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Nechako River Map-Area

by those forced from their normal channels by ice or glacial debris that blocked
their course. Many of these channels are the erosional part of a subglacial stream,
an esker representing its depositional part. It will be noted on the map that many
eskers lead directly to one of these gullies or channels.

The large meltwater channels are the most outstanding glacial features. Along
their course stretch the major rivers and most of the long, narrow lakes char-
acteristic of this area. These channels were formed by meltwater streams pouring
off a rapidly wasting and disintegrating glacier. The streams followed pre-existing
depressions that were virtually clear of active ice and contained only disconnected
fields of almost stagnant ice, and they formed the steep cut-banks and terraces
that border, in part, all these drainage channels. Where no cut-banks or terraces
occur to-day—thus leaving a gap in the channel wall—it is assumed that these
gaps were then filled with ice. This is a reasonable assumption as such bordering
areas commonly have a knob-and-kettle topography suggestive of stagnant ice.

The main channels were the Francois Lake, the Ootsa Lake, the Tetachuck,

' and the Entiako. Apparently the last two adequately handled all the water in their

systems, but the first two at times carried more water than they could contain,
so that the Francois Lake channel overflowed southward to Cheslatta Lake and
eastward from its east end—neither course is followed by the present drainage.

The Ootsa Lake channel is probably the most spectacular drainage system
in the area. It overflowed its channel via three outlets northward from the Ootsa
Lake valley into the Cheslatta Lake valley and one southward into the Chelaslie
Lake valley. It is interesting to note that two of these north-flowing channels
were cut sufficiently low to require the erection of small dams across them to
; ensure the necessary flooding for the Alcan Project. The volume of water entering

| the upper Nechako River valley was immense, so much so that the Nechako

| Canyon either was unable to handle the flow or was blocked. Whatever the

reason water was forced to turn eastward through Big Bend Creek and into the
Euchiniko River valley and northward via several small channels to the lower
Nechako River valley. Prominent cut-banks occur along its course, particularly
along Intata and Natalkuz Lakes and terraces are prominent along its entire
course. Through most of its course, this meltwater stream was actively eroding
and the deposition that did occur was coarse sand and gravel. Silt or clay was
however deposited along the lower part of Big Bend Creek, possibly because the
flow of the stream slowed as the topographic divides were crossed. Banks and
terraces occur along most of the course but there are many places where obvious
confining features are lacking and the stream in these places does not appear to
have spread out over low ground—probably was confined by stagnant ice.

Vanderhoof Lake Silt and Clay

The only important lake deposits are those laid down in the part of the
Vanderhoof Lake basin occurring in the northeast part of the area. These deposits
and their extent in Carp Lake area have been briefly described (Armstrong and

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