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A Journey to a New Land

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Dr. Brent Ward

Department of Earth Sciences, Simon Fraser University

Paleoenvironmental Reconstruction

One of the goals of the Port Eliza research was to reconstruct the environment from the time just before glaciers covered the outer coast of Vancouver Island. A paleoenvironmental reconstruction is based on the use of what we call proxy data. We certainly don’t have any hard climate data such as average temperatures and amount of precipitation from before historical records, so we have to look at alternate records that can give us an idea of what climate was like. And so a proxy is looking at a record that could be influenced by the climate of the time. And an obvious example of this would be to reconstruct what the vegetation was, because vegetation is quite often controlled by temperature and precipitation. So a common proxy paleoenvironmental record is to look at say, pollen grains, and re-construct what the vegetation was like.

We do have a bit of pollen from the Port Eliza Cave. There is not much tree pollen in it which confirms some of the other proxies we have in that there weren’t that many trees in the area. There are a lot of low shrubby plants such as herbs and forbs surviving in the area. The other proxy record we are using is looking at the bones that we find and trying to compare the ecological ranges of modern species and what sort of environments they like and get an idea of what the environment was like when these bones were deposited.

One of the key indicators is the alpine marmot because their elevational range is controlled by summer temperature. The fact that we have an alpine marmot existing at pretty close to present-day sea level indicates that summers were cooler than they are at present. We also see from the Savannah sparrow and Townsend’s vole and some of the other voles that generally prefer an open environment, that there weren’t that many trees. Generally, the fact that we don’t have many trees indicates that it was probably cooler than present.