The Earth is made up of layers, much like the inside of an onion. At the center is the core. It is divided into the solid inner core and the liquid outer core. The core is the hottest part of the planet, and it is surrounded by a middle layer of melted rock that moves like a liquid, called the mantle.

The upper-most part of the mantle becomes solid. Above this is the crust. The crust is made up of hard rock and is the outer layer of the Earth. Together, these solid parts are known as the lithosphere.

Above the lithosphere is the atmosphere, which is the air that surrounds the planet. Below the lithosphere is the asthenosphere. In the asthenosphere, heat from the core causes rocks to melt. The melted rock in the asthenosphere moves like a thick, sticky liquid. Scientists have a name for the point where the lithosphere changes to the asthenosphere. It is called the lithosphere-asthenosphere boundary (LAB).

There are two types of lithosphere. Continental lithosphere is found on land, while oceanic lithosphere makes up the sea floor.

Plate Tectonics

The lithosphere is divided into huge slabs called tectonic plates. The heat from the mantle makes the rocks at the bottom of lithosphere slightly soft. This causes the plates to move. The movement of these plates is known as plate tectonics. Most tectonic activity takes place where these plates meet. They collide, tear apart, or slide against each other.

Tectonic activity is responsible for many natural events. These include earthquakes and volcanoes. Plate tectonics is what allows mountains and deep ocean trenches to form.

Our Planet's Five Influences

The hard rock of the lithosphere is just one influence on the Earth. Ice, liquid water, air and living things play an equal role in shaping the environment.

For example, soil is created through a combination of environmental factors. Wind or rain can wear down rocks in the lithosphere. Then, plant and animal remains mix with these rocks to create fertile soil.

These five influences shape every environment on Earth. In mountain ranges, the lithosphere interacts with the thinner air and snow to create a cool or even icy climate zone. Wind can wear rocks into sandy deserts. Healthy soil and rain make it easy for living things to grow in the forest. Plants and animals have adapted over time to fit all of Earth's environments.

Extraterrestrial Lithospheres

All non-gas planets have lithospheres, but they are not all alike. The lithospheres of Mercury, Venus and Mars are much thicker and more rigid than Earth's lithosphere.