Earth Science: Internal Structure and Plate Tectonics

Vocabulary flashcards detailing Earth's internal composition, liquid core dynamics, plate tectonic boundaries, and geological occurrences.

Continental crust

The less dense, granitic outer layer of Earth's surface with a density of 2.7 and an approximate thickness of $35\,km$.

Oceanic crust

The dense, basaltic layer of Earth's surface with a density of 2.9 and an approximate thickness of $7\,km$.

Mohorovičić discontinuity (Moho)

The boundary surface located between Earth's crust and the underlying mantle.

Peridotite mantle

The ductile and plastic layer beneath Earth's crust with a density ranging from 3.0 to 3.4.

Liquid outer core

The layer of Earth's interior where convection currents generate the magnetic field that prevents solar wind from stripping away the atmosphere.

Lithosphere

The rigid outer layer of Earth comprising the crust and upper mantle that forms tectonic plates.

Earthquake

A event caused when pressure builds at a fault along tectonic plate edges, friction creates a locked fault, and pressure is suddenly released upon slipping.

Tsunami

A massive displacement of water caused by an underwater earthquake.

Divergent plate boundary

A tectonic boundary where plates spread apart, causing seafloor spreading or continental rifting, volcanism via decompression melting, and earthquakes.

Seafloor spreading

The process by which new oceanic crust forms at mid-ocean ridges and spreads outwards, pushing older crust away from the ridge.

Convergent plate boundary (Oceanic and Continental)

A boundary where denser oceanic crust subducts beneath continental crust, bringing seawater into the mantle to lower its melting point and form volcanoes.

Convergent plate boundary (Continental and Continental)

A boundary where two buoyant continental plates collide without subducting, forcing the crust upward to construct very large mountains.

Convergent plate boundary (Oceanic and Oceanic)

A boundary where older, colder, and denser oceanic crust subducts under another oceanic plate, resulting in underwater trenches and volcanic islands.

Transform plate boundary

A boundary where two plates slip past each other without producing volcanoes, causing earthquakes such as along California's San Andreas fault.

Hotspots

Plumes of magma originating in the mantle that force their way through the overlying crust, forming chain structures like the Hawaiian islands.