Volcanic eruptions on the Seward Peninsula formed maars, like Devil Mountain Maar pictured here, that are larger than those found anywhere else on Earth. NPS photo.

Volcanoes in Alaska are most often associated with the Ring of Fire, which stretches from the Aleutians along the state’s southern coast through the southeast panhandle. So it may be a surprise to learn there are expansive lava flows in the Bering Land Bridge National Preserve on the Seward Peninsula. 

These are the northernmost volcanic features in North America that were created during the last ice age. When scientists studied these lava flows, they discovered an entirely new type of eruption. 

Maars are shallow craters that form when a volcanic eruption creates a circular depression in the earth that often later fills with water. They’re common volcanic features, but the maars in the Bering Land Bridge Preserve are far larger than any others on Earth. At the time of the eruptions, permafrost in the area was about 100 yards thick. When incredibly hot magma touched the frozen ground, it superheated the ice into steam and caused massive explosions. 

“These eruptions turned the Earth inside out. The lakes are surrounded by fragments of older rocks and sediments from the depths of the Earth,” according to an explanatory article by the National Park Service. Devil Mountain Maar Lake is nearly five miles long, 3.7 miles wide, 328 feet deep, and is surrounded by a 15-story bedrock cliff. “It may be truly hard to imagine the energy it took to create such a large depression,” the NPS writes. 

These unique interactions between magma and permafrost at first seemed isolated to Alaska’s Seward Peninsula. But similarities between the formations studied in Alaska and features on the surface of the planet Mars, where the average air temperature is -81 degrees, led scientists to believe that Mars has likely been shaped by interactions between magma and permafrost.

Author

Alexander Deedy is the assistant editor and digital content manager for Alaska magazine.

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