46 SURFACE GEOLOGY. 



5. Changes in the Beds of Elvers. 

 1. On Connecticut River. 



On the maps which I have given of Connecticut and Deerfield rivers, I have 

 marked numerous ancient river beds. These are of two kinds, the most ancient, 

 showing a deserted rocky gorge, where once the stream flowed at a higher level 

 than at present ; and the other, a depression in alluvial meadows, once the bed 

 of the stream, and from which it has been generally slowly deflected by the 

 wearing away of a bank. Changes of the first sort probably present us with old 

 river beds of the antediluvian period, as I shall attempt to show in my paper on 

 Erosions ; but the latter class are postdiluvian, and sometimes occur in our own 

 times ; one good example of which change may be seen along the Connecticut, at 

 the foot of Mount Holyoke. I was surprised to find how numerous these ancient 

 river beds are, and I doubt not that time and further research would bring to light 

 many more than I have exhibited on the maps. I will briefly describe such as I 

 have found. Of some of them I am not quite sure, but generally they are distinct. 

 The antediluvian river courses it is sometimes difficult to distinguish from erosions 

 by the ocean ; and the alluvial ones may be confounded with the troughs between 

 glacis terraces. 



The most southerly deserted beds of Connecticut river are in Portland, opposite 

 Middletown. The present bed of that stream through the first range of moun- 

 tains, appears to me to be in a measure postdiluvian. It curves around two hills 

 of considerable height, between which, as it appeared to me, is a former bed of 

 the stream. I feel quite confident, also, that it once ran on the east side of both 

 the hills, at a considerable elevation above the present level. 



On the west side of the river, I think I can trace an ancient, though postdiluvial 

 bed of the river, through Wethersfield, passing a little west of the village, and 

 also through the west part of Hartford, so as to unite with the present bed a little 

 above the city, bringing the city upon the east bank, had it then existed. 



Along the east bank a depression commences on the east margin of the meadows, 

 in East Hartford, and continues as far as the south part of Enfield. I have not, 

 however, followed the old bed through the whole of this distance, and may be 

 in error. 



In the town of Springfield, a similar appearance is exhibited along the foot of 

 the highest terrace on which the United States Armory stands, from a small stream 

 at the south end of the town, to near the mouth of Chicopee river. I think the 

 river once ran where we now find the principal street of the place. An isolated 

 terrace, a little north of the town, marks the west bank of the former stream, as 

 shown on Section No. 3, Plate I. 



Commencing in the west part of South Hadley, an ancient bed is marked on the 

 map, passing to the east part of Granby, through a part of Ludlow, thence into 

 the west part of Belchertown, where it passes through the gorge between the east 

 end of Mount Holyoke (or Norwottuck, as the eastern part is called), and the 



