The Earth System - The Earth System 2/19/09 7:38 PM The...

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Unformatted text preview: The Earth System 2/19/09 7:38 PM The Planets Terrestrial Planets o Mercury, Venus, Earth, Mars Jovial Planets o Jupiter, Saturn, Neptune, Pluto The Earth in space Smallish planet orbiting a medium star on the edge of a medium galaxy Earth hurling through space at 66,600 miles/hr Energy & Mass Balance Earth is mostly self-contained except that except nearly all the energy comes from the sun an88d there is a small amount of mass exchange to and from the earth The Earth Functions as a System of Interconnected Spheres Spherical layers arranged by density Most interactions between spheres are along the interfaces of the spheres Geosphere all solid parts Hydrosphere Atmosphere Biosphere Earths Interconnected, Dynamic Layers Energy from solar radiation o Atmosphere top, least dense layer, about 100km thick o Hydrosphere oceans, lake, rivers, groundwater o Cryosphere Polar ice caps, alpine glaciers o Biosphere All life Energy from Earths interior o Lithosphere outer rigid shell, includes crust(0.4% of Earths mass) and upper mantle o Asthenosphere weak, ductile layer of mantle o Deep mantle (67.1% of Earths mass) o Outer core liquid iron (30.8% of Earths mass) o Inner core solid iron (1.7% of Earths mass) Geosphere Layers How do we know? Crust observe directly (oceanic, continental) Upper mantle material from volcanoes Deep mantle and core o Meteorites pieces of broken planet Stony (mantle material) Fe-Ni (core material) o Seismic waves produced by earthquakes Compressional (pass through solid, liquid, gas) Shear (pass through solid only) Characteristics Mantle o High density silicate minerals (O, Si, Mg, Fe, Ca, Fe) o The first ~100km of mantle is strong and rigid (solid) o the rest is weak and deformable, ductile (plastic) Outer core o Mostly Fe, but also Ni, S, O o Liquid because of high temp o Density of 11 g/cm3 Inner core o Mostly Fe, but also Ni o Solid because of high pressure o Density of 13 g/cm3 Geodynamo System: Convection in outer core = Earths Magnetic field Convection o Moves hot water from bottom to the top, cools, moves laterally, sinks, warms and rises again o Asthenosphere and Outer core Liquid Outer Core o Convection possible because its a liquid o Core consists of Fe, which is a goof conductor o Generates a magnetic field o Radiates far into space Shields Earth from much Solar radiation Makes life on Earth possible Plate tectonics in Geosphere Driven by convection generated by internal heat of the Earth Lithosphere o Cold, rigid shell of sold Earth o Crust and upper rigid mantle (down to ~ 100km) o Zero thickness at some plate boundaries (volcanic) o Up to 200km thick under old, cold parts of continents Asthenoshpere o Ho, weak, ductile upper mantle that deforms with plate motion Deep mantle appears to be part of convecting cells Plate motion of cm/yr Crust Key Points...
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The Earth System - The Earth System 2/19/09 7:38 PM The...

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