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A Journey to a New Land

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Dr. Brent Ward

Department of Earth Sciences, Simon Fraser University

Raised Sea Caves

My research centres around the stratigraphic and paleoenvironmental record that can be preserved in what we call raised sea caves. Sea caves form along open coastlines by wave action, where waves preferentially erode certain portions of the cliffs that occur along the coast. So, many sea caves are presently forming along Vancouver Island and the Queen Charlotte Islands. If these sea caves formed when relative sea level was considerably higher than present, then they have the potential to preserve sediments that pre-date the last glaciation.

The key principal behind raised sea caves and the stratigraphic record preserved in it is that these caves are openings that are occupied by animals that live in the area. During glaciation the mouth of the cave is covered by the ice and what this does is form a small lake underneath the ice sheet which allows the deposition of finegrained laminated sediments that basically seal in or preserve any bones or organic matter that was on the floor of the cave before the ice covered the cave. Then as long as the cave does not fall below relative sea level after that and be washed out by wave action, if we excavate through the laminated clays we can find records of plants and animals that lived in the area before the ice covered it.