Unformatted text preview: easing material Material coalesces into planets, moons or comets Other material is ejected to the periphery Our Solar System 4 inner planets (terrestrial) 4 outer planets (gaseous) Solar nebula photographed by Hubble The Earth Core is composed of mixtures or alloys of iron
(pressure is more than a million times that at the surface and temperature is estimated to be at 4000 4000C); has a solid inner core and a liquid outer core (earth's magnetic field may be produced by the motion of the liquid material in the iron -rich ironouter core) Layer outside the earth's core is the mantle; it is solid but very hot, near the melting point of rocks, so it flows almost like a liquid, though much slower; it is 70% of the earth's volume The Earth Outermost layer is the crust; it is extremely thin
(is thinner under the oceans than under the continents) Oceanic crust is made of basalt (low in silica and high in iron and magnesium) and has a higher density compared to continental crust, which is made of granite (high content of aluminum and magnesium silicate with quartz and feldspar) and has a lower density Thus, continents lie above sea level and oceanic crust lies below sea level because of density differences Formation of the Oceans: Prevailing Theory The major trapped volatile was water (H2O). Others
included nitrogen (N2), the most abundant gas in the a...
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- Spring '09