20 BULLETIN 54, U. S. DEPARTMENT OF AGEICTJLTURE. 



little basins are indistinguishable and never more than a few feet in height. A very- 

 slight increase in rainfall would be sufficient to flood and drain them and wash their 

 salt back into the Great Salt Lake. 



The present area of the Great Salt Lake Basin is perhaps 25,000 square miles. Includ- 

 ing the Great Salt Lake Desert and the other similar areas of local playas and marshes, 

 but excluding the basins cut off by real though recent divides, the area is 33,760 

 square miles. Including former tributaries, now the Steptoe and Ruby groups, 

 and the "WTiite Valley, Rush, and Cedar Basins, the area is 42,300 square miles. 



THE STEPTOE BASIN. 



During the Lahontan period one of the main tributaries of Lake Bonneville headed 

 between the Egan and Schell Creek Ranges, well south of the thirty-ninth parallel, 

 flowed northward through the great trough of the Steptoe and Goshute Valleys, 

 crossed the Toano Range and entered Lake Bonneville east of the present railroad 

 station of Cobre. Since that time alluvial deposition, probably assisted by local 

 uplift, has barred the pass in the Toano Range and cut off the Goshute Valley from 

 discharge. At the same time alluvial damming and stream decay have broken the 

 former through-flowing stream into a score of separate basins, each with its local 

 playa and each separated from the other by low and indistinguishable divides. The 

 whole valley has become an area of practically no drainage and no point or points of 

 considerable concentration can be distinguished. This early drainage line still 

 receives the insignificant discharge of what was once a considerable stream from the 

 Antelope Valley, and it once received also the drainage of the Ruby group about to 

 be described. The area of -the Steptoe, Goshute, and Antelope Valleys with their 

 tributaries is 3,930 square miles. Adding the Ruby group, the total becomes 6,590 

 square miles. 



THE RUBY GROUP OF BASINS. 



The R-uby group lies on the crest of the Bonneville-Lahontan divide, south of the 

 Clover group already discussed and between the Ruby and Egan Ranges. It con- 

 sists of the Ruby Valley to the north, with two parallel north-south valleys, the Butte 

 and'the Murray ^ lying south from it and formerly tributary to it. The deepest 

 depression of the Ruby Valley proper lies at its western edge under the steep slope 

 of the Ruby Range and contains Ruby and Franklin Lakes. Eastward from this de- 

 pression the valley rises very gradually toward the low gap of the Goshute Pass be- 

 tween the Egan and Pequop Mountains. It is reasonably certain that the Ruby 

 Valley previously discharged through this gap into the Goshute Valley and thence 

 to Bonneville. The topography of the pass is complicated by alluvial deposition 

 and apparently by recent and local movement, and it is not possible to determine 

 with assurance whether the Ruby Valley of the Lahontan period had an unresisted 

 drainage into the Goshute Valley or contained a lake which overflowed thereto over 

 a permanent dam. The writer has not found conclusive signs of lake occupation in 

 the Ruby Valley and hence inclines to the former opinion. In either case the valley 

 lacks interest from the present viewpoint. 



Of the southern tributaries of the Ruby Valley, the Butte Valley is confined only 

 by a low and inconspicuous divide across its northern end. This divide is alluvial 

 and probably very recent, and there can be little question of the previous free 

 drainage of the valley toward the north. It contains a rather poorly developed playa 

 with an area of approximately 12 square miles. The Murray Valley is separated 

 from the R,uby Valley by divides of similar character, but higher and better defined. 

 They too are believed to be post-Lahontan, and the earlier outward drainage is be- 



• This valley is known locally as Long Valley, but there boinf; numerous other Long Valleys in the Great 

 Basin, and this name being in general use for another basin (see p. 29), it is impossible to retain it here. 



