210 EROSIONS. 



point on the Rutland and Burlington road at Mount Holly being 1350 feet above the 

 river at Bellows Falls. Hence if the Connecticut valley above Bellows Falls had been 

 filled with water to the height of 722 feet above the present level of the river, the water 

 would not have flowed out laterally either into the valley of the Merrimac, or of Lake 

 Champlain. Nor can there be any doubt that there is a barrier on the north, high enough 

 to prevent communication with the valley of the St. Lawrence. 



Now it so happens that where the Northern Railroad has excavated a trench through 

 the eastern watershed in Union, 30 feet deep and 1200 feet long, it has laid open several 

 large pot-holes in the granite. These we consider decisive proof that a cataract once 

 existed at this spot, since we know of no other agency that could produce pot-holes. 

 Both on the east and west sides of the cut we find swamps surrounded by gravel beds or 

 modified drift, with brooks starting the one for Merrimac and the other for Connecticut 

 River. But we see at once that these have had nothing to 'do with the powerful erosions 

 that are manifest at this spot. A large stream of water must have poured over the barrier 

 from the Connecticut into the Merrimac valley. Had the current been from the south- 

 east the marks of river action would have been on the northwest side ; but instead of this 

 we find on that side strong evidence of drift agency, while the pot-holes are on the Merri- 

 mac side of the ridge. 



On examining the west mural face and the top of Kilburn Peak, we find marks of what 

 seems to be ancient river action, which the subsequent erosions of the drift agency did not 

 obliterate. On account of the difficulty of distinguishing between the two agencies, or we 

 might say between fluviatile and oceanic agency generally, all of which have been brought 

 to bear upon this spot, we feel no great confidence in this corroboratory proof of the former 

 outflow of water as high as Kilburn Peak. 



The facts, however, that have been stated, force us very strongly to the conclusion that 

 the Connecticut valley above Bellows Falls must have been once filled with water as high 

 as the gorge in Union, that is, 722 feet, above the top of Bellows Falls, and conse- 

 quently that the mountains there must have been once united, and the gorge have been 

 worn down to its present depth by fluviatile conjoined with oceanic agency. The great 

 lake above, which once had an outlet at Union in the Merrimac valley, was subsequently 

 drained by the way of Bellows Falls. What diverted the current from Union to Bellows 

 Falls it may not be easy to determine, if we suppose the present levels not to have been 

 changed. But in some other cases we have strong reason to believe that during the 

 sojourn of the continent beneath the ocean at the drift period, gravel accumulated in val- 

 leys which on a previous continent were the beds of rivers, so that when the continent 

 rose, the rivers had to seek out new channels. No facts at the Union gorge will sustain 

 such an hypothesis in respect to the last submergence of the continent. Yet the change 

 of outlet may have occurred at an earlier date ; we mean at some previous submergence. 

 It would be strange, also, if some of those plicating movements, which we know to have 

 occurred in our country even later than the coal period, should not have somewhat affected 

 the metamorphic strata along the Connecticut; though we think that the principal changes 

 of level occurred at an earlier date. Yet the change of outlet under consideration may 

 have required a vertical movement of only a few feet. Upon the whole, we think the two 

 causes that have been suggested will reasonably explain all the changes of outlet with 



