• View of Grand Canyon National Park at sunset from the South Rim

    Grand Canyon

    National Park Arizona

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  • For the Next Several Days, Expect Thunderstorms and Locally Heavy Rain

    Monsoonal weather patterns have moved into the Grand Canyon area decreasing fire danger. As a result, on Tuesday, July 8 at 8 a.m. fire managers lifted fire restrictions within Grand Canyon National Park. More »

  • Temporary North Rim Road Closures Due to Galahad Fire Began May 29

    As of Thursday May 29, two road closures are in effect for public and firefighter safety. W4 road is closed from FS268B road south to Pont Sublime. W1 road is closed from W4 to western end of the Basin. More »

Geologic Activity

Fallen rock beside a Grand Canyon trail.

Fallen rock beside a Grand Canyon trail

NPS PHOTO

The overall silence and stillness that many visitors experience at the Grand Canyon does not hint of the geologic processes that are active today, or in the recent past, in the canyon. Except for the occasional visitor who hears a rock fall, or a rare large landslide, it is not apparent that the canyon is actively getting bigger. However, the erosional processes that originally formed the Grand Canyon are still active today as the Colorado River and its tributaries slowly cut deeper into the canyon.
 
In the recent geologic past, volcanic activity dramatically impacted the Grand Canyon. In the western Grand Canyon hundreds of volcanic eruptions occurred over the past two million years. At least a dozen times, lava cascaded down the walls of the Inner Gorge, forming massive lava dams that blocked the flow of the Colorado River. Three of these lava dams were over 1,000 feet high, forming lakes similar to reservoirs such as Lake Powell or Lake Mead. Some of the lakes were over 100 miles long and filled the lower portion of the Grand Canyon for many years before finally over-topping the dam and eroding much of it away. Cinder cones and the remnants of lava flows and dams are visible in the Toroweap area and from the river near Lava Falls.

Just southeast of Grand Canyon, near Flagstaff, is Sunset Crater Volcano National Monument, where in A.D. 1064 a series of eruptions built the park’s namesake cinder cone. About 45 earthquakes occurred in or near the Grand Canyon during the 1900’s. Of these, five registered between 5.0 and 6.0 on the Richter Scale. Dozens of faults cross the canyon, with at least several active in the last 100 years.
 

Grand Canyon Geology
Introduction - In Depth - Training Manual

Did You Know?

Yavapai Observation Station

Grand Canyon's Yavapai Observation Station (1928) located one mile (1.6 km) east of Market Plaza, features exceptional canyon views. Geology exhibits allow park visitors to see and understand the complicated geologic story in ways that all can understand. Exhibits and bookstore open daily. More...