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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snowline reached a low altitude along the coast between Cape Caution and Banks<br />
Island, as revealed by cirque basins at sea-level in the Kitimat Ranges and Hecate<br />
Lowland. This was a large centre <strong>of</strong> ice accumulation from which ice moved east-<br />
ward and northeastward across the Interior Plateau and also westward across the<br />
Hecate Depression.<br />
Ice accumulated at the various centres as mountain, cirque, and valley glaciers<br />
that eroded their typical landforms. All the mountain belts exhibit in varying de-<br />
grees glacial landforms produced by cirque, mountain, and valley glaciers. Areas <strong>of</strong><br />
highest summits in the Coast Mountains, <strong>Columbia</strong> Mountains, and the Rocky Moun-<br />
tains display these features to the greatest extent (see Plates XIIA and XXX).<br />
Ice accumulated gradually by the coalescing <strong>of</strong> numerous ice-tongues into ice-<br />
caps, and the rounded ridges and domed summits characteristic <strong>of</strong> mountain ice-cap<br />
erosion are displayed over wide areas in the Kitimat Ranges (see Plate XA) , in parts<br />
<strong>of</strong> the Cassiar and Omineca Mountains, and in the Hart Ranges. This type <strong>of</strong> topog-<br />
raphy may have been partly destroyed or completely obliterated in some areas by<br />
intense late-stage cirque and alpine glaciation.<br />
Eventually the entire Cordilleran region was covered with ice whose surface<br />
reached a maximum elevation over the southern interior <strong>of</strong> more than 8,000 feet.*<br />
At this stage <strong>of</strong> maximum ice coverage, movement <strong>of</strong> the ice was largely independent<br />
<strong>of</strong> the underlying topography, and was controlled to a large extent by climatic factors.<br />
Ice Movement<br />
Ice moved across <strong>British</strong> <strong>Columbia</strong> from the Coast Mountains, and in the<br />
plateau areas <strong>of</strong> the interior it left evidence <strong>of</strong> its direction <strong>of</strong> movement in the<br />
orientation <strong>of</strong> drumlins and flutings (see Plate XXV), The ice moved in a general<br />
easterly direction across the Nechako and Fraser Plateaus (see Fig. 10). Farther<br />
to the north, ice moved southeastward parallel to Babine Lake and then swung<br />
eastward in a great arc south <strong>of</strong> Stuart Lake. From the area between Whitesail<br />
Lake and Anahim Lake, ice moved eastward and northeastward across the Nechako<br />
Plateau to the Rocky Mountains. From Chilko Lake, Taseko Lakes, and Williams<br />
Lake ice moved northeastward and northward to join the main flow, which in part<br />
overrode the Misinchinka and Hart Ranges between the McGregor and Peace<br />
Rivers (see Plate XXXVIB) and debauched onto the Alberta Plateau in a fan-<br />
shaped area west <strong>of</strong> Dawson Creek.<br />
Farther north ice moved onto the Nahlin, Kawdy, Teslin, and Nisutlin<br />
Plateaus and moved generally in a northwesterly direction over the plateaus into<br />
Yukon Territory. On the east side <strong>of</strong> the Cassiar Mountains ice moved north-<br />
eastward and eastward across the Liard Plain (see Plate XXXVIIA), escaping<br />
down the valley <strong>of</strong> the Liard River and across the surface <strong>of</strong> the Liard Plateau.<br />
On the Thompson Plateau, south <strong>of</strong> an ice divide which lay between Clinton<br />
and Williams Lake, ice moved southeastward and southward across the surface<br />
<strong>of</strong> the plateau to escape southward into the State <strong>of</strong> Washington.<br />
Elsewhere the ice has recorded the direction <strong>of</strong> its movement by the landforms<br />
it created, and one may discern that ice moved southward down the Iskut River<br />
valley from the vicinity <strong>of</strong> Kinaskan and Kakiddi Lakes; southward through the<br />
Nass Basin and down the Nass, Skeena, and Kitimat River valleys; northwestward<br />
through Hecate Strait and westward through Dixon Entrance past the northern part<br />
<strong>of</strong> Graham Island; westward from the mainland across the northern end <strong>of</strong><br />
Vancouver Island; southward and southeastward down the Strait <strong>of</strong> Georgia and<br />
southwestward across the southern end <strong>of</strong> Vancouver Island; and, as the Puget<br />
Lobe, southward down Puget Sound into Washington.<br />
* Glacial Map <strong>of</strong> Canada, Geol. Sure., Canada, Map No. 1253~. 1968.<br />
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