10 KEMP'S ORE DEPOSITS. 



The Uintah fountains are an east and west chain in its northern 

 portion. The rocks on the north are chiefly Tertiary, with Meso- 

 zoic and Paleozoic in the mountains. To the south are found 

 Cretaceous and Triassic strata, with igneous rocks of great extent. 

 The principal upheaval of the Wasatch began at the close of the 

 Carboniferous and seems still to be in progress. 



X. Region of the Great Basin. Between the Wasatch and 

 the Sierra Nevada ranges is found the Great Basin region, once 

 lake bottoms, now very largely alkaline plains of Quaternary age. 

 The surface is diversified by subordinate north and south ranges, 

 formed by great outflows of eruptive rocks, and by tilted Paleozoic. 

 The ranges are extensively broken and the stratified rocks often 

 lie in confused and irregular positions. There is no drainage to 

 the ocean. 



XL Region of the Pacific Slope. The depression of the Great 

 Basin is succeeded by the heights of the Sierra Nevada. On the 

 west the Sierras slope down into the Central Valley of California. 

 The flanks are largely metamorphosed Jurassic and Cretaceous 

 rocks with great developments of igneous outflows. The surface 

 rises again in the Coast ranges, which slope away farther west to 

 the ocean. In addition to the Jurassic and Cretaceous, the Tertiary 

 and Quaternary are also developed, and in the Coast ranges are 

 many outflows of igneous rock. The principal upheaval of the 

 Sierra Nevada began at the close of the Jurassic, that of the Coast 

 range at the close of the Miocene Tertiary. 



XII. Region of the Northwest. Washington and Oregon, 

 along the coast, are formed by Cretaceous and Tertiary strata 

 similar to California. But inland, immense outpourings of igneous 

 rocks cover the greater portion of both States and extend into 

 Idaho. On the north the Carboniferous is extensive, running east- 

 ward into Montana. Quaternary and Tertiary lake deposits are 

 also not lacking. 



1.01.06. On the Forms Assumed by Rock Masses. All sedimen- 

 tary rocks have been originally deposited in beds, approximately 

 horizontal. They are not of necessity absolutely horizontal, be- 

 cause they may have been formed on a sloping bottom or in a delta, 

 in both of which cases an apparent dip ensues. We find them 

 now, however, in almost all cases changed from a horizontal posi- 

 tion by movements caused primarily by the compressive strain in 

 the earth's crust. Beds thus assume folds known as monoclines, 

 anticlines, and synclines. 



