GEOLOGICAL AND MINERALOGICAL NOTES: 



NO. 5. 



BY JOHN H. SEARS. 



THE following notes on some of the granitic and crystal- 

 line rocks of Essex County, Mass., preliminary to a more 

 extended paper, have been prepared in order to record the 

 more important results of my field work during the au- 

 tumn and winter of 1891-92, which throw much light on 

 the perplexing questions of classification of the endless 

 variety of forms which our volcanic, plutouic and sedi- 

 mentary rocks assume. 



(A) Augite- Syenite. (Vom Rath.) Within the city 

 limits of Gloucester, bounded on the north by Warner St., 

 and extending several hundred yards on Prospect St. to the 

 south and southwest, is a large mass of this typical augite- 

 syenite. Occasional outcrops are also seen south of this in 

 East Gloucester, near Bass Rocks, and in the cove in 

 Gloucester harbor west of Ocean pond, which embraces 

 the larger part of Eastern Point and in a westerly direction 

 there are outcrops near Goose cove, Annisquam. One 

 large dome-shaped mass near the corner of Quarry St., 

 Bay View, is of a coarser texture and greener in color, and 

 resembles the augite-syenite of Essex and Manchester. 

 From this last named outcrop to the northeast side of 

 Plum cove, Lanesville, there are numerous outcrops in old 



(8) 



