No economic activity could have taken place in Western Canada without extensive
surveys not only of the geography but also of the resources.
By the mid-nineteenth century, there had been two government
enquiries and two scientific expeditions. These supported
the fervor to create a nation, which spurred the Fathers of
Confederation.
The surveying of the
Crowsnest Pass illustrates the importance of the surveys to
settlement and industrial activity. The best description is found in
George
M. Dawson's "Preliminary Report on the Physical and Geological
Features of that portion of the
Rocky Mountains between
Latitudes 49° and 51° 30'." Dawson, who is best remembered for
his extensive exploration work with the
Geological Survey of
Canada, spent a total of twenty-nine weeks during 1883 and 1884
surveying the Rockies, and his report is probably the most
comprehensive analysis of the region's natural history to date.
He outlined the general character of the Pass in the following
words:
It [the Crowsnest
Pass] follows up the Middle Fork of the Old Man, or Crow Nest
River to its source, beyond the Crow Nest Lake, crossing a low
summit to the headwaters of a branch of Michel Creek, a
tributary of the Elk. Another summit is crossed between Michel
Creek and Coal Creek, also a tributary of the Elk. Coal Creek is
then followed down to the Elk. After reaching the Elk, the trail
runs along the east bank of the river to the canon where a
bridge has been thrown across. The wide Kootenay
valley is finally entered at a point a few miles north of the
western end of the North Kootenay
Pass.
Geologically considered, Dawson noted that the eastern
section of the Pass was part of the great eastern Cretaceous or
Crow Nest Trough. The trough was approximately seven miles wide
and its eastern margin was defined by the Paleozoic limestone
outcrops of the Livingstone Range. Rocks of similar age were
also found in the Elk River Valley which formed the western
limit of the Pass. When descending that portion of the river
south of 49 30', Dawson reported that the mountains to the east
were composed primarily of Cretaceous rocks, while those on the
west, the Lizard Mountains, were evidently made up of rock of
the Paleozoic series.
The geology of the mountains within the Crowsnest Pass, both
general and structural, was a topic later explored by several
eminent geologists. In 1911, W. W. Leach of the Geological
Survey of Canada ("Geology of the Blairmore Map Area") analyzed
in great detail the strata represented in the Pass and concluded
that the most prominent horizon markers were: firstly, "a
massive, very hard cherty conglomerate at the base of the Dakota
formation and immediately overlying the coal-bearing beds";
secondly, "a thin bed of bluish, shaly limestone, associated
with seal-brown weathering clacareous sandstones, and occupying
a middle position in the Dakota formation"; thirdly, "the
volcanic breccias and ash beds overlying the Dakota and overlain
by the Benton shales"; and finally, "a bed of very hard,
siliceous light-weathering sandstone, about 20 feet thick, which
occurs about 500 feet above the base of the Benton shales."
The location of the coal-bearing strata within the Crowsnest
Pass Presents a curious phenomenon. On the western side of the
Pass the more substantive lodes are found within the
Fernie-Michel-Corbin coal basin, whereas on the eastern side
they are restricted to the region between Coleman and Lundbreck.
There exists, then, an eighteen mile gap between
Coleman,
Alberta and Michel-Natal,
British Columbia in which little or no coal is to be found.
Dawson, in 1883-1884, was the first to note this apparent anomaly.
When discussing this series of volcanic ridges located within
the Crow Nest Trough, he stated that "the
rocks met with west of the volcanic series, to the end of the
Lake [Crowsnest Lake], probably represent those underlying the
coal horizon." He noted further that the first outcropping
of coal west of the Crowsnest Volcanics was located near the
western summit of the Pass. "Marten Brook ... is interesting,"
he wrote, "on account of the occurrence of coal on it. In
a section at the trail-crossing, on the west side, is a seam
showing a thickness of at least three and possibly four feet
of very fair coal. . . ." The attitude of the
coal
deposits also differs from east to west. In Alberta, the seams are broken
due to faulting and appear as outcrops pitching to the west. The
degrees of slope vary from 30° at McGillivray Creek to 85° near
Frank. In British Columbia, on the other hand, the coal measures
generally assume the form of a flat-bottomed basin, and where
local faulting has occurred, the angle of the dips are rarely
more than 40°.
Of the many
geological features found within the Pass, few
have attracted more attention than have the Crowsnest Volcanics.
In 1902, W. W. Leach of the Geological Survey of Canada noted
the usefulness of the volcanics as horizon markers, and to this
day they continue to serve as a topic of both scientific and
popular inquiry. The work by J. D. Mackenzie, entitled simply_
The Crowsnest Volcanics, is probably the most comprehensive of
the many articles written in a scholarly vein. Summarizing the
conditions of deposition, Mackenzie concluded that:
At the time when the deposition of the Crowsnest volcanics
began, the area they now cover was occupied by a shallow sea
probably of fresh water containing islands. "There is no
recognized evidence to show whether the vents emptied into the
air, or were submarine; any cones that may have been built up
above sea-level would naturally be destroyed during the
incursion of the sea in Benton time. The thickness of the
deposits in relation to their lateral extent seems to indicate
that the beds are due to the simultaneous effect of several
small volcanoes of moderate activity, rather than to the action
of one large vent. The eruptions were of the explosive type,
unaccompanied by flows except very locally, and took place in
continual sequence during a relatively short period of time. By
far the greater part of the ejected material fell into the sea,
and there was deposited in more or less well stratified beds.
From a layman's point of view, the most interesting aspect of
the volcanics' deposition was the magnitude of the eruptions. In
this connection, Mackenzie compared the eruptions of Mount
Katmai in Alaska and Tomboro on the island of Sumbawa with those
of the Crowsnest field and concluded that it was not unlikely
that fragments the size of a brick traveled through the air to a
distance of fifteen miles from the volcano. He also hypothesized
that "much of the finer ash and dust from the . . . eruptions
were carried out of the zone of deposition of the larger
fragments by air and water currents."
Dr. George Mercer Dawson
This article is extracted from Les Hurt, Bibliography of the
Crowsnest Pass (Unpublished Report: Historic Sites
Service, Alberta Community Development,
no date). The Heritage Community Foundation and the
Year of the Coal Miner Consortium would like to thank Les Hurt and
Alberta Community Development for permission to reprint this
material.
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