Test: Our Changing Earth - 1

The lithosphere, which is the rigid outermost shell of a planet (the crust and upper mantle), is broken into tectonic plates. The Earth's lithosphere is composed of seven or eight major plates and many minor plates.Lithospheric plates are regions of Earth's crust and upper mantle that are fractured into plates that move across a deeper plasticine mantle. Earth's crust is fractured into 13 major and approximately 20 total lithospheric plates.

The lithosphere is broken into a number of plates known as the lithospheric plates. These plates move around very slowly because of the movement of the molten magma inside the earth which moves in a circular manner.

It means that the earth movements are divided on the basis of forces and the forces are Exogenic and Endogenic forces

The forces coming from within the earth and causing horizontal and vertical movements are called as endogenic forces A.K.A. Comet and meteoroid impacts, the tidal force of the moon and the radiation from the sun are all exogenic. Weathering effects and erosion are also exogenic processes.

Endogenic forces are those forces which act in the interior of the earth. Exogenic forces that work on the surface of the earth. These movements like volcano and earth quakes cause mass destruction over the surface of the earth. A volcano is a vent (opening) in the earth’s crust through which molten material erupts suddenly.

Exogenic (A.K.A. exogenetic) refers to external processes and phenomena that occur on or above the surface of the earth. Comet and meteoroid impacts, the tidal force of the moon and the radiation from the sun are all exogenic. Weathering effects and erosion are also exogenic processes. Exogenic forces are mainly driven by solar energy and gravitational energy. Weathering, mass movements, erosion and deposition are exogenous processes. Running water, wind, snow and waves are agents in exogenous processes and these agents are also known as “Geomorphic agents”.Some other examples of exogenous process are rainfall, snowfall, hailstorm, erosion ,tsunamis, avalanches, winds, wave currents etc. hence,volcano is not a Exogenic force.

The lithosphere is broken into a number of plates known as the lithospheric plates. These plates move around very slowly because of the movement of the molten magma inside the earth which moves in a circular manner. Endogenic forces cause the sudden movements like earthquakes, volcanoes, landslides which cause mass destruction over the earth's surface.

A volcano is an opening in the Earth's crust that allows molten rock, gases, and debris to escape to the surface.

The place in the crust where the movement starts is called the focus. The place on the surface above the focus is called the epicenter. Vibrations travel outwards from the epicenter as waves. The greatest damage is usually closest to the epicenter and the strength of the earthquake decreases away from the center.

 When the Lithospheric plates move, the surface of the earth vibrates. The vibrations can travel all round the earth. These vibrations are called earthquakes.