Diatoms: microscopic algae as environmental indicators
These are three highly magnified images of freshwater diatom microfossils. These siliceous (or glass-walled) algae are abundant and diverse components of the biota of most lakes, ponds, and rivers. As their cell walls are made of silica (or glass), they preserve well in lake sediments. Different species are characteristic of different types of environments and the abundance of different species in the lake sediments can be used to determine past environmental conditions. By looking at many layers of lake sediments (the slices from a core) environmental changes over time can be determined.
The diatom at left is a Cyclotella sp. Photo : K.M. Ruhland
This diatom is a Diploneis sp. Photo : K.M. Ruhland
This diatom is a Navicula sp. Photo: K.M. Ruhland
This photograph is of a Thule overwintering site, as reconstructed by the Canadian Museum of Civilization. It is situated at Resolute Bay, Cornwallis Island, Nunavut, which is north of the Somerset Island site described in this paper. (Photo by: J.P. Smol)
Whale bones under water.
Photo: J.P. Smol
Unexcavated Thule whale bone dwelling, Bathurst Island, which is north of the site described in this paper. Dwelling roof support of whale bones has collapsed. Allen P. McCartney provides scale. (Photo by J.M. Savelle)
Excavated Thule whale bone dwelling at PaJs-13, Hazard Inlet, Somerset Island, showing abundant whale bone used in original dwelling construction. Cored pond is at upper left of photograph. (Photo by: Junko Habu)
Thule Culture (at Archeological Survey of Canada )
Marianne S.V. Douglas , Canadian Circumpolar Institute
John P. Smol , Queen's University - web link
James M. Savelle , McGill University - web link
Jules M. Blais , University of Ottawa - web link
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