Regional Geology of North America

The Yellowstone Hotspot is associated with a hot mantle plume that is slowly migrating eastward; it is currently beneath the northwestern Wyoming region (Figures 131 to 133). The Yellowstone Hotspot is responsible for a series of great volcanic centers that have linked together to form the Snake River Plain—about 16 million years ago the Yellowstone Hotspot was located under western Oregon. As the hotspot slowly moved eastward under the North American plate it created a series of supervolcanoes that intermittently experienced massive caldera-style eruptions followed by massive floods of basalt that filled the calderas and blanketed the surrounding region, slowly creating the Snake River Plain. The Yellowstone Volcano, one of the world's largest, is currently over the hotspot. Although Yellowstone National Park is most famous for its hotsprings and geysers, the volcano also has a caldera (a massive lava-filled crater) that is 70 miles across. Yellowstone has experienced at least three massive caldera-style eruptions: 2.1 million years ago, 1.2 million years ago and 640,000 years ago, each many hundreds to thousands of times larger than any eruptions in modern history. We can assume more will happen in the future!

Thermopolis, Wyoming claims to have the largest hotsprings in the world. Thermopolis is possibly located over the leading edge of the eastward-moving Yellowstone hotspot. (Figure 134).

Fig. 131. Migration of the Yellowstone Hotspot and formation of the Snake River Plain across Idaho.	Fig. 132. View of Old Faithful Geyser erupting in Yellowstone National Park in northwestern Wyoming.	Fig. 133. Grand Canyon of the Yellowstone with Lower Falls, Yellowstone National Park, Wyoming.	Fig. 134. Thermopolis, Wyoming claims to have the world's largest hot springs, may be hotspot related.