Earth's Internal Heat - Vocabulary Flashcards

A set of vocabulary flashcards covering Earth's internal heat sources, mantle/crust structure, core composition, seismic waves, and heat transfer concepts.

Internal heat sources

The sources of Earth's interior heat, including accretional heat, radioactive decay, and frictional heating.

Accretional heat

Heat produced as dust and gas particles collide and coalesce to form Earth.

Radioactive decay

Heat released as unstable isotopes decay inside the planet, warming the interior.

Frictional heating

Heat generated by friction and collisions during the early formation and movement of Earth.

Magmatism

The process of magma formation and movement that leads to volcanic activity.

Magma

Melted rock beneath the surface that can form magma chambers or erupt as lava.

Decompression melting

Melting caused by a decrease in pressure as mantle rocks rise toward the surface.

Flux melting

Melting caused by the addition of volatiles (e.g., water) that lower the melting point of rocks.

Thermal melting

Melting caused by an increase in temperature within mantle rocks.

Asthenosphere

The semi-rigid, ductile layer of the mantle beneath the lithosphere that flows slowly.

Mantle

The thick middle layer of Earth between the crust and core, subdivided into upper, middle (asthenosphere), and lower mantle.

Crust

The outermost solid shell of Earth, divided into oceanic crust and continental crust.

Oceanic crust

Thin, dense crust composed mainly of basalt; generally younger than continental crust.

Continental crust

Thicker, less dense crust composed mainly of granitic rocks; generally older than oceanic crust.

Lithosphere

The rigid outer shell of Earth, including the crust and upper mantle; broken into tectonic plates.

Mohorovicic Discontinuity (Moho)

Boundary between the crust and the mantle where seismic velocities change.

Upper mantle

The portion of the mantle directly beneath the crust; part of the lithosphere.

Lower mantle

Deeper portion of the mantle beneath the upper mantle, more rigid and viscous.

Mantle convection

The slow circulation of mantle material driven by heat, which helps move tectonic plates.

Convection currents

Rising hot mantle material and sinking cooled material, forming a circular flow within the mantle.

Outer core

The liquid iron-nickel layer surrounding the inner core; generates Earth's magnetic field.

Inner core

A solid sphere mainly of iron and nickel at Earth's center, extremely hot and under high pressure.

Earth's magnetic field

Geomagnetic field produced by the motion of the liquid outer core around the solid inner core; shields Earth and interacts with solar wind.

Auroras

Northern and southern lights caused by solar particles interacting with Earth's magnetic field.

Seismic waves

Waves of energy produced by earthquakes that travel through Earth and reveal its internal structure.

P-waves (primary waves)

The fastest seismic waves; compressional waves that travel through solids and liquids.

S-waves (secondary waves)

Shear waves that move only through solids; do not travel through liquids and create shadow zones.

P-wave shadow zone

Regions where P-waves are weak or absent due to refraction by the core.

S-wave shadow zone

Regions where S-waves are absent because the liquid outer core blocks them.

Isopach lines

Contour lines on maps showing lines of equal crust thickness.

Plate tectonics

Theory that Earth's lithosphere is divided into plates that move over the viscous asthenosphere due to mantle convection.

Heat transfer (conduction, convection, radiation)

Three modes of transferring thermal energy: conduction (direct contact), convection (fluid movement), and radiation (electromagnetic waves).