ROCKS OF MOUNT DESERT ISLAND 585 



From Green and Sargent mountains 



1. Gabbro-diabase. — Predominating labradorite, with diallage, magnetite, zoisite , 

 augite, mostly in traces, crystals of both chief constituents idiomorphic. Very 

 much altered. From Green Mountain knob, ± £ mile south of summit. 



2. Crypto-crystalline chloritic schist, with serpentine and various secondaries. 

 Fragment from summit of Sargent mountain. 



3. Weathered dolerite, very much altered; plagioclase (labradorite), very much 

 decomposed ; ferro-magnesian mineral ; serpentine and chlorite. From south slope 

 of Green mountain. 



4. Chlorite schist, with many subordinate constituents. Fragment from south 

 slope of Green mountain. 



5. Weathered granite (pegmatite) ; quartz, with cavities, some containing liquid ; 

 feldspar, much kaolinized ; some biotite. From Great Snake flat, south of Green 

 mountain. 



6. Basalt (diabase), with magnetite and chlorite. From Great Snake flat, Green 

 l noun tain. 



7. Metamorphosed ferruginous sandstone with primary quartz. Fragment (?). 

 From summit of Sargent mountain. 



8. Very fine grained devitrified rock. From Green Mountain knob, =b half a 

 mile south of the summit. 



From the north shore 



I. Light aphanitic felsite with localities showing quartz ; fine grained. The 

 smaller grains rounded, while the larger are more frequently angular. The princi- 

 pal large constituent is mica (biotite). From dike near the Ovens. 



II. Diabase with interlaced labradorite blades; augite predominating over feld- 

 spar ; magnetite. From dike half a mile east of the Ovens. 



III. Dolerite but little altered; augite, labradorite, magnetite, and probably 

 olivine. From dike between the Ovens and Parkers point. 



IV. Unaltered feldspathic fine grained granite, the crystals sharp-edged and 

 well defined ; fine grained white granite dike. From Hulls cove, northeast shore. 



V. Quartzite with decomposed material between the grains. Some larger grains 

 rounded and smaller grains angular. From between the Ovens and Parkers point. 



VI. Quartzite with biotite ; magnetite ; a clastic metamorphosed by heat — not 

 fused. From massive quartzite between the Ovens and Parkers point, dip north 

 20 degrees east, 80 degrees, the rock enclosing ovoid nodule whose long axis cor- 

 roborated the conclusion as to bed plane. 



VII. Very fine grained felsite. From dike between Ovens and Parkers point. 



VIII. Very fine grained felsite. From Hayns point near the Ovens. 



PLUMOSE DIABASE AND PALAQONITE FROM THE HOLYOKE TRAP-SHEET 



BY B. K. EMERSON 



The paper is printed a3 pages 91-130 of this volume. 



