HOOSAC MOUNTAIN. 95 



tant it forms locally a crumbly quartzite which has been quarried; in the 

 intervening space we have the same phenomenon of transition of quartzite 

 to gneiss described before near Dry brook; that is, we have small layers 

 or lenses of the quartzite in the gneiss. 



West of the contact of schist and quartzite under the bridge, the two 

 rocks extend some hundred feet downstream: then the}' rise together to 

 the bluffs and run into the open meadows, where we find outcrops of biotite- 

 gneiss overlying the quartzite. No contact with the quartzite can be found, 

 but the three rocks follow one another in several sharp turns, in which they 

 seem to conform in structure. The strike turns within 3<><) yards from 

 north fi() c west, with northeast dip, to north 45° east, with westerly dip. 

 Tins carries tin- rock down southeast to an outcrop along the road, where 

 we have in place a large ledge of the quartzite-breccia indicating a sharp 

 turn. Some hundred feet northeast an outcrop of the quartzite strikes 

 north and south, dipping east. These outcrops are scattering, and from 

 this point north we have a large drift-covered area with no outcrop what- 

 ever (see map, PI. i). They are mentioned in detail because they occur 

 in the south end of the hill in which "Burlingames" massive quartzite is 

 found, about half a mile distant, and it seems probable that this is the same 

 quartzite very much crumpled (corresponding to the "canoe" in which all 

 the rocks here are folded). This enables us to connect it with "Burlrn- 

 gameV quartzite and with the line of quartzite observed at intervals all the 

 way south from the tunnel line. 



We have heretofore been dealing with the boundaries of the great area 

 of (Vermont) gneisses and quartzites between the Stockbridge limestone on 

 the west, the lloosac schists on the east, and the granitoid gneiss (Stamford 

 gneiss) on the north, covering on the map parts of Windsor, Dalton, and 

 Savoy. The attempt has not been made to determine in detail the structure 

 of the interior of this mass, although a glance at the numerous observations 

 on fhe map will show that the ground has been fairly well covered. It is 

 impossible, so far as our work has gone, to recognize definite horizons within 

 this mass, and without these it would be hopeless to trace out the exact 

 structural features. 



It was mentioned, in speaking of the contact of the Vermont quartzite 



