Upper-mantle convection currents rise near surface at 20 locations {plume, mantle} {hot spot, mantle}|. Plumes have 300,000 meters diameter. Plumes in crustal-plate middle can send alkali-rich basalt lava up to surface to form volcanoes, as in Hawaiian Islands.
Physical Sciences>Earth Science>Planet>Plate Tectonics>Mountain Building
5-Earth Science-Planet-Plate Tectonics-Mountain Building
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Date Modified: 2022.0224