A CONTRIBUTION TO THE GEOLOGY OF SOUTHERN MAINE 533 



Related Types. — On the mainland and neighboring islands are 

 many granitic dikes and bathyliths. Microscopic examination 

 of many of these revealed mineralogical similarity to the type 

 just described, but with some variation between the proportions 

 of constituents. An estimation of these constituents in terms of 

 standard minerals reveals the fact that class and order are 

 evidently the same as for the type just described, but that 

 there is some variation in the relative amounts of alkalies and of 

 lime. The commonest types from the mainland appear to fall 

 into I. 4. 3. 4, yellowstoneose, no analyses of which were made. 



THE DOSALANES. 



Meta-grano-sitkose. II. 3. 3. 4. (Quartz-augite-Diorite ; Actino- 

 lite Schist.) Occurrence. — The rock thus classified is one of the 

 most remarkable of the whole region. It forms dikes on 

 Fisherman's Island in a country rock of sandy biotite schist. 

 The dikes frequently parallel the structure, and, as they weather 

 into a gray sand and frequently contain inclusions of the schist, 

 they appear deceptively like a sedimentary rock. They are how- 

 ever found unmistakably cutting the bedding at various angles. 



Megascopic Character. — In a fresh hand specimen the igneous 

 nature of the rock is unmistakable. Pink with green spots is its 

 general appearance. The texture is moderately coarse to fine. 

 Actinolite and a schistose structure develop in the crushed parts. 



Microscopic Character. — In the less crushed varieties the fol- 

 lowing minerals were observed, in order of abundance : a greenish 

 augite, quartz, plagioclase (albite and oligoclase), zoisite, 

 brown hornblende, titanite, biotite, apatite. In the more 

 crushed varieties actinolite develops almost to the exclusion 

 of the other ferro-magnesian minerals, while there is a marked 

 increase in zoisite; microcline is abundant, and the quartz is 

 completely crushed. 



Similar Types. — The rock just described is confined to the 

 general vicinity of Fisherman's Island. On Ocean Point are a 

 few dikes which may be of the same rock, but the actinolite is not 

 conspicuous in them. The dikes on Ocean Point are like most 

 of the dikes of the region in cutting their enclosing rock sharply, 

 in which respect they differ from the sitkose just described. 



