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Waves
- Starts from wind
- counter clockwise
- converts to gravity
- travel in circles
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wave refraction
when the wave bends
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burm
- highest part of beach
- filled with debris
- big waves dump debris onto burm
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backshore
slopes back towards land
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forshore
- faces ocean
- goes off to low side terrace
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winter has bigger waves because of storms
- low pressure system
- frequent
- affect larger areas
- different from hurricanes
- break onto beach building onto burm
- scoops sand up, makes beach higher narrower
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summer has smaller waves
- pushes sand up to the beach
- makes beach wider
- not as steep
- finer grains
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lagoons
- muddy/swampy
- when sea level drops, big area is exposed
- when sea level rises, are is submerged
- water is brackish (mix of fresh and salt water)
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barrier islands
- string of sandbars
- not sure of origin
- strong long shore currents
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tidal inlets
- tides move in/out twice a day
- strong currents prevent deposition
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long shore current
moves sand down the beach
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overwash fans
- storm wave deposits from hurricanes
- happens during storm surge, submission of barrier island
- large waves erode beach on ocean side--->dumps sand on lagoon side--->"overwash fan"
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winds blow from east
- winds push water, piles up along the ocean side of barrier island
- also as eye approached barrier island, low air pressure draws water up into the eye
- overall rise in sea level "storm surge"
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eye reaches barrier island
- max storm surge-->submerges parts of barrier island--->overwash
- higher seal level in ocean then in lagoon-->water rushes from ocean to lagoon-->severe erosion of barrier island, can create new tidal inlet
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eye enters lagoon
- storm surge is now in lagoon-->higher sea level in lagoon that occurs-->water rushes from lagoon to ocean-->further erosion of tidal inlet
- waves/water erode beach, sand is dumped offshore in sand bars
- winds shift and blows from west-->east
- more rain
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beach loss
- dams across rivers
- sea level rise
- human structures designed to prevent beach loss accelerates erosion elsewhere
- expensive
- disrupts beach equilibrium
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groins
- walls built perpendicular to beach
- traps sand pinning down long shore currents
- once you start to build groins, you must do to whole beach
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jetties
- walls built perpendicular to beach around mouth of harbor
- prevents mouth from filling with sand
- concentrates tidal currents-->stronger current, prevents disposition
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beach replenishment
- dump sand on beach to replace lost sand (dump trucks)
- piped from offshore dredging bars
- expensive, must be done every ~5 years
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breakwater
- wall built parallel to beach just offhshore
- creates a quiet zone, less wave erosion
- causes deposition when hits dead spot behind breakwater
- long shore current brings sand but dies behind break water
- big erosion down current from breakwater
- therefore must extend breakwater down long shore current
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sea wall
- wall built behind beach in front of structures
- protects structures from storm waves
- Problem: storm waves hit wall-->reflect-->pull sand off beach
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artificial dunes
- dune built behind beach
- acts as a sea wall
- protects structures from storm waves
- protects from storm surge
- wind pushes sand against fence-->traps sand and build dunes-->plant grass to stabilize
- problem: storm waves hit dune-->roll back to ocean and pull sand off beach
- expensive to maintain
outer banks are doomed due to sea level rise - any gaps in dune-->funnels storm surge
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tsunamis
- seismic sea wave
- earthquake
- volcano
- underwater landslides
- sudden shift in ocean floor
- caldera collapse
- gravity waves
- very long wavelengths
- low heights ~.5 meters
- not noticeable in open ocean
- very fast moving 500-1000 km/hr
- harmless in open ocean
- reach shore, shallow depths create friction-->heights build
- at beach 50% chance of a trough reaching first-->water withdraws from beach
- crest-rush of swash, can move several km's inland
- turbulent, lots of debris
- can be monitored: know speed and direction
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Peak oil concept
- follows bell shaped curve
- curve climbs if new discovery keeps pace with inc. demand
- curve drops if new discovery lags demand
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geology of oil
- plankton: microscopic plants and animals
- "floaters"-live in surface waters in bodies of water
- usually when plankton dies, corpses are oxidized or broken down by bacteria
- need geologic setup to allow corpses to reach bottom mud
- dense salty water stays deep
- does mix with O2 from air because of layers of less dense water at surface
- becomes O2 poor as it encounters sinking dead plankton
- organics reach bottom sediment
- partially oxidized and broken down by bacteria
- blank, stinky, tarry mud
