Class #5 Notes for GSC 103: Formation of Rocks
Class #5 Notes for GSC 103: Formation of Rocks GSC 103-O
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This 12 page One Day of Notes was uploaded by Juan Rios on Saturday January 31, 2015. The One Day of Notes belongs to GSC 103-O at University of Miami taught by Professor Peter Leech in Fall. Since its upload, it has received 371 views. For similar materials see Evolution of Modern Earth and Enviroment in Geology at University of Miami.
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Date Created: 01/31/15
GSC 103 Final Exam Review Thursday April 232015 350 PM 1 Lecture 17 Atmosphere Wind and Deserts a Why is there Wind i is air in motion 1 produced by the uneven heating of the earth39s surface by the sun ii various land and water formations it absorbs the sun39s radiation unevenly b Hadley cells i lowlatitude overturning circulations 1 air rising at the equator and air sinking at roughly 30 latitude 2 T responsible for the trade Winds in the Tropics and control low latitude weather patterns c Intertropical Convergence Zone ITCZ i also called equatorial convergence zone ii belt of converging trade Winds and rising air that encircles the Earth near the equator 1 The rising air produces high cloudiness frequent thunderstorms and heavy rainfall d Coriolis effect i is a de ection of moving objects When the motion is described relative to a rotating reference 1 clockwise rotation a the de ection is to the left ofthe motion ofthe object 2 counterclockwiserotation b the de ection isto the right e Saltation i speci c type ofparticle transport by uids such as Wind or water ii It occurs When loose material is removed from a bed and carried by the uid before being transported back to the surface f Sand dunes i is a hill of sand built by either Wind or water ow ii Dunes occur in different shapes and sizes iii formed by interaction With the ow of air or water g Ergs i is a broad at area of desert covered With Windswept sand With little or no vegetative cover 1 Approximately 85 of all the Earth39s mobile sand is found in ergs h Loess i geologically recent deposit ofsilt ii usually yellowish or brown in color iii tiny mineral particles brought by Wind to the places Where they now lie i De ation i in geology erosion by Wind ofloose material from at areas ofdry uncemented sediments l deserts dry lake beds oodplains and glacial outwash plains j Desert pavement i desert surface covered With closely packed interlocking angular or rounded rock 1 pebble and cobble size k Five types of desert i Subtropical l Subtropical deserts the hottest deserts Subtropical deserts are very hot and dry in the summer cooler but still dry in the Winter Rainfall happens in short bursts sandy or coarse and rocky Plants and animals in subtropical deserts must be able to Withstand the hot temperatures and lack of moisture ii Continental 1 Continental deserts occur in the centers of large continents 2 inland Winds travel from the sea over land a They lose moisture in the form of rain i By the time they reach the center of a large continents they are very dry 999 59 iii Rain shadow 1 patch of land that has been forced to become a desert because mountain ranges blocked all plantgrowing rainy weather a Death Valley i a desert in the US states of California and Nevada is so hot and dry because it is in the rain shadow of the Sierra Nevada Rising Air Cools and Condenses iv Coastal 1 found on the western edges of continents nearthe Tropics of Cancer and Capricorn 2 Because local wind systems dominate the trade winds these deserts are less stable than other deserts 3 Winter fogs produced by upwelling cold currents frequently blanket coastal deserts and block solar radiation V polar 1 Polar deserts are areas with low annual precipitation 2 Low temperature 3 mostly bedrock or gravel plains 4 Snow dunes instead of sand dunes 2 Lecture 18 Streams and Drainage a Runoff i Water moving across surface of land 1 Overland ow a Sheets of water with no channel 0 oods 2 Stream ow a Streams of water in channels b Drainage basins i An area of land where all of the surface water converges to a single point ii De ne a drainage basin by a single points iii Often branch out to small drainage basin c Why humans build near rivers i Use for transportation ii Valley oods and easy to build on iii Soil deep and fertile iv Water is a available i Ancient Egyptians ii Nile river runs from south to north d Meandering i Forms in area of low relief and ne grain sediment ii Typical river iii Faster of the outside of the channels 1 Erosion iv Slower at the inside 1 deposition e braided channels i Channels repeatedly splitting and rejoin ii Often formed by periodically variable streams in area of easily erodible material iii Characteristic of oods and glaciallyfed rivers f Oxbow lake a Lake formed when two curve moving towards each othermeet g Placer deposits a Rivers sorting can create concentrated mineral deposits h Floods a When a river rises above the river