Fairbanks.] 



Geology of Point Sal. 



53 



not over a half inch in thickness, but they sometimes reach two 

 inches and more, rarely four or five. In these cases they are 

 almost perfectly pure, while the intermediate bands containing the 

 ferro-magnesian silicates are not pure but contain feldspar in vary- 

 ing proportions. A hand specimen was obtained containing bands 

 of feldspar from one-eighth of an inch to two inches in width. 



About 2,000 feet west of Point Morrito an irregular body of 

 serpentine (altered picrite) appears extending parallel to the shore 

 for several hundred feet, cutting off the gabbro in the upper part of 



Figure 5. — Inclusions of gabbro in serpentine on the contact. 



the cliffs from that forming the arms which extend out into the water. 

 Its relation to the gabbro is an interesting one, but difficult to 

 understand. The following sketch from a photograph (Fig. 5) shows 

 the manner in which the gabbro is inclosed in the serpentine. 

 Both are perfectly massive, no appearance of shearing being notice- 

 able in this vicinity. They appear mixed on their edges in the 

 most intricate manner. The stringy and ragged edges of the gab- 

 bro, the mutual penetrations and apparent inclusions of one in the 

 other near their line of contact, make it appear as if both were more 

 or less viscous at the time of the intrusion of the picrite. It does not 



