52 



SURFACE GEOLOGY. 



the upper portion of the delta of Little Sugar river is of the height men- 

 tioned. Its principal mass is 50 feet lower, being the terrace cut by the 

 railroad one third mile north of the river. It is almost wholly composed 

 of gravel, in which the largest pebbles are one foot in diameter. In the 



Fig. 14.— Folded Clayey Layer in horizontally stratified 

 Gravel, North Charlestown. Scale, i inch^io feet. 



midst of this gravel a stratum li to 3 feet thick, consisting of clay in 



layers a third of an inch thick, interstratified with a clayey sand, was 



exposed for 75 feet on the west side of this cut. Along half this distance 



it was levelly stratified, but beyond was irregularly crumpled, as shown 



in Fig. 14, apparently by lateral pressure. 



The wide, high delta of Black river has been cut through by Button 

 brook, and has been variously terraced both by this brook and by Black 

 river. A considerable portion of its plain between these streams is cov- 

 ered by heavy white pine woods. This delta increases the height of the 

 upper terrace for more than two miles southward. The delta of Williams 

 river is less extensive than the preceding, and at the same time has less 

 thickness, as it has been partly protected from erosion by ledges, which 

 in some places form its border. 



Two miles north from Williams river the west bank of the Connecticut 

 exhibits an interesting section (Fig. 15) of synclinal strata of clay and 



sand eroded to a level top, and over- 



laid by levelly stratified sand. The 

 synclinal deposit appears to be the 

 lower part of that which once filled 

 the valley. After its upper portion 

 had been carried away, the overlying 

 sand was brought in by a tributary, and subsequently terraced by the 

 river. The most noticeable feature of the modified drift north and south 

 from here is the wide interval or meadow, which extends from Charles- 

 town village to Bellows Falls, and lies partly on each side, being several 

 times crossed by the river. 



Fig. 15. — Section of River-Bank, 

 Rockingham, Vt. Scale i inch^rr 

 100 feet. 



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