divergent plate boundary
A tectonic boundary where two plates are moving away from each other and new crust is forming from magma that rises to the Earth's surface between the two plates. The middle of the Red Sea and the mid-ocean ridge (running the length of the Atlantic Ocean) are divergent plate boundaries. Also called passive margin spreading zone See more at tectonic boundary. Compare convergent plate boundary.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.