Chapter 17 Plate tectonics
Panagea
Ancient landmass made up of all the continents that began to break apart about 200 mya.
Magnetometer
Device used to map the ocean floor that detects small changes in magnetic fields
tectonic plates
Huge pieces of earth's crust that covers it's surface and fits together at the edges.
Isochron
Imaginary line on a map that shows points of the same age; formed at the same time.
rift valley
Long, narrow depression that forms when continental crust begins to separate at a divergent boundary.
divergent boundary
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.
convergent boundary
Place where two tectonic plates are moving toward each other; is associated with trenches, islands arcs, and folded mountains.
transform boundary
Place where two tectonic plates slide horizontally past each other; is characterized by long faults and shallow earthquakes.
subduction
Process by which one tectonic plate slips beneath another tectonic plate.
Paleomagnetism
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.
ridge push
Tectonic process associated with convection currents in Earth's mantle that occurs when weight of an elevated ridge pushes an oceanic plate toward a subduction zone.
slab pull
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.
seafloor spreading
The hypothesis 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.
continental drift
Wegner's hypothesis that Earth's continents were joined as a single landmass, called pangea, that broke apart about 200 mya and slowly moved to their present positions.
magnet reversal
When Earth's magnetic field changes polarity between normal and reversed.