Plate Tectonic Theory

outer core

liquid part of the core

mesophere

lower part of the mantle

core

middle of the Earth

crust

the outer thin layer of the Earth

Alfred Wegener

A German meteorologist who proposed a hypothesis in 1915 that stated that all the continents were once joined together in a single land mass in the past and they have moved apart since.

convection currents

A cyclical motion occurs because of density differences in the mantle. Heated, less dense regions of the mantle rise, and denser, cooler regions sink due to gravity. The combined motions serve as the engine for crustal plate movement.

mountain building

A major geological event; occurs when continental plates of equal density converge.

sea-floor spreading evidence

A parallel pattern of rock material found at identical locations on each side of the Mid-Atlantic Ridge reveals rock of the same geologic age and polarity.

Pangaea

A super-continent containing all of Earth's land that existed about 225 million years ago.

more dense

At this plate boundary the oceanic crust is subducting because it is (more dense/less dense) than the continental crust?

lithosphere

Cool, rigid, outermost layer of Earth that is divided into enormous pieces called tectonic plates; consists of the crust and the rigid uppermost part of the mantle.

ocean trench

Deep and narrow depressions in the seafloor where the subducted plate moves into the asthenosphere.

divergent plate boundaries

Found where two plates move away from each other. When both of the separating plates are oceanic plates, material from the mantle rises up and creates new seafloor.

convergent plate boundaries

Found where two plates move toward each other and collide. Depending on what types of plates are colliding, one may dive beneath the other to be recycled back into the mantle while the other rises up, or both may rise to form a new system of mountains.

a system of satellites together form a ____________ that measures tectonic plate movement

Global Positioning System or GPS

divergent boundaries

Occurs when two tectonic plates move away from each other.

continental crust

Surface layer above sea level; the part of the Earth's crust that comprises the continents; an average thickness of 20-30 miles; primarily composed of granite

transform-fault boundary

The boundary between two plates that slide past one another -- sudden shifts that result in major geological events such as earthquakes and the release of stored energy.

subduction

The large number of volcanoes shown around the Pacific ocean is due to what process occurring along the trenches here?

fossils

The mineralized remains of organisms, showing how long-dead organisms lived and how their bodies were structured.

oceanic crust

The portion of earth's crust located under the oceans and that primarily contains basalt. It is relatively dense, and is 3-5 miles thick.

subduction

The process in which a denser plate is pushed downward beneath a less dense plate when plates converge; occurs at continental to oceanic boundaries and oceanic to oceanic boundaries.

asthenosphere

The solid layer with plasticity in the upper mantle that is located just below the lithosphere; lithospheric plates "float" and move on this layer.

Continental Drift theory

The theory that continents were once connected but have drifted apart.

oceanic

The volcanoes shown in the map are primarily due to the subduction of what type of crust? (oceanic or continental)

Plate Tectonic Theory

Theory that the lithosphere is divided into tectonic plates that slowly move on top of the asthenosphere.

earthquakes

These events occur along ALL types of plate boundaries

trench

This feature is at convergent subduction zones where oceanic crust is forced into the asthenosphere(mantle).

volcano

This feature is found along converging boundaries where subduction is occurring

mountain

This feature is found along converging continent-continent plate boundaries

fault

This feature is found along transform plate boundaries

ring of fire

This is the name for all the volcanoes located around the Pacific Ocean. The red line shows the volcanoes around the Pacific Ocean.

subduction

This process occurs at a convergent plate boundary between ocean and continental crust or ocean and ocean crust

earthquakes

What event occurs along this type of plate boundary? (eruptions or earthquakes)

volcano

What feature forms along the continent at this type of plate boundary? (mountain or volcano?)

faults

What feature is found along the plate boundary shown in the diagram? (faults or trenches)

mid-ocean ridge

What feature is found at the plate boundary shown in the diagram? (trench or mid-ocean ridge)

seafloor spreading

What process is occurring at the plate boundary shown in the diagram?

convergent

What type of plate boundary is shown in the diagram?

divergent

What type of plate boundary is shown in the diagram?

transform

What type of plate boundary is shown in the diagram?

rift valley

a deep valley that forms where two plates move apart on land

seafloor spreading

a process of plate tectonics in which new oceanic crust is created, magma swells up as the tectonic plates spread apart, the magma is then cooled by the sea water and forms mountain ranges such as the mid-Atlantic Ridge.

mantle

part between the crust and the core

tectonic plates

pieces of the crust that move

convergent

plate boundary where two plates are colliding into each other

divergent

plate boundary where two plates are separating from each other

transform fault

plate boundary where two plates slide past each other

inner core

solid part of the core