The Theory of Plate Tectonics

These flashcards cover key terms and concepts related to the theory of plate tectonics, including types of plate boundaries, their movements, and associated geological features.

Plate Tectonics

The theory that pieces of Earth’s lithosphere are in constant motion, driven by convection currents in the mantle.

Lithosphere

The rigid outer layer of the Earth, consisting of the crust and upper mantle.

Asthenosphere

The partially molten layer of the mantle below the lithosphere that allows the plates to move.

Convection Currents

Movement caused within a fluid by the tendency of hotter and therefore lighter material to rise, and colder, denser material to sink.

Plate Boundaries

The edges where two tectonic plates meet, which can be divergent, convergent, or transform.

Divergent Boundary

A plate boundary where two plates move away from each other, causing rifting and seafloor spreading.

Convergent Boundary

A plate boundary where two plates collide, leading to features such as trenches and mountains.

Transform Boundary

A plate boundary where two plates slide past each other horizontally, causing shearing.

Normal Fault

A fault where the rock above the fault plane moves downward in relation to the rock below.

Reverse Fault

A fault where the rock above the fault plane moves upward in relation to the rock below.

Strike-Slip Fault

A fault where rocks on either side move horizontally past each other.

Compression

A type of stress that occurs when rocks are squeezed together.

Tension

A type of stress that occurs when rocks are pulled apart.

Shearing

A type of stress that occurs when rocks are pushed in opposite directions.

Subduction Zone

An area where one tectonic plate is being forced under another plate.

Rift Valley

A lowland region formed by the divergence of tectonic plates.

Mid-Ocean Ridge

An underwater mountain range formed by divergent tectonic plates.

Volcanic Arc

A chain of volcanoes formed above a subducting plate.