Finals

Stress

A force that changes the shape of Earth’s crust by pushing, pulling, or twisting rocks.

Tension Stress

Pulls crust apart at divergent boundaries, causing the crust to get thinner.

Compression Stress

Squeezes the crust together at convergent boundaries, resulting in folds or breaks.

Shearing Stress

Pushes rocks past each other in opposite directions at transform boundaries.

Normal Fault

A fault caused by tension stress where the hanging wall moves down and forms at divergent boundaries.

Reverse Fault

A fault caused by compression stress where the hanging wall moves up and forms at convergent boundaries.

Strike-Slip Fault

A fault caused by shearing stress where rocks slide sideways past each other without a hanging wall or footwall.

Focus (in earthquakes)

The point underground where the earthquake starts.

Epicenter

The point on Earth’s surface directly above the earthquake focus.

P-Waves

The fastest seismic waves that travel through solids and liquids, causing push/pull motion.

S-Waves

Seismic waves that arrive second and travel through solids only, causing side-to-side motion.

Surface Waves

The slowest seismic waves that cause the most damage, moving in a rolling/circular motion.

Modified Mercalli Scale

Measures earthquake intensity based on people's observations and damage.

Richter Scale

Measures earthquake magnitude using seismograph readings, best for small/local earthquakes.

Moment Magnitude Scale

Measures total energy released, most accurate for large earthquakes.

Seismograph

A machine that detects earthquake vibrations.

Seismogram

The recording made by a seismograph showing the strength and timing of seismic waves.

Magma

Molten rock underground.

Lava

Magma that has reached the Earth's surface.

Hotspot

A place where hot mantle material rises through the crust, forming volcanic islands.

Pyroclastic Flow

A fast-moving mix of hot gas, ash, and rock fragments during a volcanic eruption.

Anticline

A fold in rock that bends upwards.

Syncline

A fold in rock that bends downwards.

Shield Volcano

A volcano formed by quiet eruptions with thin/runny lava creating wide gentle slopes.

Composite Volcano

A volcano that forms from both explosive and quiet eruptions, resulting in layers of ash and lava.

Cinder Cone Volcano

A steep-sided volcano made mostly of ash and cinders that erupts explosively.

Caldera

A huge crater formed when a volcano collapses into an empty magma chamber.

Climate

The average weather in a given area over a long period.

Albedo

How much sunlight a surface reflects.

Meteor

A meteoroid that is burning in Earth's atmosphere.

Meteorite

A meteoroid that hits the Earth's surface.

Nebula

A giant cloud of gas and dust in space where stars form.

Protostar

An early-forming star.

Neutron Star

A dense leftover core after a supernova.

Black Hole

A region in space where gravity is so strong that nothing, not even light, can escape.

Galaxy

A vast collection of stars, gas, dust, and planets.

Milky Way

The galaxy that contains our solar system.

Elliptical Galaxy

An oval-shaped galaxy containing older stars.

Spiral Galaxy

A galaxy with spiral arms containing younger stars.

Irregular Galaxy

A galaxy with no clear shape, containing lots of gas and young stars.