- long organic molecules-->burial over time with more sediment--> higher temperature and pressure with burial
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diagenesis
- shallow burial within a few 100 meters
- some oxidation and bacterial breakdown
- from oil, molecules are still long and heavy
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catagenesis
- 3.5-5km deep 50-150 degrees celsius
- "cracking"- long chains of organic molecules split into various shorter molecules
- dozens of different compounds
- oil becomes less viscous, more lighter
- Crude Oil
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Matogenesis
- >150 degrees celsius
- oil has cracked to methane (natural gas) CH4
- rocks become metamorphic-slates, phyllites
- graphite residue, no more oil
- to find oil: sedimentary rocks only
- black shale to sever as some
- not rocks too young
- not cracked enough
- not rocks too old-->over cracked, oil has escaped
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collecting oil
- collected in "oil traps"
- geologic structure
- right rocks in right order
- top: "cap rock"- impermeable, prevents oil in reservoir from leaking
- middle: "reservoir rock" - permeable rock, porous, pores connect
- bottom: "black shale"- contains original black mud
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secondary oil recovery technique
- only 1/3 of the oil in a reservoir rock is easy to extract via regular pumping
- 2/3 is stuck in pores of reservoir-->adds expense
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Dynamite Reservoir Rock
- fractures
- adds more permeability, oil can flow better
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water flooding
drill a secondary well-->pump in water under pressure-->forces oil into main well
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steam flooding
- pump steam into secondary well
- adds pressure
- heats the oil-->less viscous, flows easier
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inject acid
- dissolves out calcite
- in limestone:widens fractures
- sandstone: dissolves calcite cement
- open pore spaces
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chemical flooding
- inject light oil
- dissolves heavier oil stuck in pores--> pump out
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inject detergents
loosens oil stuck to grains-->pump out
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pump CO2
CO2 mixes with water-->helps dissolve the oil
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Coal Main Use
generate electricity-->50% of energy in US
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From Fossil Vegetation
- -Swampsalong rivers
- coastal swamps
- lots of vegetation
- lots of stagnate water
- vegetation falls into water-->begins to decompose, uses up dissolved O2 in water
- O2 poor with anaerobic bacteria-->accumulates partially dcomposed organics
- found in sedimentary rocks only
- not in rocks older than ~350 million yrs
- the US had 2 great coal forming eras: eastern coal: Appalachian & Midwest, and collision with Africa
- 2nd era: 60 million years ago--> rivers flowing off east side of rocky mts--> swamps--> coal
- coal forms in horizontal layers (very predicatble)
- quality of coal is consistent over al ayers extent
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Peat
- can be dredged from swamp
- contains wood
- can see plant fossils
- contains water and gases
- smoky when burned
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Lignite
- "brown coal"
- over time, increased burial, higher temp and pressure
- cellulose breaks down--> higher Carbon content
- water is pressed out, less gas
- no more wood, can still see plant impression
- burns with a yellow smoky flame
- not suitable for power plants
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bituminous
- black, not very shiny
- sooty, soils hands
- burns with yellow flame, less smoke
- okay for power plants
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anthiacite
- black & shiny
- sooty, soils hands
- short blue flame
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US has greatest reserves of coal
- US- 23.6%
- India - 18.7%
- China - 12.9%
- Russia - 10.2%
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Other constitutions of coal
- mud and sand (other sediment)--> does not burn, forms ash
- sulfides: pyrite, iron sulfide --> can also contain heavy elements, lead, arsenic, mercury, uranium
- problems: mud/sand create ash, sulfides burns creating SO2 mixes with water in clouds and creates sulfuric acid (acid rain)
- Piles of coal and waste rock contains sulfide--> rain percolates through piles--> chemical reaction, forms rust and sulfuric acid--> acid mine drainage--> moves into surface and ground water
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Surface coal mining
- excavate a large pit ("open pit")
- remove overburden--> expose coal--> mine coal
- Pros: fast and cheap, big machines, big trucks, can extract all of the coal
- Cons: overburden, lots of wasted rock, stored in piles near mine. loose material erodes quickly--> gets into streams --> sediment clogs streams
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underground coal mining
- used for deeper coal
- coal that is dipping
- Pros: less overburden removed, less waste rock
- Cons: more expensive, must leave some coal behind to support roof. pump out groundwater. pump in lots of air
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contour mine
- mine the side of the mountain
- follow coal around mt similar to contour line
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room and pillar
- mine corridors that crisscross of coal
- leave behind squarre pillars of coal to support
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longwall mining
- mine corridor
- install a cutter and grind up coal and mine the long wall
- coal falls into a conveyor belt
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