1/12/10
Chapter 17 Vocabulary
Plate Tectonics
Continental Drift (p. 444) Wegener’s hypothesis that the
Earth’s continents were joined as a single landmass called
Pangaea, that broke apart about 200 Million years ago and
slowly moved to their present positions.
Pangaea (p.444) Ancient landmass made up of all the
continents that began to break apart about 200 million years
ago.
Isochron (p. 452) Line on the map that connects points of the
same age.
Magnetic Reversal (p. 451) Changes in the Earth’s magnetic
field over geologic time, recorded in the ocean-floor rocks and
continental basalt flows.
Magnetometer (p. 448) Device used to map the ocean floor
that detects small changes in the magnetic fields.
Paleomagnetism (p. 451) Study of Earth’s magnetic record
using data gathered from iron-bearing minerals in rocks that
have recorded the orientation of Earth’s magnetic field at the
time of their formation.
Seafloor Spreading (p. 453) Hess’s theory that new ocean
crust is formed at mid-ocean ridges and destroyed at deep-sea
trenches: occurs in a continuous cycle of magma intrusion and
spreading.
Covergent Boundary (p. 457) Place where two of Earth’s
tectonic plates are moving toward each other; is associated with
trenches, island arcs, and folded mountains.
Divergent Boundary (p. 456) Place where two of Earth’s
tectonic plates are moving apart; is associated with volcanism,
earthquakes, and high heat flow, and is found primarily on the
seafloor.
Rift Valley (p. 456) Long, narrow depression that forms when
continental crust begins to separate at a divergent boundary.
Subduction (p. 457) Process by which one tectonic plate slips
beneath another tectonic plate.
Theory of Plate Tectonics (p. 455) States that the Earth’s
crust and upper mantle are broken into plates, which are huge
rock slabs that move in different directions and at different rates
over Earth’s surface.
Transform Boundary (p. 459) Place where two tectonic
plates slide horizontally past each other, characterized by long
faults and shallow earthquakes.
Ridge Push (p. 461) Tectonic process associated with
convection currents in Earth’s mantle that occurs when the
weight of an elevated ridge pushes an oceanic plate toward a
subduction zone.
Slab Pull (p.462) Tectonic process associated with convection
currents in Earth’s mantle that occurs as the weight of the
subducting plate pulls the trailing lithosphere into a subduction
zone.