Post-Glacial Fossil Mollusca in Western Canada

Abstract

From the standpoint of biological geography, the most significant event in the recent history of Canada has been the occurrence of widespread severe glaciation. This resulted in the whole of the previously existing fauna being either exterminated or driven southward. When the ice sheets receded northwards at the end of the last glacial period, this region was once more populated by animals, including both fresh water and terrestrial mollusca, the remains of which are to be found in various post-glacial deposits. The migration of animals into this new territory did not take place all at once, and it is noteworthy that no fossil mollusca have been found in the deposits laid down during the early stages of the glacial retreat. The purpose of this paper is to give in concise form the history of the present molluscan fauna of this region in so far as it is evidenced by the post-glacial fossils found in the region. The series of fossil-bearing deposits herein described is far from complete, and many additional finds will doubtless be made in the course offuture field work. Nevertheless, a sufficient number of observations has been made to indicate the general nature and duration of the molluscan immigration into the area.