328 KRAMM— SERPENTINES OF THE CENTRAL [June 6, 



altitude of about 3,000 feet and Mount Harbin and Mount Hanna 

 are its prominent peaks. 



Half of a mile west of Pine Mountain the serpentine ceases to 

 be a continuous area. Isolated outcrops are found in three direc- 

 tions which have the general trend of the branches of the Mayac- 

 mas range. They are along the southern flank of the southern 

 range and a number of quicksilver mines indicate the general direc- 

 tion. From the road connecting these mines they are seen as 

 rugged barren masses, prominent on account of the bluish green 

 color and the dimensions of the outcrop. Float of actinolite schist 

 is quite abundant, and glaucophane schist is seen in place. 



Another series of outcrops follows the range north of the Big 

 Sulphur or Pluton Creek south of Mount Cobb. They are found 

 as far west as the headwaters of Squaw Creek. 



Occasional areas are also found north of Cobb Mountain, hav- 

 ing a general trend towards Pine Mountain. The largest of these 

 is a few hundred yards west of Glenbrook Springs and covers per- 

 haps one half of a square mile. 



The serpentine as a whole along this belt differs from the pre- 

 viously described ones in that it lis in a more advanced state of 

 decomposition. Specimens even of moderate freshness could not 

 be obtained. The nodular variety is prominent in the neighborhood 

 of ^tna Springs but the nodules also, are well on the way towards 

 decomposition. 



Where the serpentine is not slickensided, a feature which is pre- 

 dominant, the structure is granular. Serpentine with this struc- 

 ture seems to be more resistant. The outcrops are higher and are 

 more bold. Often they are protected by a layer of moss. If 

 such an outcrop then has jointing in approximately parallel lines it 

 resembles sandstone to such an extent that to differentiate it, it is 

 necessary to break the rock. 



All slides made from specimens along this belt show similar 

 features. Antigorite more or less stained with oxide of iron still 

 shows the structure due to its origin from olivine in some slides, 

 while in others decomposition has erased all genetic indications and 

 nothing but a homogeneous greenish mass remains. Enstatite is 

 still observed in fresher specimens and is besides chromite the only 



