A mantle plume is a column of hot, solid material that rises from deep within the Earth's mantle. This upward movement occurs due to the heat generated by the Earth's core, causing the mantle material to become less dense and rise toward the surface. Mantle plumes can lead to volcanic activity when they reach the crust, forming features like volcanic islands. One well-known example of a mantle plume is the Hawaiian hotspot, which has created the Hawaiian Islands over millions of years. As the Pacific tectonic plate moves over this stationary plume, new islands are formed while older ones erode and sink.