44 BULLETIN 54, U. S. DEPARTMENT OF AGRICULTURE. 
cally parallel with the Nevada-California line, while a lesser though deeper branch 
diverges a little to the west between the great Amargosa Range on the west and the 
Resting Springs and Kingston Mountains on the east. 
It was this western branch which was followed by the Amargosa River, the eastern 
trough being occupied by a northward-flowing tributary which joined the greater river 
near what is now the station of Death Valley Junction on the Tonopah & Tidewater 
Railroad. Just north of the Avawatz Mountains the Amargosa was joined by the Mojave 
and the united river turned sharply to the west through an apparently structural pass 
between the Avawatz Range and the south end of the Amargosa Mountains, thus enter- 
ing the southern end of the Death Valley depression. This Quaternary Amargosa was 
a river of no small proportions beside which its present descendant is indeed puny. 
Stream decay and the building of alluvial dams have robbed it of over half its length and 
nearly three-fourths of its drainage area, and the former great valley is cut into a multi- 
tude of shallow basins and local playas, each with its tiny tributaries and its ‘‘alkali” 
flat. At the northern end of the Ralston Valley an area of nearly 1,750 square miles has 
been cut off by an alluvial divide about 150 feet high, itself losing its former tributary 
from Cactus Flat. Next southward a segment of the early valley has been cut off to 
form the basin of Stonewall Flat, while just beyond, under the shadow of Stonewall 
Mountain, lie two other playas, and westward in the formerly tributary valley between 
Jackson and Montezuma Peaks liesa third, all now cut off behind recent alluvial divides. 
From these basins south to the Bullfrog Hills is the basin of Sarcobatus Flat, with an 
area of nearly 800 square miles and carrying besides its main playa many smaller and 
more local ones, and several once tributary valleys now cut off to form small basins. 
Once this flat discharged southward through a valley north of the Bullfrog Hills, but 
this is now closed by two alluvial divides with a small inclosed basin between. South- 
ward of this divide the channel of the Amargosa proper is still essentially clear, though 
many more or less local playas and saline flats have been left along the filled floor of the 
trough and in small tributary valleys. However, another considerable tributary has 
been lost by the cutting off of over 1,400 square miles of the eastward-trending trough 
already noticed and which now forms the Pahrump Basin. Alluvial divides have not 
only cut this valley from the main drainage, but have split it into three parts, the Stew- 
art Valley to the north, the Pahrump Valley proper in the middle, and the Mesquite 
Valley at the south. The divide which bars the latter is of considerable elevation and 
may conceivably be pre-Lahontan. If so the basin belongs to the class of the perma- 
nently inclosed, but the writer does not incline to this opinion and prefers to regard it 
as formerly a part of the Amargosa. South of the Pahrump hes the Ivanpah Basin, but 
this is probably pre-Lahontan and is separately discussed on page 45. 
The mutilation of the Amargosa, though due essentially to aridity and stream 
decay, may quite possibly have been affected favorably or unfavorably by local and 
recent movement. The detailed history of the valley is extremely complex and, 
though as interesting as it is intricate, is scarcely germane to the present study. 
Apparently both Tertiary and Quaternary have seen a chain of lake basins, whose 
alternate filling and cutting has gone on under the complex interaction of frequent 
though moderate movement and of continuous and complicated climatic change. 
These changes have been incessant and are still in progress, but it is not believed 
that during or since the Lahontan period they have affected the essentials of the 
topography or caused the persistent concentration of drainage elsewhere than in the 
Death Valley sink. 
The area of the Amargosa drainage is given In connection with Death Valley on 
page 43. 
