786 DESCRIPTIVE GEOLOGY. 



.part of its extent, and at its moutli apparently extends also along the foot- 

 hills to the west. The eastern slopes were not examined, but the basalt 

 body probably connects with that of the low ridge, which connects these 

 mountains with the Montezuma Range. 



Kamma Mountains. — To the north of the Pah-tson Mountains, and on 

 the western edge of the larger Mud Lake, or Black Rock Desert, as it is 

 sometimes called, is an irregular group of hills, whose highest summits 

 which rise from 2,000 to 3,000 feet above the desert are arranged in the 

 shape of a crescent, called the Kamma Mountains. Tlirough these hills 

 runs the wagon-road from the bend of the Humboldt River to California 

 laid out by General Lander, and sometimes known as Lander's cut-off. 

 In the middle of the group, a few miles from the edge of the desert, is a 

 group of springs, important because of the infrequency of springs in this 

 arid region, and because they afford the last good camping-place before 

 entering the desert region to the westward, known as the Rabbit Hole 

 Springs. Their water is tolerably pure, having a slight flavor of sulphur, 

 and of a temperature of about 60° F. They were carefully walled in by 

 General Lander, but the walls and adjoining stone house have largely fallen 

 into ruin. 



These mountains divide themselves into three natural groups, a south- 

 western, separated from the others by a dry water-course, which affords a 

 more favorable route for a wagon-road to the Humboldt, except for its want 

 of springs ; a middle group, over which the present road runs ; and a north- 

 ern, bordering the desert. The southwestern group consists of a high, 

 rounded ridge, whose slopes are unusually well covered, for this region, 

 with soil and surface accumulations. Its main mass is of siliceous slates 

 and quartzites, which were not sufficiently well exposed to show defined 

 structure-lines. On the northern slopes, they stand nearly vertical, and 

 carry several mineral veins. These rocks have been provisionally referred 

 to the Koipato group of the Triassic. On the main crest is exposed a body 

 of diorite of massive, rather tabular, structure, and conchoidal fracture, hav- 

 ing a dark-brownish color on the weathered surfaces, but in fresh fracture ' 

 showing a fine-grained crystalline mass of dark-greenish color, in which, 

 however, only small crystals of plagioclase can be distinguished by the 



