Overview of Earth's Spheres
The Earth consists of four 'spheres' which pertain to the Earth's major reservoirs of matter and energy.
LITHOSPHERE: The solid, rocky shell of the Earth is the lithosphere. This outermost layer of rock is about 100 km thick.
ATMOSPHERE: The thin layer of air that surrounds our planet is the atmosphere. It contains nitrogen, oxygen, carbon dioxide, and other gases.
BIOSPHERE: All living organisms are part of the biosphere. This includes everything from plants to animals to one-celled organisms. It permeates the other spheres.
HYDROSPHERE: All of the water that is on or near the earth's surface is part of the hydrosphere. This includes large areas of ocean water, ice in glaciers, and moisture in the air.