44 BULLETIN 54, U. S. DEPARTMENT OF AGRICULTURE. 



rally parallel with the Kevada-Califoniia 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 greatci river 

 near what is now the station of Death Valley Junction on the Tonopah & Tidewater 

 Railroad . Just north of the Avawatz Mountains the Amai^osa 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 StoncAvali 

 Mountain, lie two other playas, and westward in the formerly tributary valley between 

 Jackson and Montezuma Peaks lies a 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 alluv-ial 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 flUed 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 w'hich 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 WTiter does not incline to this opinion and prefers to regard it 

 as formerly a part of the Amargosa. South of the Pahrump lies 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 comi^licated 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. 



