What is Seafloor Spreading?
Seafloor spreading is a constant geologic phenomenon and a primary driver of continental drift. The process begins when the crust is heated from beneath by upwelling in the mantle, sometimes called a mantle plume. This creates a three-armed rift called a triple junction, usually with each rift at a 120° angle to the rest . The crust along the length of the rift is heated by the underlying mantle, becoming more plastic and less dense. The crust rises, creating a broad dome and widening the rift. The heated region pushes the crust outwards from the rift ever so slightly (at a rate of 5-10 cm a year, about the same speed your fingernails grow), causing the seafloor spreading. Over millions of years, this process drives continental drift, bringing together continents, then dividing them, in a process called the supercontinent cycle. This process runs its course every 250-500 million years. The last time there was a supercontinent, Pangaea, was about 200 million years ago. Within the next 2
