CCHS Plate Tectonics Brown (copy)

Lithosphere

A mechanical layer of earth which is rigid and brittle and breaks into segments. It includes the crust and very top of mantle.

Asthenosphere

A mechanical layer of earth located within the mantle below the lithosphere, that has the ability to flow, so is called a plastic-solid.

continental crust

part of outermost compositional layer of earth. Usually made of granite (mostly quartz and feldspar minerals)

oceanic crust

part of outermost compositional layer of earth, usually made of basalt (magnesium and iron-rich igneous rock).

Continental Drift Hypothesis

hypothesis states that at one point in time, all the continents on Earth were together in a large land mass called Pangaea and have since moved apart.

Plate Tectonic Theory

Describes and provides evidence for the existence and movement of Earth's plates.

convection current

A rising and sinking loop of slow flowing asthenosphere due to differences in density, temperature and pressure.

hot spots

plumes of very warm mantle material that rises up in essentially fixed locations.

pole reversal

a switch in the direction of Earth's magnetic field so that the magnetic north pole becomes the magnetic south pole and the magnetic south pole becomes the magnetic north pole.

reverse polarity

A magnetic field opposite to that which exists at present.

normal polarity

a magnetic field that is the same as that which exists at present

pillow basalt

round blobs of basaltic lava cooled in water (mid-ocean ridge)

Sonar

A device that determines the distance of an object under water by recording echoes of sound waves

Trench

Deep, steep valley on the ocean floor created by subduction.

upwelling

the movement of magma towards the surface at divergent boundaries

continental shelves

Areas where continental surfaces extend under the shallow ocean water around the continents

glacial striations

scratches or gouges cut into bedrock by glacial abrasion

Graben

a block of crust between faults that has shifted downward in relation to the blocks on either side (creates a valley)

Horst

higher blocks/ridges (either shifted upward or remaining stationary) on either side of grabens (Creates a ridge)

Slab Pull

the force created by the sinking of a dense oceanic plate into the mantle.

Ridge push

The force magma pushes onto continental crust forming

Plumes

Narrow tube like

Mega Plumes

Giant Upwelling, explaining large elevated regions

wilson cycle

a model that describes the opening and closing of ocean basins