III.—Recent Observations on the Glaciation of British Columbia and Adjacent Regions

1888 ◽  
Vol 5 (8) ◽  
pp. 347-350 ◽  
Author(s):  
Geo. M. Dawson

Previous observations in British Columbia have shown that at one stage in the Glacial period—that of maximum glaciation—a great confluent ice-mass has occupied the region which may be named the Interior Plateau, between the Coast Mountains and Gold and Eocky Mountain Kanges. From the 55th to the 49th parallel this great glacier has left traces of its general southward or southeastward movement, which are distinct from those of subsequent local glaciers. The southern extensions or terminations of this confluent glacier, in Washington and Idaho Territories, have quite recently been examined by Mr. Bailley Willis and Prof. T. C. Chamberlin, of the U.S. Geological Survey. There is, further, evidence to show that this inland-ice flowed also, by transverse valleys and gaps, across the Coast Range, and that the fiords of the coast were thus deeply filled with glacier-ice which, supplemented by that originating on the Coast Range itself, buried the entire great valley which separates Vancouver Island from the mainland and discharged seaward round both ends of the island. Further north, the glacier extending from the mainland coast touched the northern shores of the Queen Charlotte Islands.

1985 ◽  
Vol 22 (4) ◽  
pp. 551-563 ◽  
Author(s):  
Iain Blown ◽  
Michael Church

Three distinct phenomena related to sudden lake drainage, which occurred in a restricted area within the southern Coast Mountains of British Columbia, are described: (i) moraine breaching by solitary wave action following an icefall into a lake; (ii) failure of a glacier ice dam by flotation and melting to produce a ‘glacier outburst’ flood or ‘jökulhlaup;’ (iii) debris torrent following a moraine breach. The possibility for a fourth failure phenomenon: moraine failure by piping, is discussed. A first attempt to develop practical hazard evaluation methods before the event, which relies on simple scale relations or index relations developed from experience of events elsewhere, is presented. Key words: dam break, debris flow, hazard evaluation, jökulhlaup, lakes, lake drainage.


2017 ◽  
Vol 43 (2) ◽  
pp. 449 ◽  
Author(s):  
J.J. Clague

Nearly all of what is now British Columbia and adjacent areas were covered by an ice sheet at the maximum of the Last Glaciation (MIS 2) about 18,000 years ago. By 11,000 years ago, the Cordilleran Ice Sheet had disappeared, a victim of warming climate, eustatic sea-level rise along its western margin, and perhaps a reduction in precipitation. Deglaciation proceeded by frontal retreat at the periphery of the ice sheet and by downwasting, complex frontal retreat, and localized stagnation in its interior areas. The chronology of deglaciation is constrained, albeit with inherent dating errors, by AMS radiocarbon and 10Be surface exposure ages. High-elevation sites at the western margin of the British Columbia Interior Plateau, east of the Coast Mountains, became ice-free between about 15,000 and 12,000 years ago. Ice cover in the southern Coast Mountains was sufficiently extensive during the Younger Dryas Chronozone (12,900-11,700 years ago) that glaciers advanced into low-lying areas north and east of Vancouver. At the same time, however, a labyrinth of dead or dying tongues of glacier ice covered some interior valleys. By 11,000 years ago, ice cover in the Canadian Cordillera was no more extensive than it is today.


1996 ◽  
Vol 33 (10) ◽  
pp. 1428-1438 ◽  
Author(s):  
Ian S. Spooner ◽  
Gerald D. Osborn ◽  
H. Barendregt ◽  
E. Irving

In the Stikine River valley, northwestern British Columbia, glacial and nonglacial sediments are preserved beneath Middle Pleistocene basalt-flow remnants that originated from Mount Edziza. The magnetic polarity is consistently normal, indicating that the sediment and the basalts were probably deposited within the Bruhnes normal polarity chron (<780 ka). The sediments record a regional glacial advance. Initial ice advance in the Coast Mountains blocked the westward drainage of the Stikine River and formed an advance-phase glacial lake. Sediments deposited in this lake form a coarsening-upwards sequence; debris-flow diamicton units that originated from the valley sides are common. The lacustrine sequence culminates in a poorly sorted ice-marginal gravel deposited as ice encroached upon the study area. There is little record of ice retreat. The basalts are deposited on fluvial and (or) glaciofluvial gravels, indicating that postglacial reincision was taking place at the time of eruption. Hence, the sediments were deposited in the glacial period immediately prior to the emplacement of the basalt. Evidence is presented that indicates that glacial conditions occurred between 341 and 352 ka, which corresponds to pre-Illinoian isotope stage 10.


1991 ◽  
Vol 69 (2) ◽  
pp. 443-448 ◽  
Author(s):  
S. A. Marshall ◽  
Terry A. Wheeler

Sphaeroceridae were collected in the Queen Charlotte Islands, British Columbia, in July 1988, and their distributional patterns were examined to test the hypothesis that the archipelago was the site of a Wisconsinan glacial refugium. A total of 27 species of Sphaeroceridae was identified. Ten of these species show widespread Holarctic distributions, four species are widespread across North America, seven species are restricted to North America west of the Rocky Mountains, three species are restricted to the coastal forest west of the Coast Range, and three species are supralittoral along the coast. There is no indication of endemism or relict distributions on the islands; the sphaerocerid fauna is similar to that found on the adjacent mainland. The most parsimonious explanation for the origin of the present sphaerocerid fauna of the archipelago is postglacial colonization from mainland North America. The sphaerocerid distribution pattern was compared with patterns for other Diptera and Coleoptera from the region. In general, the Sphaeroceridae corroborate the pattern seen in most other insect taxa, with postglacial dispersal from mainland source areas accounting for the present sphaerocerid fauna of the Queen Charlotte Islands.


1980 ◽  
Vol 13 (3) ◽  
pp. 322-326 ◽  
Author(s):  
J. J. Clague ◽  
J. E. Armstrong ◽  
W. H. Mathews

AbstractRadiocarbon dates from critical stratigraphic localities in southern British Columbia indicate that the growth history of the late Wisconsin Cordilleran Ice Sheet was different from that of most of the Laurentide Ice Sheet to the east. Much of southern British Columbia remained free of ice until after about 19,000 to 20,000 yr ago; only adjacent to the Coast Mountains is there a record of lowland glacier tongues in the interval 22,000 to 20,000 yr B.P. A major advance to the climax of late Wisconsin Cordilleran glacier ice in the northern States was not begun until after about 18,000 yr B.P. in the southwest of British Columbia and after about 17,500 yr B.P. in the southeast. The rate of glacier growth must have been very rapid in the two to three millennia prior to the climax, which has been dated in western Washington at shortly after 15,000 yr B.P.


1971 ◽  
Vol 8 (7) ◽  
pp. 743-752 ◽  
Author(s):  
Howard W. Tipper

During Fraser Glaciation central British Columbia was covered by glacier ice that accumulated in the Coast and Cariboo Mountains, flowed inwardly as a piedmont glacier to the Interior Plateau and thence northeasterly as an ice sheet toward the Rocky Mountains. After withdrawal of the Fraser ice sheet a limited re-advance of ice from Cariboo and Coast Mountains took place but not as a coalescent ice sheet. Drumlinoid forms, eskers, meltwater channels, kettled deposits, and lacustrine deposits provide ample evidence from which a glacial history of the area can be deduced. Although Fraser Glaciation is not believed to have culminated as an ice dome over central British Columbia, there is some evidence to suggest that earlier glaciations did form such a dome from which ice flowed radially over the Coast and Rocky Mountains.


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