The Grand Canyon is a huge canyon in north-western Arizona, carved by the Colorado River. It is about 277 miles long, up to 18 miles wide and about a mile deep on average. The river began cutting it about 5 to 6 million years ago, through rocks up to 1.8 billion years old. It became a national park in 1919.
the Grand Canyon quick facts
- The Grand Canyon is about 277 miles (446 km) long and about a mile deep on average.
- The Colorado River began carving it about 5 to 6 million years ago.
- Its oldest rock, the Vishnu Schist, is about 1.8 billion years old.
- The North Rim is about 1,200 feet higher than the South Rim.
- More than 4.4 million people visited Grand Canyon National Park in 2025.
What is the Grand Canyon?
The Grand Canyon is an enormous canyon in the north-west of Arizona, in the United States. A canyon is a deep valley with steep sides, usually cut by a river.
This one was carved by the Colorado River. It is famous for its size, its strange rock shapes and its colours. As you look down its walls, the rocks change from red and buff to grey, green, pink, brown and violet.
It is protected as Grand Canyon National Park, which became a national park on 26 February 1919. In 1979 it was also named a UNESCO World Heritage Site, one of the most special places on Earth.
| Grand Canyon in numbers | |
|---|---|
| Length (along the river) | about 277 miles (446 km) |
| Width | from about 160 m to 29 km (18 miles) |
| Average depth | about 1 mile (1.6 km) |
| South Rim | about 7,000 feet (2,100 m) above sea level |
| North Rim | about 8,000 feet (2,400 m) above sea level |
| Park size | 1,904 square miles (4,931 km²) |
| Visitors in 2025 | 4,430,653 |
| National park since | 26 February 1919 |
How big is the Grand Canyon?
The Grand Canyon winds for about 277 miles (446 km). It starts near Lees Ferry, close to the Utah border, and ends at the Grand Wash Cliffs, near Nevada. Driving that distance would take about five hours on a highway.
Its width changes a lot. In its narrowest places it is only about 160 m across. In its widest, it is about 29 km (18 miles) from rim to rim.
On average, it is about a mile (1.6 km) deep. In its deepest parts, the river runs more than 6,000 feet (1,800 m) below the rim. You could stack more than four Empire State Buildings on top of each other and still not reach the top.
The first part of the canyon, from Lees Ferry down to where the Little Colorado River joins the Colorado, has its own name: Marble Canyon.
The two sides of the canyon are not the same height. The North Rim is about 1,200 feet (365 m) higher than the South Rim, which is why it is cooler and gets more snow.
The Shape of the Canyon
- Near which place does the Grand Canyon begin?
- What is the first part of the canyon, down to where the Little Colorado River joins, called?
- About how wide is the canyon at its narrowest?
- Why is the North Rim cooler and snowier than the South Rim?
How the Grand Canyon formed
The Grand Canyon took an extremely long time to form. Scientists at the US National Park Service remember the story with the word DUDE: Deposition, Uplift, Down-cutting and Erosion.
Deposition means laying down. Over hundreds of millions of years, layer after layer of sand, mud and other material settled in seas, rivers and deserts, and slowly turned into rock.
Uplift came next. Between about 70 and 30 million years ago, the movement of the Earth’s tectonic plates pushed the whole region upwards, creating a high, fairly flat area called the Colorado Plateau.
Down-cutting began only about 5 to 6 million years ago. The Colorado River started to carve its way down through the rock layers, like a knife slowly cutting through a layer cake.
Erosion is still going on today. Rain, ice, wind and side streams keep wearing away the canyon walls. In fact, the canyon is getting wider faster than it is getting deeper.
Building a Canyon
- Deposition Over hundreds of millions of years, sand and mud settle in seas, rivers and deserts and turn into layers of rock.
- Uplift Between about 70 and 30 million years ago, moving tectonic plates push the region up into the Colorado Plateau.
- Down-cutting About 5 to 6 million years ago, the Colorado River starts carving down through the rock layers.
- Erosion Still happening today: rain, ice, wind and side streams wear away the canyon walls.
A history book made of rock
The rocks in the canyon walls are like the pages of a giant history book. The deeper you go, the older the rocks are. Many of the layers hold fossils of creatures that lived in ancient seas, deserts and swamps, long before the canyon existed.
The oldest rocks, at the very bottom in the inner gorge, are almost 2 billion years old. One of them, the Vishnu Schist, is about 1.8 billion years old.
The youngest layer, at the top, is called the Kaibab Formation. It is about 270 million years old. That means even the youngest rock is far older than the canyon itself.
The book has some missing pages, though. In places, huge stretches of time are missing, because rock was worn away before new layers were laid down on top. Even so, Encyclopaedia Britannica says no other place on Earth shows such a long and detailed record of our planet’s past.
Fact or Myth: Pages of Rock
- The deeper you go in the canyon walls, the older the rocks are.
- The youngest rock layer, the Kaibab Formation, sits at the bottom of the canyon.
- Even the youngest rock at the top is far older than the canyon itself.
- The rock record in the canyon is complete, with no time missing.
- Many layers hold fossils of creatures from ancient seas, deserts and swamps.
The Colorado River
The Colorado River is the sculptor of the Grand Canyon. On its 277-mile journey through the canyon, it drops about 2,000 feet (610 m).
It is wider and deeper than it looks from the rim. On average it is about 300 feet (91 m) across and about 40 feet (12 m) deep.
Today, the river is controlled by two big dams. Upstream is Lake Powell, created by the Glen Canyon Dam in 1963. Downstream is Lake Mead, created by the Hoover Dam in 1936.
The river’s name comes from Spanish: colorado means coloured red, after the reddish mud it once carried. The river also gives its name to the state of Colorado, where it begins, high in the Rocky Mountains.
