Faikranks.J 



Geology of Point Sal. 



55 



picrite, show every variation between the troctolite and the non- 

 feldspathic peridotite. Between this point and the Chute at Point 

 Morrito, the different facies of the feldspathic and non-feldspathic 

 rocks appear in such variety, and show such complex intrusive rela- 

 tions, that it is difficult to give an intelligible description. The 

 serpentinized picrite, which lies between these complex bodies of 

 gabbroitic rocks and the mainland, continues toward the southeast 

 until it narrows and passes into the cliffs. At the last spot where 

 it was observed it forms a dike-like intrusion across the banding 

 of the gabbro, and both are in turn cut by a narrow dike of norite- 

 gabbro. The confused mixture of the serpentine with the gabbro, 

 which has already been described, is characteristic of the contact 

 at different spots. There are many illustrations of the inclusion 

 of the gabbro in the serpentine. It is shown clearly that the gabbro 

 was fully consolidated and subsequently broken up by the basic 

 magma which ate its way in resorbing the solid rock, until it left 

 long arms of nearly isolated or wholly inclosed fragments. Dur- 

 ing this process little movement seems to have taken place, and 

 since consolidation none at all. Inclusions of gabbro, often several 

 feet long, show the same uniform banding as that adjoining the ser- 

 pentine. The banding may be parallel to the long diameter of the 

 inclusions, or oblique, and when several fragments appear near 

 together, it is approximately parallel in them all. 



The gabbro forming the last rocky projection west of Point 

 Morrito has also a varied character. Much of it is finely banded, 

 the bands extending for many feet in perfectly straight lines. An 

 interesting inclusion of dark hypersthene gabbro, having an ellipti- 

 cal shape, occurs inch sed in a coarser rock of the same character. 

 The bands of the inclosing rock are cut off by the inclusion. A 

 dike of peridotite, cutting the gabbro and gneissoid troctolite, con- 

 tains inclusions of the adjoining rocks. These vary in size from 

 very small grains up to elliptical masses four inches in diameter, 

 and are so strung along in the dike that it presents a distinctly 

 banded structure. In addition, the dike itself is banded with streaks 

 of a lighter colored feldspathic peridotite. Another dike of serpen- 

 tine 12 feet wide contains large masses of lighter colored feldspathic 

 material, apparently representing fragments of gabbro partially 

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