TOPOGEAPHIC FEATURES OF THE DESERT BASIlSrS. 43 



THE DEATH VALLEY BASIN. 



East of the Panamiut trough, lies the great trough of Death Valley, the deepest depres- 

 sion on the continent and with its tributary drainage, the third of the three greater 

 divisions of the Great Basin, the other two being Bonneville and Lahontan. In itself 

 the trough of Death Valley is not especially large, nor is it exceptional for anything 

 except depth. It derives its unusual interest to the present inquiry from the fact 

 that it at present receives the drainage of the Amargosa Eiver and but recently 

 received that of the Mojave River as well. These river systems are briefly described 

 in the two following sections. It is sufficient here to note that they entered the 

 Death Valley trough at its southern extremity through a common channel. 



The floor of Death Valley is an immense playa occasionally constricted but not 

 broken by tongues of alluvium pushed outward from the moimtains. (PI. VI, fig. 1.) 

 This playa is very nearly of one level, but there is apparently a very shallow depression 

 close to the eastern wall of the valley, northeast of Bennetts Wells, and which is usually 

 occupied by a shallow lake of saturated brine. Wet-weather drainage lines reach this 

 sink both from the north and south, the latter carrying what remains of the water of the 

 Amargosa. The whole playa is extremely saline, much of it is constantly moist and 

 muddy, and all ground waters are nearly saturated brines. In places on the playa 

 common salt has crystallized in the surface clays in such a way as to form a broken 

 crust or "salt reef" not unlike in appearance the "ice pillars" produced by frost in 

 moist clay soils (Plate VI, fig. 2). The irregularities of this broken crust have some- 

 times an altitude of several feet and are quite without parallel in North America, 

 though Dr. Ellsworth Huntington informs the writer that similar forms occur on the 

 salt desert of Lob Nor in central Asia. The north arm of Death Valley contains a 

 playa-Hke flat which is comparatively nonsaline and has a present drainage south- 

 ward. All other tributaries are mountain streams of usual type. 



The most interesting question concerning the Death Valley depression is that of its 

 age. The Panamint Range, which forms its western boundary, is uji questionably 

 ancient and the great apron which fringes its valleyward slope seems also to be very 

 old. But the Funeral Mountains to the east are apparently much more recent, beds of 

 apparently Tertiary age are prominent within them, and it is quite possible that they 

 and the present topography of the valley originated quite within the period we are 

 discussing. Neither space nor available data permit the discussion of this question in 

 detail. It must suffice for the writer to express his personal opinion that this movement 

 though mainly post-Tertiary and probably still in progress, is essentially pre-Lahontan 

 and has not affected the fundamentals of the valley topography. 



The drainage area now tributary to the Death Valley flat, including that part of the 

 Amargosa where the channel is still un clogged, is very nearly 7,970 square miles. The 

 cut-off portions of the Amargosa drainage add an additional 5,430 square miles, and the 

 Mojave drainage, past and present, aggregates 10,160 square miles, making a grand 

 total of 23,560 square miles in the entire Lahontan period basin. 



AMARGOSA DRAINAGE SYSTEM. 



The main trunk of the Amargosa River occupies the fourth and eabtemmost of the 

 system of troughs parallel to the Sierra Nevada. In Lahontan times its remotest 

 tributaries headed far north in the trough valleys of Nevada, touching the fringe of the 

 Lahontan drainage at the divides which head the branches of the Ralston Valley. The 

 tributaries from these two branches were joined a little to the south by a third flowing 

 westward from Cactus Flat and the augmented stream continued southward west of 

 Stonewall Mountain and the Pahute Mesa, across the Sarcobatus Flat and through a 

 narrow pass in the Bullfrog Hills into the Amargosa Desert and the valley still followed 

 by the river. Somewhat north of the thirty-sixth parallel the great trough divides, its 

 main branch rising southeastward toward the Pahrump and Ivanpah Valleys, practi- 



