THE PELHAM AND WILBKAHAM AKKA. 45 



suggest water-wear. These are cemented by newly deposited quartz and 

 feldspar. It contains cavities, which are often negative crystals with very 

 large, motionless bubbles, and other long trains of cavities, showing in 

 great numbers smaller bubbles in rapid motion, not affected by being 

 heated to 70° C. 



Orthoclase predominates. Albite and microcline are present. Biotite 

 occurs in deep brownish-green .scales. There is little nuxscovite. 



A single square prism of deep-red rutile was seen in the slide. 



Zircons are rare. Single large grains of menaccanite were seen, 

 changing to leucoxene. 



THE ACTINOLITE QUABTZITE. 



The central portion of the Pelham gneiss area presents two peculiari- 

 ties as compared with the other similar areas, viz, the senes of oli^^ne- 

 enstatite rocks and the great quartzite beds here described. 



The biotite of the gneiss disappears at a certain level and reappears 

 again as suddenly, leaving a gi-eat bed, perhaps 300 feet thick, between 

 two beds of the Monson gneiss which can not be distinguished from 

 each other. The intervening quartzite bed varies from a fine-grained 

 quartzite to an equally fine-grained quartz-feldspar mass, with needles of 

 tremolite or pale grass-green actinolite, just ^^sible to the eye, scattered 

 through the mass. It becomes at times a more distinctly bedded rock, and 

 almost continuous films of the same pale-green actinolite appear on the 

 foliation faces. Small garnets are quite commonly disseminated, and at 

 times distant, minute scales of an amber mica replace the actinolite. 



Distribution. — The outcrop of the rock is quite peculiar and depends 

 upon the great flatness of the dome of the gneiss syncline in Pelham. 

 The bed is exposed by the double scalping of the undulating surface of 

 this syncline, and appears, therefore, in one closed ring in Shutesbury and 

 in a loop open to the south in Pelham. 



Beginning in the northwest corner of Belchertown, it runs north along 

 the eastern slope of the Pelham range, passing just east of Pelham post- 

 office and just west of the poor farm, and continues north thi-ough the 

 center of Shutesbury and a little beyond it; then it turns sharplv soutliAvest, 

 and its dip, which had been low east, becomes westerly. It tlien runs 

 southwest into Pelham again and ends in the high peak of Hvgeia. Its 



