Unit 4 Vocab Flashcards
Continental drift
hypothesis that a single large landmass broke up into smaller land masses to form the continents, which then drifted to their present locations
puzzle pieces
continents seem to fit together like puzzle pieces if we were to cut and move the shapes from the map
mid-ocean ridges
long undersea mountain chain that has a steep, narrow valley at its center, that forms as magma rises from the asthenosphere, and that creates new oceanic lithosphere (sea floor) as tectonic plates move apart
sea-floor spreading
the process where new oceanic lithosphere (sea floor) forms as magma rises to Earth’s surface at mid-oceanic ridges and solidifies, as older, existing seafloor moves away from the ridge
Paleomagnetism
study of the alignment of magnetic minerals in rock, specifically as it relates to the reversal of Earth’s magnetic poles; also the magnetic properties that rock acquires during formation
Normal Polarity
magnetic rocks point N
Reversed Polarity
magnetic rocks point S
Geomagnetic reversal time scale
scientist arrange the pattern of normal polarity and reversed polarity to create a time scale as recorded by paleomagnetism
plate tectonics
theory that explains how large pieces of the lithosphere, called plates, move and change shape
Lithosphere
solid, outer layer of Earth that consists of the crust and the rigid upper part of the mantle (sea floor)
Asthenosphere
the solid, plastic layer of the mantle beneath the lithosphere
Divergent Boundaries
boundary between tectonic plates that are moving apart
Convergent boundaries
boundary between tectonic plates that are colliding
ocean-continental (subduction zones)
ocean crust is denser so it subducts under the continental
continental-continental
both plates are equally or nearly equal in density so neither subducts and we get thickening forming mountains
oceanic-oceanic
both very dense so one eventually gives and produces a deep trench and sometimes islands arcs due to production of magma
transform boundaries
boundary between tectonic plates that are sliding past each other horizontally
Convection
movement of heated material due to differences in density that are caused by differences in temperatures
ridge push
as the cooled, older rock slides down the ridge of the slope it exerts a force on the rest of the plate