The Physical Layers of the Earth

Vocabulary-style flashcards covering the physical and chemical characteristics of Earth's layers, including their state of matter, thickness, and composition.

Atmosphere

The outermost gaseous layer of the Earth, approximately $140\text{ km}$ thick, composed of $78\%$ nitrogen, $21\%$ oxygen, and $1\%$ trace gases.

Lithosphere

The solid outer layer approximately $100\text{ km}$ thick consisting of the crust and upper mantle, divided into rigid tectonic plates.

Asthenosphere

A plastic-like, semi-fluid layer of rocky silicates and oxides, about $200\text{ km}$ thick, that allows tectonic plates to move and interact.

Mesosphere

A solid layer with an average thickness of $2,885\text{ km}$ where rocks flow gradually, contributing to convection currents that drive tectonic plates.

Outer Core

A liquid layer of iron and nickel, about $2,270\text{ km}$ thick, responsible for generating the Earth's magnetic field via electric currents.

Inner Core

The densest and hottest layer of Earth, a solid sphere of iron and nickel with a radius of about $1,276\text{ km}$ ($1,491\text{ miles}$).

Crust

The thinnest ($2-7\text{ miles}$) and coolest layer, composed of silicon, aluminum, granite, and basalt with a density of $2.7-3.3\,\text{g/cm}^3$.

Convection Currents

The main method of heat transfer from the core to the crust, occurring in the mantle and causing changes in the Earth's surface.

Greenhouse Effect

The process through which the atmosphere regulates the planet's temperature to support life.

Mantle

The thickest layer of the Earth (about $1,800\text{ miles}$) composed of magnesium and other metals, which is solid but capable of flow.

Density of Outer Core

The concentration of matter in the liquid outer layer, ranging from $9.9-12.3\,\text{g/cm}^3$.

Density of Inner Core

The concentration of matter at the center of the Earth, ranging from $12.6-13.0\,\text{g/cm}^3$ (also cited as $12.-13.9\,\text{g/cm}^3$).

Composition of the Lithosphere

Mainly composed of granite and basalt silicates.

Magnetic Field

Produced by movement within the outer core, this shields the Earth from solar wind and cosmic radiation.