Plate Tectonics and Ocean Basins

Flashcards covering the fundamentals of plate tectonics, seafloor spreading, crust types, and the physical characteristics of global ocean basins.

Plate tectonics

A process involving the movement of large plates on the earth's mantle, explaining oceanic crust creation, destruction, and global patterns.

Subduction

The downward movement of one plate into the earth's mantle when two plates collide, preventing the Earth from increasing in size despite new crust formation.

Oceanic-continental interaction

An interaction where the oceanic plate sinks, leading to mountain buildings and volcanism, such as the Andes.

Oceanic-oceanic interaction

A collision where one plate sinks, often resulting in the formation of volcanic islands like the Aleutian Islands.

Continental-continental interaction

A collision where neither plate sinks easily, causing rocks to buckle into major mountain ranges such as the Himalayas.

Shear boundary

A plate boundary where plates slide past each other; friction and sudden release produce earthquakes, famously seen at the San Andreas Fault.

Seafloor spreading

The process that creates new seafloor as plates move away from each other at the mid-ocean ridges.

Magnetic reversals

Past events where Earth's magnetism reversed; recorded by magnetic particles in molten rock that align to magnetic north and freeze in place upon cooling.

Mid-ocean ridges

Underwater volcanic mountain chains that constitute a major geological structure at plate boundaries.

Trenches

Deep depressions where plates converge and are destroyed through subduction.

Radioactive decay

The source of heat within Earth that drives the movement of giant irregular plates.

Continental drift

The hypothesis proposed by Alfred Wegener in $1912$ suggesting continents once joined as Pangaea before separating.

Pangaea

The name of the supercontinent where all continents were once joined together.

Oceanic crust

A dense, dark layer of basalt approximately $5\,\text{km}$ thick that floats lower and is more likely to sink in collisions.

Continental crust

A lighter, less dense layer of granite measuring between $20\,\text{--}\,50\,\text{km}$ thick.

Mantle

Solid rock near its melting point that can slowly flow and deform over long timescales, behaving like a plastic solid.

Outer core

The liquid layer of Earth's core whose movement is linked to the generation of Earth's magnetic field.

Inner core

The solid center of the Earth that remains solid despite extreme temperatures due to very high pressure.

Ocean connectivity

The linkage between basins and seas that enables the transport of water properties like temperature and salinity and allows organism dispersal.

Southern Ocean

A circumpolar ocean that connects other oceans and has an average depth of $4,500\,\text{meters}$.

Pacific Ocean

The largest ocean basin with an approximate area of $166,000,000\,\text{sq. km}$ and an average depth of $4,190\,\text{m}$.

Atlantic Ocean

An ocean basin with an approximate area of $86,500,000\,\text{sq. km}$ and an average depth of $3,740\,\text{m}$.

Indian Ocean

An ocean basin with an approximate area of $73,000,000\,\text{sq. km}$ and an average depth of $3,870\,\text{m}$.

Arctic Ocean

The shallowest and smallest ocean basin with an average depth of $1,330\,\text{m}$ and an area of approximately $9,500,000\,\text{sq. km}$.

Earth's water coverage

Approximately $71\%\,$ of the Earth's surface is covered by water, reflecting a dominance of marine environments.

Hemispheric distribution pattern

The geographical observation that the Northern Hemisphere has more land, while the Southern Hemisphere holds more ocean.