Rocky Mountains

The Rocky Mountains, often called The Rockies, are a range of mountains in the western United States and Canada. They stretch from the northernmost part of British Columbia, in Western Canada, to New Mexico, in the Southwestern United States. Part of the mountain range in Colorado is a national park, called Rocky Mountain National Park. The Rocky Mountains are more than 3,000 mi (4,800 km) long. The highest point in the Rocky Mountains is Mount Elbert, at 14,433 feet (4,401 m).

The Rocky Mountains are relatively new and were formed from 55 million to 80 million years ago during the Laramide orogeny. North America began to move westwards as Pangaea broke up. A number of tectonic plates began to slide under the North American plate. The angle of subduction was shallow and resulted in a broad belt of mountains running down western North America. Since then, further tectonic activity and erosion by glaciers have sculpted the Rockies into dramatic peaks and valleys. 

The rocks in the Rocky Mountains had been formed long before the mountains were raised. The oldest rock is Precambrian metamorphic rock, which forms the core of the North American continent. There is also Precambrian sedimentary argillite, dating back to 1.7 billion years ago. During the Paleozoic, western North America lay underneath a shallow sea, which deposited many kilometers of limestone and dolomite.

In the southern Rocky Mountains, near present-day Colorado, the ancestral rocks were disturbed by mountain building about 300 million years ago, during the Pennsylvanian. The mountain building produced the ancestral Rocky Mountains. They consisted largely of Precambrian metamorphic rock forced upward through layers of the limestone. The limestone had been laid down in a shallow sea. The mountains eroded throughout the late Paleozoic and early Mesozoic, leaving extensive deposits of sedimentary rock.

 References 

Category:Mountain ranges of the United States
Category:Western United States
Category:Mountains of Canada