The Earth is a unique planet of the Solar family. It is composed of four spheres – the lithosphere, atmosphere, hydrosphere and biosphere. This lesson deals with the internal (endogenetic) processes of the Earth: its layers, rocks, plate tectonics, earthquakes and volcanoes.
1. Spheres of the Earth
The Earth's surface is a vast area of 510 million sq.km, where four spheres interact. The abiotic spheres are the lithosphere, atmosphere and hydrosphere; the biotic sphere is the biosphere.
| Sphere | Meaning |
|---|---|
| Lithosphere | The solid outer part of the Earth |
| Atmosphere | A thin layer of gases that surrounds the Earth |
| Hydrosphere | The watery part of the Earth's surface – oceans, rivers, lakes and water vapour |
| Biosphere | The layer of the Earth where life exists |