convection current		material that makes up the ocean floor.
lithosphere		zone of mantle beneath the lithosphere that consists of slowly moving rocks.
divergent boundary		border formed by the direct collision of two lithosphere plate.
convection		transfer of heat through the movement of a fluid material.
seafloor spreadway		steep narrow valley formed as lithosphere plates separation.
island arc		undersea mountain range with a steep narrow valley along the center.
mid-atlantic ridge		single landmass thought to have been the orgin of all continents.
rift valley		material that makes up landmasses.
panthalassa		movement of the ocean floor away from either side of a mid ocean ridge.
convergent boundary		theory that the lithosphere a make up of plates that float on the asthenosphere.
continental drift		hypothesis stating that the continent once formed a single landmass broke up and drifted to their present location.
ocean crust		chain of volcanic island formed along an ocean trench.
continental crust		thin outer shell of the earth consisting of the crust and the rigid upper mantle.
astenosphere		deep valley in the ocean floor that form along a subduction zone.
plate tectonics		boundary formed by two lithospheric plates that are moving apart.
ocean trench		giant ocean surrounding pangaea.
pangaea		movement in a fluid caused by uneven heating.
mid-ocean ridge		system of undersea mountain ranges that wind around the earth.