Mover and Shaker

In 1961, the geophysicist and geologist John Tuzo Wilson looked out over the world’s largest active volcano, Mauna Loa. He saw how, beyond its “smoking crater rim,” the Pacific islands of Maui, Moloka‘i, O‘ahu, and Kaua‘i trace a shallow curve and recede into the distance, “much like a convoy of ships some 600 km long.” Inspiration struck, and Wilson ripped a page from his notebook, flicked his cigarette lighter, and proceeded to move the page horizontally over the flame, “momentarily pausing to burn a hole before pulling the paper onwards, leaving a track of singed craters.” Hawai‘i’s volcanic archipelago, he realized, had been born on the ocean’s floor, originating from a fixed column of red-hot magma bubbling through the earth’s crust. Mountains had arisen from thea sea in succession over millions of years, each moving on to make way for the next. Wilson was witnessing the action of plate tectonics.