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vertical
and longitudal profiles of Yukon Territory.
General resolution of Landsat images, approximately 80 m
is delusive as the criterium for limitation of the size of
detectable landforms.Third generation of Landsat data (prints
or diapositives) have reduced resolution due to the repro-
duction. Also local, variable, physiographical conditions
influence the range of detectable landforms, which could
vary from few hundred meters to kilometers. As examples of
well detectable landforms could be listed medial, marginal and
frontal morains in St.Elias Mtns. ,pattern of braided river
channels in large proglacial valleys, alluvial fans,deltas
and laguns in Arctic coastal zone, aufeís phenomena at the
bottom of Arctic valleys and intermontagne depressions, man
induced landforms related to the mineral exploration and
road construction. The largest, well detectable forms
belong to structural relief: mountain ridges, structuraly
controled valleys, escarpments.
Landforms which interpretability is subdued, due to the
scarcity of indicators, are characterised by flatness ,
lack of lineaments or diseection, conformity of vegetation.
To this group belong surfaces of denudaton, pediments, large
river terraces, plains with fluvial ,lacustrine, fluvioglacial
or thick frost rubble cover. Indicators of these forms are
located more frequently in the merginal zones, but the transi-
tional character of many forms must be also taken under
consideration.
Variable, physiographical conditions of Yukon Territory
were always analysed together with morphological interpretation
of images. The knowledge of these variances was based on
the study of references and reconessance field work in
different part of Yukon.
Example of Landsat Mosaic interpretation; Nortwest part of
Yukon Territory.
Photo No.1 shows fragment of Landsat mosaic in scale
1:1,000,000covering northwest part of Yukon Territory and
adjacent fragment of Northwest Territgry. Geographical
coordinates are 68-70?« N and 135-1414 W.
The area is located in arcticand subarctic zones with
continuous permafrost (Brown,1967). According to geological
regionalisation of Canada into provinces and their subdivisions,
(Douglas, 1973), the area lies in the contact zone between
Arctic Continental Shelf, represented in the subaerial zone
by Arctic Coastal Plain and Mackenzie Delta, Cordillera Orogen,
represented by Northern Yukon Fold Complex.
Bostock, in his Physiographical Regionalisation (Bostock,
1948,1967) identified Arctic Coastal Plain with divisions;Yukon
Coastal Plain and Mackenzie Delta, Cordillera Region with
divisions; British Mtns.,Old Crow Range,Porcupine Plateau,
Old Crow Plain and Richardson Mtns. Bostock(1948) described
also smaller physiographical units but without their precise
delineation and cartographical representation.
More detailed geological investigations in this part of
Canada have been carried out systematjcally from 1955,
(Operation Porcupine of Canadian Geologic Survey).