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The Seafloor in Microcosm

Scientists can’t observe magma moving beneath the seafloor, so WHOI geologist Glenn Gaetani makes his own. He subjects tiny capsules of powder (with a composition similar to the rocks in Earth’s upper mantle) to crushing pressure and intense heat in his laboratory. Through three-dimensional microtomography, he can then spy the internal structure of the mineral grains, revealing how melting magma pools and flows along the edges and corners of the dark grains. The work is part of a larger effort at WHOI to understand Earth processes, including how magma forms and rises through seafloor cracks to carpet the ocean bottom with new crust.(Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)