Earth Science Final Exam Study Guide Journey to the center of the Earth Chapter 2 Earth s magnetic field o Protects earth s surface from harmful solar wind o deflection aurora borealis Earth s composition overall o Iron oxygen mainly then silicon magnesium etc Earth s crust composition o Oxygen and silicon mainly Plate Tectonics Chapter 3 and 4 Distinction between crust and mantle o Chemical makeup asthenosphere vs lithosphere o Physical makeup rigidity bc temp o L crust and upper mantle rigid o A plastic Number of plates 15 20 types of plate boundaries o by earthquakes o active and passive o divergent MOR o convergent Subduction o transform how plates interact at boundaries o Subduction oceanic fault occurs with MOR not after Junctions o Old oceanic more dense so sinks under asthenosphere o Wadati benioff zone o Ocean crust not as old as continental bc of it o Causes volcanic arcs o Continental can t be subducted bc too buoyant o down going plates melt and produce magma which rises to the surface and leads to volcanoes Sea floor spreading o Upwelling mantle erupts at MOR o New crust moves away o Ocean crust sinks beneath continent with contact Minerals and Rock Groups Chapter 5 Most abundant class of minerals o Silicate minerals Three types of rocks order of most abundance Cooling and consolidation of magma o Igneous o Metamorphic o Sedimentary Igneous or sedimentary that changed bc high temperature pressure Chemical precipitation of material from water at surface or by deposition and cementation of particles and debris transported by water wind ice Igneous Rocks Chapter 6 Mafic vs felsic o Felsic more silica than mafic o Mantle is more mafic than crust o Increase silica increase viscosity resistance to flow Higher silica higher viscosity slower flow o Rhyolitic o Gabbro intrusive cools slow large grain lower silica Higher temperature lower viscosity higher gas content o basaltic extrusive cools quick crystals fine grain Geothermal gradient o Temperature increases with depth Categorization of intrusive magma o Tabular bodies traced laterally uniform thickness Dikes crosscuts rock Sills parallel to rock o Plutons large deep igneous body disrupting bedding bc rise of magma Metamorphic Rocks Chapter 8 Metamorphism occurs in solid state not including weathering or melting Four agents of metamorphism o Heat pressure differential stress hydrothermal fluids o Not all required often co occur o Rocks heated and chemically changed by the intrusting of a body of hot Contact metamorphism magma Sedimentary Chapter 10 Types of sedimentary rock o Clastic solid fragments and grains cemented together o Biochemical consist of shells of organisms o Organic consist of carbon rich remnants of plants o Chemical made from minerals precipitated directly from water Sandstone shale o Sandstone clastic rock sand size particles often deposited in beaches Quartz most common o Shale clay size quiet water environments organic rich source of natural gas Transgression regression o Transgression Flooding due to sea level rise o Regression Exposure due to sea level fall Volcanoes Chapter 9 Shield broad o slightly dome shaped basaltic lava cinder cone o conical piles of tephra stratovolcanoes o composite o large cone shaped o alternating layers of lava and tephra o most common for explosiveness and feslic lava eruptive styles and connection to magma type and viscosity o basaltic mafic lava very hot low silica low viscosity thin and fluid flow fast and farther o andesitic viscous slow flow mound around vent o rhyolitic most viscous rarely flow cause pressure and volcano explodes o effusive eruptions produce lava flow commonly basaltic create shield o explosive eruptions produce pyroclastic flows andesitic or rhyolitic form strato Continental hot spot vs Oceanic o C more feslic lava because melted by hot spot and gets included in lava Earthquakes Chapter 10 Hypocenter Epicenter o spot within earth where waves originate o surface location above hypocenter o 3 seismic stations tell location Circle around each station and radius to distance to epicenter Circles will intersect and point of intersection epicenter Seismic Waves o Order of waves P waves first S waves second surface last o Body waves pass through earth s interior Primary compressional push pull only back and forth fastest Secondary Shear shaking motion slower up and down motion o Surface Waves along earth s surface Slowest most destructive Love back and forth motion snake Ground moves perpendicular to travel direction Rayleigh ripple motion circular motion churning effect Like sheer Locations of Earthquake occurrences globally o Linked to plate tectonic boundaries Mountain Building Chapter 11 Folds o Due to ductile deformations bend bc high temperature and pressure o Show process that shaped rocks in that area o Types Anticline fold shaped like an arch Syncline fold opening upward like a trough Joints Faults o Natural crack or fracture by brittle deformation o No displacement difference from fault o Fractures in rocks because displacement o Major earthquake and two plates moving side to side o Can be very long or very tiny o Ubiquitous all scales o Compression and divergence o Strike slip no vertical vs Dip slip vertical o Types Marker bed bed in rock that can be clearly identified between hanging and footwall tell which way hanging wall moved with respect to footwall o Fault Orientation Hanging wall block above fault vs Footwall block below fault if in tunnel in fault head is by hanging wall block vs standing on footwall block Reverse and Thrust Fault o Hanging wall pushed up the foot wall convergent o Reverse is steeper than thrust o Thrust continental collision stress Normal Fault o Hanging wall pulled down the footwall o Crust pulled apart divergent Geologic Time Chapter 12 Relative Ages correlation o Fossils strata geologic maps latitude longitude depth to show o Rates of sedimentation vary greatly even if seemingly pattern o Gaps exist in sediment record Unconformity a boundary between layers representing a gap between 2 ages touching Absolute o Isotopes elements with varying numbers of neutrons o Rate occurs consistently o Radioactivity elements transform randomly into another isotope of same element or another element o Rate of decay unaffected by environmental changes o Radiometric dating uses naturally occurring radioactive isotopes to tell absolute age of minerals rocks The Cambrian Explosion o Precambrian before 542 million years ago o life