:.\ ITERATIONS ACEOSS THE GEEAT EASIN OF UTAH. 



• period : some of them may even be Post-Tertiary. They are nowhere 

 others — generally till depressions in the older rocks, creek- valleys, &c, 

 loditied by erosion. Xear Fort Laramie they form considerable bluffs, 

 rally less thickness along the road. I observed them in the hills west 

 ar Bitter Creek, etc.; also again on the ridge between the Red Buttes 

 nee Rock, and at numerous points of the Sweetwater Valley. These 

 lly change according to the character of the surrounding mountains from 

 e formed: they become coarser, conglomeratic, or more argillaceous; 

 hid strata of a different appearance, but apparently of the same age, in 

 near 1 lorseshoe Creek, La Honte Creek, &c. The Tertiary strata in the 

 1 be described in the following section No. IV. 



Af/ncH/tun: — 11ns section of the country is considerably elevated. The lowest 

 points cannot be less than 4,f>oo feet high, which is given by Captain Stansbury as 

 the elevation of Fort Laramie. This altitude, combined with the elimatological char- 

 acter of this region, the remarkably great and sudden changes of the temperature, 

 and the shortness of the summer season, are disadvantageous to agricultural pursuits, 

 but not more so, it would appear, than in the Salt Lake country. The prevalence of 

 sandstone formations is felt unfavorably in the composition of the soils, but I have no 

 doubt that there are numerous points, especially along the creeks, where cultivation 

 would prove successful, although the country at large must remain a desert as long as 

 the present physical conditions last. 



Builduiff materials are abundant throughout the district. Rocks, marble, lime, 

 clay tor adobes and brick, and even timber, in limited quantity, can be obtained nearly 

 everywhere within a few miles of the road, and at some points there is plenty of it. 



Iron. — Iron-ore appears to be largely distributed in the Rocky Mountains. Sev : 

 eral of the granites contain the specular ore in so large a quantity that pure pieces of 

 it can be broken off, and we may presume that deposits of the mineral exist with the 

 granites. Pieces of siliceous specular ore, more or less mixed with slate rock, have 

 been frequently noticed among the drift pebbles, and appear to originate from the met- 

 amorphie schists or altered rocks, dims tar, however, we cannot conceive how the 



ver be 



any i 



\\ e have not observed indications of other mineral veins, nor of gold-bearing 

 rocks. The geological formations at some points appear to be similar to those of the 

 Park Mountains, in the neighborhood of Pike's Peak; but we have so little reliable 

 information in regard to the geological configuration, and the association of the gold 

 m that district, that we cannot now draw a parallel. Long before the gold excitement 

 began in that country, I have heard it stated that some grains of gold had been found 

 in Medicine Bow Creek, but nobody ever succeeded in finding more of it. Still it 

 might be premature to deny its existence altogether. 



Salts. — Along some parts of the road, especially near Sweetwater River, we find 

 the soil in places covered with saline efflorescences and salt-ponds, which mostly dry 

 up in summer and leave white incrustations on the surface. These salts are partly 

 carbonates with an alkaline base, partly sulphates, especially of soda and magnesia, 



