Geysers, springs and hotspots are evidence that Yellowstone is an active volcano and will erupt in the future! Yellowstone's largest eruption, Lava Creek eruption, over 640,000 years ago. A 1,000 times the volume of Mount St. Helen's eruption in 1980. The Lava Creek erupted with violent force that blasted volcanic ash across more than 15 states. After the explosion, the rhyolite dome volcano lacked magma that supported the structure. The volcano collapsed creating Yellowstone’s Caldera. Basalt lava flows uplift the lithosphere Yellowstone's caldera. To see the plateau rhyolite flows click here.
Underneath the North American Plate lives Yellowstone's hotspot of deeply rooted magma of extraordinary size and volume. The lithosphere moves southwest while the hotspot remains stationary, creating gigantic calderas in its path. This scar of calderas forms the Snake River Plain, a flood basalt. Follow the link to "Explore volcanic fields" and see the process’ in motion!
|Section cut of Yellowstone's hotspot.(Click to here enlarge)|
|Intrusive volcanic sills near Tower Falls. (Click image to enlarge)|