546 
BULLETIN OF THE NATURAL HISTORY SOCIETY. 
post-glacial fall of some nine feet in height near its foot, having 
great salmon pools below it. Then the valley is again open for 
a little, but very soon another gorge is entered, leading to the 
Square Forks. Here it joins the much large South Branch. But 
this locality is of such special interest that I have already described 
it in a separate note (No. 105). 
We consider now the origin of the South Branch. The origin 
of its sources is complicated by their presence in the curious 
broken country east of Kagoot, but they appear to be old rivers 
which very likely had an early course eastward into the North- 
west. The southerly courses down to the Lake Branch appear 
to be of comparatively new, perhaps “ interglacial,” origin. But 
below Lake Brook the valley seems older, and is probably one of 
the Northumbrian series which formerly swung northeast until 
captured by the Big Sevogle, which extended back farther after 
capturing the South Branch. (Compare Note 105). 
Below the Square Forks the river flows for a mile and a 
quarter in an extensive gorge, from which it issues to become a 
wide valleyed, intervaled and terraced, swift-flowing stream, such 
as is characteristic of all our rivers in the Carboniferous forma- 
tion. This part of the Sevogle, if I read the collective evidence 
aright, is newer than the northeast-southwest valleys of this 
region, and owed its formation to the causes which produced the 
north and south (Minaqua) part of the Northwest near by. 
(Note 93). 
