Processes that Shape Earth

continental drift

the hypothesis that the continents slowly drifted to their current positions after having been part of a single, giant landmass that broke apart

fault

a break in Earth’s crust where the rocks on either side have moved

plate tectonics

the scientific theory that the lithosphere is made up of rigid pieces, called tectonic plates, that move across Earth’s surface

seafloor spreading

the process by which the rocks on either side of the mid-ocean ridge slowly pull away from each other, allowing molten rock to rise, solidify, and form new seafloor

subduction

the process by which a collision between two tectonic plates forces the denser plate under the less dense plate

divergent plate boundary

a region where two tectonic plates move away from each other

convergent plate boundary

a region where two or more of Earth's tectonic plates collide or move directly toward each other

transform plate boundary

a zone where two tectonic plates slide horizontally past one another

mid-ocean ridge

a continuous, global underwater mountain system formed by tectonic plates pulling apart and magma rising and cooling

trench

a depression that forms at boundaries between two tectonic plates that are converging, or moving toward each other

crystal

a solid structure with atoms arranged in a repeating geometric pattern

extrusive rock

igneous rock that forms when magma cools quickly on Earth’s surface

igneous rock

rock formed from the cooling and solidification of magma on or below Earth’s surface

intrusive rock

igneous rock that forms when magma slowly hardens below Earth’s surface

metamorphic rock

rock changed in composition or texture by heat and pressure

mineral

a substance that is made of crystals and has a specific chemical composition and geometric shape

rock cycle

the continuous set of processes by which rock can change from one type to another; a model of how the flow of energy drives the cycling of rock material in the geosphere

sedimentary rock

rock formed from the deposition of dissolved materials, rock fragments, or the remains of organisms