Grand Canyon Information:
The Grand Canyon is an erosional feature that has been carved by the Colorado River and other sources over the course of millions of years. The Grand Canyon National Park is located entirely in the U.S. state of Arizona. Famous for its vast panoramic views, and magnificently colored rock strata, it is easy to understand why the Grand Canyon is one of the Seven Natural Wonders of the World.
The Grand Canyon extends for 277 river miles (446 km) and ranges from 4 to 18 miles (6.5 to 29 km) wide. In some areas, it reaches a depth of over 1 mile (1.6 km) from rim to river. The Grand Canyon National park was established in 1919, one of the first National Parks in the country. It covers a total of 1902 square miles (4927 square km), and if you were to fill it with water (or rubbish as many people have jokingly suggested) you would have over 1000 cubic miles (4169 cubic km) of water!
Until recently, the Grand Canyon was thought to have been shaped over the last 6 million years, but recent research ( March 2008) has suggested a much longer time frame of 17 million years. According to the new data, the Grand Canyon is thought to have formed as two separate canyons that eventually merged in a major event about 6 million years ago.
Although the canyon is thought to have been carved in the last 17 million years, the rocks exposed are much much older. The Vishnu Complex at the bottom of the canyon is dated at about 1.84 billion years old!
Even the youngest rock in the Grand Canyon (not counting fairly recent volcanic eruptions) is 270 million years old! Its called the Kaibab Limestone, and it makes up the top-most layer of the canyon. At one time there were younger rock layers above the Kaibab Limestone, but they have all been eroded away over time. You can still see pieces of this younger rock at Red Butte (southeast of the South Rim Entrance Station), and Cedar Mountain (visible from Desert View on the South Rim).
The different layers of the canyon were mostly deposited in various coastal environments over the last 2 billion years. At different points in time, the area where the Grand Canyon now exists has been warm shallow sea, sandy beach, coastal swamp land, and even desert. These different environments deposit different types of sedimentary rock, leading to the various layers present today. Harder rocks such as limstone and hard sandstone erode to form cliffs, while softer rocks such as shale, mudstone, and weak sandstone erode to form slopes. This gives the Grand Canyon the terraced look it is famous for. Some layers contain a small amount of iron that oxidizes and colors the outside of the rock a rusty red.
Around 65 million years ago, all of the land around the Grand Canyon (now called the Colorado Plateau) began to lift. This uplift brought the sedimentary layers of the Grand Canyon from near sea-level to over 10000 ft (3000 m). Erosion eventually lowered the rim of the canyon to the current 7000 ft (2100 m) on the South Rim. With a huge amount of material now up above sea level, the stage was set for a powerful river and its tributaries to carve out this magnificent canyon!
