A model that can explain the observations about the ages of volcanic rocks and their distance from Hawaii is the existence of a hot spot within Earth's mantle. As the Pacific Plate moves over the relatively stationary hot spot in the mantle, volcanoes form on the surface of the plate. As the plate continues moving to the northwest, volcanic rocks that accumulated are carried off the hot spot, and erosion begins to wear them down. New volcanoes form on the plate above the hot spot. The island of Hawaii is currently above the hot spot.
! Click the image to see how a chain of volcanic islands forms as a plate moves over a hot spot in the mantle. Use the movie controls to watch the animation several times and examine separate frames.