214 WV. S. Shaler—F luviatile Swamps of New England. 
New England streams do not bear a large amount of coarse 
sediment, but also because the continued -rise of the swamp 
deposits causes the deltas to be masked by the growth of plants 
and the accumulation of peaty matter. It seems evident that 
we have not yet come to a point where the conditions have 
attained their equilibrium though it may well be that the pres- 
ent condition of these basins is affected by the artificial dams 
which have recently been constructed across their main chan- 
nels. I believe that, if these dams were removed, the accumula- 
tion of detritus would continue. 
The general character of the swamps which border the north- 
ward flowing rivers, merits some consideration. In the first 
place we note the fact that they do not belong to the group of 
sphagnum.deposits, for the reason that the alternations of water 
level are too great to permit the extensive development of these 
mosses. These fluviatile swamps are divisible into three classes. 
There are those which are formed in areas so frequently sub- 
jected to overflow and so constantly penetrated with water that 
they cannot afford a site for any of our perennial shrubs to 
maintain a place upon them. These areas are occupied in their 
lower part by rushes and in the higher by the ordinary marsh 
grasses of this country. Above this level we have a belt or 
ground, generally narrow, in which the grasses give place to 
various bushy but low growing plants of which the alders are 
the most common. Above this we have in certain places a 
wide field of swamps which are really only very wet woods, 
water-covered in the times of the greater floods, say once or 
twice a year, but generally two or three feet above the level of 
ordinary inundations. 
These wide inundated plains demand explanation; this I am 
not yet able to give. It seems to me, however, from their as- 
pects and the trifling sections I have been able to secure, none 
of which extend more than three feet below the surface, that 
they may be true terrace plains formed perhaps during a time 
when the channel of the river was at a lower level than it is at 
present. These plains may have been converted into swamps 
by the same changes in the drainage conditions which have so 
embarrassed the flow of the stream. 
The foregoing statement will make it clear that there isa 
great difference in the drainage conditions of the streams which 
flow from and toward the north in the belt of country included 
in eastern New England. A little further consideration of the 
facts will make it also clear that this difference is probably not 
one of the original nature but has recently been brought about. 
We note in the first place that the valleys of the rivers, which 
flow from south to north, show evidences of an erosive power 
which the rivers no longer possess. As is indicated in the dia- 
