While mapping currents and the movement of deep-sea sediments off the eastern coast of New Zealand, geologist Lionel Carter came upon something unexpected: evidence of a unique volcanic recycling system in which seafloor sediments plunge into Earth’s interior, erupt out of volcanoes in the New Zealand Alps, and then settle onto the ocean floor to begin the cycle anew. The entire process, says Carter, probably takes some 3 million years to complete.
Carter, who works at the New Zealand National Institute of Water and Air in Wellington, knew that the seafloor sediments he was studying originated in the New Zealand Alps. Both the sediments and the rocks and soil on the slopes of the Alps contain identical amounts of a specific type of mica, a mineral consisting of aluminum, potassium, and other elements. This mica signature told Carter that the sediments had eroded from alpine slopes, washed into rivers, and ...
