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University of California. 



[Vol. 2. 



absorbed. Their long diameters lie parallel to the walls of the dike. 

 Traversing both the serpentine and gabbro are fine-grained dikes a 

 few inches to a foot wide, which contain feldspar, olivine, hypersthene, 

 augite and magnetite. 



Along the western side of Point Morrito the peridotite has been 

 highly differentiated petrographically, and intruded by later dikes, 

 producing a great complication. The cliffs, as far east as the Chute, 

 consist of rock often coarsely crystallized, the predominant compo- 

 nent in different spots being either olivine, augite, or hypersthene, 

 with occasionally considerable feldspar. This mass is perhaps 1,000 

 feet long, and has an irregular outline. It extends to the water, and 

 nearly to the northern side of the complex on the hill above the 

 point; and, although the exposures back from the ocean are poor, 

 it has apparently been forced into the gabbro, terminating on the 

 edges in a series of dikes, and inclosing masses of the gabbro. The 

 relations are the same as those of the serpentinized picrite a little 

 farther west, both bodies undoubtedly belonging to the same intru- 

 sive. 



This peridotite magma presents great differences in different 

 parts. At the western end it is a dark, compact rock, containing 

 disseminated feldspar, and forming a picrite. In the direction of the 

 main body it becomes coarser, with less feldspar and abundant 

 diallage. Between it and the gabbro occurs a dike of intermediate 

 composition. In the high cliffs at Point Morrito the olivinitic facies 

 is mixed with the pyroxenic in the most confused manner. Over 

 portions of this area the olivine and green diallage appear in about 

 equal proportions, forming wehrlite; in others each component ap- 

 pears segregated by itself to form pure masses of olivine or diallage. 

 These segregations have an irregular form, each extending out in 

 shreddy projections into the other, or the one forming well-defined 

 veins in the other. There is no banding or system in the relation 

 between the two. This interesting condition of things is shown 

 for several hundred feet in the middle and upper portion of the 

 cliffs. On the west side of the Point are the largest areas of almost 

 pure bright green diallage, the crystals reaching one to two inches 

 in length. Where the olivine is abundant, that component has the 

 appearance of forming a paste in which the pyroxene rests, or the 



