1878.] United States Survey of the Territories, — 99 
` toward Salt lake. After it emerges from the gap west of Soda 
springs, it flows out into a wide valley which opens directly into 
that of the Upper Portneuf. In this valley the divide between 
the two rivers is only a basalt plain, and in the eruption of this 
lava we may look for the clew to the extraordinary course of 
Bear river. 
The latter half of the season was devoted to Bear river, Bear 
lake, and Cache and Malade valleys. 
There is but little doubt that the waters which once filled the 
_ Salt Lake basin covered also the broad Cache valley. The 
_ modern tertiary deposits are found jutting against the mountains, 
and seem to pass gradually into the more recent deposits found 
in the central portion of the valley. The clays, sands and marls 
of these modern beds are beautifully exposed along Bear river, 
which cuts its way across the north-western part of the valley. 
_ On the west the mountains are broken or isolated ranges, which 
seem to have risen above the waters of the old lake as islands. 
_ The terraces are well marked on their sides, connecting with the 
_ Salt Lake valley through the gap of Bear river. 
= West of this gap, and extending northward, is the Malade 
= valley. It is broad and filled with modern lake deposits. Silu- 
_ rian rocks outcrop on the east and Carboniferous on the west. At 
_ the divide between the Malade and Marsh creek is another of the 
_ old outlets of the ancient Salt lake when its waters were at the 
= highest level. Although the area surveyed was large (13,000 
_ square miles), good collections of fossils were made and data 
obtained for the elucidation of many interesting problems in 
~ relation to the age of the mountains. 
Dr. F. M. Endlich, geologist of the Sweetwater divison, states 
hat within the area described above he found a well diversified 
ORTAS E E a Pe ee ae AE T A A N Poe hae ah ted 
addition to the lower bluffcountry in the southern portion, fur- 
_ surveyor. 
slevation the geological formations change. Instead of the youngest 
