Range Structure in California. — Cainj^bell. 311 
BASIN-RANGE STRUCTURE IN THE DEATH 
VALLEY REGION OF SOUTHEASTERN 
CALIFORNIA.* 
By M. R. Campbell, Washington, D. C. 
Recently attention has been called to the geologic structure 
of the mountain ranges of Nevada and southeastern Califor- 
nia. An attempt has been made to show that they are gen- 
erally anticlinal in structure, and that the tilted-block type 
which Gilbert has described, and which is generally known 
as basin-range structure, is of rare occurrence. 
The object of the present paper is to show that, although 
minor folding was observed in the Death Valley region, the 
mountains are generally composed of huge blocks of strata 
that have been strongly tilted and then eroded into their pres- 
ent forms. 
The region described is traversed by two systems of struc- 
tures ; one extendmg in a north-south direction, being the 
southern extension of the true basin ranges of Nevada, and the 
other crossing these in a northwest-southeast direction parallel 
wdth and presumably an ofif-shoot from the main line of the 
Sierra Nevada. The movements which produced these struc- 
tures seem to have been preceded by an epoch of slight fold- 
ing in which the Palaeozoic strata were somewhat deformed. 
This was followed presumably in Eocene time by faulting and 
tilting along northwest-southeast axes which formed parallel 
mountains and valleys trending in the same direction as the 
Sierra Nevada. In the valleys so formed lakes accumulated, 
probably through a change in climatic conditions, and sedi- 
ments having a thickness of several thousand feet were laid 
down. In these lake beds are the great deposits of salt, gyp- 
sum, soda, and borax, which have made the region famous. 
Following this period of sedimentation came one of movement 
along north-south axes, which lifted and tilted the surface into 
immense mountain ranges trending parallel with the new axes. 
Panamint, Death and Amargosa valleys were thus formed, 
and Funeral and Panamint mountains were raised up between 
• Abstract of a paper read at the Washington meeting of the Geolosical 
Society of America, Dec, 1902. 
