Mackenzie River
At , the Mackenzie River drainage basin encompasses nearly 20 percent of Canada. About , or 54 percent of the basin, lies above Great Slave Lake. Permafrost underlies about three-quarters of the watershed, reaching up to deep in the Mackenzie Delta. As a whole, the Mackenzie basin receives only meager to moderate rainfall, averaging over the entire basin, though mountain areas experience much higher precipitation, and areas near and north of the Arctic Circle receive much lower precipitation.
Geography of Canada
The southern parts of Quebec and Ontario, in the section of the Great Lakes (bordered entirely by Ontario on the Canadian side) and St. Lawrence basin (often called St. Lawrence Lowlands), is another particularly rich sedimentary plain. Prior to its colonization and heavy urban sprawl of the 20th century, this Eastern Great Lakes lowland forests area was home to large mixed forests covering a mostly flat area of land between the Appalachian Mountains and the Canadian Shield. Most of this forest has been cut down through agriculture and logging operations, but the remaining forests are for the most part heavily protected. In this part of Canada the Gulf of St. Lawrence is one of the world's largest estuary (see Gulf of St. Lawrence lowland forests).