Exploring Arizona’s Volcanic Legacy
Arizona, a state known for its desert landscapes, is home to over 1,000 volcanoes and three active volcanic fields. The most extensive of these is the San Francisco Volcanic Field located near Flagstaff. While these fields are considered dormant, meaning they could erupt again, the timeline for such events spans geological periods, often thousands of years apart.
The latest volcanic activity in the region took place approximately 1,000 years ago at Sunset Crater, a notable cinder cone close to Flagstaff. These cinder cones are characterized by their steep sides and form rapidly during brief, explosive eruptions. In contrast, Arizona also features shield volcanoes, which are the largest type of volcano on Earth. These are recognized by their broad, convex shape and gentle slopes, with the House Mountain volcano situated between Sedona and the Verde Valley serving as a prime example.
Lava domes, such as Mt. Elden near Flagstaff, are another volcanic structure found in Arizona. These formations arise from slow-moving, thick lava flows and are circular and mound-shaped. However, the most striking volcanic feature in Arizona is Humphreys Peak. Standing at nearly 13,000 feet, it is the state’s highest point and an extinct stratovolcano, distinguished by its steep sides and classic cone shape.
Volcanic occurrences in Arizona are infrequent when compared to other western regions of the United States. Despite their rarity, these eruptions have significantly influenced the local landscape, leaving behind lava flows and evidence of explosive geological events. Beneath the tranquil deserts of Arizona lies a history marked by intense volcanic activity.
This Earth Note was written by Carrie Calisay Cannon and produced by KNAU and the Sustainable Communities Program at Northern Arizona University.
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