SS Chapter 17 Flashcards
Plate Tectonics
The theory that the earth is broken into plates and are in motion due to convection currents in the asthenosphere (upper mantle)
Alfred Wegener
Proposed the continental drift theory in the 1900s
Pangea
Term for the super continent which contained all the plates together
Crust
The thin and solid outermost layer of the Earth above the mantle
Lithosphere
The solid, outer physical layer of the Earth that consists of the the crust and the rigid upper part of the mantle
Asthenosphere
The soft physical layer of the mantle on which the tectonic plates move
Transform Boundary
The boundary between tectonic plates that are sliding past each other horizontally
Continental Drift
The hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations
Sea-floor spreading
The process by which new oceanic crust forms as magma rises towards the surface and solidifies at divergeny boundaries.
Convergent Boundary
The boundary formed by the collision of two plates
Divergent Boundary
The boundary between two tectonic plates that are moving away from each other
Rift valley
Long, narrow depression formed at divergent boundaries
Subduction
Process in which two plates collide and the denser ocean plate descends below the other
Convection current
A current caused by the rising of heated fluid and sinking of cooled fluid believed to drive plate movement in the mantle of the earth
Mid-ocean ridge
An underwater mountain range made at divergent plate boundaries
Volcano
A weak spot in the crust where magma has come to the surface
Earthquake
A shaking or sliding of the ground. It is caused by the sudden movement of masses of rock along a fault or by changes in the size and shape of masses of rock far beneath the earth’s surface.
Continental crust
The portion of the earth’s crust that primarily contains granite, is less dense than oceanic crust, and is 20-50 km thick
Oceanic crust
Thinner, more dense, younger crust making ocean floor
Mariana Trench
The location of the deepest trench on earth made from two oceanic crusts converging.
San Andreas Fault
A major geological fault in California formed by a sliding transform boundary.
siesmic waves
vibrations that travel through Earth carrying the energy released during an earthquake
Theory of Continental Drift
Idea that at one point in time all of the continents were one super continent called Pangea.
Deep Ocean Trench
Extremely deep areas in the ocean that are created by a subducting plate
Ocean basin
Areas that are below sea level
Hot spot
An area in the mantle that is super heated and melts through the crust (like a blow-torch)
Seismographs
Measures and records earthquake magnitude based on the energy released in an earthquake.
Tsunami
A giant wave usually caused by an earthquake beneath the ocean floor.
Epicenter
The location on the surface directly above the focus
