The Wrangell Mountains form the volcanic heart of the park. Covering over 2,000 square miles, the Wrangell Volcanic Field is made up of thousands of lava flows and some of the highest peaks in North America, and includes Mount Wrangell, one of the largest (by volume) active volcanoes in the world.
The Wrangell volcanoes were formed over the last 5 million years by massive eruptions which were the result of tectonic collisions along the Pacific and North American crustal plates. Volcanism in this region started much earlier than that (as much as 26 million years ago), but all that remains of that early volcanism is the rocks themselves—the volcanic mountains from that time period have long since been eroded away. Although this activity has slowed for the past few thousand years, there is still heat at shallow depth, as evidenced by Mount Wrangell's occasional steam plumes, and by a series of active mud volcanoes east of Glennallen.
Mount Wrangell (14,163')
Mount Wrangell is the only volcano in the Wrangell Mountains that is currently active. During the winter and on cool summer mornings, it is not unusual to see a steam plume rising out of the vents situated in craters along the margin of the summit caldera. In spite of frequent puffs of steam, geologists tell us that Wrangell is showing no signs of erupting any time soon. But those steam vents remind visitors that there is still heat below and that this massive volcano is still active.
When did Mt. Wrangell last erupt?
Minor eruptive activity has been noted on Mt. Wrangell in 1784, 1884-5, and 1900.
Geodiversity Atlas ~ Geodiversity refers to the full variety of natural geologic (rocks, minerals, sediments, fossils, landforms, and physical processes) and soil resources and processes that occur in the park. A product of the Geologic Resources Inventory, the NPS Geodiversity Atlas provides information in support of education, Geoconservation, and integrated management of living (biotic) and non-living (abiotic) components of the ecosystem.
Magnificent, breathtaking views of snow-covered Wrangell Mountain peaks await every visitor to this part of Alaska. Knowing that these large mountains are volcanoes provokes many intriguing questions: When did they last erupt? How tall are they? Will they erupt again? You can learn these answers and more, by downloading The Guide to the Volcanoes of the Western Wrangell Mountains. (30 pages, pdf format, 8.5 MB)