Exam3studyguide.pdf GSC 107
Popular in Natural Disasters - Hollywood Vs. Reality
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This 6 page Study Guide was uploaded by Angela Cameron on Monday October 12, 2015. The Study Guide belongs to GSC 107 at University of Miami taught by in Fall 2015. Since its upload, it has received 118 views. For similar materials see Natural Disasters - Hollywood Vs. Reality in Geology at University of Miami.
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Date Created: 10/12/15
Cameron 1 Natural Disasters Exam 3 Study Guide Rivers amp Floods QVXA 0 Q Total Flow 0 V Velocity Narrow Stream Faster Velocity Wider Stream Slow Velocity Causes deposition at deltas o A Area 0 Be able to identify meandering and braided streams o Meandering Curvy and snakelike Most Common Thalweg Deepest and highest velocity part of the stream Have point bar and cut bank 0 Braided Do not meander Form broad multichannel paths High Bedload Overloaded with sediment Deposited in islands between small channels Promoted by dry climate with little vegetation protecting slopes from erosion Point bar and cut bank 0 Point Bar Sediment deposition Inside of bend 0 Cut Bank Streams preferably erode Outside of meander beds Oxbow lake formation 0 Meandering stream 0 Comes closer and closer together until oodwater breaks through the neck between them 0 Occurs along CUT BANK 0 Looks like a hoof What is a oodplain o A broad strip of land built up by sedimentation on either side of a stream channel 0 Erosion and deposition of meanders moves river back and forth to create broad valley bottom Long term Bene ts farmers Causes problems for development Buffs Raised topography along the sides of a oodplain OOOO Landstes Cameron 2 0 Causes of landslides o Overstepping Adding material to the top of the slope Undercutting material from the toe o Instability of slope material Added water Removal of vegetation Earthquakes Types of downslope movement 0 Debris ows Mixed sediments 47 Water Examples Lahars ash Mud ows mudclay Triggers Heavy rainfall Earthquakes Volcanic eruptions o Rockfalls Develop in steep mountainous areas of cliffs Nearly vertical fractures or weaknesses Causes Pried loose by freezing water Triggered by ground shaking Large boulders bounce or roll far from the cliff Small fragments collect in m slope Talus Cones o Rocks come to rest at their angle of repose o Debris avalanches Rockfall material which breaks into small fragments Flows at high velocity in coherent stream Huge scale debris flow 0 Rotational slides and slumps Homogeneous cohesive soft materials slide on curving slip surface concave to sky Curvature rotates slide mass as it slips 0 Upper end of slide block tilts back as it moves 0 Lower part of slide moves outward from slope o Translational slides Move on preexisting weak surfaces Parallel to slope Occur on inherently weak layers such as Shale Old fault or slide surfaces Fractures Often move faster and farther than rotational slides May move as coherent mass or break up into debris ows 0 Soil creep Slow downslope movement of soil and weak rock Involves nearsurface movement by alternate expansion and shrinkage of soil Cameron 3 39 PFOCESSE Expansion pushes out perpendicular to slope Shrinkage collapses particles straight down Net change is slow movement downhill Causes kneeling trees 0 Snow avalanches Zone of Weakness Boundary between layer of dry snow and layer of tightly packed or frozen snow Conditions depend on Slope steepness Weather Temperature Slopefacing direction Wind speed and direction Vegetation Conditions within snowpack Triggers Weight of skier crossing slope Vibrations of snowmobile Movement of glacier Changes in temperature 0 FreezeThaw Action Earthquake Power Snow Avalanche Sinkholes Cornice o Overhanging edge of snow on a ridge or gully 0 Can build up horizontally due to wind blowing over 0 Can break off and start a bigger avalanche Formation H20 C02 H2CO3 carbonic acid CaCO3 limestone H2CO3 Ca2 2HCO339 o Weathering Action 0 Dissolves Limestone o Creates Caves Dissolvable rock types 0 Salt Halite o Gypsum o Limestone o Other Carbonates Cave formation stalactites and stalagmites o Cave Formation Limestone dissolves in slightly acidic rainwater Faster in humid areas Rainfall and surface water percolate through joints in limestone Dissolved carbonate rock is carried away from the surface Small depression gradually forms 0 Sinkhole Formation Sediments spall into a cavity Cameron 4 The cohesive covering sediments form a structural arch The cavity migrates upward by progressive roof collapse The cavity eventually reaches the ground surface creating a sinkhole o Stalactites At top of cave Form by rainwater running down limestone o Stalagmites Bottom of Cave Form by rainwater dripping down from stalactites Groundwater water table level uctuations 0 Can lead to sinkhole formation 0 Greatest potential for sinkholes Surface water percolates into ground recharging aquifers 0 Anything that causes the water table to uctuate can worsen sinkholes Underground mining of salt and gypsum Construction 0 Highest rate of dissolution occurs at level of water table Karst topography o A landscape of ragged quottoothyquot and beautiful rock formations o Formed from dissolution of limestone bedrock Wild res The three stages of re 0 Preheating Heating up 0 Flaming Combustion Catches on re 0 Glowing Combustion After the re Glowing left behind Ladder fuels 0 Underbrush 0 Process Low brush and branches ignite rst Spread re to tree branches Then tree tops 0 Crown res 0 Fire spreads by jumping from treetop to treetop 0 Once re has reached the crown of a tree intensity and rate of spread of a re go up dramatically o Smaller branches and needles at the top of a tree burn rapidly o A cluster of trees in a crown re can burn up in less than a minute 0 Types of evidence of res 0 Camp res o Cigarettes o Accelerants Gasoline 0 Lighting Strike Fulgurite Glassy residue Elongated fused mineral grains Cameron 5 o Preserves pattern of lighting strike 0 Wind direction 0 Direction of re movement Scorched sides of trees Unburned 39shadows39 0 In uence of topography O 0000 Impacts Flames rise because heat expands air Makes it less dense Move rapidly upslope Move slowly downslope Canyons can funnel air upward like a chimney 0 Where asteroids come from where comets come from O O Asteroids Chucks of space rock Asteroid Belt Between Mars and Jupiter Remnants of material that did not coalesce into planets when other planets formed around the Sun Possibly a missing planet Comets Ice and Rock Nucleus and Tail Come from Oort cloud Vast spherical region around the Sun Extends more than 100000 times Earth39s distance from sun 0 Contains billions of comets Kuiper Comet Belt Lies in plane of solar system 0 Contains millions of comets Types of meteorites 0 Iron Meteorites 6 Depressions from melting o Stonyiron meteorites lt1 Mg Fe Si Looks like smooth rock 0 Chondrites 93 Olivine Pyroxene Mg Fe Si Looks like jagged rock 0 Open and complex craters 0 Open Small Impacts Small Ejecta Blanket Some material falls back into the crater Looks like contact lens 0 Complex Wider than 10 km Central peak in center Annular trough Looks like butt cheeks Large Ejecta Blanket Looks like belly button Shatter Cones Coneshaped Rough striations radiating downwards and outward Caused by large energy output 0 Form in negrained rocks 0 Point of imperfection o Chicxulub crater timing size of asteroid effects 0 Timing 65 million years ago Cretaceous Period 0 Size Crater 195 km diameter Asteroid 10 to 15 km diameter 0 Effects Shocked quartz Impact droplets Impact breccias lridium spike Earthquake Tsunami deposits 0 Mexico Texas Cuba Prolonged darkness Wild ressoot deposits Acid rainfrom volcanism and res Dinosaurs died out Allowed smaller mammals to take over Cameron 6
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