DEERFIELD EIVBK AND TEIBUTAEIES. 597 



the stream. In the following more minute description of these lakes more 

 stress is laid upon the shiftings of the ice front during the formation of each 

 lake and on the character of its deposits. 



THE DEERFIELD RIVER AND ITS TRIBUTARIES ON THE NORTH. 



This Stream lies so nearly in the direction of the melting of the ice 

 that it was a main channel for the exit of its waters, and was not itself 

 encumbered, except that once the readvance of the ice in the Connecticut 

 Valley threw- a dam across its mouth. The same is true in the main of its 

 northern branches. 



The deep, tortuous, and most picturesque valley of the Deerfield 

 widens slightly in Charleraont and Shelburne, and here a considerable body 

 of sand was gathered, and in several i)laces pretty series of intermediate 

 ten-aces have been cut in this deposit of the flood period and above the 

 present flood plain of the river. Exactly as in Russell the Westfield River 

 encircled a great hill in midstream, so the flooded Deerfield surrounded a 

 great hill in Shelburne, and the railroad makes a short cut through the 

 abandoned waterway. 



Below^ Shelburne Falls the river runs in a deep canyon till it reaches 

 the Connecticut, and it is hard to say whether the great height of the 

 Charlemont-Shelburne beds is due entirelv to the setting back of the waters 

 above this deep, narro^^" gorge or partly to possible ice dams. In all this 

 distance there are only traces of terraces referable to the flood period or to 

 any subsequent time, but the stream runs deep in a rocky gorge. 



It is characteristic also of the streams that enter the Deerfield from the 

 north that either they were open waterways during the melting- of the ice — 

 and they are therefore now deeply sunk in empty valleys with traces of 

 their high flood terraces in coarse gravel beds left as remnants in sheltered 

 places and with narrow and interrupted flood plains — or they seem to have 

 been occupied by the ice during the height of the flood, at least in their 

 upper reaches, and so are wholly empty of anything except till above the 

 low level of recent flooding. This seems to have been the case with the 

 Deei-field itself above the tunnel entrance, and fine terminal moraines (1 m) 

 have been thrown across the stream at several places during the recession 

 of this last lobe of the ice. 



The curious "delta ten-aces" which appear where the tributaries on the 

 north side meet the main stream are discussed elsewhere (see p. 605). 



