Convection Currents, Plate Tectonics
Divergent
Plates pull apart and magma rises up.
Transform
Plates slide past each other
Alfred Wegener
Proposed the continental drift theory in the 1900s
When rock material is heated by Earth's core, will it rise or sink?
Rise
When rock material is cool towards the top of the mantle, will it rise or sink?
Sink
trench
extremely deep areas in the ocean that are created by a subducting plate
rift valley
long, narrow depression formed at divergent boundaries
Andes Mountains
A large system of mountain ranges located along the Pacific coast of South America formed above the subduction zone of two convverging plates.
San Andreas Fault
A major geological fault in California formed by a sliding transform boundary.
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.
volcano
A weak spot in the crust where magma has come to the surface
Convergent
Equally dense plates collide and make mountains or If plates are different densities, subduction occurs, one plate slides under the other.
North American Plate
Lithospheric plate that includes almost all of North America and part of the Atlantic Ocean.
Transform Boundary
The boundary between tectonic plates that are sliding past each other horizontally
Divergent Boundary
The boundary between two tectonic plates that are moving away from each other
Convergent Boundary
The boundary formed by the collision of two plates
Continental Drift
The hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations
mantle
The layer of hot, solid material between Earth's crust and core. The thickest layer.
Mariana Trench
The location of the deepest trench on earth made from two oceanic crusts converging.
Convection
The movement caused within a fluid by the tendency of less dense material to rise and denser material to sink
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
Sea-floor spreading
The process by which new oceanic crust forms as magma rises towards the surface and solidifies at divergeny boundaries.
What causes the movement of crustal plates?
The rising and sinking of material in the mantle.
Asthenosphere
The soft layer of the mantle on which the tectonic plates move
Lithosphere
The solid, outer layer of the Earth that consists of the the crust and the rigid upper part of the mantle
Plate Tectonics
The theory that the earth is broken into plates and are in motion due to convection currents in the asthenosphere (upper mantle)
Crust
The thin and solid outermost layer of the Earth above the mantle
Plate Tectonics
Theory that the Earth's crust is divided into tectonic plates which move around due to convection currents in the mantle.
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
subduction
process in which two plates collide and the denser ocean plate descends below the other
Pangea
term for the super continent which contained all the plates together
oceanic crust
thinner, more dense, younger crust making ocean floor