Hayclen.] ^^ [FebruaiT 19,1869. 



Green River crossing and Bryan Station, fine specimens of fossil fishes 

 occur in rocks which resemble the Solenhofen slates. West of Bryan, 

 fresh water shells of the genera Gorbicula, Limnea, Physa, Paludina, Mela- 

 nia, and TInio occur in the greatest quantities. This basin extends to 

 Quaking Asp ridge, 22 miles west of Fort Bridger. 



We then come to a series of variegated beds, whose dominant color is 

 red or reddish, of estuary or marine origin, with coal beds from 6 to 15 

 feet thick. These extend far westward to the Wasatch mountains, pos- 

 sibly farther. The evidence inclines one to regard them of cretaceous 

 age, but they may be older tertiary. 



In Weber valley there is an immense thickness of the older sedimentary 

 rocks from the Jurassic inclusive to the Silurian inclusive, the thickness 

 of which I estimated at from 5,000 to 10,000 feet. 



The Wasatch range is composed of metamorphic rocks, mostly gneisic, 

 which are well shown in the valley of Weber river for the distance of 4 

 miles. 



The Union Pacific Railroad from Omaha to Salt Lake valley, a distance 

 of nearly 1200 miles, really pass through metamorphic roclcs but twice; 

 first in crossing the Laramie range, a distance of 20 or 30 miles, and in 

 the Weber valley through the Wasatch range, 4 miles. At Rawling's 

 Springs, the syenites are seen on the north side of the road for a little 

 distance, but not immediately along it. 



It will thus be seen that over the vast region known as the Rocky 

 Mountain district proper, the area that can be colored on a geological 

 map as occupied by igneous or metamorphic rocks is comparatively small, 

 while the more modern formations as tertiary and cretaceous, are met 

 with everywhere even up to the summits of the loftiest ranges and some- 

 times covering them. 



Note. The illustration, Plate 1. Fig. 2, Pulpit Rock, shows the high 

 nearly vertical bluffs of conglomerate, at the entrance of Echo creek into 

 the Weber river, Utah Territory. I am inclined to regard these rocks 

 as older tertiary, from the fact that they lie along the coal beds of this 

 region, but they may be cretaceous. 



Twin Peaks, No. 1, Plate 1, form a part of a mountain range, enclosing 

 Salt Lake valley. The terrace system is well shown, as described in the 

 preceding paper. 



