Earth Sciences

Cards · 55

Plate Tectonics

The theory that Earth outer shell is divided into large moving plates, driven by mantle convection currents that shape global geology.

Subduction Zone

A convergent boundary where a denser tectonic plate sinks beneath a lighter plate into the mantle, often triggering deep earthquakes and volcanism.

Mid-Ocean Ridge

An underwater mountain range formed by seafloor spreading, where divergent plates separate and magma rises to form new oceanic crust.

Continental Drift

The historical hypothesis that continents were once joined in a supercontinent (Pangaea) and gradually moved across Earth surface over geological time.

Lithosphere

The rigid, brittle outer layer of Earth comprising the crust and the uppermost solid mantle, fragmented into tectonic plates.

Asthenosphere

The mechanically weak, semi-fluid upper layer of the mantle beneath the lithosphere that permits tectonic plate movement through plastic flow.

Mantle Convection

The slow, churning circulation of heated rock in the mantle driven by internal thermal energy, providing the primary driving force for plate motion.

Transform Fault

A strike-slip plate boundary where tectonic plates slide horizontally past one another, generating friction that produces shallow, powerful earthquakes.

Magma

Molten or semi-molten rock beneath Earth surface that cools slowly into intrusive igneous rock or erupts via volcanoes as lava.

Lava

Molten rock that reaches Earth surface through volcanic vents, cooling quickly in air or water to form extrusive igneous rocks.

Pyroclastic Flow

A high-density, fast-moving avalanche of hot gas, ash, and rock fragments expelled catastrophically during an explosive volcanic eruption.

Shield Volcano

A broad, gently sloping volcano built by successive flows of low-viscosity basaltic lava erupting non-explosively over long periods.

Stratovolcano

A tall, steep-sided volcanic cone built of alternating layers of hardened lava, tephra, and ash, prone to explosive eruptions driven by viscous magma.

Hotspot

An isolated, persistent area of volcanism fed by an abnormally hot mantle plume rising from deep within Earth, independent of plate boundaries.

Weathering

The breakdown of rocks and minerals on Earth surface through mechanical disintegration, chemical alteration, or biological activity in situ.

Erosion

The physical removal and transportation of weathered sediments from one location to another by wind, running water, ice, or gravity.

Deposition

The geological process where transported sediments, soil, and rocks settle out of wind, water, or ice and accumulate in resting layers.

Metamorphic Rock

Rock transformed from a pre-existing protolith by intense heat, confining pressure, and chemically active fluids without fully melting.

Sedimentary Rock

Rock formed by the compaction and cementation of mineral and rock fragments, organic matter, or chemical precipitation over geological time.

Igneous Rock

Rock formed directly through the cooling and solidification of molten magma beneath the crust or lava on Earth surface.

Rock Cycle

The continuous transition of Earth materials between igneous, sedimentary, and metamorphic forms through cooling, erosion, pressure, and melting.

Paleomagnetism

The study of Earth ancient magnetic field preserved in magnetic minerals of cooling rocks, providing key evidence for seafloor spreading.

Epicenter

The point on Earth surface positioned vertically directly above the hypocenter or focus where an earthquake ruptures.

Focus (Hypocenter)

The exact underground location where tectonic stress exceeds rock strength, causing a sudden rupture that initiates seismic waves.

P-Waves (Primary Waves)

Compressional seismic body waves that travel fastest through solids, liquids, and gases by vibrating particles parallel to wave propagation.

S-Waves (Secondary Waves)

Shear seismic body waves that move particles perpendicularly to wave propagation and can travel only through solid materials.

Liquefaction

A phenomenon where water-saturated, loose granular sediment temporarily loses its mechanical strength and behaves as a liquid during seismic shaking.

Foliation

The repetitive layering or planar alignment of platy mineral grains in metamorphic rocks caused by directional tectonic stress.

Karst Topography

A distinctive landscape characterized by sinkholes, caves, and underground streams formed by the chemical dissolution of soluble rocks like limestone.

Alluvial Fan

A fan-shaped deposit of sediment formed when a fast-flowing mountain stream suddenly slows and spreads out upon reaching a flat plain.

Delta

A wetland landform created at a river mouth where sediment drops out of suspension as river currents decelerate into standing water.

Glacial Moraine

An unsorted accumulation of glacial debris, till, and boulders transported and deposited directly along the margins or snout of a melting glacier.

Troposphere

The lowest atmospheric layer containing most of Earth air mass and water vapor, where convection drives nearly all weather systems.

Stratosphere

The atmospheric layer directly above the troposphere containing the ozone layer, characterized by temperature increasing with altitude.

Coriolis Effect

The apparent deflection of moving air and water caused by Earth rotation, deflecting currents rightward in the Northern Hemisphere and leftward in the South.

Albedo

The measure of the reflectivity of Earth surface; high albedo surfaces like ice reflect solar energy, while dark ocean surfaces absorb it.

Greenhouse Effect

The warming of Earth lower atmosphere caused when gases like carbon dioxide and methane absorb and re-emit infrared radiation emitted by the surface.

Hadley Cell

A large-scale tropical atmospheric circulation pattern where warm air rises at the equator, flows poleward aloft, sinks in the subtropics, and returns.

Jet Stream

A narrow, fast-flowing meandering air current in the upper troposphere driven by sharp temperature contrasts between polar and tropical air masses.

Cold Front

The leading edge of a cooler, denser air mass advancing into a warmer air mass, forcing warm air up rapidly and producing stormy weather.

Warm Front

The boundary where a lighter, warm air mass gently glides up and over retreating cold air, producing widespread stratus clouds and gentle precipitation.

Occluded Front

A composite atmospheric boundary formed when a fast-moving cold front overtakes a warm front, lifting the warm air completely off the surface.

Dew Point

The atmospheric temperature to which air must be cooled at constant pressure to become saturated with water vapor, initiating condensation.

Orographic Precipitation

Rainfall or snowfall produced when moist air is mechanically forced upward over elevated terrain, cooling adiabatically and condensing.

Rain Shadow

A dry geographic region on the leeward side of a mountain range created because descending air warms adiabatically and holds moisture.

El Niño

A recurring climate phenomenon marked by weakening trade winds and abnormal warming of central and eastern equatorial Pacific surface waters.

La Niña

A periodic climate anomaly featuring unusually strong trade winds and colder-than-average sea surface temperatures in the equatorial eastern Pacific.

Thermohaline Circulation

A global deep-ocean conveyor system driven by density gradients originating from variations in water temperature (thermal) and salinity (haline).

Upwelling

The wind-driven displacement of surface ocean waters that draws cold, nutrient-rich water from depth up to the photic zone, fueling productivity.

Tsunami

A series of immense ocean waves generated by sudden vertical displacement of the seafloor due to undersea earthquakes, landslides, or caldera collapses.

Aquifer

An underground permeable geological formation of rock, sand, or gravel capable of storing and yielding significant amounts of groundwater.

Water Table

The upper boundary of the phreatic zone where pore spaces in sediment and rock are completely saturated with groundwater.

Permafrost

Ground, sediment, or bedrock that remains continuously frozen at or below zero degrees Celsius for two or more consecutive years.

Milankovitch Cycles

Long-term collective variations in Earth orbital eccentricity, axial tilt, and precession that alter seasonal solar distribution and trigger ice ages.

Isostasy

The state of gravitational equilibrium between Earth lithosphere and asthenosphere, causing crust to float higher or sink based on density and thickness.