CGRG Bibliography of Canadian Geomorphology
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Author : Haas, J.N.; and McAndrews, J.H.
Date : 2001.
Title : Amphi-Atlantic drought during the mid-Holocene as recorded from palaeoecological studies in southern Ontario (Canada) and Europe.
Publication : St. John's 2001. Geological Association of Canada - Mineralogical Association of Canada 2001 Joint Annual Meeting / l'Association géologique du Canada - l'Association minéralogique du Canada réunion annuelle conjointe. Memorial University, St. John's, Newfoundland, May 27-30 2001.
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Abstract
High resolution paleoecological analyses from Shepherd Lake (southern Ontario, Canada) show that rapid lake level fluctuations were responsible for alterations in the aquatic and terrestrial flora and fauna 5700-5100 years ago. Thermophilic aquatic plants (Najas flexilis, Chara foliolosa) and animals (Trichoptera, Chironomidae, Mollusca etc.) indicate water table regressions of several meters, which are likely linked to warmer and drier summer climate. The impact of such summer drought on the upland flora is visible in the classical and catastrophic hemlock decline (Tsuga canadensis) starting 5700 years ago in large parts of north eastern America. Our results from Shepherd Lake imply that drought heavily affected hemlock trees because of their inability to sustain reduced soil and atmospheric humidity. The question is raised, if such mid-Holocene drought in northeastern North America simultaneously happened on the other side of the Atlantic, i.e. Europe, and which consequences it may have had on prehistoric societies and former plant and animal ecosystems.
Bibliography of Canadian Geomorphology