Recent crustal uplift in Yellowstone National Park

Comparison of precise leveling measurements made in 1923 with those made in 1975, 1976, and 1977 reveals that the 600,000-year-old Yellowstone caldera is being uplifted relative to its surroundings. Maximum relative uplift since 1923 is in excess of 700 millimeters - about 14 millimeters vertically per year. The most likely cause of this rapid and unusually large surface deformation is a recent influx of molten or partially molten material to a location within the crust beneath Yellow-stone National Park. Copyright ?? 1979 AAAS.