How well do you know the Grand Canyon?
The Grand Canyon reveals nearly two billion years of Earth's history in its walls. Six questions, from easy to hard, with explanations.
Did you know?
- The Grand Canyon Skywalk, a glass bridge extending about 70 feet over the canyon's edge, is on Hualapai tribal land, not inside the national park. It opened in 2007.
- California condors, among the largest flying birds in North America, were reintroduced near the Grand Canyon in the 1990s. Visitors sometimes spot them soaring above the South Rim.
- Rafting the full length of the Grand Canyon on the Colorado River can take two to three weeks. Permits for private trips are awarded through a lottery because demand is so high.
Reading Earth's history in stone
The Grand Canyon is about 277 river miles long, up to 18 miles wide and more than a mile deep. Its layered walls reveal an extraordinary record of Earth's past, from ancient seas and deserts to volcanic activity. For many visitors, standing at the rim offers a first real sense of how vast geological time can be.
How the canyon formed
The canyon formed as the Colorado River cut downward while the Colorado Plateau slowly rose. Rain, frost and flash floods widened the canyon over time. Scientists still debate exactly how quickly different sections formed, but most agree the main carving happened over the last five to six million years.
Layers of time
Each rock layer represents a different chapter of history. Some formed from sand dunes, others from shallow seas that left fossils of marine creatures. A famous gap in the record, called the Great Unconformity, marks where hundreds of millions of years of rock are missing.
Life in the canyon
The canyon's depth creates different climates from rim to river. Forests grow on the cooler North Rim, while the bottom is hot desert. This variety supports many plants and animals, including bighorn sheep, California condors and more than 70 species of mammals.
Native American heritage
The Grand Canyon has been home to Native American peoples for thousands of years. Several tribes, including the Havasupai, Hualapai, Hopi and Navajo, have deep cultural connections to the canyon, and many sites within it are considered sacred.
Visiting safely
Summer temperatures at the bottom can exceed 110°F (43°C), and hiking back up is much harder than hiking down. Rangers warn visitors not to try to hike to the river and back in a single day. Carrying plenty of water and starting early are essential for safe hiking.