Abstracts
Abstract
Changes in the geography of Atlantic Canada since the last glacial maximum (LGM) are grouped into three phases. The first phase (LGM – ca. 13 ka BP) commences with glaciers at the edge of the continental shelves, and ends with the glaciers having retreated to near modern coasts. In the second phase (ca. 13 ka BP‑10 ka BP), glaciers were mainly on land; on the continental shelves there were scattered small ice caps and an outer-shelf archipelago. Early in phase three, beginning ca. 10 ka BP, glaciers were largely absent, and the archipelago was gradually submerging; elsewhere, falling relative sea levels caused emergence. Multibeam sonar mapping has revealed the geomorphic evidence of submerged terrestrial environments of phases II and III, including fluvial, deltaic, and coastal systems. The best-preserved fluvial systems are in Northumberland Strait and the Bras d’Or Lakes. Elsewhere, multibeam bathymetric data allow discrimination between fluvial and non-fluvial channels. Deltas were mainly preserved in the special circumstances of Newfoundland fjords. Submerged coastal systems are common in the Bras d’Or Lakes, but rare elsewhere. Landscape preservation is ascribed to special circumstances. Paleogeographic reconstructions have applications in the field of evolutionary biology and archaeology.
Résumé
Les changements de la géographie du Canada atlantique depuis le dernier maximum glaciaire (DMG) sont regroupés en trois phases. La première (DMG, environ 13 ka avant le présent) débute au moment où les glaciers occupent le rebord des plates-formes continentales et se termine lorsqu’ils ont reculé jusqu’à proximité des lignes de rivage contemporaines. Pendant la deuxième phase (de 13 ka à 10 ka avant le présent), les glaciers se trouvaient principalement sur les terres; il y avait de petites calottes glaciaires éparses sur les plates-formes continentales et un archipel sur la partie extérieure des plates-formes. Au début de la troisième phase, il y a environ 10 000 ans, les glaciers étaient en grande partie absents et l’archipel s’enfonçait progressivement dans les eaux; ailleurs, les niveaux relatifs de la mer, alors à la baisse, engendraient une émergence des terres. La bathymétrie au sonar a révélé des indices géomorphologiques de milieux terrestres submergés pendant les phases II et III, incluant des systèmes fluviaux, deltaïques et côtiers. Les systèmes fluviaux les mieux conservés se situent dans le détroit de Northumberland et les lacs Bras d’Or. Ailleurs, les données bathymétriques permettent de distinguer des chenaux fluviaux d’autres chenaux non fluviaux. Les deltas ont été principalement conservés dans les cas particuliers que constituent les fjords de Terre-Neuve. Les systèmes côtiers submergés sont communs dans les lacs Bras d’Or, mais rares ailleurs. La préservation de ces paysages dépend de circonstances spéciales. Ces reconstitutions paléogéographiques ont des applications dans les domaines de la biologie évolutive et de l’archéologie.
Appendices
References
- Bell, T., Daly, J., Liverman, D.G.E., Shaw, J., Batterson, M.J. and Smith, I.R., 2005. Late Quaternary Relative Sea-Level Change on the West Coast of Newfoundland. Géographie physique et Quaternaire, 59: 129-140.
- Bell, T., Batterson, M.J., Liverman, D.G.E. and Shaw, J., 2003. A new late-glacial sea-level record for St. George’s Bay, Newfoundland. Canadian Journal of Earth Sciences, 40: 1953-1970.
- Bell, T., Liverman, D.G.E., Batterson, M. and Sheppard, K., 2001. Late Wisconsinan stratigraphy and chronology of southern St. George’s Bay, Newfoundland: a re-appraisal. Canadian Journal of Earth Sciences, 38: 851-869.
- Bonifay, D. and Piper, D.J.W., 1988. Probable late Wisconsinan ice margin on the upper continental slope off St. Pierre Bank, eastern Canada. Canadian Journal of Earth Sciences, 25: 853-865.
- Boyd, R., Bowen, A.J. and Hall, R.K., 1987. An evolutionary model for transgressive sedimentation on the Eastern Shore of Nova Scotia, p. 87-114. In D.M. Fitzgerald and P.S. Rosen, ed., Glaciated Coasts. Academic Press, New York.
- Bradley, B. and Stanford, D., 2004. The North Atlantic ice-edge corridor: a possible Palaeolithic route to the New World. World Archaeology, 36: 459-478.
- Bousefield, E.L. and Thomas, M.L.H., 1975. Postglacial distribution of littoral marine invertebrates in the Canadian Atlantic region, p. 47-60. In J.G. Ogden III and M.J. Harvey, ed., Environmental Change in the Maritimes. Nova Scotian Institute of Science, Halifax, 109 p.
