PRE GLACIAL DKAINAGE AND EROSION. 511 



President Hitchcock draws the inference from the facts detaihxl above 

 "that the Connecticut River did not excavate its own bed through these 

 mountains, for had the barrier at Northampton been more than 134 feet 

 above its present bed it nmst have emptied into the Sound at New Ilaveu. 

 We must seek some other cause, therefore, for the origin of the passage 

 between Holyoke and Mount Tom." I draw the opposite conclusion, and 

 beheve the history of the erosion of the A'alley to have been as foUows: 



The streams occupied their present valleys in the crystalline rocks 

 before and during the Triassic (at levels, of coui-se, much higher than the 

 present), and entered the Triassic estuary near where their gorges now 

 end at the border of the sandstone. On the recession of the waters the 

 Connecticut followed down the deepest line in the middle of the long 

 bay and the tributaries took a direct course down the slope to this line 

 of greatest depth to join the main river. 



I imagine that the dislocation of the sandstones took place after this 

 drainage was established, and so slowly that the streams were not seriously 

 disturbed, but cut down through the sandstones till they reached the trap 

 sheets, and then through these until the four gorges were carved. 



Many facts point to the conclusion that these valleys were cut much 

 deeper than the present bed of the river, and down, indeed, to or below the 

 present level of the sea. Piles driven in clay at the Northampton bridge 

 went 10 feet below sea level. The Belden artesian well, south of the North- 

 ampton station, struck rock 25 feet below sea level, and soundings showed 

 the clays to have great depth beneath the main street crossing: these may 

 represent an old course of the Mill River. Borings of the United States 

 survey of the Connecticut River between Chicopee and Longmeadow were 

 carried to points 19 and 21 feet above sea level and 43 feet below without 

 meeting rock, and 1^ feet above sea level striking rock.' In each of the 

 four gorges here specially under discussion no rock appears in the stream 

 beds. All the points cited above lie along the old channel, at places 

 specially sheltered from glacial erosion. 



From this one may conclude, in passing, that the tails along the Con- 

 necticut are located in portions of its course which do not coincide with 

 this ancient one. 



I T. G. ElhB, Report of survey of Connecticut River : Ex. Doc. 101, Forty-fifth Congress, second 

 session, 1878, p. 122. 



