210 WV. S. Shaler—F luwwiatile Swamps of New England. 
of iron sulphate by organic matter. This particular process is 
probably confined to short distances from the surface; for I 
know of no indication of the formation of iron sulphate far 
from the oxidizing influence of the atmosphere. But there 
may be other solvents yet for these and other minerals which 
can form at great depths and, if such there be, 1 am convinced 
they are cases in which they, and not those which it has been 
my good fortune to trace in the foregoing pages, have been in- 
strumental in the segregation of ores. 
U. S. Geological Survey, Dec., 1886. 
Art. XXIV.—Fluviatile Swamps of New England; by N. 8S. 
SHALER. 
[Published by permission of the Director of the United States Geol. Survey.] 
IN examining the fresh water swamps of New England I have 
found it necessary to consider in a carefu] manner the geo- 
graphical distribution of one class of these deposits, viz: The 
swamps formed along the banks of rivers. This work has been © 
done with the intention of presenting the matter in a report on 
the inundated lands of the United States, but a part of the 
results seem to have an important bearing on the question of 
recent changes in the altitude of the continent in relation to the 
sea and are therefore stated in the following pages in order that 
they may be at the service of students who are interested in 
this problem. 
Let us first note the fact that the greater part of the New 
England streams flow from north to south or with slight devia- 
tions from this direction. Except at the head-waters of these 
southward flowing streams, where the brooks have too little 
volume to clear their beds of the glacial waste which encum- - 
bers them, the valleys of this group contain no swamps. There 
are, it is true, occasional small areas of marshy ground upon 
the bordering terraces of these rivers; these, in all the cases I 
have examined, are evidently ‘‘moats” or the cut-off portions 
of the old stream beds which have been abandoned by the 
rivers in their changes of channel. . 
All these southward flowing streams show that they have, for 
a considerable time, been cutting their beds downward through 
a deep layer of detrital material which was evidently deposited 
in their channels while the ice sheet was disappearing from the 
district on which they lie. This is indicated by the fact that, 
above the alluvial plain, at present overflowed in the times 0 
flood, there is usually one, occasionally several, terraces which 
bear the mark of river action and to which the stream never 
attains. 
