Big Giant Draymond Balls

Elastic Rebound Theory

A theory explaining how stress builds up along faults until rocks suddenly fail, causing earthquakes and releasing energy in the form of seismic waves.

Seismic Waves

Vibrations that travel through the Earth after an earthquake, explosion, or other sources of energy release.

P-waves

Primary or compressional seismic waves that travel fastest through the Earth, causing particles to move in the same direction as wave propagation.

S-waves

Secondary or shear waves that travel more slowly than P-waves, causing particles to move perpendicular to the direction of wave propagation.

Surface Waves

Seismic waves (Love and Rayleigh waves) that travel only on the Earth's surface at slower speeds than body waves.

Epicenter

The point on the Earth's surface directly above the focus (hypocenter) of an earthquake.

Hypocenter

The location below the Earth's surface where an earthquake originates.

Magnitude

A measure of earthquake size based on the amount of energy released, typically expressed on a logarithmic scale.

Modified Mercalli Intensity (MMI) Scale

A scale measuring the intensity of earthquake shaking based on observed effects, ranging from I (not felt) to XII (total destruction).

Magma

Molten rock beneath the Earth's surface that forms deep underground.

Lava

Molten rock that flows onto the Earth's surface from a volcano.

Mineral

A naturally occurring, inorganic solid with a specific chemical composition and characteristic crystal structure.

Rock

A naturally occurring aggregate of minerals or non-mineral matter (like glass or organic material).

Igneous Rocks

Rocks formed by the cooling and solidification of magma or lava.

Sedimentary Rocks

Rocks formed by the deposition and cementation of sediments or by chemical precipitation.

Metamorphic Rocks

Rocks formed when existing rocks are changed by heat, pressure, or chemical processes.

Rock Cycle

The continuous process by which rocks are created, changed, destroyed, and reformed due to geological processes driven by plate tectonics and the climate system.

Radiometric Dating

A technique used to determine the age of rocks and minerals by measuring the decay of radioactive isotopes with known half-lives.

Half-life

The time it takes for half of the atoms of a radioactive isotope to decay into a stable form.

Lithosphere

The rigid outer shell of the Earth that includes the crust and uppermost mantle, which is broken into tectonic plates.

Asthenosphere

The partially molten, ductile layer of the upper mantle beneath the lithosphere, on which the tectonic plates move.

Plate Tectonics

A unifying theory in Earth sciences that explains the movement and behavior of Earth's lithosphere and the geological processes that result from plate interactions.

Continental Drift

Wegener's early hypothesis that continents were once joined together and have moved apart over time.

Zircon

A mineral commonly used in radiometric dating due to its ability to preserve uranium; oldest Earth zircons are about 4.4 billion years old.

Divergent Boundary

A plate boundary where two tectonic plates move away from each other, creating new crust as magma rises to fill the gap.

Convergent Boundary

A plate boundary where two plates move toward each other, resulting in either subduction or continental collision.

Transform Boundary

A plate boundary where two plates slide horizontally past each other, creating strike-slip faults.

Subduction Zone

An area where an oceanic plate descends beneath another plate into the mantle.

Mid-Ocean Ridge

An underwater mountain range formed at divergent boundaries where new oceanic crust is created.

Continental Rift Zone

A divergent boundary within continental crust, characterized by parallel rift valleys and volcanism.

Oceanic Trench

A deep depression in the ocean floor formed at convergent boundaries where an oceanic plate subducts.

Faint Young Sun Paradox

The contradiction between evidence of liquid water on early Earth despite the Sun being 30% less luminous than today.

Big Bang Theory

The leading theory explaining the origin of the universe, which posits that the universe began as a single point about 13.8 billion years ago and has been expanding ever since.

Nebular Hypothesis

The scientific theory describing how the solar system formed from a cloud of gas and dust that contracted under gravitational forces to form the Sun and planets about 4.6 billion years ago.

Accretion

The process by which smaller particles and bodies in space collect together due to gravity to form larger bodies like planets and moons.

Planetesimals

Small solid objects formed during the early stages of solar system development, typically ranging from several kilometers to hundreds of kilometers in size.

Terrestrial Planets

The rocky, inner planets of our solar system (Mercury, Venus, Earth, Mars), composed primarily of heavy elements like silicon, oxygen, iron, and aluminum.

Jovian Planets

The gas giants of the outer solar system (Jupiter, Saturn, Uranus, Neptune), composed primarily of light elements like hydrogen and helium.

Doppler Shift

The change in frequency of a wave in relation to an observer who is moving relative to the wave source; a key phenomenon used to determine that galaxies are moving away from us.

Hubble's Law

The observation that galaxies are moving away from us at speeds proportional to their distance, providing evidence for an expanding universe.

Electromagnetic Spectrum

The range of all possible frequencies of electromagnetic radiation, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

Moon-forming Impact

The collision between a Mars-sized body and early Earth about 4.51 billion years ago that is believed to have formed our Moon.

Cosmic Microwave Background Radiation

The faint glow of light that fills the universe, dating back to about 380,000 years after the Big Bang when atoms first formed.

Redshift

The stretching of light waves from distant galaxies, indicating they are moving away from us and providing evidence for the expanding universe.

Dark Matter

An unidentified form of matter that doesn't interact with electromagnetic forces but has gravitational effects that can be observed in the universe.

Dark Energy

A mysterious form of energy that appears to be accelerating the expansion of the universe.

Habitable Zone

The region around a star where conditions might allow liquid water to exist on a planet's surface.