138 Scientific Geology. 



or two feet in diameter. The hill of sand and clay, which now rises ab- 

 ruptly on the west side of the present stream, probably once exten- 

 ded as far east as this cataract and chasm ; and here was a ridge, 

 which threw back the waters of the stream over the whole of 

 Greenfield meadows, 4 or 5 miles in extent. For in various places 

 along these meadows, we find terraces ; generally two, but never 

 more. The hill of sand and clay at this gorge was probably worn 

 away gradually ; and as the surface of the sandstone rapidly slopes 

 towards the west, this would cause the bed of the river to sink, and 

 the terraces to be formed. In this way the bed of the river has 

 changed laterally 10 or 12 rods, and sunk 40 or 50 feet. 



Perhaps the following sketch may assist in rendering the preced- 

 ing statement intelligible. It may not be entirely correct ; but it ex- 

 hibits the principal features of the spot. 



a, a, former bed of the river. 



b, b, terraces : these are in the upper part of the gorge, and not in 

 Greenfield meadows. 



d, d, level of the Connecticut valley : a tertiary hill with steep 

 declivity. 



e, e, sandstone ledge. 



g, Meeting House in Greenfield. 



s, s, stage road to Deerfield. 



i, i, i, successive ridges of sandstone more elevated than d, d. 



Beds of other Rivers. 



Judging only by the eye, I think we may safely state that since the 

 Connecticut and its tributaries began to flow through the great valley 

 that has been described, they have excavated their beds nearly 100 feet. 

 The Connecticut at Northampton is still more than 100 feet above 

 tide water at New Haven. At Springfield it is only 64 feet. This 



