A delta is a deposit of sediment at the mouth of a river that accumulates as the river flows into a standing body of water such as a lake or ocean. Because sediment tends to be rich in nutrients, deltas become fertile wetlands inhabited by diverse wildlife. Among the largest deltas in Canada are those of the Mackenzie and Saskatchewan rivers, as well as the Peace-Athabasca Delta (where the Peace, Athabasca and Birch rivers meet). Certain deltas offer advantageous access to natural resources and maritime transportation, but development projects are often controversial due to the ecological importance of these environments.
The Canadian Shield refers to the exposed portion of the continental crust underlying the majority of North America. The crust, also known as the North American Craton, extends from northern Mexico to Greenland and consists of hard rocks at least 1 billion years old. With the exception of the Canadian Shield, the rocks of the North American Craton are buried deep within the continent and covered by soil and other material. At 5 million km2, the Shield makes up roughly 50 per cent of Canada’s land mass. Shaped like a horseshoe — or the shields carried during hand-to-hand combat — the Canadian Shield extends from Labrador in the east to include nearly all of Québec, much of Ontario and Manitoba, the northern portion of Saskatchewan, the northeast corner of Alberta, much of the Northwest Territories and Nunavut and into the Arctic Archipelago. (It also reaches into parts of the United States, in New York, Wisconsin and Minnesota.) While at times a barrier to settlement, the Shield has also yielded great resources, including minerals, coniferous forests and the capacity for hydroelectric developments.2
Ellesmere Island, at 196 236 km2, is the third-largest island in Canada, the 10th-largest island in the world and the most northerly island in the Arctic Archipelago. It is located in Nunavut and is separated from Greenland by Kane Basin and Kennedy Channel, and from Devon Island to the south by Jones Sound.
Wetlands cover about 14 per cent of the land area of Canada, and are the natural habitat of over 600 species of plants, animals and insects. In addition to providing a home for these plants and animals, wetlands are an essential part of the environment because they prevent flooding, filter toxins, store groundwater and limit erosion. The most common wetland habitats are swamps, marshes, and bogs.