THE LYMAN SCHISTS OF NEW HAMPSHIRE 371 



often they were obviously angular. Naturally the shearing has 

 increased the irregularity of their shapes. 



The quartz-plagioclase porphyry pebbles have been deformed 

 less than the other varieties. Their average dimensions may be 

 expressed by the ratio 2:1.25:1. They range up to two feet in 

 length. 



The dark fragments, mentioned above, are often drab-colored 

 on the weathered surface, but dark-greenish when fresh. As will 

 be explained presently, they are chlorite and actinolite schists. 

 They are of medium fine grain and of uniform texture, they are 

 markedly sheared, and their shape is very irregular, even jagged. 

 Some were found to be 10 or 12 feet long and only 1 or 2 feet wide. 

 Others are less elongate (Fig. 2) . 



As compared with the pebbles, the paste of this conglomerate 

 schist is in relatively small amount. Nor does it seem to have 

 been derived from an argillitic substance. It looks rather as if 

 it had been fine clastic debris, of texture ranging from fine sand- 

 stone to fine conglomerate, derived from the same sources whence 

 came the larger pebbles. Its appearance is that of metamorphosed 

 tufaceous material. Partly on account of the metamorphism and 

 partly because of similarity of character, the paste is not sharply 

 defined from the pebbles. On fresh surfaces of the rock the pebbles 

 are distinguished with difficulty, and even on weathered exposures, 

 where the psephitic structure is best brought out, the details are 

 blurred. 



The Mormon Hill locality. — On a traverse across the strikes 

 on Mormon Hill, one passes over a series of schists much like those 

 near Young's Pond. They are porphyries, tuff-like clastic rocks, 

 and fine and coarse psephites, all sheared. They dip steeply north- 

 west. In one place obscure cross-bedding indicated that the 

 stratigraphic sequence was younger westward; and in another 

 locality the same fact was shown by an unconformable contact 

 between tuff-like schist on the southeast and conglomerate schist 

 on the northwest. The series was roughly measured as having 

 a breadth of outcrop of 800 feet. 



The porphyry schist of this region differs from that near Young's 

 Pond in lacking quartz phenocrysts. Its phenocrysts are all of 



