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North America


outline of North America, North American plate, phosphate rock, tropic of Cancer, Jurassic Period

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North America is roughly wedge shaped, with its broadest expanse in the north. Most of its bulk is in the middle latitudes, with a considerable northern section in the Arctic and a narrow part around the tropic of Cancer. The continent sprawls east-west across some 176 of longitude, from longitude 12 west at Nordost Rundingen (Northeast Foreland) in northeastern Greenland to longitude 172 east at the western extremity of Attu Island, Alaska. Its north-south extent is some 69, from latitude 83 north at Cape Morris Jesup in eastern Greenland to latitude 14 north in southern Mexico. North America is bordered on the north by the Arctic Ocean; on the east by the Atlantic Ocean; on the south by the Gulf of Mexico, Central America, and the Pacific Ocean; and on the west by the Pacific Ocean. The area of the continent is 23.7 million sq km (9.2 million sq mi).

The outline of North America is exceedingly irregular; some extensive coastal reaches are relatively smooth, but by and large the coastline is broken and embayed, with many prominent offshore islands. The continent has three enormous coastal indentations: Hudson Bay in the northeast, the Gulf of Mexico in the southeast, and the Gulf of Alaska in the northwest. There are many small islands near the eastern and western coasts, but the most prominent islands are in the far north.

Geological History

According to a widely accepted theory, almost all of North America is situated on the North American plate, an enormous platform considered one of about a dozen major units constituting the structural mosaic of the earth's crust. It is thought that North America was once joined to modern-day Europe and Africa and that it began to break away about 170 million years ago, in the Jurassic Period, with the process of continental drift accelerating about 95 million years ago, in the Cretaceous Period. As North America drifted west at a rate of 1.25 cm (0.5 in) per year, the plate underlying the Pacific Ocean is believed to have thrust under the North American plate, thereby causing widespread early folding, evident today in a series of high mountains along the western coast. As the Atlantic Ocean widened, it caused extensive faulting along the eastern coast, resulting in the creation of mountains and offshore islands.

Mineral Resources

North America has large deposits of many important minerals. Petroleum and natural gas are found in great quantity in northern Alaska, western Canada, the southern and western conterminous United States, and eastern Mexico; huge beds of coal are in eastern and western Canada and the United States; and great iron-ore deposits are in eastern Canada, the northern United States, and central Mexico. Canada also has major deposits of copper, nickel, uranium, zinc, asbestos, and potash; the United States contains great amounts of copper, molybdenum, nickel, phosphate rock, and uranium; and Mexico has large reserves of barite, copper, fluorite, lead, zinc, manganese, and sulfur. All three countries have significant deposits of gold and silver.

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