The Rathdrum tribune. (Rathdrum, Idaho) 1903-1963, 1916-03-10
Idaho a Wonder State

Idaho. has maly inter sling
features in its physical geography,
writes ID. G. Livingstone, professor Of
geology in the university of Idaho.
Ii Is, on the whole, remarkably
rugged state and is we'll named the
,"Gem Of the Mountains" Both Ice
and fire In the form Of glaciers and
volcanic activity have played part
In its formation as we'll as the erosiye
power Of streams In cutting down
their channels. Few states show the
action Of all the geological forces OF
nature In the way that Idaho does.
The Purcell Trench is striking
illustration Of these forces. This is
that long, deep aud narrow depression
that runs northwatd from the south
end OF Lake Cwur d'Aleue through
Rathdrum prairie and Lake Pend d.
Oreille, extending on into British
Columbia, through the Kootenal
| i''N' Nhu AitO" tdkCs IL varies III
width from about two to nearly
twenty miles and is comparatively
fiat with slight general slope north
ward OF g.. feet d mile from Lake
CGur d'Alene to the Canadian boun-
dary. AS The Kootenai liver is ev,
somewhat flaLter than this the valley
Is flooded In the spring aud conse.
quently the task OF draining this
fertile country is exceedingly difllcui.
The trench is bounded on the we,6
by mountain ranges, which include
part OF The Selkirks, that rugged
range, whose northern end In British
| Columbia affords the Canadian Pacn;
railroad much Ut It's scenic beauty.
On the e4St the trench Is bounded hy
lower mountains. The trench has
probably been formed by faulting-
that is ti,Sure Or series Of Hssu.es
was formed on one or both sides of
the trench, and long block of ground
was depressed, or else the nelghbor--
Ing mountains were elevated. Posi-
bly, this occurred million or more
years ago-not u long period from u
geological viewpoint. 1t must, how
ever, have been before eastern north
America was covered with the great
glacial ice sheet which apparently
shaped the trench ln large measure
after the first formation and caused
the existence of both Cnur d'Alene
and Pend d'Oreille lakes and also the
smaller lakes. This great Ice sheet
came only short distance into Idaho.
Tongues Of ice from it came down
Priest River and Purcell Trench To
the southern end OF Lake Pend d.
Orellle and must have caused consid-
erable disturbance 10 the drainage os
the region.
Before this the trench was no
doubt occupied by large stream flow
ing north, which received the water
from Kootenai, Clarks Fork. Occur d.
Alene, and st. Joe rivers. As the
glacier extended south IL damned
this stream, forming one large lake.
Into this vast accumulation of
sediment was brought both by the
; glaciers and the streams. The water
evidentl, rose until 1t {, nnd an
outlet to the west in Spokane river,
which draining the lake to its present
level left large amount OF gravel,
boulders, and other deposits, forming
the floor Of the present Rathdrum
prairie. Farther north and east the
warmer water of Clarks Fork evident
ly kept the glacier melted aud thus
preserved th4 deep depression of Lake
glacial sediment. As the ice retreat :
ed still further north channel open
Ing along he present Pend d'Oreille
} river dfained the big lake still more
and The Kootena river began to
follow iissod channel, through which
ii still flows. This IN brief Is the
probable origin of these beautiful
lakes and rivers, but the explanation
must not be considered final, because
the geological data thus far secured
are very meager.