the geology f the country along the whole line of our explorations, and add much to 

 the- value of this report. (They have since been Bnished and bear the date of ( kstober, 



1860.) The map extends from the Missouri River, near Fort Leavenworth, to the 

 Sierra Nevada, near Genoa, in Carson Valh v. I have strictly refrained from extending 

 the colors which represent the different formations beyond the limits of my persona 

 observations on this expedition, under your command, and on the expedition ondei 



Lieut. F. T. Bryan, Topographical Kngineers, from Leavenworth to Bryan's Pass, h 

 the Rocky Mountains, in 1856. Only in two instances 1 have deviated from this rule 

 in order to indicate on the map the geology of immediately connecting routes, viz, 01 

 Platte River, below Fort Kearnev, in regard to which T have made use of the informa 

 Hon communicated bv Dr. F. V. Ilavden, in the preliminary reports of Lieutenan 

 Warren's expeditions in Nebraska Territory, and on the extension of Iieutenanl Bryan', 

 route toward Fort Brid-er, between Bryan's Pass and Green River, to which 1 hav 

 assumed a formation, of the existence of which I could entertain no doubt, from th, 

 oeneral des,ription of the roeks bv ( 'aptain Stansbury, Topographical Mutineers, in hi 

 report on the exploration of the Salt Lake region, when compared with what 1 ha, 



U ( ,rmitv\md little' diVtmbed stra'tiiicatio'n of the formations in the Green River Valle } 

 1 would, however, not have that far departed from my rule if it had not been in orde 



^TTie 3 xnajThts been executed on the scale of tin- general map accompanying th 

 reports of the explorations ot a railroad route to the Pacific Ocean, viz, 1: 3,000,001 



or about 47.:) Kn-llsh miles to 1 inch. As I have represented 20 different formatio, 

 on the map, this scale is rather too small, at least in the sections of the Rocky Moun 

 ainsandof Utah, wbere the strata are considerably disturbed, and th, different form; 



or about 15.8 miles to on 

 would be desirable to hai 

 ing of the different formal 



'■B: 



dd be 



r taken from vo 

 nd substituted* 



executed with n 



>r the smallei 

 rach fewer ei 



deal ma 

 r map. 



p, which i 

 The color 



dprobabb 



even cheaper on a large 

 1,500,000 for the horizoi 

 vertical scale is 1: 75,00< 

 course of the route tnv 



r scale, 

 ital disfc 



-tilth i 

 • the 



and 20 times di 

 nch, equal to 1,2 



those of the ro 

 Lave continued 



ate, but 1 ha 



it to the Fa 



es of the ens 



follows 

 •r, folloi 



so that th 

 the genera 

 ring all it 



windings. The altitudes 



the higher mountains ai 

 having represented the < 



£i:§; 



, 11 

 d and 



ent ami th 



centrd elevlted portion,' it appeared desirable also to illustrate graphically the striking 

 difference exhibited by the short western descent. 1 or this portion, west oi the sum- 

 mit of the Sierra Nevada, I do not claim more than a general correctness, while the 

 details are imaginary, 

 tions of the mountain ranges in the Rocky Mountains and in Utah are composed ot 



