Geology of Canada

Canada's geological architecture is dominated by its central foundation, a Precambrian shield. This is the largest area of Archean rocks in the world, more than 2.5 billion years old. The oldest rocks found in Canada so far are dated at 4.0 billion years. Most of this Precambrian shield consists of granitic rocks and gneiss laced with sinuous greenstone volcanic belts and broader areas of sedimentary rocks. It was consolidated by the end of Paleoproterozoic time, also known as Laurentia. Its southeast portion, the Grenville Province, was stabilized about one billion years ago.

Orogenic belts between the Archean fragments contain younger deposits. There are continental, oceanic, and collisional deposits Three younger deformed belts, mainly of Phanerozoic rocks (>545 Ma), surround the shield:

The Appalachian belt, in the southeast, attached to ancestral North America in early- and mid-Paleozoic times (475-375 Ma).
The Cordillera of western Canada, large areas of continental and oceanic fragments, added to North America during the Mesozoic era at various times (180 Ma-present).
The Innuitian belt in the Arctic Islands was attached in the mid-Paleozoic about 400 Ma.

After the Appalachian and Innuitian belts were deformed, they were superimposed by extensive less deformed basins dominated by sedimentary rocks. Large parts of the Precambrian shield are covered by a thin layer of undeformed sedimentary rocks, mainly of early Paleozoic age. Cretaceous strata form basins, as in Hudson Bay, and fault-bounded troughs in and near Hudson Strait and north of Baffin Island. A westward-thickening wedge of Mesozoic and Cenozoic sediments was deposited in Western Canada Basin. This sediments were derived from elevated sources in the mountains of the deforming ancestral eastern Cordillera.

The long history of the Canadian shield is the reason for the existence of numerous mineral deposits, valuable ores and gemstones. Most famous incident is probably the great gold rush to Alaska, which was only one (and the biggest) of numerous rushes. Until today Canada produces a certain amount of various raw materials. Most important are Aluminum, Asbestos, Coal, Copper, Gold, Iron Ore, Lead, Nickel, Potash, Salt, and Zinc.

But all those interesting ores and rocks, are not very good for karst formation and the existence of caves. Only part of the rare sedments of Canada consist of limestone, or at least marble. And many of those areas lie in flat basins, with a high ground water table and no chance for the formation of caves.

The most interesting cave areas of Canada are located at Vancouver Island at the west coast and in the southeastern part of Canada from the Great Lakes to the east coast.

Geology of Canada

See also