- Carter, R.W.G., Orford, J.D., Forbes, D.L. and Taylor, R.B., 1987. Gravel barriers, headlands and lagoons: an evolutionary model, p. 1776-1792. In Coastal Sediments 87, American Society of Civil Engineers, New Orleans, 12-14 May 1987, 2209 p.
- Courtney, R.C. and Shaw, J., 2000. Multibeam bathymetry and acoustic reflectance imaging of the shelf seabed. Geoscience Canada, 27: 31-42.
- Cumming, E.H., Aksu, A.E. and Mudie, P.J., 1992. Late Quaternary glacial and sedimentary history of Bonavista Bay, northeast Newfoundland. Canadian Journal of Earth Sciences, 29: 222-235.
- de Cárdenas, E., 2004. Relative isolation of the Flemish Cap cod population. Abstract, The Ecosystem of the Flemish Cap, 8-10 September 2004, Dartmouth, Nova Scotia, Canada. Northwest Atlantic Fisheries Organization Symposium.
- Dyke, A.S., 1996. Preliminary paleogeographic maps of glaciated North America. Geological Survey of Canada, Ottawa, Open File 3296.
- Dyke, A.S. and Prest, V.K., 1987a. Late Wisconsinan and Holocene history of the Laurentide Ice Sheet. Géographie physique et Quaternaire, 41: 237-263.
- Dyke, A.S. and Prest, V.K., 1987b. Late Wisconsinan and Holocene retreat of the Laurentide Ice Sheet. Geological Survey of Canada, Ottawa, Map 1702A, scale 1:5 000 000.
- Dyke, A.S., Andrews, J.T., Clark, P.U., England, J.H., Miller, G.H., Shaw, J. and Veillette, J.J., 2002. The Laurentide and Innuitian ice sheets during the last glacial maximum. Quaternary Science Reviews, 21: 9-31.
- Emery, K.O. and Uchupi, E. 1972. Western North Atlantic Ocean: topography, rocks, structure, water, life, and sediments. American Association of Petroleum Geologists, Tulsa, 532 p.
- Fader, G.B.J., 1989. A late Pleistocene low sea-level stand of the southeast Canadian offshore, p. 71-103. In D.B. Scott, P.A. Pirazolli and C.A. Honig, ed., Late Quaternary Sea-Level Correlation and Applications. Kluwer Academic Publishers, Dordrecht, 229 p.
- Fader, G.B.J. and Pecore, S., 1989. Surficial geology of the Abegweit Passage of Northumberland Strait, Gulf of St. Lawrence. Geological Survey of Canada, Ottawa, Open File 2807, 4 p. and maps.
- Forbes, D.L., Boyd, R. and Shaw, J., 1991. Late Quaternary sedimentation and sea level changes on the inner Scotian Shelf. Continental Shelf Research, 11: 1155-1179.
- Forbes, D.L., Shaw, J. and Eddy, B.G., 1993. Late-Quaternary sedimentation and the postglacial sea-level minimum in Port Bay and vicinity, west Newfoundland. Atlantic Geology, 29: 1-26.
- Josenhans, H. and Lehman, S., 1999. Quaternary stratigraphy and glacial history of the Gulf of St. Lawrence, Canada. Canadian Journal of Earth Sciences, 36: 1327-1345.
- King, L.H., MacLean, B. and Fader, G.B.J., 1974. Unconformities on the Scotian Shelf. Canadian Journal of Earth Sciences, 11: 89-100.
- King, L.H. and Fader, G.B.J., 1986. Wisconsinan glaciation of the Atlantic continental shelf of southeast Canada. Geological Survey of Canada, Ottawa, Bulletin 363, 72 p.
- King, L.H. and Fader, G.B.J., 1990. Late Wisconsinan ice sheet margins of the Laurentian Channel. Geological Society of America, Boulder, Abstracts with Programs 22, 28 p.
- Kranck, K., 1972. Geomorphological development and post-Pleistocene sea level changes, Northumberland Strait, Maritime Provinces. Canadian Journal of Earth Sciences, 9: 835-844.
- Locat, J., 1977. L’émersion des terres dans la région de Baie-des-Sables–Trois-Pistoles, Québec. Géographie physique et Quaternaire, 31: 297-306
- Marshall, H.D., Johnstone, K.A., Pope, A.M. and Carrr, S.M., 2004. Population Genomics and Stock Structure of Atlantic Cod on (& off) the Flemish Cap: insights from whole-mitochondrial-genome DNA sequences. The Ecosystem of the Flemish Cap, 8-10 September 2004, Dartmouth, Nova Scotia, Canada. Northwest Atlantic Fisheries Organization Symposium.
