Module 19 - Plate Tectonics and Earth's Structure

Vocabulary flashcards based on lecture notes covering Earth's origin, internal structure, plate tectonic boundaries, subduction processes, and geologic hazards.

Earth's Formation

The process 4.6 billion years ago in which Earth formed as a molten sphere that slowly cooled, causing heavier elements like iron to sink towards the center and lighter elements like silica to float towards the surface.

Earth's Core

A dense mass of solid nickel, iron, and radioactive elements that release massive amounts of heat, consisting of a solid inner core and a liquid outer core.

Mantle

A liquid layer of magma surrounding Earth's core that is kept liquified by intense heat from the core.

Asthenosphere

The solid, flexible outer layer of the mantle located directly beneath the lithosphere.

Lithosphere

A thin, brittle layer of rock floating on top of the mantle that is broken up into tectonic plates.

Crust

The very outer layer of the lithosphere that forms Earth's surface.

Theory of Plate Tectonics

A hypothesis proposed in 1912 stating that all continents were once joined together as Pangea and over time drifted apart, supported by fossil, rock formation, and continental shape evidence.

Divergent Plate Boundary

A boundary where tectonic plates move away from each other due to a rising magma plume from the mantle, forming mid-oceanic ridges, volcanoes, seafloor spreading, and rift valleys on land.

Convection Current

A thermal current where magma heated by Earth's core rises towards the lithosphere, cools and expands to force oceanic plates apart, and solidifies into new lithosphere.

Convergent Plate Boundary

A boundary where tectonic plates move towards each other, leading to subduction and forming mountains, island arcs, volcanoes, trenches, and tsunamis.

Subduction

The process at a convergent boundary where one tectonic plate is forced beneath another plate.

Oceanic-Oceanic Convergent Boundary

A convergent boundary where one oceanic plate subducts underneath another, forcing magma up to the lithosphere surface to form mid-ocean volcanoes, island arcs, and off-shore trenches.

Oceanic-Continental Convergent Boundary

A convergent boundary where a dense oceanic plate subducts beneath a continental plate, melting back into magma and forcing magma up to create narrow coastal mountains such as the Andes, volcanoes on land, and trenches.

Continental-Continental Convergent Boundary

A convergent boundary where one plate subducts underneath another, forcing surface crust upward to form mountain ranges such as the Himalayas.

Transform Fault Plate Boundary

A boundary where plates slide past each other in opposite directions, creating a fault in the rock surface and causing earthquakes.

Fault

A fracture in a rock surface created when tectonic plates slide past each other.

Tsunami

Large, destructive ocean waves caused by strong oceanic seismic activity that can travel large distances to impact nearby coastal areas.