536 BULLETIN of the natural history society. 
this washing-out took place by action of the great rush of water 
during the final rapid melting of the g acial ice, after which the 
reduced river retired into its lowest channels. 
Thus can the arrangement of the Square Forks be explained 
by the aid of a single assumption, that of a fluctuation in the 
glacia. continuity. Such a fluctuation might consist simply of 
local or limited, backward or forward, movements of the margin 
of the retreating ice sheet, or it might consist in a distinct inter- 
glacial period of considerable duration, of which evidence has 
been found in Ontario, in New England,* and other parts of the 
world, f though not yet, I believe, in New Brunswick. There is, 
however, one fact about these valleys which seems well-nigh 
conclusive for the interglacial explanation, namely, the old valleys 
A, G, D must have remained blocked long enough to permit the 
present gorges to be cut from their tops down to well below the 
leveCs of the rock floors of the older valleys, else on removal of 
the choking drfft, the streams would have resumed their courses 
through the old valleys. Such a cutting, of at least 50 to 75 feet 
of solid rock, must have required a very long period of time, far 
longer than could be furnished by an interval between local 
fluctuations of the margin of the ice-sheet. Moreover, there is 
other evidence with a bearing upon the subject. On the North 
Branch of Sevogle, as I have described in 1 a note later to be 
printed, within three miles above the Square Forks, occur two 
sets of very fine great gorges, which, while possessing the 
characteristic glacial -gorge features (including vertical walls), 
are nevertheless bottomed almost everywhere by drift and occu- 
pied by a flood-plained stream much smaller than that which must 
have formed them. Also in places distinct post-glacial gorges, 
with falls, occur within the older large gorges. Here, again, 
there seemS to me no way of explaining these double gorges 
except by the assumption that the larger were formed earner, 
and since they are glacial, but neither pre-glacial nor post-glacial, 
they can only be interglacial. 
I am o? opinion, therefore, that the Square Forks of Sevogle 
with the associated gorges present good evidence of the former 
existence of an interglacial period in Eastern Canada. 
* Compare Science, Vol. 24, 499. 
j Compare address on the Interglacial Problem in Nature, Vol. 74, 389. 
