Pollen is preserved in lake or bog sediments that accumulate each year. This preservation results in a sequence of pollen assemblages representing the succession of past vegetation. For example, Tertiary sediments 10-20 million years old, under the Mackenzie Delta, NWT, contain deposits of spores which indicate that a rich coniferous forest grew there, similar to modern forests in coastal BC and Washington. Analysis of the spore content of such rocks is used in the search for fossil fuels and the petroleum industry employs palynologists as part of this exploratory activity. Pollen analysis of sediments that have accumulated since the end of the latest GLACIATION reveal the vegetation changes and tree migrations that have produced the present vegetation of Canada.
In addition to showing the responses of vegetation to climatic change, pollen data indicate effects of human cultures such as clearing, burning and agriculture. A pollen record from a small lake near Toronto shows evidence of maize cultivation (1380 AD) in an Iroquoian village near the site, and evidence of forest clearance. The same site shows the beginning of European agriculture by the abrupt rise in frequency of ragweed pollen. Palynology is used in quality control tests of honey to identify the source plants used by bees, and it has been used in forensic science to solve crimes (eg, when pollen adhering to clothing can indicate the scene of a crime).
Author J.C. RITCHIE
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