GEOLOGICAL FORCES AT WORK
It seems to me that never before have I seen the geological forces
of nature so obviously at work. Elsewhere I have seen great valleys,
cliffs, islands, etc., held on good evidence to be the results of
such and such powers formerly very active; but here on the Athabaska
I saw daily evidence of these powers in full blast, ripping, tearing
reconstructing, while we looked on.
All the way down the river we saw the process of undermining the
bank, tearing down the trees to whirl them again on distant northern
shores, thus widening the river channel until too wide for its normal
flood, which in time, drops into a deeper restricted channel, in
the wide summer waste of gravel and sand.
Ten thousand landslides take place every spring, contributing
their tons of mud to the millions that the river is deporting to
the broad catch basins called the Athabaska and Great Slave Lakes.
Many a tree has happened to stand on the very crack that is the
upmost limit of the slide and has in consequence been ripped in
two.
Many an island is wiped out and many a one made in these annual
floods. Again and again we saw the evidence of some island, continued
long enough to raise a spruce forest, suddenly receive a 6-foot
contribution from its erratic mother; so the trees were buried to
the arm-pits. Many times I saw where some frightful jam of ice had
planed off all the trees; then a deep overwhelming layer of mud
had buried the stumps and grown in time a new spruce forest. Now
the mighty erratic river was tearing all this work away again,
exposing all its history.
In the delta of the Slave, near Fort Resolution, we saw the plan of
delta work. Millions of tons of mud poured into the deep translucent
lake have filled it for miles, so that it is scarcely deep enough
to float a canoe; thousands of huge trees, stolen from the upper
forest, are here stranded as wing-dams that check the current and
hold more mud. Rushes grow on this and catch more mud. Then the
willows bind it more, and the sawing down of the outlet into the
Mackenzie results in all this mud being left dry land.
This is the process that has made all the lowlands at the mouth
of Great Slave and Athabaska Rivers. And the lines of tree trunks
to-day, preparing for the next constructive annexation of the lake,
are so regular that one's first thought is that this is the work
of man. But these are things that my sketches and photographs will
show better than words.
When later we got onto the treeless Barrens or Tundra, the process
was equally evident, though at this time dormant, and the chief
agent was not running water, but the giant Jack Frost.