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e : ot 0 S M-gmaoqqo Figure 13.3: Hotspot Volcano Formation over Time.’ scientists are divided over how magma is generated in hotspots. Some suggest that hotspots originate from super-heated material from as deep as the core that reaches the Earth’s crust as a mantle plume. Others argue the molten material that feeds hotspots is sourced from the mantle. Of course, it is difficult to collect data from these deep-Earth features due to the extremely high pressure and temperature. How hotspots are initiated is another highly debated subject. The prevailing mechanism has hotspots starting in divergent boundaries during supercontinent rifting. Scientists have identified a number of current and past hotspots believed to have begun this way. Subducting slabs have also been named as causing mantle plumes and hotspot volcanism. Some geologists have suggested another geological process not involving plate tectonics may be involved, such as large space objects crashing into the Earth. Regardless of how they are formed, dozens are on the Earth. Some well-known examples include the Tahiti Islands, Afar Triangle, Easter Island, Iceland, Galapagos Islands, and Samoan Islands. The United States is home to two of the largest and best-studied hotspots: Hawai’i and Yellowstone." The locations of selected prominent hotspots are shown in Figure 13.4. EXPLANATION \ ¥ L o ——— Divergent plate boundaries— §\\ 3 """“.‘ 7 Where new crust is generated D £ o L e as the plates pull away from AR SN A H oo e each other. % R gr W S e .c‘» “,.4,:' ™ P i 3 . \“\ B \1 < N Vo] s ““"Vg.s\‘.\“:\;\&_ oY \§\§\ ¥ e R b ] | debiis Convergent plate boundaries— Where crust is consumed in the Earth's interior as one plate dives under another. Transform plate boundaries— Where crust is neither produced nor destroyed as plates slide horizontally past each other. .\ Plate boundary zones—Broad o belts in which deformation is diffuse and boundaries are not i : well defined. 2 . - . e N g L .\‘!/H‘ y o : g - ® Selected prominent hotspots AN T ‘ Figure 13.4: Plate Tectonics Map with Selected Prominent Hotspots. : fure by National Park Service is in the public domain Bure by USGS is in the public domain