Earth's Interior

Plate Tectonics

A scientific theory explaining how Earth's crust moves and is divided into large, rigid plates that shape the planet's surface.

Continental Drift

An early theory proposed by Alfred Wegener in 1912 suggesting that continents were once joined in a supercontinent called Pangaea.

Pangaea

The supercontinent that existed millions of years ago, where all continents were once connected.

Fossil Evidence

Similar plant and animal fossils found on different continents supporting the idea that continents were once connected.

Subduction

The process where one tectonic plate moves under another, creating deep ocean trenches and volcanic arcs.

Minerals

Naturally occurring, solid substances with a specific chemical composition and a definite crystalline structure.

Rock Cycle

A continuous process that describes how rocks change over time involving three main types: igneous, sedimentary, and metamorphic.

Igneous Rocks

Rocks formed from cooled and solidified magma or lava.

Sedimentary Rocks

Rocks formed from compacted and cemented sediments.

Metamorphic Rocks

Rocks formed when existing rocks are changed by heat and pressure.

Hardness

A mineral's resistance to being scratched, measured using Mohs Scale of Hardness.

Cleavage

The tendency of a mineral to split along flat surfaces.

Streak

The color of a mineral's powder when rubbed on an unglazed white tile.

Luster

How light reflects off a mineral's surface, which can be metallic or non-metallic.

Convection

Circular motion caused by heat differences, occurring in liquids and gasses.

Seismic Waves

Waves produced by earthquakes that help map Earth's internal structure.

Acid Test

A method for identifying carbonate minerals by observing reactions with acids.

Uplift and Exposure

Geological processes that bring buried rocks to the Earth's surface, restarting the weathering process.

Weathering and Erosion

The series of mechanisms by which sediments are transported and deposited.

Convergent Boundaries

Tectonic plate boundaries where plates move toward each other, often causing one plate to be forced below another.

Divergent Boundaries

Tectonic plate boundaries where plates move apart from each other, resulting in the formation of new crust as magma rises.

Transform Boundaries

Tectonic plate boundaries where plates slide past one another horizontally, often causing earthquakes.

Mantle

The thick layer of Earth located between the crust and the core, composed of semi-solid rock that flows slowly.

Inner Core

The solid innermost layer of Earth, primarily made of iron and nickel, and extremely hot.

Outer Core

The liquid layer of Earth's core, also composed of iron and nickel, lying beneath the mantle.

Crust

The thin outer layer of Earth, consisting of solid rock, that forms the planet's surface.

Criteria for Minerals

A substance must be naturally occurring, inorganic, solid, have a definite chemical composition, and a crystalline structure to be classified as a mineral.