Fairbanks.*] 



Geology of Point Sal. 



57 



latter penetrates the olivine in veins. Where the pyroxene is in 

 excess, the reverse is the case. In the fresh specimen the olivine is 

 black, but it always appears reddish on weathered surfaces. 

 Towards the water's edge this olivine-pyroxene rock is replaced by 

 a banded feldspathic one, the bands running parallel with the coast, 

 and dipping towards the land. It appears first as dikes in the 

 olivine and pyroxene, while near the water's edge the latter are en- 

 tirely replaced. The different bands of this more feldspathic magma 

 do not have the appearance of being separate dikes. Although in 

 places the division lines are strongly marked, yet in general there 

 is a more or less blending of the more feldspathic bands into those 

 less feldspathic. These bands might be explained by movement in 

 a heterogeneous magma which rose through the wehrlite before the 

 complete solidification of the latter. At the western end of the 

 wehrlite, where it is the most coarsely crystallized, there is a body 

 of saxonite having a width of at least 40 feet in the upper part of 

 the cliffs. It has an exposed length of several hundred feet, extend- 

 ing up the hill towards the gate in the road. It is generally a dark- 

 brownish rock, in which appear large crystals of hypersthene. It 

 blends on the one hand into a facies with no olivine, and on the 

 other into the olivine-pyroxene rocks. On the lower edge of this 

 area there is a segregated mass of hypersthene and feldspar, which, 

 with perfect correctness, might be called norite. A varying amount 

 of feldspar is characteristic of the whole hypersthene area. A vein 

 similar in manner of formation to those in the gabbro traverses the 

 feldspar-hypersthene rock. It consists of those two components in 

 large crystals, the hypersthene reaching a diameter of one to one 

 and a half inches. No sharp lines could be drawn between the 

 picrite on the west and the wehrlite, saxonite, and pyroxenite on the 

 east. The hypersthene replaces more or less completely the augite 

 of the picrite to form the saxonite, but is always associated with 

 some feldspar. The small area of hypersthene feldspar rock is 

 inclosed on all sides by the peridotite, and must be looked upon as a 

 segregation from the magma. Dikes and veins of every conceivable 

 variation between the olivine rock and the feldspathic ones, pene- 

 trate this complex between Point Morrito and the gabbro on the 

 west. Many of these are banded and some are coarsely crystallized, 



