The Grand Canyon in Arizona in the southwest USA is one of the most spectacular gorges in the world.
The Grand Canyon is about 466 km long and and varies in width from less than 1 km to over 30 km.
In places the Grand Canyon is so narrow that motorcycle stunt riders have leaped right across from one side to the other.
The Grand Canyon is about 1600 m deep, with almost sheer cliff sides in some places.
Completed in 1936, and formerly called Boulder Dam, the Hoover Dam was renamed in 1947 to honor President Hoover.
Temperatures in the bottom of the Canyon can be as much as 14 degrees centigrade hotter than they are at the top, and the bottom. of the Canyon gets only 180 mm of rain per year compared to 660 mm at the top.
The Grand Canyon was cut by the Colorado River over millions of years as the whole Colorado Plateau was rising bit by bit. The bends in the river’s course were shaped when it still flowed over the flat plateau on top, then the river kept its shape as it cut down through the rising plateau.
As the Colorado cut down, it revealed layers of limestone, sandstone, shale and other rocks in the cliffs.
The shadows cast by the evening sun reveal
The Colorado is one of the the layer upon layer of rock in the steep sides major US rivers, 2334 km long. of the Grand Canyon.
The Hoover Dam across the Colorado is one of the world’s highest concrete dams, 221 m high.
The Hoover Dam creates the 185 km long Lake Mead, North America’s biggest artificial lake.