Week 2 Lecture- Earth Structure
Week 2 Lecture- Earth Structure GEO 101
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This 4 page Class Notes was uploaded by Emma Foster on Saturday January 24, 2015. The Class Notes belongs to GEO 101 at University of Alabama - Tuscaloosa taught by Keene in Spring2015. Since its upload, it has received 127 views.
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Date Created: 01/24/15
Earth Structure 1 Internal Layers How we know about the layers 2 Magnetic field 3 Atmosphere Earths Magnetic Field 9 Geographic north magnetic south Magnetic poles wander amp reverse What does this tell us about the earth 9 has to be something that is capable of maintaining a magnet Magnetic field grows really weak in reversal The Earth39s mviagnet39c Fuefd What is Earth made of Iron 321 Oxygen 301 Silicon 151 Magnesium 139 Other 88 The La ers of the Earth How do we know about the layers Seismic Geology Uses natural or added wave energy Measure how the waves behave The Interior of the Earth Waves move differently through different materials Distance and time 9 Velocity Velocity helps determine property Change in velocity determines boundaries Seismic wave refraction amp re ection l high frequency l low frequency 2 way travel time down amp back Wave paths in the Earth If Earth was homogeneous 9 Exactly the same inside All waves would transfer straight through Earth No waves Eadhgyakg I Q 5 0 Crust 9 Continental 1525 miles less dense mostly made out of granite Oceanic 46 miles more dense made out of basalt PHYSICALLY DIFFERENT FROM ONE ANOTHER Continental crust g A v 4 1 n o v v o 3 a 39 h a s 39 quot o z o J nu Q s 39 V y w a w 39 A m I 39 5 I 39 I Q Mantle 9 Soft solid plastic solid but can change shape Ex Play dough Largest Layer becomes softer as it goes down transition zone Three parts hotter as you go down Convection movement water air liquid solid cold is coming down amp heat rises How do we know composition 9 rocks thought to have originated there 9 seismic waves 0 more pressure amp temperature with depth9 acts more plastic Core 9 Iron rich 9 outerliquid 9 innersolid 9 creates magnetic field 0 Re ects particles that would burn us all gt helps create atmosphere How do we know core composition meteorite composition seismic waves 4 Swave don t travel through liquid Pwave travel one side to another Density General properties Get deeper 9 pressure amp temperature rise Temperature pressure rock type physical properties Heat At 100km rock gets soft The core may be 8492 degrees F Heat in core from 0 Formation 0 Friction 0 Radio activity Boundaries Between layers there will be boundaries Change between sections amp subsections Moho mohorovicic discontinuity We have not drilled to it 0 Boundary between crust and upper mantle The Layers of the Earth Lithosphere crust upper mantle transition zone ROCK Athenosphere lower mantle PLASTIC Laver overview 9 CRUST cool hard 9 LOWER MANTLE warm plastic 9 UPPER MANTLE warmer hard 9 OUTER CORE hot liquid 9 INNER CORE super hot solid Atmosphere Exists due to magnetic field Denser toward surface Combination of gases 78 nitrogen 21 oxygen 1 other