6 University of Michigan 



The altitude of Carlin, situated at the southern end of the 

 basin on the margin of the Humboldt Valley, is given on the 

 government maps as 4,930 feet. In general then, it can be said 

 that the basin floor has an elevation of about 5,000 feet, but 

 unlike many of the Great Basin valleys it is very far from 

 being level. The only extensive flats are in the valleys of the 

 larger streams, viz., along the Humboldt River, Maggie and 

 Susan Creeks (PI. I, Figs, i, 2, PI. H, Fig. i). Elsewhere the 

 basin floor has high ridges of waste material separated by deep 

 valleys tributary to the Annie, Maggie and Susan Creeks (PI. 

 II, Fig. 2). The general height of these ridges increases to- 

 ward the mountains, the ridges are continuous with the divides 

 between the canyons on the mountain slopes, and the valleys 

 merge into the mountain canyons (PI. II, Fig. 2, PI. III,. 

 Fig. i). 



In a general way, the soils vary from a rather compact 

 loam on the flood plain of the Humboldt River, and a fine silt- 

 like loam interspersed with alkali spots on the flats at the foot 

 of the slopes along the sides of this valley and in the valleys 

 of the other basin streams, through a more or less gravelly 

 loam on the basin ridges, which becomes coarser toward the 

 mountains, to a stony loam interspersed with rock outcrops and 

 boulders on the mountain slopes (PI. Ill, Fig. 2). 



The highest elevations in the area investigated are in the 

 Cortez Mountains, the Carlin Peaks in this range attaining a 

 height of 7.754 feet. As on the parts of the other ranges ex- 

 amined, however, which are much lower, there are relatively 

 few rock outcrops. The outcrops are, nearly everywhere, of 

 small extent (PI. Ill, Figs, i, 2), and many of them have also 

 been broken up into large rocks, while many of the talus slopes 

 have disintegrated into stony soil. The extensive rock out- 

 crops occur where the larger streams flow through the ranges,. 



