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Grand Canyon National Park

History: How the Grand Canyon Was Formed

© 2006 National Park Services The Colorado River cut through layers of rock to form the Grand Canyon. See more pictures of national parks.

In the Grand Canyon, the Colorado River has cut through the accumulated layers of the earth's surface to reach what Norman MacLean dubbed "the basement of time." A billion years of history can be seen at a glance, from the Precambrian bedrock at the distant river's edge to fossilized sand dunes only a million years old at the rim.

Some of the earth's oldest rock lies at the bottom of the Grand Canyon. Thousands of feet thick, the rock is made up of sediments. About 300 million years after it formed, monumental geologic forces lifted the rock back up into a great range of mountains that may have been six miles high, or about the height of the Himalayas.


Over time, the mountains eroded into a plain. About one billion years ago, that plain was raised into a second mountain range. These mountains were also worn away by millions of years of rain, wind and frost.

During later ages, the entire region sank beneath an inland sea, with primitive shellfish fossilizing in sea bottoms that eventually hardened to shale. Eons later, the region rose again as a high plateau; the former sea bottom was now on top and the ancient rocks below.

This is when the Colorado River went to work, first cutting into the upper layers about six million years ago. Carving inch by inch over the millennia, the river finally reached the oldest rocks nearly a mile below the surface.

Grand Canyon History: Inhabitants and Exploration

People lived in the canyon centuries ago, but the first Europeans to explore the area were 13 members of Coronado's expedition, who arrived around 1540. One wrote a letter of disgust because his expedition had encountered an unbridgeable barrier to further exploration of the Grand Canyon. In the 1850s, the U.S. Army sent a surveying party into the area, and in 1869, John Wesley Powell, a one-armed Major, became the first modern explorer in the canyon's history.

Powell set out with a small party in four boats to explore as much of the length of the Colorado River and the canyon as he could. It was an exciting journey that cost the Major two of his boats. But he proved that the canyon could be explored.

© 2006 National Park Services Native Americans believed the canyon was a path to the land beyond death. For modern geologists, it is a path that leads back to the planet's beginnings.

Accounts of his bold river run were widely published, leading to an increased public interest in the Southwest. By the 1880s, a prospector named John Hance, who was known for his quick wit and tall tales, had begun leading sightseeing parties into the canyon.

Hance's legacy lives on today. The Grand Canyon, with its rich geological history and its stunning views, is one of the world's most popular sightseeing destinations.

©Publications International, Ltd.

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