724 GEOLOGY OF OLD HAMPSHIRE COUXTY, MASS. 



THE INTERMJEDIATE TERRACE A]S^D THE BARRIER AT THE LILY 

 POND IN GILL, AN ABANDONED WATERFALL. 



Mr. Warren Upham, in his Survey of the Terraces of the Connecticut 

 River in New Hampshire/ described a "second apparently connected series 

 of ten-aces which mark one of the principal flood plains formed by the 

 river during its work of erosion." It is "most clearly continuous below 

 the south line of Brattleboro, but seems to be traceable from White River 

 Falls." 



In the center of the State I was not able to trace any well-marked 

 series corresponding- with that described by Mr. Upham, but commencing 

 at the north line it runs down the i-iver, well marked and continuous, to 

 the begimiing of the canyon below Northfield Farms, and it had long been 

 a problem to me why the terrace so broadly worn into the older sands in 

 the north was so faintly represented farther south. 



A study of the sandstone ridge at the Lily Pond^ quarry of Triassic 

 "bu-d tracks" in the summer of 1882 made it clear to me that here had been 

 the site of a waterfall of the Connecticut which had worn back two short 

 canyons about 100 feet long, in the northern and deepest of which the Lily 

 Pond lies, and that the two had included a rocky island between them, just 

 as is the case at present with Turners Falls, and on a larger scale with 

 Niagara. This held up the waters to the level of the 300-foot teirace 

 above this point. 



After an amount of erosion which must have represented a considerable 

 lapse of time, the stream, wearing into the sands of the great delta on the 

 south, cut round the edge of the ridge to the left and sunk suddenly to 

 nearly its present level, abandoning (a) its course through the Lily Pond 

 and Bartons Cove, and (b) the other branch starting from the other notch in 

 the ridge and running parallel with the iirst, and, like it, still represented by 

 a "cove" extending back some distance along the abandoned channel. The 

 river took thus a more circuitous com-se tlu-ough the " narrows," and had 

 still to cut down somewhat to reach its present level, as the prolongation of 

 the sandstone ridge appears just above the water level on the other side 

 of the stream, coming out from under the thick delta sands. This is doubtless 

 the reason why the width of the stream is so small at this point. 



' Geology of New Hampshire, Hitchcock, Vol. Ill, p. 58. 



-This is the third Lily Pond mentioned in this chapter; one is in Sonth Vernon, Vermont, the 

 other in West Northheld, and this is just east of the Factory village, in the town of Gill. 



