The presentation by ACWADAM on earth system deals with the four elements that make up this system. Earth science generally recognizes four spheres, the lithosphere, the hydrosphere, the atmosphere, and the biosphere; these correspond to rocks, water, air, and life. These four interdependent parts or the earth's spheres are described as:

• the lithosphere, which contains all of the cold, hard, solid rock of the planet's crust (surface), the hot semi-solid rock that lies underneath the crust, the hot liquid rock near the center of the planet, and the solid iron core (center) of the planet
• the hydrosphere, which contains all of the planet's solid, liquid, and gaseous water,
• the atmosphere, which contains all of the planet's air, and
• the biosphere, which contains all of the planet's living organisms.

These spheres are so closely connected that a change in one sphere often results in a change in one or more of the other spheres. The presentation deals with the interrelations between earth’s spheres or processes.

This presentation is part of the training modules on planning, development and management of groundwater with special reference to watershed management programmes by ACWADAM. Please write to ACWADAM at acwadam@vsnl.net for sourcing these presentations.