|asthenosphere (əsˈθiːnəˌsfɪə, -ˈθɛn-)|
|See also isostasy a thin semifluid layer of the earth (100--200 km thick), below the outer rigid lithosphere, forming part of the mantle and thought to be able to flow vertically and horizontally, enabling sections of lithosphere to subside, rise, and undergo lateral movement|
|[C20: from astheno-, from Greek asthenēs weak + |
|a printed punctuation mark (‽), available only in some typefaces, designed to combine the question mark (?) and the exclamation point (!), indicating a mixture of query and interjection, as after a rhetorical question.|
|an extraordinary or unusual thing, person, or event; an exceptional example or instance.|
|asthenosphere (ās-thěn'ə-sfîr') Pronunciation Key
The upper part of the Earth's mantle, extending from a depth of about 75 km (46.5 mi) to about 200 km (124 mi). The asthenosphere lies beneath the lithosphere and consists of partially molten rock. seismic waves passing through this layer are significantly slowed. Isostatic adjustments (the depression or uplift of continents by buoyancy) take place in the asthenosphere, and magma is believed to be generated there. Compare atmosphere, hydrosphere, lithosphere.