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Glaciers of North America— GLACIERS of CANADA

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Glaciers of North America— GLACIERS of CANADA Glaciers of North America— GLACIERS OF CANADA GLACIERS OF THE COAST MOUNTAINS By GARRY K.C. CLARKE and GERALD HOLDSWORTH SATELLITE IMAGE ATLAS OF GLACIERS OF THE WORLD Edited by RICHARD S. WILLIAMS, Jr., and JANE G. FERRIGNO U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1386–J–1 The Coast Mountains of Canada extend from southwestern British Columbia to southwestern Yukon Territory. Highland ice fields and associated outlet glaciers are present along the erosionally dissected mountain blocks. Mining is difficult in this area because of the glaciers, and prehistoric and historic jökulhlaups have resulted from glacier-dammed lakes CONTENTS Page Abstract ---------------------------------------------------------------------------- J291 Introduction----------------------------------------------------------------------- 291 FIGURE 1. Index map of the Coast Mountains, British Columbia, and surrounding area in Canada and the United States. ---------- 292 2. Annotated Landsat MSS image of part of the Coast Mountains near Stewart, British Columbia, and the Granduc mining development ------------------------------------------------- 293 3. Annotated Landsat MSS image of part of the Boundary Ranges of the Coast Mountains near the confluence of the Stikine and Iskut Rivers, British Columbia and Alaska ------ 294 Hazards and Problems Created by Glaciers ------------------------------- 292 Glaciers and Mining-------------------------------------------------------- 292 Glaciers and Outburst Floods ------------------------------------------- 295 Recreational and Scientific Roles of Glaciers----------------------------- 296 FIGURE 4. Annotated Landsat MSS image showing the region of Garibaldi Provincial Park, British Columbia ----------------- 297 References Cited----------------------------------------------------------------- 299 CONTENTS III SATELLITE IMAGE ATLAS OF GLACIERS OF THE WORLD GLACIERS OF NORTH AMERICA— GLACIERS OF CANADA GLACIERS OF THE COAST MOUNTAINS By GARRY K.C. CLARKE1 and GERALD HOLDSWORTH2 Abstract The Coast Mountains follow the Pacific coast of Canada and extend from southwestern British Columbia to southwestern Yukon Territory. The predominantly granitic bedrock forms elevated blocks that have been deeply dissected by erosion, yielding a distinctive pat- tern of disjointed highland ice fields that are drained by radiating outlet glaciers. Popular interest in the glaciers of the Coast Mountains centers on the hazards and problems that they engender and on their attractions as a recreational resource. Scientific interest has largely focused on their status as climate indicators. We touch on these various themes by discussing the glacier-associated problems of the Granduc mining operation near Leduc Glacier in northwestern British Columbia, the outburst floods of glacier-dammed Flood Lake, and the recreational and scientific roles of small glaciers in Garibaldi Provincial Park near Vancouver, British Columbia. Introduction The Coast Mountains of Canada lie almost entirely within British Columbia and extend from near the Fraser River slightly north of the lat 49° N. boundary between Canada and the United States to just across the lat 60° N. boundary between British Columbia and Yukon Territory, a distance of some 1,500 km (fig.1). The section north of the Skeena River that follows the irregular border between the Alaskan “panhandle” and British Columbia is sometimes called the Boundary Ranges, and the sec- tion south of the Skeena River, the Pacific Ranges. Physiographically, the Coast Mountains resemble deeply dissected elevated blocks (Bostock, 1948). This gives the present-day glacierization a characteristic pattern: highland ice fields, drained by radiating outlet glaciers, are separated from one another by deep valleys. In late Wisconsinan time, when the region was covered by the Cordilleran ice sheet, these valleys were ice- filled, and the tops of the highest peaks protruded as nunataks; drainage to the Pacific Ocean was mainly by calving from tidewater glaciers. The end of this last glaciation left a spectacular fjord coastline and a network of U-shaped valleys that, in places, cut completely across the Coast Mountains. These valleys are now occupied by the major westward-flow- ing rivers of Canada. The pattern of highland ice fields broken by deep valleys is repeated over the entire length of the Coast Mountains. Some typicalttytypical examples are the Frank Mackie highland glacier complex and Manuscript approved for publication 7 March 2002. 1 Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancou- ver, British Columbia V6T 1Z4, Canada. 