Volcanoes
Western Canada has many volcanoes and is part of the Pacific Ring of Fire, a system of volcanoes found around the margins of the Pacific Ocean. There are over 200 young volcanic centres that stretch northward from the Cascade Range to Yukon. They are grouped into five volcanic belts with different volcano types and tectonic settings. The Northern Cordilleran Volcanic Province was formed by faulting, cracking, rifting, and the interaction between the Pacific Plate and the North American plate. The Garibaldi Volcanic Belt was formed by subduction of the Juan de Fuca Plate beneath the North American Plate. The Anahim Volcanic Belt was formed as a result of the North American Plate sliding westward over the Anahim hotspot. The Chilcotin Group is believed to have formed as a result of back-arc extension behind the Cascadia subduction zone. The Wrangell Volcanic Field formed as a result of subduction of the Pacific Plate beneath the North American Plate at the easternmost end of the Aleutian Trench.
Volcanism has also occurred in the Canadian Shield. It contains over 150 volcanic belts (now deformed and eroded down to nearly flat plains) that range from 600 million to 2.8 billion years old. Many of Canada's major ore deposits are associated with Precambrian volcanoes. There are pillow lavas in the Northwest Territories that are about 2.6 billion years old and are preserved in the Cameron River Volcanic Belt. The pillow lavas in rocks over 2 billion years old in the Canadian Shield signify that great oceanic volcanoes existed during the early stages of the formation of the Earth's crust. Ancient volcanoes play an important role in estimating Canada's mineral potential. Many of the volcanic belts bear ore deposits that are related to the volcanism.
Canadian Arctic
Main article: Northern Canada
While the largest part of the Canadian Arctic is composed of seemingly endless permafrost and tundra north of the tree line, it encompasses geological regions of varying types: the Arctic Cordillera (with the British Empire Range and the United States Range on Ellesmere Island) contains the northernmost mountain system in the world. The Arctic Lowlands and Hudson Bay lowlands comprise a substantial part of the geographic region often designated as the Canadian Shield (in contrast to the sole geologic area). The ground in the Arctic is mostly composed of permafrost, making construction difficult and often hazardous, and agriculture virtually impossible.
The Arctic, when defined as everything north of the tree line, covers most of Nunavut and the northernmost parts of Northwest Territories, Yukon, Manitoba, Ontario, Quebec, and Labrador.
Hydrography
Canada holds vast reserves of water: its rivers discharge nearly 9% of the world's renewable water supply, it contains a quarter of the world's wetlands, and it has the third largest amount of glaciers (after Antarctica and Greenland). Because of extensive glaciation, Canada hosts more than two million lakes: of those that are entirely within Canada, more than 31,000 are between 3 and 100 square kilometres (1.2 and 38.6 sq mi) in area, while 563 are larger than 100 km2 (38.6 sq mi)