Subduction is a geological phenomenon that quite literally shapes the planet over time. Taking place at convergent plate boundaries, it involves the sinking of one tectonic plate underneath another and is a primary cause of earthquakes.

Although this process is a key aspect of plate tectonics, what causes subduction to eventually cease, and the effect subduction has on the deepest portions of the Earth's crust and the upper part of the mantle, remain a mystery.

UC Santa Barbara geologist John Cottle and three graduate students have begun a six-week stint of field research in Antarctica to explore these unknowns by studying the age and composition of igneous rocks at the very end of the subduction cycle. Because this process occurs deep within the Earth, they are focusing on rocks in the root of an ancient subduction zone now exposed in Antarctica's Transantarctic Mountains.