Web site navigation : home > North America > The Natural Environment > Geological History

Search this website ::

The Natural Environment

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.

Search this website ::