capacity b Usually caused by excess rain i Glacial lake outburst oods i Channeled ii Scablands 1 The channels scablands were created by a catastrophic ood 1 A glacial lake outburst ood iii English Channel 1 The oor of the English channel contains braided channels a The main hypothesis is a glacial lake outburst ood 200000 years ago 3 Lecture 19 Groundwater a Water table i describes the boundary between watersaturated ground and unsaturated ground 1 Below the water table rocks and soil are full of water ii Pockets of water existing belowthe water table are called aquifers b Zone of aeration i Region in the ground in which 1 spaces are filled with air c Zone of saturation Porosity and permeability i Region in the ground in which pore spaces are filled with water 1 Porosity a measure of how much of a rock is open space b Permeability is a measure of the ease with which water can move through a porous rock W Grou ndwater q ualitv Precipitation ii a Aquitards i A watersaturated sediment or rock whose permeability is so low it cannot transmit any useful amount of water Aquifers i Underground layer of waterbearing permeable rock or unconsolidated materials ii groundwater can be extracted using a water well Groundwater ow i the movement of water that travels and seeps through soil and rock underground Spnngs a location where groundwater naturally emerges from the Earth39s subsurface in a defined ow in an amount large enough to form a pool or streamlike ow Ogallala aquifer a is a shallow water table aquifer located beneath the great plains in the United States b One of the world39s largest aquifers Water hardness a the amount of dissolved calcium and magnesium in the water 1 Hard water is high in dissolved minerals a calcium and magnesium Carbonate caves a Speleothems are crystal deposits which form on the ceiling walls and oor of caves b As rainwater seeps through the soil and absorbs carbon dioxide 1 This carbon dioxide makes the water acidic and able to dissolve limestone calcium carbonate Karst a landscape formed from the dissolution ofsoluble rocks b It is characterized l sinkholes caves and underground drainage systems 1 Injection wells a An Injection well is a device that places uid deep underground into porous rock formations such as sandstone or limestone b These uids may be water wastewater brine salt water or water mixed with chemicals 1 long term C02 storagewaste disposal enhancing oil production mining and preventing salt water intrusion 4 Lecture 20 Ocean Circulation a Ekman spiral a structure of currents or winds near a horizontal boundary in which the ow direction rotates as one moves away from the boundary b Ekman transport a the net motion of uid as the result of a balance between Coriolis and turbulent drag forces c Geostrophic ow a an oceanic ow in which the pressure gradient force is balanced by the Coriolis force b The direction of geostrophic ow is parallel to the isobars with the c high pressure to the right of the ow in the northern hemisphere d high pressure to the left in the southern hemisphere d Conservation of angular momentum spinniness a angular momentum is distributed between the spin of the planet and its revolution in its orbit e Western boundary currents a Warm fast currents b Move towards the pole f Eastern boundary current a Slow cool currents b Moves towards the equator g Thermohaline ow a Flow is ow which is driven by temperature and salinity saltiness h Sea Surface Temperature a Temperature i Higher at the equator ii Lower at the poles i Mixed layer a b C Surface layer of the Ocean Very warm Does not miX with the cold water in lower depths j Shutting down the Therrnohaline ow 5 Lecture 20 Tides and Coasts a Gravity gradient controlstides a b C Tides are the rise and fall of sea levels caused by the combined effects of gravitational forces exerted by the moon sun and rotation of the Earth exerted by one body on another is not constant across it the nearest side is attracted more strongly than the farthest side b Two tides per day High tide Low tide a b c Spring tides a b A tide that occurs when the difference between high and low tide is greatest come twice a month i approximately at the full and new moon Spring tides occur when the sun and moon are directly in line with the earth i Gravitational pulls reinforce each other d neap tides a b A tide that occurs when the difference between high and low tide is least comes twice a month i in the first and third quarters of the moon Neap tides occur when the sun earth and moon form a right angle i the gravitational pull of the sun counteracts the pull of the moon e the phases ofthe Moon CCCCCC NT G I GIBBOUS FULL f How tides change the rotation of the Earth and Moon a Tidal breaking slows the Earth39s rotation and speeds up the Moon39s motion in its orbit b As the Earth spins friction between the ocean and Earth drags line joining the Earth and the Moon C The Moon39s gravity pulls on the bulge and holds it back d The drag is transmitted trough the ocean to the Earth