68 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



In a later section, signed specially by President Hitchcock,^ this is 



said : 



On the south line of Massachusetts almost the whole breadth of the range, not 

 less than 20 miles, is tolerably well characterized gneiss. Yet as we pass northerly 

 on the line of strike along the eastern margin the gneiss is rapidly succeeded by mica 

 and talcose schist, and the gneiss becomes so pinched up as to form a mere wedge 

 before we get across the State; and it is doubtful whether the mica-schist does not 

 absolutely cut off the gneiss ere we reach the north line. We incline to the opinion, 

 however, that a narrow belt of Green Mountain gneiss does exteiid across the whole 

 State. 



In accordance with this ojnnion, a baud of gneiss is represented in the 

 section through Hoosac Mountain on the line of the tunnel and occupying 

 its middle third.^ 



These further details are given concerning the gneiss along the north 

 border of the State: 



The eastern part of this range as it first appears in Vermont is a very distinct 

 gneiss. ... It lies much to the east of tlie Green Mountains. . . . That which 

 forms the axis of the Green Mountains in the southeast part of Stamford is scarcely 

 distinguishable from mica-schist. ... In the village of Stamford and at Hart- 

 wellville the gneiss almost passes into quartz rock. . . . 



In Whitingham and Readsboro there is a large amount of dolomite and saccha- 

 roid limestone present in the gneiss in the form of beds. The gneiss west of Deer- 

 field River in Readsboro is rather peculiar. It is a very coarse, greenish, massive 

 rock, sometimes containing multitudes of garnets and blotches of what resembles clay 

 slate. Most of the course of Deerfield River in Vermont lies in the trough of a 

 synclinal. Hence the strata of gneiss in a part of their course, as in Wilmington, 

 are nearly horizontal.^ 



Distribution. — An inspection of the map w^ill show that the Hoosac schist 

 extends farther east here (at the north) than farther south, and that its upper 

 boundary is more irregular. Entering the town of Rowe from Vermont, the 

 upper boundary goes southwest across that town, crosses the Deerfield River 

 at the northwest corner of Florida, and, bending in a great semicircle open 

 to the north, it leaves the county across the west line of Monroe, so that 

 nearly the whole of this town is underlain by this rock in a broad anticline, 

 with north south axis and sharp southward pitch. 



North of the tuimel entrance, at the last house on the river road before 

 the Monroe line is reached, the Hoosac schist is abundantly exposed behind 

 the house and 800 feet south of the line, while about the same distance 

 farther south the overlying Rowe schist occurs. The latter is a much 



I Kept. Geology of Vermont, Vol. 1, 1861, p. 470. -' Ibid., pi. 15, fig. 5. » Ibid., p. 463. 



