26 SURFACE GEOLOGY. 



nothing seen in the surface geology of the valley above would require 

 such a barrier. The depth of till thus removed must have been variable, 

 sometimes probably amounting to lOO feet; and more or less of this exca- 

 vation seems to have taken place along the entire extent of these falls. 

 The irregular surface left by the ice has been thus reduced to a chan- 

 nel of nearly regular slope with no abrupt falls, cut through the till, 

 which still covers the ancient bed in which the river flowed before the 

 glacial period. 



Lozver Connccticiit Valley. The early pioneers retained the Indian 

 name Cods, which they found applied to the fertile intervals of Lancaster 

 and Haverhill. These were the Upper and Lower Coos, separated by 

 the Fifteen-miles falls. By a similar division, the whole extent below 

 these falls is here called the lower valley. This is comparatively level 

 and straight, with a southerly course nearly the same as that of the upper 

 valley. In a direct distance of 1 1 8 miles from the mouth of Passumpsic 

 river to Massachusetts line, the river flows 137 miles, descending from 

 460 to 180 feet above the sea, or two feet to the mile. The principal 

 falls in this distance are Beard's falls at Barnet, 5 feet; Mclndoe's falls, 

 10 feet; Dodge's falls, three and a half miles south, 5 feet; at Woods- 

 ville, about 10 feet; White River falls, 35 feet (see map, vol. i, p. 302); 

 Sumner's or Quechee falls, two miles below the mouth of Quechee river, 

 5 feet; and Bellows falls, 49 feet, — making a total of 119 feet, and leav- 

 ing an average descent, excluding falls, of ig^ feet per mile. 



The modified drift of this lower valley is everywhere well developed, 

 and occurs in extensive terraces of various heights, three or four often 

 on each side, the upper one being usually from 150 to 200 feet above the 

 river, while the lowest is the interval or meadow. The largest plains are 

 expanses of the upper terrace, or of still higher tributary deltas. These 

 areas are generally of a clayey, moist, productive soil, quite in contrast 

 with the dry sandy plains of Merrimack river, Ossipee lake, and other 

 parts of the state. The nearest resemblance to these barren "pine-plains" 

 is found at Woodsville, in the high delta of Lower Ammonosuc river, on 

 the north side of Black river in Springfield, Vt., and in the high, broad 

 plain of Hinsdale. The latter is the only one of these areas which can 

 be compared in size with the extensive plains of central and eastern New 

 Hampshire. 