i slowin its rotation a g Size of waves a Crests i The peak ofthe wave b Troughs i The lowest point on the wave c The wavelength or horizontal size of the wave is determined by the horizontal distance between two crests or two troughs h Berrns a a at strip of land raised bank or terrace bordering a river or canal i Sandbars a Offshore Bar submerged or partly eXposed ridge of sand or coarse sediment that is built by waves offshore from a beach j Rip currents a water current that can be found near beaches b It is a strong localized and rather narrow current of water i strongest near the surface of the water ii moves directly away from the shore cutting through the lines of breaking waves k Preventing mitigating beach erosion a physically adding sand to beaches to replace losses is really the best fix b address the causes not the symptoms 6 Lecture 21 Global Glaciation a j AI I Four types ofglacier by size Ice shelves a Cirque i Smallest b Valley Glacier i Glacial valley tend to be broad and U shape 1 Fjord a The U shape valley Where a valley glacierused to be b Carves it out ice melts ad lls it in With water c Piedmont Glaciers i Glaciers spread beyond theirvalley ii Piedmont foothills d Ice caps i When piedmonts keep spreading and stick together Crevasses a Where the glacier bed has a steep slope b The glacier breaks apart Faults in the ice How glaciers move Polar glacier a remain below freezing temperatures year round b Frozen to the ground 1 Limits basal sliding Temperate Glaciers a Remain at or above their freezing temperatures b Characterized by a lm of meltwater at their base Moulins a Carry meltwater from surface to the base of the ice sheet Glaciers generate geological features through two process a Erosion i Drumlins 1 Where large glaciers pass and grind through the rick b Deposition l Erratics 2 moraines Last Glacial Maximum 20000 years ago Weathering of the Himalayas Causes of Antarctic glaciation a Breakup of Pangea probably caused a long term cooling a India collided With Eurasia and formed Himalayan mountains b Antarctica begins to move towards the South Pole i Albedo 7 1 Refelcts sunlight because the surface is white k Causes of Greenland glaciation l Milankovic cycles a The effect on Earths climate of change in earths orbit i quotWobblesquot 1 Earths tilt controls the seasons 2 Cool summer causes northern ice sheets to grow Lecture 22 Climate Change a Blackbody radiation b Earth s energy balance a Observed sunlight Emitted infrared radiation b Hotter the earths get the more infrared radiation it emits i Once observations equals emitting then earth stops heating up and stays constant c How greenhouse gases work a The Maj or greenhouse gases a Water vapor causes about 80 of greenhouse effect b 11 caused by C02 b Greenhouse gases work by letting visible light through but absorbs infrared light a Infrared light which has been absorbed by greenhouse gases is re emitted b Some of the infrared radiation gets emitted back towards the Earth Some sunlight that hits the earth is reflected d Keeling curve a Mean measurement of Carbon dioxide b Mauna Loa record e Suess effect a Hans Suess a An atom undergoes radioactivity decay when it spontaneously changes into another atom or isotope f Dendroclimatology a Looks at tree rings to reconstruct past climates a Rainy hotthick b Dry cold thin g Hockey Stick graph Temperature change h Computer models and climate predictions a Climate is predicted using general circulation models 1 Break up earth into small little boxes a IPCC 2 IPCC also includes projections for sea level rise 8 Lecture 23 Minerals and Energy a Enrichment factor a Increase in concentration required to make a deposit an ore b Makes it pro table and mined b Four main processes for producing ores i Hydrothermal a Hydrothermal mineral deposits are formed when water seeps through the crust of the earth near to magma chambers ii Magmatic a Partial crystallization i Concentrates minerals as they crystallize in magma chamber iii Sedimentation a Evaporates i Halite and Gypsum b Placers i Minerals are usually deposited in comers of rivers iV Weathering a Residual mineral deposits i Are formed by chemical weathering and leaching i Laterites One Important source for aluminum c How power plants work i Spinning a coil ofwire in a magnetic eld generates electricity a Energy resources are largely biogenic d Coal and petroleum i Coal is mostly from the carboniferous a Carboniferous b Compresses down until it becomes coal e Other sources of power i Nuclear l About 20 of US power is nuclear compared to France which is 75 ii Geothermal 1 Uses hot water pumped from deep in the earth iii Hydroelectric l Largest source of energy 2 Production has been increasing worldwide 3 Paraguay is 100 hydroelectric and one ofthe worlds largest electric eXports iV Wind 1 Small but fasting growing 2 Uses Wind turbines to extract energy from moving air V Solar 1 Convert light into electrons creates electricity 2 Solar thermal a Takes heat to boil water to make energy