TOPOGEAPHIC FEATURES OF THE DESERT BASINS. 17 



mation at hand is not sufficient to permit a detailed statement of its past and present 

 drainage conditions. However, a brief personal visit indicates that it is divided by 

 the east-west uplift of the Simpson Park and Roberts Mountains into two divisions of 

 different affiliations. South of this uplift lie the Monitor, Kobeh, and Dry Valleys, 

 which drain or drained to the Diamond Valley. North of the divide the country was 

 once tributary to the Humboldt River and comprised two northward-flowing stream 

 systems — that of Horse and Pine Creeks to the east and that of the Grass and Crescent 

 Valleys to the west, the two being separated by the Cortez Mountains. Both of these 

 drainage lines have suffered severely by stream decay and have been broken into 

 numerous shallow basins and local playas, the exact limits of which can not be deter- 

 mined from existing information. So far as known there are no areas of considerable 

 or long-continued drainage concentration, and all playas and marshes are believed to 

 be not only local but very recent. 



The total area of the region believed to have been tributary to the Humboldt is 

 2,430 square miles. 



THE GIBSON BASIN. 



East of the Sulphur Spring Range, which forms the eastern border of the Crescent 

 area, the parallel troughs and ranges again become the distinctive features of the 

 topography. The first of the troughs is mainly occupied by Diamond Valley, which 

 has probably always been landlocked, and will be discussed among the trough valleys 

 of Nevada. East of this, between the Diamond and Ruby Ranges, lies the great trough 

 of the Huntington and Gibson Valleys, which, bending a little to the west, extends 

 southward through the Little Smoky, Hot Creek, and Reveille Valleys, well below the 

 thirty-eighth parallel. The northern part of this trough, containing the Huntington 

 and South Fork Valleys, now drains to the Humboldt. Just south of this is the Gib- 

 son Valley, the northward drainage of which is cut off by a low and poorly defined 

 divide southwest of Hastings Pass. This divide is probably largely alluvial, but may 

 be due in part to minor and local cross-uplift. At any rate, it is believed to be recent, 

 and the Gibson Valley is believed to belong to the former drainage of the Humboldt. 

 Another alluvial divide cuts the Little Smoky Valley just north of the thirty-ninth 

 parallel into two divisions, one of which drains northward into the Gibson, the other 

 southward into Hot Creek and Railroad Valley. This divide marks the southern 

 limit of the Lahontan Basin in this trough. The area of the Gibson Basin, including 

 the tributary part of the Little Smoky Valley, is 1,150 square miles. It contains a 

 long, narrow playa (Newark Lake) having an area of over 30 square miles. This playa 

 is somewhat saline, but the salinity is believed to be recently acquired and the con- 

 clusion of recent outward drainage removes any expectation of extensive salt deposits. 



THE CLOVER GROUP OF BASINS. 



The north-south mountain line represented by the Ruby Range is almost every- 

 where the line of the Bonneville-Lahontan divide, but beyond the northeast corner of 

 this range and perched on the very crest of the divide lies the Clover group of three 

 closely connected basins which are believed to have belonged to the Lahontan division. 

 This group consists of two parallel north-south valleys, the Clover to the west and the 

 Independence to the east, separated in their northern parts by the Independence 

 Mountains. To the south these mountains vanish and the valleys merge. Independ- 

 ence Valley contains two local depressions due to recent alluviation and containing 

 playas of the usual type. Clover Valley has a single depression, which is the deepest 

 in the group and contains the shallow water body of Clover or Snow Water Lake. Inde- 

 pendence Valley is completely landlocked except for its connection with Clover 

 Valley. The latter has two low passes, one north into the Humboldt River, about 200 

 feet above the valley bottom and the other south into the Ruby Basin and a little 

 19750°— Bull. 54—14 3 



