Mantle plumes, Hawaiian island age progression, fixed vs moving plume debate
The Hawaiian-Emperor chain records Pacific plate motion over a fixed deep-mantle plume. Ages increase NW: Hawaii (active) → Maui (1.3 Ma) → Oahu (3.7 Ma) → Kauai (5.1 Ma) → Midway (27.7 Ma) → Detroit Seamount (81 Ma). Rate: ~9 cm/yr.
Morgan (1971): narrow thermal diapirs from core-mantle boundary. Critics: no clear seismic signature for many "hot spots." Alternatives: edge-driven convection, lithospheric cracks. Iceland, Hawaii, Yellowstone have clearest plume evidence.