EES 1030 Lecture 13Outline of Last Lecture I. Plate TectonicsII. Continental DrifIII. Supercontinent PangaeaIV. Seafloor spreadingV. Geomagnetic ReversalsVI. Magnetism of Seafloor RocksVII. Three types of plate boundaryVIII.What drives plate motionsIX. Hot spots and mantle plumesOutline of Current Lecture X. The Earth’s InteriorXI. SeismologyXII. Global Network of Seismic StationsXIII.Body WavesXIV. The Crust-Mantle BoundaryXV. Seismic TomographyXVI.Earth’s layered structureXVII. The CoreXVIII. Earth’s Magnetic FieldThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best Used as a supplement to your own notes, not as a substitute.XIX.The MantleXX. The CrustXXI.The Oceanic CrustXXII. The Continental CrustXXIII. Layers defined with physical propertiesXXIV. Plate Tectonics and Internal HeatCurrent Lecture- Seismologyo The study of seismic waves generated by earthquakes and large explosions. o Seismic waves move at different velocities through rocks with different properties: density, elasticity, composition, pressure, and temperature- Global Network of Seismic Stationso Established to monitor international nuclear bomb test ban treaties- Body Waveso Travels through the Earth’s interior- The Crust-Mantle Boundaryo The Moho (Mohorovicic discontinuity) - Seismic Tomographyo Can see variations in lithosphere, subducting slabs etc. Need high-power computers.- Earth’s layered structureo Layers defined by  Composition Physical Properties such as mechanical strength- The Coreo An iron-rich sphere with a radius of 3486 km (2161 miles) – larger than the planet Marso Inner core: solid inner sphereo Outer coreo Iron is the only common element in the solar system that has the right density to form coreo Iron meteorites contains 5-10% nickelo Early differentiation: dense iron sank to form core, light silicate minerals formed mantle- Earth’s magnetic fieldo Large permanent bar magnet deep in Earth? Unlikely. Temperatures too hot for any material to retain its magnetismo Movement of electrically-conducting liquid iron in outer core  geodynamo- The Mantleo Solid rocky (silica-rich) shell that extends to a depth of -2900 km (1900 miles)o Makes up 82% of Earth’s volume- The Crusto Earth’s outer skin: range in thickness from -3km (2 miles) at some oceanic ridges to -80k (50 miles in some mountain belts)o Comprises 0.6% of Earth’s volumeo Two distinct types: Oceanic Continental- Different ages and compositions- The Oceanic Crusto Oceanic crust: density – 3.0 g/cm3o Compositino = mafic igneous rock basalto Oceanic crust is young <200 Ma- The Continental Crusto Continental crust: density -2.7 g/cm3o Composition = felsic igneous rock and andesiteo Some parts of continents are ancient (2-4 Ga)- Layers defined by physical propertieso With increasing depth, Earth’s interior is characterized by gradual increaseo Lithosphere: “rock” sphere, relatively cool, outer rigid shell of Earth. Forms the Earth’s tectonic plates that move. Comprises crust + uppermost Mantle varies in thickness from 70 km to 250 kmo Conduction: Heat transferred through crust by conductiono Convection: Heat transferred through mantle- Plate Tectonics and Internal Heato Major sources of Earth’s internal heat Heat from radioactive decay of isotopes of uranium, thorium, and potassium Heat released as iron crystallized to form the solid inner