78 GEEEN MOUNTAINS IN MASSACHUSETTS. 



flat east. After reaching the crest of the mountain the line of contact turns 

 approximately north and south with north and south strike of the structure 

 of both rocks, the dip of the structural plane is rolling and often is west- 

 erly. When we come to the extreme end of the west side of the granitoid 

 gneiss area, where the line makes a sharp turn to the east, we find well 

 marked in both rocks and in the transitional forms a strike nearly due east 

 and west and a rather gentle northerly dip (strike north 77° to 85° west 

 dip 10° northerly). The coarse transitional rocks belonging to the white 

 gneiss series can be traced to the round spin - about 1 mile north of Savoy 

 Hollow, where by a sudden crumpling the rocks turn around to a north to 

 south strike and an easterly dip and then run northward. 



If we go back to the contact of the two rocks first described (south of 

 Spruce hill), and follow it east, we find that the line of contact preserves its 

 east and west strike for half a mile and then begins to turn southerly. The 

 conglomerate preserves its character fairly well for that distance; lint half a 

 mile further the strike is about north and south or north 10° west, showing 

 considerable variations, but there is always an easterly dip of 20°. The line 

 of contact here turns southerly and is concealed by drift. Haifa mile farther 

 south we find the coarse transitional gneiss, instead of the conglomerate, 

 striking here north 42 D west and dipping 45° east. For three-quarters of 

 a mile this rock continues until we come to the shore of the second pond 

 crossing Profile v, PI. v. Around the shores of this pond the relations of the 

 rocks are well exposed. On the west shore the typical granitoid gneiss occurs 

 with blue quartz, with a north to south strike and easterly dip of the 

 structure. For 1,000 feet east of here we have a series of outcrops, partly 

 in the water, which consist of the coarse transitional gneiss, often contain- 

 ing granulitic lenses that resemble the pebbles of the conglomerate. 

 There are many loose outcrops of the genuine conglomerate with blue 

 quartz, granulite, and gneiss pebbles, which make it very probable that 

 ledges of this rock exist here. Half way across the pond we find the con- 

 tact of these coarse transitional gneisses with the Hoosac albite-schist, the 

 latter resting on the gneiss and the structure of the two rocks absolutelv 

 conformable — strike north 10° east, dip 25° easterly. The schist is very 

 garnetiferous, as usual near the contact, and covers the rest of the 



