Rocky Mountains

The Rocky Mountains, often called the Rockies, are a broad mountain range in western North America. The Rocky Mountains stretch more than 3000 miles (4800 km) from British Columbia to New Mexico, extending through Canada and much of the breadth of the contiguous United States. The highest peak is Mount Elbert, in Colorado, which is 14,440 feet (4401 m) above sea level. Mount Robson (12,972 feet/3954 m) is the highest peak in the Canadian Rockies. The Rocky Mountain System is a United States physiographic region.

Geography and geology

The Rocky Mountains are commonly defined to stretch from the Liard River in British Columbia, down to the Rio Grande in New Mexico. The mountains can also be considered to run to Alaska or Mexico, but usually those mountains are considered to be part of the entire American cordillera, rather than part of the Rockies.

Related Topics:
Liard River - Rio Grande - Alaska - Mexico - American cordillera

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The younger ranges of the Rocky Mountains uplifted during the late Cretaceous period (140 million-65 million years ago), although some portions of the southern mountains date from uplifts during the Precambrian (3,980 million-600 million years ago). The mountains' geology is a complex of igneous and metamorphic rock; younger sedimentary rock occurs along the margins of the southern Rocky Mountains, and volcanic rock from the Tertiary (65 million-1.8 million years ago) occurs in the San Juan Mountains and in other areas. Millennia of severe erosion in the Wyoming Basin transformed intermountain basins into a relatively flat terrain. The Tetons and other north-central ranges are magnificent granitic intrusions of folded and faulted rocks of Paleozoic and Mesozoic age (Peterson 1986; Knight 1994).

Related Topics:
Cretaceous - Precambrian - Igneous - Metamorphic rock - Sedimentary rock - Tertiary - San Juan Mountains - Wyoming Basin - Tetons - Paleozoic - Mesozoic

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Periods of glaciation occurred from the Pleistocene Epoch (1.8 million-70,000 years ago) to the Holocene Epoch (fewer than 11,000 years ago). Recent episodes included the Bull Lake Glaciation that began about 150,000 years ago and the Pinedale Glaciation that probably remained at full glaciation until 15,000-20,000 years ago (Pierce 1979). Ninety percent of Yellowstone National Park was covered by ice during the Pinedale Glaciation (Knight 1994). The "little ice age" was a period of glacial advance that lasted a few centuries from about 1550 to 1860. For example, the Agassiz and Jackson glaciers in Glacier National Park reached their most forward positions about 1860 during the little ice age (Grove 1990).

Related Topics:
Pleistocene - Holocene - Bull Lake Glaciation - Pinedale Glaciation - Glacier National Park

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Water in its many forms sculpted the present Rocky Mountain landscape (Athearn 1960). Runoff and snowmelt from the peaks feed Rocky Mountain rivers and lakes with the water supply for one-quarter of the United States. The rivers that flow from the Rocky Mountains eventually drain into three of the world's five Oceans: the Atlantic Ocean, the Pacific Ocean, and the Arctic Ocean. These rivers include:

Related Topics:
Oceans - Atlantic Ocean - Pacific Ocean - Arctic Ocean

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• Arkansas River
• Athabasca River
• Colorado River
• Columbia River
• Fraser River
• Kootenay River
• Missouri River
• Peace River
• Platte River
• Rio Grande
• Saskatchewan River
• Snake River
• Yellowstone River

The Continental Divide is located in the Rocky Mountains and designates the line at which waters flow either to the Atlantic or Pacific Oceans. Triple Divide Peak (8020 feet/2444 m) in Glacier National Park (US) is so named due to the fact that water which falls on the mountain reaches not only the Atlantic and Pacific, but the Arctic Ocean as well.

Related Topics:
Continental Divide - Atlantic - Pacific - Triple Divide Peak - Glacier National Park (US) - Arctic

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