TOPOGEAPHIC FEATURES OF THE DESERT BASINS. 21 



lieved to have been unrestricted. The valley now contains a number of local playas, 

 but no area of considerable drainage concentration ia known. 



The Ruby Valley proper has a present drainage area of 1,200 square miles, Butte 

 Valley has 740 square miles, and Murray Valley 720 square miles, making a total area 

 of 2,660 square miles for the group. 



THE WHITE VALLEY BASIN. 



The White Valley Basin is a north-south trough lying between the Confusion and 

 the House (or Antelope) Ranges and directly south of the Great Salt Lake Desert. 

 It is essentially structural in origin and is entkely surrounded by mountains or hills. 

 However, the lower hills to the north were overtopped by the waters of Lake Bonne- 

 ville, and even on the recession of these waters it is probable that the White Valley 

 maintained for a time an outflow to the Great Salt Lake Basin, either through the 

 low hills west of the Fish Spring Range or through Sand Pass Canyon between this 

 range and the House Range and leading into the Fish Spring Valley. Both of these 

 passes are now over 300 feet above the floor of the valley, but may have been raised 

 by recent alluvial deposition. In any event, the separate existence of the White 

 Valley Basin can not antedate the final recession of the waters of Bonneville. The 

 area of the present basin is 920 square miles, and it contains two playas separated by 

 a low alluvial divide crossing the valley from east to west somewhat south of its mid- 

 dle. The northern playa is the larger and probably slightly the lower. 



THE RUSH VALLEY BASIN. 



The Rush Valley is essentially similar to that last discussed, but lies north and east 

 from it between the Onaqui and Stansbury Mountains on the west and the Oquirr 

 Range to the east. The surrounding divides are entirely structural, but the valley 

 originally drained into that of the Great Salt Lake through a gap in the northern 

 divide just north of the present town of Stockton. This gap was below the waters 

 of Bonneville and the waves of that lake built a sand bar across it. When the waters 

 receded this bar became a dam essentially similar to the one formed by Lahontan, at 

 the southern end of Humboldt Lake, as described on page 14. In this case, how- 

 ever, the dam has never been breached and the drainage of the valley is still retained 

 behind it, forming a small brackish lake in a portion of the pre-Lahontan river chan- 

 nel. The area now tributary to this lake is 700 square miles. 



THE CEDAR VALLEY BASIN. 



This is a third basin essentially like those of the White and Rush Valleys. It lies 

 just east of the latter and between the Oquirr and Lake Ranges. The latter range 

 is low and poorly defined and the waters of Lake Bonneville transgressed it in several 

 places, forming of the Cedar Valley a partially inclosed sound separated from the 

 water body of Utah Lake Valley on the east by a chain of islands. There is also a 

 fairly low pass leading westward from the Cedar Valley into the Rush Valley described 

 above, and it is possible that this also was below the highest stage of Lake Bonneville. 

 To the east the connection with the Utah Lake Valley was probably retained until 

 quite late in the recession of the great lake and the inclosed character of the Cedar 

 Valley appears therefore to be quite, recent. Its present area is 300 square miles. 

 It contains two playas of usual character. 



THE SEVIER BASIN. 



Structurally the present Sevier Basin consists of three parallel troughs trending 

 approximately north and south . The middle of these, though the largest and probably 

 the deepest, is less well defined than the others. In its northern portion it expands 

 to form the great filled valley of the Sevier Desert. In its middle portion it is com- 



