Thermal Energy Drives Plate Tectonics

fault

A crack in the earth's crust that is caused by sliding plates

rift valley

A deep valley that forms where two plates move apart

subduction

A geological process in which one edge of a crustal plate is forced sideways and downward into the mantle below another plate

magma

A molten mixture of rock-forming substances, gases, and water from the mantle

lithosphere

A rigid layer made up of the uppermost part of the mantle and the crust.

outer core

A shell of hot, liquid metal beneath the mantle and above the inner core

composite volcanoes

A tall, cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials

oceanic-oceanic plate convergence

A type of convergent plate boundary along which to oceanic lithospheric plates collide and one is subducted beneath the other.

hot spot

An area where magma from deep within the mantle melts through the crust above it

oceanic-continental plate convergence

An oceanic and a continental plate colliding, forcing the denser oceanic plate to slide beneath, forming a trench. This can result in the formation of conical volcanoes, perhaps in a volcanic belt.

mid-atlantic ridge

An underwater mountain chain located where two plates move apart

transform fault

Area where the earth's lithospheric plates move in opposite but parallel directions along a fracture (fault) in the lithosphere.

divergent plate boundary

Boundary between tectonic plates in which the two plates move away from each other, and new crust is created between them

Evidence for CD theory

Continents fit together like a puzzle, similar fossils in distant continents, similar glaciers, similar mountain ranges

hawaiian islands

Created by pacific plate moving northwest over a hotspot. Oldest is Kauai youngest is the Big Island

volcanic island arc

Forms at an oceanic-oceanic convergent boundary. String of volcanoes that result from melting related to the subduction of the older, denser oceanic crust.

seismometer

Instrument used to measure horizontal or vertical motion during an earthquake.

magnitude

Measure of the energy released during an earthquake

rift push

Process where tectonic plates move away from the ridge, as new material at a ridge or rift pushes older material aside

convergent plate boundary

The boundary between two plates that move toward each other

transform plate boundary

The boundary between two plates that slide past each other

Paleoglaciation

The extent of ancient glaciers and the marks they left behind

tectonic plates

The large pieces of land in the Earth's crust

focus

The point along a fault at which the first motion of an earthquake occurs

epicenter

The point on Earth's surface directly above an earthquake's focus

sea floor spreading

The process by which molten material adds new oceanic crust to the ocean floor

asthenosphere

The soft layer of the mantle on which the lithosphere floats.

seismology

The study of earthquakes

mantle

The thick layer of the earth below the crust that is made of dense rock that is under high pressure

crust

The thin and solid outermost layer of the Earth above the mantle

trench

a long narrow depressing in the ocean floor, usually parallel to the plate boundary and marking a subduction zone

mantle convection

a recurring current in the mantle that occurs when hotter, less dense material rises, cools, and then sinks again. This current is believed to be one of the driving forces behind tectonic plate movement.

volcanoes

an opening in the Earth's crust through which molten lava, ash, and gases are ejected.

layers of the earth

crust, mantle, outer core, inner core

magnetic reversal

happens when the flow in the outer core changes, and Earth's magnetic field changes direction; when Earth's magnetic field changes polarity between normal and reversed

volcanic belt

long chain of volcanoes commonly found where oceanic-continental plate convergences occur

secondary waves

move up and down and side to side; 2nd to arrive; travel only through solids

continental-continental plate convergence

oceanic lithosphere is subducted beneath continental lithosphere and a continental volcanic arc develops

subduction zones

places where plates are pushed down into the upper mantle

surface waves

seismic waves that travel along the Earth's surface

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.

inner core

the molten core of the Earth.

seismogram

the record of an earthquake's seismic waves produced by a seismograph

plate boundary

the region where two tectonic plates are in contact

continental drift theory

the theory that the continents have not always been in their present locations but have moved to them over millions of years

seismic waves

vibrations that travel through Earth carrying the energy released during an earthquake

earthquakes

violent shaking or shifting motion of the ground caused by the sudden movement of rock far beneath Earth's surface

shield volcanoes

volcanoes that form over hot spots; the largest volcanoes on Earth

rift eruptions

volcanoes that occur where magma erupts through long cracks in the lithosphere where tectonic plates are spreading apart

magnetic stripping

when new magma on the sea floor cools and solidifies. When it does this the molecules of the magma/rock orient themselves to the polarity of the earth at that time. Also, when the polarity of earth reverses, the orientation of the new crust is also reversed.

spreading ridge

when the magma beneath Earth's surface raises and then cools, forming new sea floor.

primary waves

1st wave, P, travels the fastest, back-and-forth waves, move through solids, liquids, and gases