Farther north in Alberta, the Athabasca and other rivers feed the basin of the Mackenzie River, which has its outlet on the Beaufort Sea of the Arctic Ocean.See Rivers of the Rocky Mountains for a list of rivers.The first mention of their present name by a European was in the journal of Jacques Legardeur de Saint-Pierre in 1752, where they were called " The Rocky Mountains are often defined as stretching from the Liard River in British Columbia south to the Rio Grande in New Mexico.Other mountain ranges continue beyond those two rivers, including the Selwyn Mountains in Yukon, the Brooks Range in Alaska, and the Sierra Madre in Mexico, but those are not part of the Rockies, though they are part of the American Cordillera.The eastern edge of the Rockies rises dramatically above the Interior Plains of central North America, including the Sangre de Cristo Mountains of New Mexico and Colorado, the Front Range of Colorado, the Wind River Range and Big Horn Mountains of Wyoming, the Absaroka-Beartooth ranges and Rocky Mountain Front of Montana and the Clark Range of Alberta.In Canada, geographers define three main groups of ranges: the Continental Ranges, Hart Ranges, and Muskwa Ranges (the latter two flank the Peace River, the only river to pierce the Rockies, and are collectively referred to as the Northern Rockies).Public parks and forest lands protect much of the mountain range, and is a popular tourist destination, especially for hiking, camping, mountaineering, fishing, hunting, mountain biking, skiing, and snowboarding.The name of the mountains is a translation of an Amerindian name that is closely related to Algonquian; the Cree name as-sin-wati is given as, "When seen from across the prairies, they looked like a rocky mass".
The Rocky Mountains formed 80 million to 55 million years ago during the Laramide orogeny, in which a number of plates began sliding underneath the North American plate.
At the end of the last ice age, humans began inhabiting the mountain range.
After Europeans, such as Sir Alexander Mackenzie, and Americans, such as the Lewis and Clark expedition, began exploring the range, minerals and furs drove the initial economic exploitation of the mountains, although the range itself never experienced dense population.
The Great Basin and Columbia River Plateau separate these subranges from distinct ranges further to the west, most prominent among which are the Sierra Nevada, Cascade Range and Coast Mountains.
The Rockies do not extend into the Yukon or Alaska, or into central British Columbia, where the Rocky Mountain System (but not the Rocky Mountains) includes the Columbia Mountains, the southward extension of which is considered part of the Rockies in the United States.