- McCulloch, M.M., Forbes, D.L., Shaw, R.W. and the CCAF A401 Scientific Team, 2002. Coastal Impacts of Climate Change and Sea-Level Rise on Prince Edward Island. Geological Survey of Canada, Ottawa, Open File 4261, CD.
- Mosher, D.C., Piper, D.J.W., Vilks, G.V., Aksu, A.E. and Fader, G.B.J., 1989. Evidence for Wisconsinan glaciations in the Verrill Canyon area, Scotian Slope. Quaternary Research, 31: 27-40.
- Peltier, W.R., 2004. Global glacial isostasy and the surface of the ice-age earth: the ICE‑5G (VM2) model and GRACE. Annual Review of Earth and Planetary Science, 32: 111-149.
- Piper, D.J.W. and Campbell, D.C.A., in press. Quaternary geology of Flemish Pass and its application to geohazard evaluation for hydrocarbon development. Geological Association of Canada, St. John’s.
- Piper, D.J.W. and Macdonald, A.W., 2002. Timing and position of late Wisconsinan ice margins on the upper slope seaward of Laurentian Channel. Géographie physique et Quaternaire, 55: 131-140.
- Rodrigues, C.A.G., Ceman, J.A. and Vilks, G., 1993. Late Quaternary paleoceanography of the deep and intermediate water masses off Gaspé Peninsula, Gulf of St. Lawrence: foraminiferal evidence. Canadian Journal of Earth Sciences, 30: 1390-1403.
- Shaw, J., 2005. Paleogeography of Atlantic Canadian continental shelves from the last glacial maximum to the present, with an emphasis on Flemish Cap. Journal of Northwest Atlantic Fishery Science, 37: 199-126.
- Shaw, J., 2003. Submarine moraines in Newfoundland coastal waters: implications for the deglaciation of Atlantic Canada. Quaternary International, 99-100: 115-134.
- Shaw, J. and Courtney, R.C.A., 2004. A digital elevation model of Atlantic Canada. Geological Survey of Canada, Ottawa, Open File 4634.
- Shaw, J. and Courtney, R.C.A., 1997. Multibeam bathymetry of glaciated terrain off southwest Newfoundland. Marine Geology, 143: 125-135.
- Shaw, J. and Forbes, D.L., 1995. The postglacial relative sea-level lowstand in Newfoundland. Canadian Journal of Earth Sciences, 32: 1308-1330.
- Shaw, J., Piper, D.E. and Taylor, R.B., 2002b. The geology of the Bras d’Or Lakes, Nova Scotia. Proceedings of the Nova Scotia Institute of Science. Volume 42, Part 1, p. 127-147.
- Shaw, J., Taylor, R.B. and Forbes, D.L., 1993. Impact of the Holocene transgression on the Atlantic coastline of Nova Scotia. Géographie physique et Quaternaire, 47: 221-238.
- Shaw, J., Grant, D.R., Guilbault, J.-P., Anderson, T.W. and Parrott, D.R., 2000. Submarine and onshore end moraines in southern Newfoundland: implications for the history of late Wisconsinan ice retreat. Boreas, 29: 295-314.
- Shaw, J., Gareau, P. and Courtney, R.C.A., 2002a. Paleogeography of Atlantic Canada 13 kyr. Quaternary Science Reviews, 21: 1861-1878
- Shaw, J., Piper, D.J.W., Fader, G.B.J., King, E.L., Todd, B.J., Bell, T., Batterson, M.J. and Liverman, D.J.E., 2006. A conceptual model of the deglaciation of Atlantic Canada. Quaternary Science Reviews, 25: 2059-2081.
- Stea, R.R. and Mott, R.J., 1989. Deglaciation environments and evidence for glaciers of Younger Dryas age in Nova Scotia, Canada. Boreas, 18: 169-187.
- Syvitski, J.P.M., 1992. Marine Geology of Chaleur Bay. Géographie physique et Quaternaire, 46: 331-348
- Todd, B.J., 2005. Morphology and composition of submarine barchan dunes on the Scotian Shelf, Canadian Atlantic Margin. Geomorphology, 67: 487-500.
- Verspoor, E., O’Sullivan, M., Arnold, A.L., Knox, D. and Amiro, P.G., 2002. Restricted matrilineal gene flow and regional differentiation among Atlantic salmon (Salmo salar L.) populations within the Bay of Fundy, eastern Canada. Heredity, 89: 465-472.
- Warren, J.S., 1976. The morphology of two transverse channels on the northeast Newfoundland Shelf. Maritime Sediments, 12: 19-32.