The vast majority of the United States is on the North American Plate. Hawaii is separate, on the Pacific Plate, as is a small portion of California. The North American Plate extends well east of the United States, reaching as far as Iceland.
The North American Plate is bordered by several additional plates, leading to notable geological phenomena at the juncture points. The most famous of the boundaries lies along the San Andreas Fault, where the North American and Pacific Plates intersect. This boundary results in frequent earthquakes, sometimes of extreme magnitude.
Beneath the North American Plate lie several hotspots. Among these is the Yellowstone Caldera, which is a massive depository of molten rock lying just below the surface of Yellowstone National Park.