6 PHILOSOPHICAL SOCIETY OF WASHINGTON. 
The writer has observed Great Basin structure to extend through- 
out Western Utah, Northern Nevada, and into’ Oregon as far as 
Malheur Lake. On the west side of the Great Basin, at the imme- 
diate base of the Sierra Nevada, there is an immense compound 
displacement that can be followed all the way from Honey Lake on 
the north to beyond Owen’s Lake on the south, a distance of over 
390 miles. Along many of the faults composing this belt the 
records of a post-Quaternary movement may be clearly recognized. 
Fault scarps produced by recent movement have been observed in 
Eagle and Carson Valleys, south of Carson City, in Bridgeport 
Valley, and on the west side of Mono Lake. The earthquake in 
Owen’s Valley in 1872, was caused by a movement along one of 
the faults of this series. 
The eastern face of the Sierra Nevada is extremely abrupt and 
its western slope is gentle. Corrugations of older date than the 
faults which determine the present relief of the mountains may be 
observed at many localities. It thus agrees in its general features 
with many of the Basin ranges. The Sierra Nevada is essentially 
monoclinal in structure, but is traversed from north to south by 
faults which divide it into separate ranges, as may be seen in the 
neighborhood of Lake Tahoe and in the elevated region west of 
Mono Lake. The Great Basin structure here extends beyond the 
borders of the area of interior drainage, and is probably limited on 
the west by the great valley of California. How far north of Lake . 
Tahoe the secondary faults that divide the mountain mass may be 
traced is unknown, but they can certainly be followed to where the 
Central Pacific railroad crosses the mountains. 
The following list indicates where observations on the faults of 
the Great Basin system may be found: 
Clarence King: Reports of the Fortieth Parallel Exploration. 
Vol. I, 1878, pp. 735, 744-746; Vol. III, 1870, 
p. 451. 
J. D. Whitney: The Owens Valley earthquake. Overland 
Monthly, Aug. and Sept., 1872. 
Joseph Le Conte: On the Structure and Origin of Mountains, with 
special reference to recent objections to the 
“Contraction Theory.” American Journal of 
Science, Vol. XVI, 1878, pp. 95112. 
ig : A theory of the formation of the great features 
of the earth’s crust. American Journal of 
Science, Vol. IV, 1872, pp. 345-355, 460-472. 
