The Earth's interior is composed of four layers, three solid and one liquid—not magma but molten metal, nearly as hot as the surface of the sun. The deepest layer is a solid iron ball ...

Plate tectonics is the theory that Earth's outer layer is made up of plates, which have moved throughout Earth's history. The theory explains the how and why behind mountains, volcanoes ...

Many parts of Earth are covered and protected by a layer of organisms called a biocrust. The layer acts as a skin for the Earth, protecting landscapes and reducing long-term damage. But climate ...