The River’s Story
- Lake Powell — Made by the Glen Canyon Dam in 1963
- Lake Mead — Made by the Hoover Dam in 1936
- Colorado — Spanish for coloured red
- Rocky Mountains — Where the river begins
- About 2,000 feet — How far the river drops through the canyon
Plants and animals
Because the canyon is so deep, it contains many different habitats, from cool, snowy forests on the North Rim to hot desert near the river. That means it is home to an amazing variety of life.
Grand Canyon National Park has about 450 kinds of birds and 91 kinds of mammals. It also has 58 kinds of reptiles and amphibians, and 18 kinds of fish, only five of which are native to the river.
It also has more than 1,400 kinds of insects and other invertebrates, and more than 1,700 kinds of plants.
| Living things in the park | Number of species |
|---|---|
| Birds | 450 |
| Mammals | 91 |
| Reptiles and amphibians | 58 |
| Fish | 18 (5 native) |
| Invertebrates | 1,443 |
| Plants | 1,737 |
People and the canyon
People lived in and around the Grand Canyon long before it became a national park. Native American peoples have lived here for thousands of years, and several tribes still live on lands next to the canyon today.
Many places in and around the canyon are sacred to them. Their stories, names and traditions are part of the canyon’s history, just as much as its rocks.
Scientists have also studied the canyon for more than a century. Because its rock layers show such a long stretch of Earth’s history so clearly, it is one of the most studied landscapes in the world.
Visiting the Grand Canyon
The Grand Canyon is one of the most popular places to visit in the United States. In 2025, more than 4.4 million people came to the national park.
Most visitors go to the South Rim, which is open all year. The North Rim is higher and more remote, and it is often closed in winter because of snow.
Spring and autumn are often the most comfortable times to visit, because summer days deep in the canyon can be dangerously hot.
There are many ways to see the canyon. Some people walk along the rim, stopping at viewpoints. Others hike down the steep trails or ride mules. Some float down the Colorado River on rafts, a trip that can take a week or more. Outside the national park, on the Hualapai Reservation, visitors can even walk out over the edge of the canyon. The Skywalk is a horseshoe-shaped walkway with a glass floor.
Staying safe
The Grand Canyon is beautiful, but it can be dangerous. The edges are steep and high, so visitors should always stay behind railings and on marked paths.
Hiking down into the canyon is much easier than climbing back out. The bottom is far hotter than the rim, so hikers need plenty of water, food and rest, and should never try to walk to the river and back in one day.
Sudden storms can cause flash floods in narrow side canyons, so it is important to check the weather and follow the park rangers’ advice. Always carry more water than you think you will need, and ask a ranger if you are not sure about a trail.
Canyon Safety
- Which part of a canyon hike is harder?
- What can sudden storms cause in narrow side canyons?
- What should hikers never try to do in one day?
Three things people get wrong
The Grand Canyon is not as old as its rocks. Its oldest rocks are almost 2 billion years old, but the river began carving the canyon only about 5 to 6 million years ago.
Both rims are not the same height. The North Rim is about 1,200 feet higher than the South Rim.
The canyon is not finished. Erosion is still shaping it, and it is widening faster than it is deepening.
Did you know? Even the youngest rock at the top of the Grand Canyon, the Kaibab Formation, is about 270 million years old, far older than the canyon itself.
Try it
Make a layer cake or a pile of different-coloured modelling clay, then slowly cut a groove down through it. You can see each layer in the sides of your canyon, just like the rock layers of the Grand Canyon.
Knowledge check
What does DUDE stand for in the story of the Grand Canyon?
Show answer
Deposition, Uplift, Down-cutting and Erosion.
Which river carved the Grand Canyon?
Show answer
The Colorado River.
Frequently asked questions
How big is the Grand Canyon?
The Grand Canyon is about 277 miles (446 km) long, from about 160 metres to 18 miles wide, and about a mile deep on average. In places it is more than 6,000 feet deep.
How was the Grand Canyon formed?
The Grand Canyon formed as rock layers were laid down, the region was pushed up between 70 and 30 million years ago, and the Colorado River carved down through it from 5 to 6 million years ago.
How old is the Grand Canyon?
The canyon itself is young: the Colorado River began carving it about 5 to 6 million years ago. The rocks it cuts through are much older, up to about 1.8 billion years.
When did the Grand Canyon become a national park?
Grand Canyon National Park was created by an act of Congress on 26 February 1919. It was named a UNESCO World Heritage Site in 1979.
What animals live in the Grand Canyon?
Grand Canyon National Park is home to about 450 kinds of birds, 91 mammals, 58 reptiles and amphibians, 18 fish and more than 1,400 kinds of insects and other invertebrates.
Is the Grand Canyon still getting bigger?
Yes. Weathering and erosion are still wearing the canyon away, and it is widening faster than it is deepening.
Sources
- US National Park Service: Grand Canyon geology — how the canyon formed, the ages of its rocks and the Colorado River
- US National Park Service: Grand Canyon park statistics — park size, visitors, river length, depth, rim heights, species counts and founding date
- Encyclopaedia Britannica: Grand Canyon — location, width, length, depth, colours, dams and its record of Earth’s history
Grand Canyon Final Quiz
- In which US state is the Grand Canyon?
- What is a canyon?
- In which year was the Grand Canyon named a UNESCO World Heritage Site?
- What is the name of the oldest rock in the canyon, about 1.8 billion years old?
- Is the canyon getting wider or deeper faster?
- Which rim do most visitors go to, because it is open all year?
- Why can summer be a hard time to visit deep in the canyon?
- What is the Skywalk?
- Why does the canyon have so many different habitats?
- Who have lived in and around the canyon for thousands of years?
