Landforms of British Columbia 1976 - Department of Geography
Landforms of British Columbia 1976 - Department of Geography
Landforms of British Columbia 1976 - Department of Geography
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material and are resistant to erosion. Their response to erosion is similar to that<br />
<strong>of</strong> granitic rocks but differs in the one important respect that they possess mineral<br />
orientation and structural characteris’tics that give alignment and orientation to the<br />
landforms. The foliation may be gently or strongly folded, and this dilference may<br />
be reflected in the topography. Thus, structurally controlled dip slopes in the<br />
Shuswap terrain are gently dipping in contrast to the more steeply dipping slopes<br />
in the Horseranch Range.<br />
Figure 7. Diagram showing the main areas <strong>of</strong> foliated metamorphic rocks.<br />
The main area underlain by foliated metamorphic rocks is the Shuswap<br />
terrain, shown on Figure 7 as extending northward from Osoyoos to Quesnel Lake<br />
and T&e Jaune. Similar rocks border Carp Lake, extend in a belt northwestward<br />
from the Wolverine Range, underlie the Horseranch Range in northern <strong>British</strong><br />
<strong>Columbia</strong>, and form ro<strong>of</strong> pendants in the Coast Mountains.<br />
INFLUENCE OF OROGENIC HISTORY<br />
<strong>Landforms</strong> reflect the deformation that a region has experienced. The funda-<br />
mental reason for the difference between the gentle relief <strong>of</strong> the Interior Plains<br />
and the varied and rugged topography <strong>of</strong> the Cordillera is the difference in type<br />
<strong>of</strong> crustal movement that the two regions have undergone. In the Plains Region,<br />
since early Paheozoic times, movements have always been vertical (epeirogenic) ,<br />
with only minor warping <strong>of</strong> the crust. Because <strong>of</strong> this fact the sedimentary rocks<br />
laid down in that region are still flat lying or only very gently tilted (&e Plate<br />
XXXVIII). In contrast, movements within the Cordillera have been erogenic<br />
(mountain-building), that is, compressive or tangential to the crust, so that sedi-<br />
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