Layers of earths crust

by Vinutha 2010-02-13 12:36:45

The Earth is divided into three main layers: the crust, the mantle, and the core.

The outer layer is the crust, which contains about 0.6 percent of the Earth's volume. The depth of the crust varies from 3.5 to 5 miles (5 to 9 kilometers) beneath the oceans to 50 miles (80 kilometers) beneath some mountain ranges. The crust consists primarily of rocks such as granite and basalt.

The layer beneath the crust is the mantle. The boundary between the crust and the mantle is known as the Mohorovicic discontinuity (or Moho for short). The Moho is the dividing line between layers of different types of rock (crust and mantle), as well as the line at which the speed and direction of seismic waves (waves of motion within the Earth) shift.

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