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=__//** Asthenosphere **//__=


 * n. A zone of the earth's mantle that lies beneath the lithosphere and consists of several hundred kilometers of deformable rock.
 * The asthenosphere is the layer of Earth that at a depth 60–150 mi (100–250 km) beneath Earth's surface.
 * It was first named in 1914 by the British geologist J. Barrell, who divided Earth's structure into three major sections.
 * The asthenosphere gets its name from the Greek word for weak, asthenis, because of the fragile nature of the materials of which it is made.
 * It lies in the upper portion of Earth's structure known as the mantle.
 * Earhquakes don't occur in the asthenosphere!
 * The asthenosphere is made of plastic rock (solid, but able to flow), and is composed of olivines, pyroxenes, spinels and garnets.
 * The asthenosphere supplies new material to replace lithospheric materials that have been displaced by some other tectonic or geologic mechanism.
 * Sometimes referred to as the ‘weak sphere’, it is characterized by being weaker and more elastic than the surrounding mantle.
 * The temperature is about 1,600 C.