2 Arctic Institute of North America, University of Calgary, 2500 University Drive, NW., Calgary, Alberta T2N 1N4, Canada; Institute for the Study of Earth, Oceans, and Space, Morse Hall, University of New Hamp- shire, Durham, NH 03824–3525; and the National Hydrology Research Centre, 11 Innovation Boulevard, Saskatoon, Saskatchewan S7N 3H5, Canada; e-mail address: [[email protected]]. GLACIERS OF CANADA J291 160°W 150° 140° 130° 120° Figure 1.—Coast Mountains, British Columbia, and surrounding area in Can- Beaufort Sea ada and the United States. ALASKA 60°N YUKON TERRITORY 110°W Juneau C O BRITISH A COLUMBIA S T r e iv R ALBERTA na Skee M O U N r T e v 50° A i R I r Edmonton N e s a S r V F ancouver Island Vancouver CANADA Pacific Ocean Seattle UNITED S TATES Colu mbia River 0 500 KILOMETERS 40° Cambria Snowfield at the head of Portland Canal (fig. 2) and the high- land ice fields of the Stikine River basin (fig. 3). Although the scientific literature on the glaciers of the Coast Mountains is surprisingly sparse, no region in Canada has such close interaction between glaciers and humans as in this area. We shall take this interaction as our theme. Hazards and Problems Created by Glaciers Glaciers and Mining Rich mineral deposits lie within the Coast Mountains, and the difficulty of exploring and mining these deposits has stimulated valuable glaciological work. The experience of the Granduc Operating Company in exploiting a copper deposit near Leduc Glacier illustrates these problems and is a fertile source of cautionary tales. Figure 2 shows the Coast Mountains at the head of Portland Canal, a remarkable fjord less than 5 km across, that extends J292 SATELLITE IMAGE ATLAS OF GLACIERS OF THE WORLD Figure 2.—Annotated Landsat MSS 130°W image of part of the Coast Moun- ke La tains near Stewart, British Colum- r se bia, and the Granduc mining w Bo development. Copper ore is trans- Bo er ported through an 18-km tunnel Bows v e ser Ri v from a mine (shown by a small box) near Leduc Glacier east to a Frank Mackie Glacier concentrator at the terminus of Berendon Glacier, then by truck to an ocean dock near Stewart. Anno- tations: 1, the Frank Mackie high- land glacier complex; 2, Cambria Berendon TTideide LakeLake Snowfield. Landsat image (21288– Glacier flatsFlats 18435, band 7; 2 August 1978; Path Ore concentrator 58, Row 21) is from the EROS Data Mine Summit Center, Sioux Falls, S. Dak. Map tunnel Salmon Lake references: Leduc Glacier sheet Leduc Glacier 104B/1 and 104B/2, 1:50,000; Iskut Glacier River sheet 104B, 1:250,000. 1 BR ITIS H C OL AL UM AS B KA IA Ninemile r e r v r i e 56°N e R v v i i r a RR e 0 10 KILOMETERS n n B o o m m l l a a S S Stewart Hyder l (ocean dock) a n a 2 C d n la rt o P 105 km from near Stewart, British Columbia, southwest to Portland Inlet. Annotations on this figure show the Granduc mine and associated develop- ments for transporting and concentrating the ore. The main practical prob- lem is to transport ore through rough glacier-covered terrain to a dock near Stewart. This is done in two steps: an 18-km-long access tunnel passing beneath Berendon, Frank Mackie, and Leduc Glaciers allows unconcen- trated ore to be moved from the mine to a mill at Tide Lake Camp near the terminus of Berendon Glacier. Tide Lake Camp is situated between glacier- dammed Summit Lake and Tide Lake Flats, the bed of a former proglacial lake dammed by Frank Mackie Glacier (Hanson, 1932; Haumann, 1960; Field, 1975). From Tide Lake Camp, the concentrated ore is transported by truck along an access road that follows the margin of Salmon Glacier, then crosses the international boundary and follows the Salmon River from Nine- mile, Alaska, to a dock at Hyder, Alaska, near Stewart. Initial supply of Tide Lake Camp and the mine site was by tractor-hauled sled along routes that passed over Salmon, Berendon, Frank Mackie, and Leduc Glaciers. Crevasses restricted use of these ice roads to the winter months when snow cover made safe crossings possible. In 1955, a fixed- wing landing strip was established on the surface of Leduc Glacier near the GLACIERS OF CANADA J293 58°N 132°W 131° 130° 133°W 58°N BRITISH COLUMBIA ALASKA S t i k i n 5 e 5 R iv 6 er 2 1 F er r Iskut Riv ed e 3 ri 4 ck S o u 57°N n d iiver e R kiin Sttii APPROXIMATE SCALE 10 0 10 20 30 KILOMETERS Wrangell Figure 3.—Annotated Landsat MSS image of part of the River); 5, Flood Glacier; 6, site of glacier-dammed Flood 6 3 Boundary Ranges of the Coast Mountains near the conflu- Lake (the 1979 outburst flood released 200 × 10 m of ence of the Stikine and Iskut Rivers, British Columbia and water and gave a peak discharge of roughly 3,000 m3 s–1). Alaska. Hydroelectric development plans for the Stikine- Landsat image (1772–19162, band 7; 3 September 1974; Iskut basin make it necessary to consider glacier hazards. Path 60, Row 20) is from the EROS Data Center, Sioux Annotations: 1, 2, highland ice fields; 3, Hoodoo Mountain Falls, S. Dak. Map references: Stikine River sheet 104 SE. (a volcano); 4, Great Glacier (according to Native Ameri- and part of 104 SW., 1:506,880; Iskut River sheet 104B, can oral tradition, this glacier once bridged the Stikine 1:250,000.
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