Divergent boundary
A tectonic plate boundary where plates move apart, allowing magma to rise and form new crust at mid-ocean ridges or continental rifts.
Seafloor spreading: The process by which magma rises at mid-ocean ridges, cools, and adds new oceanic crust. It is the main mechanism that creates ocean floor as plates separate.
Plate tectonics: The theory that Earth's outer shell is divided into moving plates whose interactions shape the surface. Divergent boundaries are one of the principal types of plate boundary.
Mid-Atlantic Ridge: The submarine mountain chain running through the Atlantic Ocean, where the American plates separate from the Eurasian and African plates. It is a classic slow-spreading ridge dividing the Atlantic seafloor.
Convergent boundary: A tectonic plate boundary where plates move toward one another, commonly causing subduction or continental collision. Unlike divergence, convergence often consumes or thickens existing crust.
Mantle upwelling: The ascent of hot mantle material toward Earth's surface, often driven by convection or reduced pressure. Upwelling supplies heat and melt beneath many spreading centers.
Lithosphere: Earth's rigid outer shell, comprising the crust and the uppermost mantle. Divergence stretches and separates this mechanically rigid shell.
East Pacific Rise: A fast-spreading mid-ocean ridge in the eastern Pacific Ocean. Its broad, magmatically active ridge contrasts with slower spreading systems.
Transform boundary: A tectonic plate boundary where plates slide horizontally past one another. Transform motion accommodates displacement without creating crust by spreading.
Decompression melting: The production of magma when rising mantle experiences lower pressure without substantial cooling. It generates much of the basaltic magma at divergent boundaries.
Oceanic crust: The relatively thin, dense crust beneath ocean basins, composed mainly of basaltic rocks. It is continually created at oceanic divergent boundaries.