6o 



University of California. 



[Vol. 2. 



branches two to three inches in thickness, from which branch 

 again still smaller ones perpendicularly, thinning out finally to 

 knife edges. The large dikes and many of the smaller ones con- 

 tain inclusions of serpentine. These inclusions are frequently 



Figure 6. — Irregular dike of diabase inclosing fragments of serpentine. 



drawn out in long, shreddy wisps. In order for these to assume 

 the form shown here, it would seem necessary for the serpentine to 

 have been in a somewhat plastic condition. Occasional dikes of 

 hornblende gabbro contain rounded and partially absorbed nodules 

 of serpentine. In one instance these inclusions appeared surrounded 

 by a green border shading into the gabbro. In one case the inclu- 

 sions of serpentine in a gabbro dike are sharply angular in outline 

 (Fig- 7)- The dark serpentine which forms the most of the coast 

 line from the Chute southeastward is intersected in many places by 

 veins one to two inches wide. These consist either of feldspar and 

 coarse crystals of green pyroxene or wholly of pyroxene. In the 



