Structure of the Earth

Compositional (Chemical) Compositional (Chemical) LayersLayers

Crust: Low densityCrust: Low density High in silicon (Si) and oxygen (O)High in silicon (Si) and oxygen (O)

Moho: Density boundary between crust and Moho: Density boundary between crust and mantle mantle

Mantle: Higher densityMantle: Higher density High in Magnesium (Mg) and Iron (Fe)High in Magnesium (Mg) and Iron (Fe)

Core: High in Nickel (Ni) and Iron (Fe)Core: High in Nickel (Ni) and Iron (Fe)

Earth: The Giant Magnet

Magnetic field created by liquid iron Magnetic field created by liquid iron convecting in outer core.convecting in outer core.

Magnetic field directs solar winds (ionized Magnetic field directs solar winds (ionized particles) around the Earth or to the poles.particles) around the Earth or to the poles.

Aurora Borealis

Heat Flow in the Earth

Heat sources: Heat sources: latent heat from the formation of the Earthlatent heat from the formation of the EarthRadioactive decay in the core and mantleRadioactive decay in the core and mantle

Temperature at core: 3000-5000Temperature at core: 3000-5000°° C C

Cooling processes:Cooling processes:Convection currentsConvection currentsPlate tectonics (volcanoes)Plate tectonics (volcanoes)

Mechanical (Physical) Layers of the Earth

Lithosphere: Crust and upper, solid part of the mantle; “plates” in plate tectonics

Asthenosphere: Partially molten part of mantle; location of convection current that drive plates

Outer core: Liquid

Inner core: SolidGreatest temperatures, solid due to intense pressure

Evidence for Structure of the Earth

Seismic (earthquake) wavesSeismic (earthquake) waves

P waves (Primary): Longitudinal P waves (Primary): Longitudinal (compressional) waves; faster, can move (compressional) waves; faster, can move through any matterthrough any matter

S waves (Secondary): Transverse waves. S waves (Secondary): Transverse waves. Can only travel through solid matter.Can only travel through solid matter.

Evidence for Structure of the Earth Cont.

S waves can not travel through the outer S waves can not travel through the outer core. core.

Rock Types

Igneous: Solidified molten magmaIgneous: Solidified molten magma

2 types of Igneous2 types of Igneous

Extrusive (volcanic) = erupted Extrusive (volcanic) = erupted lavalava

Cools more quickly, so only small crystals Cools more quickly, so only small crystals form. form.

Intrusive (plutonic) = never erupted Intrusive (plutonic) = never erupted magmamagma

Cools more slowly within the earth, so larger Cools more slowly within the earth, so larger crystals can form.crystals can form.

Quartz= Silica (SiOQuartz= Silica (SiO22), light ), light color. Magma high in silica is color. Magma high in silica is viscous.viscous.

High silica magma found in High silica magma found in more explosive volcanoes due more explosive volcanoes due to build up of pressure with to build up of pressure with more viscous magma. more viscous magma. Forms stratovolcano (cone Forms stratovolcano (cone shape)shape)

Low silica magma found in less Low silica magma found in less explosive volcanoes. explosive volcanoes. Form shield shape.Form shield shape.

Extrusive Igneous Rock

BasaltBasalt AndesiteAndesite RhyoliteRhyolite

Low in silicaLow in silica High in SilicaHigh in Silica

BlackBlack Pale pink, greyPale pink, grey

Intrusive Igneous Rock

GabbroGabbro DaciteDacite GraniteGranite

Low in SilicaLow in Silica High in SilicaHigh in Silica

BlackBlack Pale Grey, pinkPale Grey, pink

Sedimentary Rock

Sedimentary rock: formed by compaction of Sedimentary rock: formed by compaction of sediments. Classified by particle size.sediments. Classified by particle size.

Sandstone

Shale

Sedimentary Rock cont.Sedimentary Rock cont.

Almost all fossils found in Almost all fossils found in sedimentary rocksedimentary rock

Almost all fossil fuels (coal, oil, Almost all fossil fuels (coal, oil, gas) found in sedimentary gas) found in sedimentary rock.rock.

Metamorphic RockMetamorphic Rock

Metamorphic rock is Metamorphic rock is rocked that has been rocked that has been changed by heat and/or changed by heat and/or pressure. pressure.

Caused by burial and Caused by burial and proximity to volcanic proximity to volcanic areas.areas.

Dense, often streaks/folds Dense, often streaks/folds Many gemstones are Many gemstones are metamorphic.metamorphic.

Rock Cycle