16 



Nahant, where it is frequently very coarse and pyroxenic, with 

 a high specific gravity. A more feldspathic variety exhibits 

 traces of bedding on the north-east shore of this peninsula, as 

 already noticed. This stratified rock is about midway between 

 the Spouting Horn and Maolis Garden, and is of very limited 

 extent. The lines of bedding trend E.-W. for one hundred 

 feet or more, and then toward the west curve abruptly, but 

 smoothly, around to the south, forming a right angle. Dip 

 vertical. This pyroxenic rock, in its several varieties, and the 

 feldspathic rock just noticed, occurring chiefly as eruptives, 

 underlie the city of Salem, and form the peninsula of Salem 

 Neck, and the islands of Great Misery, Little Misery, Pope's 

 Head, and Eagle Island. The stratified rocks of this series 

 consist usually of inter stratified, frequently alternating, pyrox- 

 enic and feldspathic beds. They are of all textures, from the 

 finest to the coarsest ; the stratified pyroxenic rocks, however, 

 are generally fine-grained, schistose, and very distinctly bedded. 

 These last are well developed on Marblehead, west of Dolliber's 

 Point, and especially about Naugus Head. 



It has been suggested that some of the coarse feldspar, so 

 abundant in the rocks of this series, may be labradorite ; but 

 the analyses thus far made do not support such a view. Yet, 

 as only two specimens have been submitted to analysis, the 

 question cannot be regarded as settled. The first specimen 

 analyzed was taken from the very coarsely crystalline, stratified, 

 feldspar rock on Dolliber's Point, Marblehead, and was placed 

 in the hands of Mrs. E. H. Richards, of the Massachusetts 

 Institute of Technology, who made the following report : — 



Si0 2 66.639 



A1 2 3 19.375 



K 2 4.500 



Na 2 10.011 



CaO traces 



H 2 traces 



100.525 



