Site MapHelpFeedbackGlossary
Glossary
(See related pages)

Below you will find key words and concepts that you should remember from this chapter.
asthenosphere  A region of Earth’s outer shell beneath the lithosphere. The asthenosphere is of indeterminate thickness and behaves plastically.
(See page(s) 84)
continental drift  A concept suggesting that continents move over Earth’s surface.
(See page(s) 77)
convection (convection current)  A very slow circulation of a substance driven by differences in temperature and density within that substance.
(See page(s) 82)
convergent plate boundary  A boundary between two plates that are moving toward each other.
(See page(s) 85)
divergent plate boundary  Boundary separating two plates moving away from each other.
(See page(s) 85)
island arc  A curved line of islands.
(See page(s) 94)
lithosphere  The rigid outer shell of Earth, 70 to 125 or more kilometers thick.
(See page(s) 84)
magmatic arc  A line of batholiths or volcanoes. Generally the line, as seen from above, is curved.
(See page(s) 85)
mantle plume  Narrow column of hot mantle rock that rises and spreads radially outward.
(See page(s) 102)
plate  A large, mobile slab of rock making up part of Earth’s surface.
(See page(s) 84)
plate tectonics  A theory that Earth’s surface is divided into a few large, thick plates that are slowly moving and changing in size. Intense geologic activity occurs at the plate boundaries.
(See page(s) 76)
polar wandering  An apparent movement of the earth’s poles.
(See page(s) 79)
sea-floor spreading  The concept that the ocean floor is moving away from the mid?oceanic ridge and across the deep ocean basin, to disappear beneath continents and island arcs.
(See page(s) 77)
subduction  The sliding of the sea floor beneath a continent or island arc.
(See page(s) 82)
transform fault  The portion of a fracture zone between two offset segments of a mid-oceanic ridge crest.
(See page(s) 88)
transform plate boundary  Boundary between two plates that are sliding past each other.
(See page(s) 85)







Physical Geo: Earth RevealedOnline Learning Center

Home > Chapter 4 > Glossary