Palaeogeographic Reconstruction of Hecate Strait British Columbia: Changing Sea Levels and Sedimentary Processes Reshape a Glaciated Shelf

  1. Michael Z. Li2,
  2. Christopher R. Sherwood3 and
  3. Philip R. Hill4
  1. J. Vaughn Barrie and
  2. Kim W. Conway

Published Online: 3 JAN 2013

DOI: 10.1002/9781118311172.ch2

Sediments, Morphology and Sedimentary Processes on Continental Shelves: Advances in Technologies, Research, and Applications

Sediments, Morphology and Sedimentary Processes on Continental Shelves: Advances in Technologies, Research, and Applications

How to Cite

Barrie, J. V. and Conway, K. W. (2012) Palaeogeographic Reconstruction of Hecate Strait British Columbia: Changing Sea Levels and Sedimentary Processes Reshape a Glaciated Shelf, in Sediments, Morphology and Sedimentary Processes on Continental Shelves: Advances in Technologies, Research, and Applications (eds M. Z. Li, C. R. Sherwood and P. R. Hill), John Wiley & Sons, Ltd, Chichester, West Sussex, UK. doi: 10.1002/9781118311172.ch2

Editor Information

  1. 2

    Geological Survey of Canada (Atlantic), Natural Resources Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2 Canada

  2. 3

    U. S. Geological Survey, Woods Hole, MA 02543-1598 USA

  3. 4

    Natural Resources Canada, Sidney, BC, Canada V8L 4B2

Author Information

  1. Geological Survey of Canada — Pacific, Institute of Ocean Sciences, P.O. Box 6000, Sidney, British Columbia V8L 4B2

Publication History

  1. Published Online: 3 JAN 2013
  2. Published Print: 26 JAN 2012

ISBN Information

Print ISBN: 9781444350821

Online ISBN: 9781118311172

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Keywords:

  • multibeam bathymetry;
  • sea level;
  • wave-cut terraces;
  • palaeogeography;
  • british bolumbia

Summary

The Pacific margin of Canada has been subject to active tectonism, sea-level change and vigorous storm and tidal energy since glacial times, resulting in a seafloor that is complex and evolving. Extensive multibeam mapping of the continental shelf in Hecate Strait provides the basis for understanding how these processes control both sedimentation and seabed morphology. Sea-level changes and changing sediment supply has resulted in the formation of large deltas, wave-cut terraces with 30 to 50 m of relief, and spit platforms that were all subsequently drowned with rising sea-level. These seabed features are now found in water depths of between 90 to 160 m and are formed from thick unconsolidated sediment. Seabed slope gradients are > 10° in places. Contour currents have eroded these slopes to generate moats 2 to 7 m deep, at the base of the wave-cut terraces. The currents are dominated by semi-diurnal tidal flow that is continually modified by wind. The currents along the north-south trending terraces result in increasing water depths, seabed sediment type and oceanographic gradients that control benthic habitats of the many species of groundfish that occur in Hecate Strait.

Analysis of the submarine features provides a re-construction of the palaeo-environment and coastal landscape during the time period 14,000 to 10,000 14C yr BP). After deglaciation, as sea-level fell, a narrow and shallow inlet formed in Hecate Strait with large embayments, spits and a delta at the inlet head. As sea-level rose the inlet broadened and a series of coastlines were formed and then flooded. The reconstruction also allows for the identification of possible early human occupation sites.