Earth's Structure and Plate Tectonics

Comprehensive vocabulary flashcards covering Earth's internal layers, continents, oceans, continental drift, seafloor spreading, tectonic plate boundaries, and associated geological features.

Earth's Crust

The outermost layer of Earth made of granite and basalt, divided into thicker continental crust and thinner oceanic crust, and broken into moving tectonic plates.

Continental Crust

The thicker and less dense portion of Earth's crust primarily composed of granite.

Oceanic Crust

The thinner and denser portion of Earth's crust primarily composed of basalt.

Mantle

Earth's thickest layer that behaves like a plastic-like fluid, divided into the upper lithosphere and lower asthenosphere.

Lithosphere

The rigid layer comprising Earth's crust and upper mantle that is broken into floating tectonic plates.

Asthenosphere

The plastic-like lower mantle layer beneath the lithosphere where heat-driven convection currents cause the movement of tectonic plates.

Convection Currents

Circulating currents in the asthenosphere driven by heat from the core, where hot, less dense material rises, cools near the crust, and sinks again.

Outer Core

The liquid core layer composed of iron, nickel, sulfur, and oxygen, whose flowing molten metals generate Earth's magnetic poles.

Inner Core

The hottest region of Earth composed of iron and nickel that remains in a solid state due to extreme pressure and density increasing with depth.

Seven Continents

The seven primary continental landmasses on Earth: North America, South America, Europe, Africa, Asia, Australia, and Antarctica.

Five Oceans

The five principal bodies of water on Earth: the Pacific Ocean, Atlantic Ocean, Indian Ocean, Arctic Ocean, and Southern (Antarctic) Ocean.

Theory of Continental Drift

The theory proposed by Alfred Wegener suggesting that Earth's continents were once joined in a single landmass called Pangaea and slowly moved to their current positions.

Pangaea

The single ancient supercontinent landmass composed of all present-day continents joined together before drifting apart.

Alfred Wegener

The scientist who proposed the Theory of Continental Drift, supporting it with jigsaw coastline fits, fossil records, and matching rock and mountain ranges.

Theory of Plate Tectonics

The geological theory building on continental drift that explains Earth's crust and lithosphere are divided into plates floating on the asthenosphere, driven by mantle convection and seafloor spreading.

Harry Hess

The scientist whose discovery of seafloor spreading provided the physical mechanism explaining how continents move.

Seafloor Spreading

The process where tectonic plates pull apart at mid-ocean ridges as rising magma cools to create new oceanic crust, pushing the seafloor outward.

Magnetite

Magnetic iron particles in molten magma that align with the current direction of Earth's magnetic field and lock in place upon solidifying.

Paleomagnetic Stripes

Symmetrical patterns of alternating magnetic polarity recorded along the seafloor, formed as magma solidifies during periodic reversals of Earth's magnetic poles.

Convergent Boundary

A plate boundary where two tectonic plates move toward each other, forming destructive subduction zones, trenches, volcanoes, earthquakes, and mountain ranges.

Subduction Zone

A destructive zone at a convergent boundary where one plate is forced downward beneath another into the mantle and melts into magma.

Divergent Boundary

A constructive plate boundary where two plates move apart, allowing magma to rise and create new crust, mid-ocean ridges, seafloor spreading, and hydrothermal vents.

Transform Boundary

A conservative plate boundary where two plates slide past each other without creating or destroying crust, causing earthquakes, tsunamis, and abyssal plains.

Mid-Ocean Ridge

A long underwater mountain range formed at a divergent boundary where separating plates allow magma to rise and create new oceanic crust with a central valley.

Ocean Trench

A long, narrow, and very deep depression in the ocean floor with steep sides that forms at a convergent subduction boundary.

Challenger Deep

The deepest known point in Earth's oceans, situated within the Mariana Trench in the western Pacific Ocean.

Earthquake

A sudden release of energy within Earth producing seismic waves, typically resulting from volcanic activity or tectonic plate movements at boundaries.

Tsunami

A large seismic sea wave triggered by underwater earthquakes or volcanic events, which slows down and grows much taller as it enters shallow coastal water.