegetable mould. 



