Geology Vocabulary

Theory of Continental Drift

 The slow movement of continents across Earth’s surface.

Theory of Plate Tectonics

Earth’s crust is made up of 7 major tectonic plates, which move due to convection currents in the mantle.

Evidence to support continental drift

• The continents look like they fit together like a puzzle.

• Same fossils discovered on completely different continents. 

• Same rock types found in North America and Europe.

• Scratches on rocks in the desert in Africa match those in Antarctica. 

Evidence to support plate tectonics

• Earthquakes and volcanoes are found near tectonic plate boundaries.

• New crust found at mid-ocean ridges; the seafloor is spreading. 

Compression

To push together

Tension

To pull apart

Shearing

To slide past in different directions

Convergent Boundary

• A tectonic plate boundary where two plates collide

• 3 different types (convergent, divergent, & transform)

Divergent Boundary

• A tectonic plate boundary where two plates move away from each other, leading to the formation of new crust

• creates mid-ocean ridge

Transform Boundary

• A tectonic plate boundary where to plates slide past each other in the opposite direction

• causes earthquakes

Continental Crust

The thick, less dense part of the Earth's crust that forms the continents.

Oceanic Crust

The thin, denser part of the Earth's crust that forms the oceans.

Fault

A crack or break in the rock or Earth’s crust

Fold

A bend in the rock.

Subduction

• When the more dense tectonic plate slides underneath the less dense tectonic plate

• Creates a trench

• Old crust goes back into the mantle

Mid-ocean Ridge

• Created at divergent boundaries

• Where magma rises and forms new crust

Volcanic Island Arc

• Created at toceanic-oceanic convergent boundaries

• A chain of islands formed by volcanic activity

Mountain Range

• Created at continental-continental convergent boundaries

Volcanoes

• Created at continental-oceanic convergent boundaries

• Formed when the oceanic plate subducts under the continental plate causing magma to rise

Ocean Trench

• Created at subduction zones

• Where old crust gets destroyed

Anticline

An upward bend in the rock

Syncline

A downward bend in the rock

Crust

The outer layer of the Earth, consisting of the continental and oceanic crust

Mantle

• semi-fluid that sways back and forth

• located directly under the crust

• where convection currents occur

Inner Core

• Contains the hottest temperatures (almost as hot as the sun!)

• Under the highest pressure from all layers above pushing inwards 

• It is a solid

Outer Core

Made of very hot liquid iron that spins around the solid inner iron core creating our magnetic field.

Earthquake

A sudden shaking of the ground caused by the movement of tectonic plates along faults / boundaries

Convection Currents

Heat from the core causes the magma to rise (less dense), then reaches the crust and cools (more dense) falling back down into the mantle

Stress

Forces that push and pull on Earth's crust, causing it to change.

Alfred Wegener

The man who proposed the Theory of Continental Drift