284 GEOLOGY OF OLD HAMPSHIEE COUXTT, MASS. 



amphibolite. The southern baud of the latter rock has a broad lateral 

 extent, because its dip coincides witli the slope of the hill. 



THE BERXARDSTOX SERIES EAST OF THE CONNECTICUT. 



Tlie adioiniuo- area east of the river in Northtield is unfortunately so 

 covered by the terrace sands that only few outcrops appear. I think that 

 the rocks of the Bernardston series find their eastern limit, through the 

 wliole leug-th of Northfield, Er\'ing-, and Montague, at the foot of the high 

 ground which Ijounds the Connecticut Valley on the east; that it ends with- 

 out any marked shore deposits, but with great crushing of the fine quartz- 

 ite, probably on a fault of great magnitude and extent; and, finally, that the 

 quartzite-schists and amphibolite, which succeed to the east in the North- 

 field hills, though presenting some points of similarity with the Bernardston 

 rocks, are to be associated rather with the series which lies west of the 

 ai'gillite and which is presumably older. 



The quartzite in Northfield. — North of this village a porphyritic quartzite 

 identical with the eastern band in the West Northfield range crops out along 

 the eastern edge of the hig-h terrace sands, but is immediately followed on 

 the east by an older sei'ies, mentioned above. It is much brecciated, and 

 abundantly cemented by hematite. It appears also in the brook bottoiiis; 

 and just over the line in Winchester a shaft has been sunk a hundi'ed feet 

 in it for lead, which appears very sparinglv in narro\A% interrupted fissures a 

 few millimeters wide, associated with barite and fluorite in equally small 

 quantities, and at the bottom containing- beautiful druses of pale-yellow, 

 saddle-shaped dolomite crystals. Below the surface the quartzite is snow- 

 white, but otherwise unchanged. The rock is a hard, white, saccharoidal 

 sandstone, regularly porphyritic, with small, clear feldspars in stout rectan- 

 gular cross-sections, for the most part striated and plainly of secondary 

 growth, since they inclose sand grains. It is here everywhere massive. 

 (See " Petrographical description," No. 5, p. 288.) Outcrops are seen in all 

 brook beds in the northern part of the town, and it approaches nearest to 

 the older series in a lane running east from the L. A. Moodj- homestead and 

 along the Winchester z-oad. It is here greatlv brecciated and full of quartz 

 and hematite veins. On the east of the boundary line several bands of the 

 older series abut obliquely against this line, so that tlie quartzite on the 

 west rests in manifest discordance, due either to unconformity or to faulting 

 of the quai'tzite against the older series. 



