Planet Earth Lecture 1 01 29 2014 Geocentric Model Heliocentric Model 270 BC Claudius Ptolemy believed geocentric universe and circular orbits but had to explain retrograde motion planets came back before started to go around again Copernicus s revolution Heliocentric view of the universe Tychonic System a hybrid of geo and heliocentric models Unmoving Earth is the center Both Sun and Moon orbit Earth 1600 Kepler showed that planets had elliptical orbits Doppler Effect Sound frequency stretching and squeezing as it passed and come towards two different areas A B Hubble Expanding Universe Big Bang theory created the Universe 13 7 Billion years ago Supernovae explode and scatter mass into space forming all remaining 92 elements Other 9 up to iron are found in the sun Codys Dick Fucking huge Bitches love it o Fucked your mom and sister wag Planet Earth Lecture 2 01 29 2014 Proto Earth was almost entirely magnum Must be sphere to be a planet Gravitational stratification of the earth into iron nickel Inner core solid outer core molten mantle lithosphere crust Earth Top 4 Elements oxygen iron silicon magnesium organic compounds Volcanoes let us sample the inner earth Drilling doesn t work Tried in Russia and only got into the crust Continental Crust Oceanic Crust 1 Average Composition of Earth s Crust Granodiorite 2 Average Composition of Ocean Crust Gabbro Basalt Most common lava rock 3 Mantle Rocks Peridotite Low silica high density Earth s Density 5 5 g cm 3 Surface Rock Density 2 5 3 0 g cm 3 Mohorovicic Discontinuity Moho Between Mantle and crust Least dense Dr Inge Lehmann discovered the Earth s inner core Earth is geothermal gradient higher temp and pressure as we go deeper into the Earth Lithosphere Rigid Brittle Crust and mantle Outer 100 150 km Asthenosphere Soft ductile Between 150 350 km Big part w plate tectonics Plate Tectonics Theory developed in 60s Outer layer of Earth s crust consists of plates Alfred Wegener German meteorologist came up w book that says continents have moved and still are across Earth Obvious fit of continents Evidence for distribution of glaciers Glaciation o 260 280 Ma Warm and Cold belts Distribution of fossils PANGEA supercontinent Harry Hess 1906 1969 Agreed w Wegener that not only does land move but also the Hess s concept of Sea floor spreading new crust gets formed in Subduction the older crust is pressed into the mantle where it oceans one spot melts Magnetic fields in oceanic crust are symmetric Can fold perfectly Positive Negative Planet Earth Lecture 3 01 29 2014 Crust Density Ocean Crust 3 g cm 3 Continental Crust 2 7 g cm 3 Lithosphere floats on asthenosphere Divergent Boundaries Where new crust is formed Divergent means to go away from Magma pushes boundaries away Rift Valley pulls two parts apart Ophiolite slice of oceanic crust that has been thrust onto continental crust Sheeted dikes Composed of gabbro coarse grain igneous material Layered Gabbro Coarse grained igneous rock Crystallize slow Bigger grain How do divergent boundaries develop Rifting Planet Earth Lecture 4 5 01 29 2014 Plate Tectonic Boundaries Convergent Boundaries Crust is consumed Continuous Crystallization All the same crystals Discontinuous Crystallization Crystals previously formed react w melt to produce new minerals Series of chemical reactions that take place in silicate magmas as Bowen s Reaction Series they cool Help us understand the evolution of magmas Tells the conditions that formed the igneous rock Magmatic Differentiation Crystal settling Magma contamination Assimilation Magma Mixing Igneous Rocks Fine Grained Coarse Grained Mixed Grain Size o Phenocrysts the large grains o Ground mass or matrix the fine material Grain Size tells us time Color tells us composition o Darker Lower silica o Lighter more silica Dike Vertical Cuts across the original layering Sill Horizontal Pushes its way in and pushes area up Pluton A large igneous rock body that has cooled beneath the Earth s surface Intrusive Cooling rate decreases with increased depth Entire ocean floor is igneous rocks Planet Earth Lecture 6 Volcanism 01 29 2014 Process of magma breaching land surface and running on the crust where it solidifies into rock Volcano Parts Magma Chamber Magma builds up here Chimney Rim Crater Flank Vents Summit central Vent Caldera Volcano Status Factors Controlling Volcanic Activity Composition of Magma o Basalt 50 o Granite 70 o Higher silica higher viscosity o Silica structures limit flow o Granite lavas have short thick flows Active erupted recently Dormant have not erupted for centuries to thousands of years can still erupt Extinct Erupted in the past but will not again Temperature of Magma o Hotter magmas are less viscous and flow better o Basalt melts lower silica higher temp o Granite melts higher silica lower temp Percentage of dissolved gasses in magma Types of basalt lavas Named after Hawaiian names since Hawaii is made of basalt Pahoehoe o Smooth or ropy Aa o Broken off sharp pieces empty is a lava tube Lava Tube A lava highway A tunnel drains the lava and if left Columnar Joints Tall columns Develop interior or thick flows during final cooling stage Form roughly hexagonal columns found in basalts Vesicles in Scoria Frozen gas bubbles in more viscous magmas Pyroclastic Material Anything blown out of the volcano Types of Volcanoes Shield Volcanoes o Biggest All made of lava basalt Cinder Core o Smallest All made of paracouten gravel pyroclastics Composite Volcano or stratovolcano o Made of both basalt and pyroclastic Classic volcano Volcanic Gases Volatile Material Planet Earth Lecture 7 Sedimentary Rocks 01 29 2014 Formed at near Earth s surface by o Precipitation o Skeletal growth o Cementing sediment loose material Occur in the upper crust as a veneer covering older igneoys metamorphic rocks Cover 80 of Earth s surface but constitute 1 of Earth s makeup Processes that break down rocks and move sediments Weathering Breakup and decomposition o Mechanical Physical breaking into smaller pieces o Chemical chemical reaction Dissolution Oxidation o Jointing exfoliation thermal contraction and expansion Hydrolysis Hydration wedging frost Root Salt Erosion Transportation of sediments Weathering attacks an edge on 2 sides Attacks corner on 3 sides Attacks a face on one side Rocks Quartz Clay Calcite Factors affecting rate of weathering Rock mineral type Climate Time Layers Soil sediment that can support growth of plant life o O Horizon upper layer Dark organic matter