Parashant is a wonderland of deeply cut canyons, plateaus, basins...and volcanoes! The Grand Canyon-Parashant landscape is story of Basin and Range stretching and Colorado Plateau uplift. On the west side of the monument Earth's crust has cracked and slumped to the west over the last 17 million years, thinning the crust significantly. This crustal extension continues west to California and has almost doubled the surface distance from Parashant to the Pacific Ocean over the last 17 million years. The eastern half of the monument is part of the Colorado Plateau, which has risen thousands of feet in elevation due to mantle heat over the last six million years.
All this earth movement is on display at Parashant. It also set the stage for very scenic erosion, including the cutting of the Grand Canyon. If you would like to learn more about why the Colorado Plateau is rising and why there have been hundreds of volcanic eruptions in the monument, start with Section 1 below. Volcanism on its own is dramatic, but the interaction of lava and water adds an extra level of drama. The Uinkaret volcanic field in Parashant is famous as the source of at least 150 lava flows that poured into the Grand Canyon. Seventeen of them blocked the Colorado River, boiling it away, then damming it. The lava dams were up to 1,400 feet high and created huge reservoirs that lasted from a few years to decades or more. Remnants of these dams can be seen at places like Whitmore Canyon Overlook in Parashant or Toroweap, in Grand Canyon National Park.
To learn more about the incredible volcanic story of Parashant, use the links below. These pages are an indepth overview of the topic but written for general audiences and students. To put this volcanism in context, see the Geology section of the website for the rest of the geologic story of Parashant over the last 600 million years.
Section 1: Setting the Stage for Volcanism
The Stretching of the Basin and Range and Rise of the Colorado Plateau
Section 2: What Kind of Eruptions Happen Here?
Magma Melts and Eruption Types
Section 3: The Uinkaret Volcanic Field and its Eruptions in Parashant
Recent Eruptions and Lava Flows Dams in the Grand Canyon
Section 4: Timeline of Events for the Most Recent Eruption 950 Years Ago
The Little Springs Eruption near Mt. Trumbull
Last updated: November 1, 2022