Articles

Pleistocene Non-Marine Mollusca of the Richardson Lake Deposit, Clarendon Township, Pontiac County, Quebec, Canada

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Abstract

The paleoeology and the quantitative changes in the non-marine molluscan assemblages from two marl sections in the Richardson Lake deposit are described. These changes and variations in lithology and shoreline features are used to reconstruct the environmental conditions prevailing during marl deposition and the development of modern Richardson Lake. The marl sections grade abruptly downward into Champlain Sea deposits and contain little extraneous material besides plant remains. Neither section represents a complete cycle of infilling of a lake, the truncation being related to decreasing water levels in the Ottawa and St. Lawrence River valleys. Of the 27 species of Mollusca recorded, 9 are post-depositional invaders the sections. The quantitative change in the aquatic species present in the sections suggests variations in depth, temperature, and pH of the waters as well as in substrate conditions. These changes are contrasted between the two sections with regard to their proximity to deeper areas of the lake and a moderating climate. Comparison of these assemblages with other Late Pleistocene and living molluscan assemblages elsewhere in glaciated regions of Eastern North America indicates that the Mollusca migrate in response to temperature changes: In this case the temperature is influenced by the advance and retreat of the continental glaciers.

How to Cite:

Gibson, G. G., (1967) “Pleistocene Non-Marine Mollusca of the Richardson Lake Deposit, Clarendon Township, Pontiac County, Quebec, Canada”, Sterkiana 25(1), 1-36.