NATURAL HISTORY AND PHYSIOGRAPHY OF NEW BRUNSWICK. 315 
connected by a narrow valley rising but slightly above the surface of 
Nepisiguit Lakes.* All the evidence seems to show, as Mr. Chalmers 
has clearly pointed out,f that the valley of these lakes in pre-Glacial 
times emptied by way of Nictor Lake into the Tobique, and with them 
must have gone the upper part of the Nepisiguit valley, at least to 
near the Third Fork Branch. There is also a low valley between these 
lakes and the Mamozekel, indicating perhaps a still earlier flow of 
these waters through that river. This part of the Nepisiguit was in 
all probability a part of one of the primitive valleys of the old pre- 
Cambrian streams flowing out of these highlands northwest into the 
pre-Silurian sea, which then occupied all of the northwestern part of 
New Brunswick. 
We pass now to the second part of the river. From Silver Brook 
to Indian Falls the river flows amidst great hills swiftly but smoothly 
over gravel in a deep drift-bottomed valley, with some rips among 
boulders, but no ledges, at least none across the stream. Eastward 
the valley grows broader, gradually developing a flood-plain, until 
Portage Brook is reached. Portage Brook occupies a very broad, and 
evidently ancient, valley, by which there is a low and easy portage to 
Upsalquitch Lake, which lies 100 feet lower than the mouth of 
Portage Brook. This valley is a continuation of the valley of the 
main river, which here turns to the south, as far as the Main South 
Branch, which runs in a continuation of the same valley. It seems 
plain, then, that the Main South Branch, the main Nepisiguit to 
Portage Brook, Portage Brook itself, and Upsalquitch Lake all occupy 
a very ancient valley formerly emptying northward. Below the Main 
South Branch the river-valley still has a flood plain, is broad, and 
has the least rapid current of any part of the whole river ; but it 
gradually narrows, and the flood plain disappears, until Indian Falls is 
reached. This part of the valley, therefore, broadens and shows 
greater age westward, though the part above broadens and shows 
greater age eastward. Now the peculiar relationship of the main 
river here to the great valley of the Main South Branch-Main River- 
Portage Brook-Upsalquitch, can only be explained by supposing 
that the latter valley was at one time the main stream emptying into 
the Upsalquitch, draining the pre-Cambrian highlands northward into 
*See the map accompanying note No. 30 (Bulletin xviii, 250). 
tSee his Reports, Geological Survey of Canada, 1885, GG ; 1887, N. 
