THE TRIASSIC PERIOD 



685 



thickens, reaching to 2,000 to 2,500 feet in the Uinta Mountains, 

 beyond which it again becomes thinner. 



On the Pacific Slope 1 



The Triassic system has its greatest development in America 

 along the Pacific coast. In the latitude of Nevada, the Pacific 

 seems to have extended eastward over the site of the Sierras to 



Fig, 468. Chugwater (Triassic) Red Beds near Shell, Wyo. (U. S. Geol 

 V Surv.) 



longitude 117 (approximately). The shore line of the Pacific 

 farther north has not been definitely located. It was probably 

 irregular, and, in general, several degrees farther east than now, 

 well up into British Columbia. Between the latitudes of 55 and 

 60, the sea is believed to have crossed the present Cordilleran 2 belt, 

 though this northern bay east of the Rockies was probably nob 

 connected freely with the areas of sedimentation in the western 

 interior. Marine beds of the Lower Trias are found as far east as 



1 King, Geol. Surv. of the 40th Parallel, Vol. I, gives an account of the 

 Triassic as far west as the Sierras in this latitude. See also many of the 

 California folios of the U. S. Geol. Surv., and the Roseburg, Ore., folio. 



2 Dawson, Science, March 15, 1901. 



