GANNETT.] EXPLORATION. 1 1 
in geographical discovery, excepting the fact that it may have deter- 
mined the route of travel between the Spanish settlements of New 
Mexico and those of California. 
Between 1832 and 1836 Capt. B. L. E. Bonneville, of the United States 
Army, while on leave of absence, engaged in the fur trade in the West, 
and coupled with it a certain amount of exploration. He traveled 
extensively over the northeastern part of Utah, including the area 
drained by Bear River and its tributaries, and sent a branch expedi- 
tion, under Captain Walker, to Great Salt Lake, down Humboldt 
River, and across the Sierra Nevada to California, returning by the 
route of the Spanish trail. No maps were prepared, and the only infor- 
mation derived from these explorations is contained in Washington 
Irving's narrative, which is very scanty and often erroneous. 
The real exploration of Utah began in 1842, when Capt. J. C. Fre- 
mont, with an army expedition, entering the region via Bear River, 
explored Great Salt Lake and the adjacent region. Upon his return 
from California in the following year he entered the Territory again, 
on the south, via Virgin River and the Sevier, reaching Utah Lake, 
and thence proceeded northeastward down Uinta River. 
Subsequent expeditions under army auspices, notably those of the 
Pacific Railroad explorations, Captain Stansbury's survey of Great Salt 
Lake, and Captain Simpson's explorations, made the main features of 
the Territory well known. 
Green and Colorado rivers, which flow mainly within this State, were 
explored by a daring boat journey undertaken and carried through bj 
Maj. J. W. Powell in 1869, and in the course of this exploration the 
greater features of the plateau region traversed by the rivers were 
delineated and their structure was explained. 
The northern portion of the State, including the area of Great Salt 
Lake, was mapped by the United States Geological Survey of the 
fortieth parallel, in or about 1870, on a scale of 4 miles to an inch. 
Between 1873 and 1878 nearly all of the Territory was surveyed on 
a scale of 4 miles to an inch by the United States Geological Survey 
of the Rocky Mountain region, under Maj. J. W. Powell, and the 
resulting maps show the topographic features of the State in consider- 
able detail. 
Since 1850 most of the level portions of the State have been subdi- 
vided by the General Land Office, and plats have been made of the 
surveyed townships. From these, with the maps of the survey of th<> 
fortieth parallel and of the Rocky Mountain region, the existing maps 
of Utah have been compiled. 
The atlas sheets referred to in the Gazetteer are published by the 
United States Geological Survey, the data borne upon them having 
been derived mainly from the work of the two organizations last 
mentioned. 
