Geology, Continental Drift, and Earth/Space Science

Crust

The part of the Earth we live on, broken into plates that float on the mantle.

Lithosphere

The zone of brittle rock that includes the crust and upper mantle.

Mantle

The largest layer of the Earth composed of very hot, dense rock, responsible for the movement of plates through convection currents.

Plate Tectonic Theory

The theory that Earth's crust is broken into pieces called plates that float on the mantle, and their movement causes geological events like volcanic eruptions and earthquakes.

Convergent Boundary

A tectonic plate boundary where plates move towards each other and can collide.

Divergent Boundary

A tectonic plate boundary where plates move away from each other, creating new crust.

Transform Boundary

A tectonic plate boundary where plates slide past each other, causing earthquakes.

Fossils

Preserved remains of living things found mostly in sedimentary rock that provide evidence of the history of life.

Law of Superposition

The geological principle that in undisturbed sedimentary rock layers, the oldest layers are at the bottom and younger layers are on top.

Relative Dating

A method of determining the age of rocks and fossils by comparing their placement within layers of rock.

Absolute Dating

A method used to determine the exact age of rocks by measuring radioactive decay.

Radioactive Dating

A technique used to determine the age of rocks by measuring the decay of radioactive elements.

Geologic Time Scale

A timeline used by geologists to represent the history of Earth and the evolution of life through different periods.

Universe

The vast space that contains all matter and energy, including galaxies, stars, and planets.

Galaxy

A large scale group of stars, bound together by gravity, typically containing about 100 billion stars.

Solar System

The collection of large and small bodies that orbit a central star, which in our case is the Sun.

Light-Year

The distance light travels in one year, used to measure distances between stars and galaxies.

Astronomical Unit (AU)

A measurement of distance equal to the average distance between the Earth and the Sun.

Planets

A celestial body that orbits a star, is rounded by its own gravity, and has cleared its orbital path of other objects.

Stars

A luminous sphere of plasma held together by its own gravity.

Black Hole

A region in spacetime with such strong gravitational effects that nothing, not even particles and electromagnetic radiation such