How big is it?

 
The Grand Canyon is 277 miles (446 km) long and varies in width from 5 miles (8 km) to 18 miles (29 km). In the village area it is about 10 miles (16 km) across. The Grand Canyon begins at Lees Ferry, which is measured as mile 0 on the Colorado River, and ends at the Grand Wash Cliffs, mile 277. In the village area it is about 5,000 feet (1,524 meters) deep as measured from the south rim and 6,000 feet (1,829 meters) deep as measured from the north rim.

Grand Canyon National Park itself contains over a million acres of land - 1,218,375 to be exact. This equates to about 1,904 square miles (4,931 square kilometers).

 
How old is it?

 
The Canyon itself is not that old, only 5 or 6 million years. The rock layers exposed at the very bottom of the Grand Canyon are almost 2 billion years old.

 
How big is the river?

 
The Colorado river averages about a hundred yards across as it runs through the Canyon. It is 1,450 miles (2,333 km) long and runs from it's source in Rocky Mountain National Park in Colorado to the Gulf of California in Mexico.

 
Why does it look like that?

 
The main reason why the Canyon looks the way it does is because the different types of rocks that it is composed of erode at different rates and in very different ways. Softer rock and rock that tends to erode easily will form slopes whereas harder rock and rock that does not easily erode will form cliffs. The best example of a slope is the Tonto Platform, located about 2/3 of the way to the bottom, which is composed primarily of Bright Angel Shale and has eroded into a wide bench. The best example of a cliff is the Redwall Limestone which forms the massive cliff just above the Tonto Platform. The various colors that you see can be attributed to the composition of the rocks in the different geologic layers. Different minerals located in the rocks cause the different colors. Sometimes the color from one layer will leach down onto lower layers as is the case with the Redwall Limestone, which is not actually red but brown, but has had its outer layer stained red by iron oxides leaching out of the layers above it.
 

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