How big is Grand Canyon? | Scale of the Universe

The Grand Canyon is a deep, winding gorge carved by the Colorado River in Arizona, in the southwestern United States. Measured along the river that runs through it, the canyon is about 450 kilometers (278 miles) long. It is up to 29 kilometers (18 miles) wide from rim to rim and, on average, about 1.6 kilometers (1 mile) deep.

Size

The National Park Service gives the canyon's length as 278 river miles (447 kilometers). River miles are counted along the Colorado River itself, starting from mile 0 at Lees Ferry, a convention that dates from the Birdseye expedition of 1923. Because the river bends back and forth, the canyon is longer than the straight-line distance between its two ends.

The US Geological Survey treats the first 62 miles (100 kilometers) below Lees Ferry separately, as Marble Canyon. It counts the Grand Canyon proper from the mouth of the Little Colorado River down to the Grand Wash Cliffs, near river mile 277.

The canyon's width varies a great deal. In Marble Canyon the gorge is only about 180 meters (600 feet) across. The average distance from rim to rim is 16 kilometers (10 miles), and the greatest is 29 kilometers (18 miles).

The South Rim averages about 2,100 meters (7,000 feet) above sea level, and the North Rim about 2,400 meters (8,000 feet). The Park Service puts the volume of the canyon, the space between its walls, at about 4.17 trillion cubic meters (5.45 trillion cubic yards).

Size comparisons

The canyon's length along the river is slightly more than the width of West Virginia, which measures about 430 kilometers (265 miles) from west to east.
The canyon is as long as about 10 and a half marathons laid end to end. A marathon is 42.195 kilometers (26.2 miles).
Its average depth, about 1.6 kilometers (1 mile), is a little more than the height of Half Dome above Yosemite Valley, which is nearly 1,500 meters (5,000 feet).
Mount Everest, 8,849 meters (29,032 feet) tall, is about five and a half times as tall as the canyon is deep on average.
The canyon's length is about half the width of the dwarf planet Ceres, which is about 950 kilometers (590 miles) across.

How the canyon formed

The rocks in the canyon's walls are far older than the canyon itself. The oldest, at the bottom of the inner gorge, are about 1.8 billion years old. Even the youngest layer, the Kaibab Formation at the rim, is about 270 million years old.

Between 70 and 30 million years ago, movements of the plates that make up Earth's crust lifted the whole region, forming the high and fairly flat Colorado Plateau. Then, beginning 5–6 million years ago, the Colorado River began cutting down into it. Erosion by side streams widened the gorge, and the same forces are still slowly deepening and widening it today.

The river and the park

The Colorado River flows about 2,330 kilometers (1,450 miles) from the Rocky Mountains of Colorado to the Gulf of California. Inside the park it averages about 90 meters (300 feet) wide and 12 meters (40 feet) deep, and it drops an average of 1.3 meters for every kilometer it flows (7 feet per mile).

Grand Canyon National Park protects the canyon and covers 4,931 square kilometers (1,904 square miles). Its wildlife includes 450 species of birds and 91 species of mammals, and it holds nearly 350 important fossil sites.