Introduction to Earth Science

Regions of the Earth

The Earth is divided into 3 major regions or spheres:

1. Atmosphere - the envelope of gases surrounding the Earth. It provides the oxygen we breathe and protects us from ultraviolet light.
2. Hydrosphere - comprising 71% of the Earth's surface, water is dynamic. It continually evaporates and precipitates to form an important Earth system.
3. Solid Earth - the solid Earth is divided into three principal regions based on composition.
   
   1. Core - dense inner sphere - center of the Earth
   2. Mantle - less dense area surrounding the core
   3. Crust - the most superficial part of the solid Earth and the least dense
      The crust is thickest in mountain ranges and the thinnest under the oceans.

   Biosphere - all biotic factors on Earth; an integral part of the planet which extends to all three parts of the Earth.

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