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The mantle is a layer inside a terrestrial planet and some other rocky planetary bodies. For a mantle to form, the planetary body must be large enough to have undergone the process of planetary differentiation by density. The mantle lies between the core below and the crust above. The terrestrial planets (Earth, Venus, Mars and Mercury), Earth's Moon, two of Jupiter's moons (Io and Europa) and the asteroid Vesta each have a mantle made of silicate rock.〔(【引用サイトリンク】 title=Earth Structure )〕〔(【引用サイトリンク】 title=Moon ABCs Fact Sheet )〕〔(【引用サイトリンク】 title=Frequently Asked Questions about Europa )〕 Interpretation of spacecraft data suggests that at least two other moons of Jupiter (Ganymede and Callisto), as well as Titan and Triton each have a mantle made of ice or other solid volatile substances.〔(【引用サイトリンク】 title=Ganymede: In Depth )〕〔(【引用サイトリンク】 title=Callisto: In Depth )〕〔(【引用サイトリンク】 title=Triton: In Depth )〕 == Earth's mantle == The interior of Earth, similar to the other terrestrial planets, is chemically divided into layers. The mantle is a layer between the crust and the outer core. Earth's mantle is a silicate rocky shell with an average thickness of . The mantle makes up about 84% of Earth's volume.〔 It is predominantly solid but in geological time it behaves as a very viscous fluid. The mantle encloses the hot core rich in iron and nickel, which makes up about 15% of Earth's volume.〔 〕 Past episodes of melting and volcanism at the shallower levels of the mantle have produced a thin crust of crystallized melt products near the surface, upon which we live.〔 〕 Information about structure and composition of the mantle either result from geophysical investigation or from direct geoscientific analyses on Earth mantle derived xenoliths and on mantle exposed by mid-oceanic ridge spreading. Two main zones are distinguished in the upper mantle: the inner asthenosphere composed of plastic flowing rock of varying thickness, on average about thick, and the lowermost part of the lithosphere composed of rigid rock about thick.〔(Lithosphere: Schlumberger Oilfield Glossary ). Glossary.oilfield.slb.com. Retrieved on 2013-05-11.〕 A thin crust, the upper part of the lithosphere, surrounds the mantle and is about thick.〔(Crust: Schlumberger Oilfield Glossary ). Glossary.oilfield.slb.com. Retrieved on 2013-05-11.〕 Recent analysis of hydrous ringwoodite from the mantle suggests that there is between one and three times as much water in the transition zone between the lower and upper mantle than in all the world's oceans combined. In some places under the ocean the mantle is actually exposed on the surface of Earth.〔(Mission to Study Earth's Gaping 'Open Wound' ). LiveScience. Retrieved on 2013-05-11.〕 There are also a few places on land where mantle rock has been pushed to the surface by tectonic activity, most notably the Tablelands region of Gros Morne National Park in the Canadian province of Newfoundland and Labrador and St. John's Island, Egypt or Zabargad in the Red Sea. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mantle (geology)」の詳細全文を読む スポンサード リンク
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