98 ON EROSIONS OF THE EARTH'S SURFACE. 



has its origin in a peat swamp, that lies immediately to the west of the highest 

 part of the gorge. ,Not long before we reach the cut for the railroad, we pass one 

 or two long ridges of sand and gravel, running N. W. and S. E., and resembling 

 very much genuine osars, and I have marked them as such on the map. The rock 

 is gneiss, traversed by large veins of coarse granite and feldspar, trap and quartz. 

 The artificial cut is 30 feet deep and 1200 feet long; and along it, near the east 

 part of the ridge, are seen the remains of several pot-holes. In short, there is the 

 most conclusive proof that a cataract once existed here, and that the waters ran 

 from the Connecticut into the Merrimack valley. For on the west side of the 

 ridge occur very distinct marks of drift agency from N. W. to S. E., and this 

 would have obliterated the river action had it been on that side ; as it would have 

 been, had the current passed from S. E. to N. "W. At present, on the Merrimack 

 side of the ridge, is a peat swamp, from which a small brook issues towards the 

 east. 



The conclusion from these facts seems irresistible, that the valley of the Con- 

 necticut was once filled with water to the height of 682 feet above its present bed, 

 and that here was one of its outlets. Over the whole of the valley, for many rods 

 to the right and left of the railroad, we see marks of very powerful aqueous 

 action, nearly obliterated, indeed, in some places by the drift agency, but still 

 manifest to a practised eye. But it is clear that the water poured through this 

 outlet before the drift period; consequently it was -on a former continent, the one 

 that was submerged at the drift period. During that last submergence, the pebbles 

 and sand, still found so abundantly on either side of the ridge, and even beneath 

 the peat in the very gorge, were deposited. 



In looking at this outlet of a lake of a former continent, one cannot doubt that 

 a great amount of erosions has here taken place. The great width of the openings 

 in the ridge, would indicate the action of waves and oceanic currents, but that the 

 waters of the lake itself did much of the work, can hardly be doubted. 



2. Gorge at Bellows Falls. — The preceding facts and reasoning make the conclu- 

 sion almost irresistible, that the gap at Bellows Falls, through which Connecticut 

 river now runs, was once closed, at least to the height of 682 feet, with the addi- 

 tion of the fall in the river between Lebanon and that place, say 40 feet, which 

 gives 722 feet. There was probably another outlet to the lake at that height, 

 and perhaps the reason why the one at Bellows Falls sunk faster than that in 

 Union lies in the character of the rock in the two localities ; that at Bellows Falls 

 being more slaty and more full of fissures. 



At Bellows Falls, as well as at Union, we have evidence that nearly the whole 

 of the erosions was accomplished previous to the drift period. For at the top of 

 the falls, that is, in the -bottom of the valley, we find very beautiful examples of 

 striae and roches moutonnees, while only a few rods or feet below them, are fine 

 illustrations of river action upon the rocky banks of the stream about the falls. 

 "We are certain, then, that the gorge was mostly excavated previous to the drift 

 period, and we may put the work at least as far back as the period of dry land, 

 which preceded the last submergence of the continent. 



I once scaled the almost perpendicular face of Kilburn Peak, on the east bank 



