Sunset Crater Volcano

National Monument

Arizona

flowers with a volcano in the background

Sunset Crater Volcano National Monument, Arizona

"The contrast in the colors is so great that on viewing the mountain from a distance the red cinders seem to be on fire. From this circumstance the cone has been named Sunset Peak."

John Wesley Powell (Civil War soldier-turned-geologist), 1885

Sunset Crater: A Colorful Volcanic Cone
The cones and lava flows of the San Francisco volcanic field, which covers about 2,000 square miles of the southwestern Colorado Plateau, result from several million years of volcanic activity. These powerful underground forces changed the landscape dramatically beginning in the winter of AD 1064-65.

Sunset Crater appeared when molten rock sprayed out of a crack in the ground high into the air, solidified, then fell to earth as large bombs or smaller cinders. As periodic eruptions continued over the next 200 years, the heavier debris accumulated around the vent creating a 1,000-foot cone. The lightest, smallest particles blew the farthest, dusting 800 square miles of northern Arizona with ash. Perhaps as spectacular as the original pyrotechnics were two subsequent lava flows: the Kana-A flow in 1064 and the Bonito flow in 1180. They destroyed all living things in their paths.

The processes that created Sunset Crater also created a sculpture garden of extraordinary forms at its base. As new gas vents opened suddenly, spatter cones sprouted from the ground like miniatures of the cone itself. Moving lava developed a crust on the surface where it cooled; caves beneath drained away. Partially cooled lava, pushing through cracks like toothpaste from a tube, solidified into wedge-shaped squeeze-ups, grooved from scraping against the harder rock.

In a final burst of activity, around 1250, lava containing iron and sulfur shot out of the vent. The red and yellow oxidized particles fell back onto the rim as a permanent "sunset" so bright that the cone appears still to glow from intense volcanic heat.

Geologic Setting
At an average elevation of 305 m (1,000 ft) above the valley floor, the rim of Sunset Crater Volcano dominates the landscape of the 3,040 acre national monument. It is part of a N 60 W trending 10 km long chain that includes Rows of Cones, Gyp Crater, and Vent512 (Blaylock, 1996). The base of the volcano is at . . . read more

Geologic History
Striking geologic features including stark black lava flows, eolian sand dunes, and cinder cones dominate the landscape of Sunset Crater Volcano National Monument. In geologic time, the eruption responsible for the present day landscape was practically instantaneous . . . read more

Geologic Features & Processes
The eruption responsible for Sunset Crater produced a 300 m (1,000 ft) high asymmetrical cinder cone that lies on the base of the east slope of the San Francisco Peaks . . . read more

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The General park map handed out at the visitor center is available on the park's map webpage.

For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.

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A geology photo album for this park can be found here.

For information on other photo collections featuring National Park geology, please see the Image Sources page.

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Roadside Geology: Wupatki Crater and Sunset Crater Volcano National Monuments.
Hanson, Sarah L., 2003.
Arizona Geological Survey.
ISBN 1-892001-19-5
paperback, 32 pages, full color photographs

This book gives an overview of the geology of Wupatki and Sunset craters as well as a road guide to stops in the national monuments. Detailed descriptions of the geology at each stop are included.

Please visit the Geology Books and Media webpage for additional sources such as text books, theme books, CD ROMs, and technical reports.

Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
ISBN 0-393-92407-6
9" x 10.75", paperback, 550 pages, full color throughout

The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!

Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.

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Information about the park's research program is available on the park's research webpage.

For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.

The NPS maintains a searchable data base of research needs that have been identified by parks.

A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.

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