The Grand Canyon

The Grand Canyon, in northern Arizona, is one of the most spectacular landforms on Earth — a gorge up to a mile (about 1,800 m) deep, 18 miles wide, and 277 miles long, carved by the Colorado River through the layered rock of the Colorado Plateau. Its walls expose nearly two billion years of geologic history in bands of colored stone, a cross-section of the planet's past so vast it humbles almost everyone who stands at the rim.

The canyon was cut over the last five to six million years as the Colorado River sliced downward while the plateau slowly rose, the river acting like a saw held against rising wood. Wind and water then widened it into the maze of side canyons, buttes, and spires seen today. The North and South Rims, only about 10 miles apart across the gulf, are separated by hours of driving and differ sharply in climate and feel.

Most of the canyon is protected within Grand Canyon National Park, which draws nearly five million visitors a year to its overlooks. Despite its fame, the inner canyon remains rugged and remote — a descent from rim to river drops through several life zones, from pine forest to desert, in a single hike.