PAH-TSON MOUNTAINS. 775 



SECTION VII. 



REGION OF THE MUD LAKES. 



BY ARNOLD HAGUE AND S. F. EMMONS. 



Pah-tson Mountains. — This group, which ti-ends approximately north 

 15° east, measures about 24 miles in length, and across its broadest expanse 

 nearly 6 miles in width, having roughly a diamond-shaped outline. It lies 

 west of the Montezuma Range, and just south of its central mass is crossed 

 by the parallel of 40° 30'. In the central group, the main summits attain 

 an elevation of over 3,000 feet above their base, rising in steep slopes both 

 to the east and west, but falling away gradually in irregular hills and ridges 

 to the north and south. Topographically, the structure is quite simple, 

 being a single ridge with numerous deeply- cut canons radiating out in all 

 directions from the culminating mass. Few mountain groups of Western 

 Nevada are more abundantly supplied with streams and copious springs of 

 fresh water, and it has, in consequence, become a favorite pasturage for 

 cattle and sheep. 



Geologically, the Pah-tson Mountains consist almost entirely of granites 

 and crystalline schists of the older rocks, followed by immense outflows of 

 rhyolites and basalts. 



The Archsean masses are represented by both granites and highly 

 crystalline schists, the latter presenting much the larger area. Granite 

 occupies a considerable part of the more elevated portions of the mountains, 

 but it is of later age than that which has been classed as evidently belong- 

 ing to the Archsean series, inasmuch as it penetrates the latter in several 

 well-defined dikes. According to field-observations, the crystalline schists 

 for a like reason would appear to be the oldest rocks in the group, as is 

 evident by their being cut by the Archsean granite. These schists form 

 the summit of Pah-keah Peak, and the high ridge which projects to the 

 southward just west of Crusoe Canon. Both in physical and mineralogical 

 habit they show the closest analogy to the schists of Trinity Canon, Mon- 



