OCNG 251: EXAM 1
121 Cards in this Set
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Oceans:
1. Pacific
2. Atlantic
3. Indian
4. Arctic
5. Antarctic or Southern Ocean
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1. Largest, deepest
2. Second largest
3. Mainly southern hemisphere
4. smallest, shallowest, ice covered
5. Connects Pacific, Atlantic, and Indian
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Seas vs. Oceans
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- Smaller and shallower than oceans
- Salt water
- Usually enclosed by land
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Who determined earth's circumference?
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Eratosthenes in 200 BC
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First world map?
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Ptolemy 150 AD *error in assumption, 29,000 instead of 40,000*
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Marco Polo
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Traveled to Cathy (China) in 1275
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Ptolemy's new map
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republished map in 1410 wanted riches from "new world" to the east
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Rediscovery of the Americas
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- Chris Columbus reached San Salvador Oct. 1492
- Thought he reached Asia owing to error in estimate of earth's size
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Latitude
Longitude
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- North & South
- East & West
- 15 degrees per hour
- Each degree = 60 mins
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How did they tell time in 1700's?
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Sun Dial
Hour Glass
Pengelium
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Who invented chronometer? (watch)
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John Harrison
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Captain James Cook
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- First accurate maps by using chronometer
- To determine time relative to Greenwich to calc. longitude
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Who devised a chart of Gulf Stream in 1769
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Ben Franklin & Timothy Folger
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Charles Darwin
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- Voyage of HMS Beagle
- Observed and described the life history of coral reefs
- "The Origin of Species"
- Natural selection
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Challenger Expedition
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first entirely devoted to science spurred by Charles Darwin's work
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Polar Oceanography
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- Fram drifted in the ice for over 3 years (1893-96)
- Drifted across the arctic proved no continent existed in arctic sea
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Oceanography & World Wars
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- Submersible Exploration
- Trieste (french)
- DSRV (found titanic)
- NR-1 (Nuclear powered sub)
- GPS
- Military application
- Transmission of sound
- Ocean-floor bathymetry
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Jacques Cousteau
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Developed scuba gear (not original founder)
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Nature of scientific inquiry
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- Natural phenomena governed by physical process
- Physical process similar today as in the past
- Scientists discover these processes and
- Make predictions
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Scientific method
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Observation
Hypotheses
Testing and modification of hypotheses
Theory
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Universe
Galaxy
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- Huge space which contains all of the matter and energy in existence
- one of billions of systems, each a giant collection of gas, dust and billions of stars
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Formation of Solar System and Earth
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Nebular Hypothesis: Contraction of gas and dust cloud by gravity, contacting from heavy elements that are drawn to the center of clouds through Fusion 4.5 billion years ago
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Internal warming of each planet
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Radioactive decay
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Earth's Internal structure
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- Lithosphere (Rigid)
- Asthenosphere (Plastic)
- Mesosphere (Rigid)
- Outter Core (Liquid)
- Inner Core (Rigid due to pressure)
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Lithosphere
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- covers earths surface
- floats on top of Astenosphere
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Oceanic Crust
Continental Crust
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Basalt (thicker)
Continental Crust (thiner)
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Archimedes Principle
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floating body displaces a volume of water equal to its own weight
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Where did the oceans and atmosphere come from?
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Outgassing (4 billion years ago) *No Oxygen*
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Ocean salinity
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Rain dissolves from rocks
Ocean salinity constant over past 4 billion years
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Earliest life forms in Ocean
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3.5 billion years ago
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Types of life organisms:
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Heterotrophs (animals): External food supply
Autotrophs (plants): Manufacture their own food supply (photosynthesis)
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Photosynthesis
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Light + Water + CO2 >> Sugar +O2
- Steep rise in Oxygen 2 billion years ago
- Most anaerobic bacteria died out
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Respiration
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Sugar + O2 >> Water + CO2 + Heat
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Radiometric age dating
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Spontaneous change/decay
half life
* Not everything can be dated b/c not everything has uranium*
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Evidence for continental drift?
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- Puzzle-like fit of continents
- App mnts match up with Caledonian mtns in Europe
- Sediment deposit and Fossils other continents
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Why reasons for different environment years ago?
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1. Climate distribution was completely different
2. Continents were at different locations (latitude)
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Plate tectonics explains:
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Global distribution of:
Volcanoes
Earthquakes
Faults
Mountain belts
Feature of seafloor
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Paleomagnetism
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Orientation and intensity of magnetism changes over time
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Magnetic DIP is dependent on
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Latitude, when plates move they retain same dip from where the rock was formed
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Magnetic Polarity
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- Completely reverses over time
- Important for proving plate tectonics using ocean floor data
- Using rocks by volcano's polarity to show reversed polarity
- "stripes" oriented parallel to seafloor "mountains"
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Trench
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- Subduction zone
- Old ocean floor destroyed
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Mid-Ocean Ridge
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- Spreading center
- New ocean floor created
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Why do plates move?
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- Thermal Convection
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Spreading over time causes...
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stripes of magnetic reversals on sea floor
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If seafloor spreading is occurring...
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age of seafloor should increase away from the spreading center
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Samples from ____ allowed scientists to collect rocks from the ocean floor
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Ocean Drilling program (ODP)
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Why do age bands vary in thickness in different oceans?
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Different rates of seafloor spreading (Pacific Antarctic Ridge fastest at 10cm/yr)
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Seafloor is much ____ than the age of the Earth
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Younger
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Evidence supports the refined theory of plate tectonics?
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- Seafloor spreading
- Symmetric magnetic stripes parallel to mid-ocean ridges
- Depth of ocean Increase away from the ridge
- Thickness of lithosphere Increase away from the ridge
- Age of seafloor is young compared to age of continents
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Divergent boundaries
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- Plates being pulled apart
- Create Ocean Basins
- Plates pull apart - rift valley
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Differences in spreading rates affect shape of ocean bottom Ridges = _____
Rounded = ______
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Slower
Faster
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Asthenosphere ____ and _____ as it moves away from ridge
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cools, shrinks
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Seafloor ______ as it moves away from ridge
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sinks deeper
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Lithosphere grows _____ over time as it moves away from ridge
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thicker
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Convergent boundaries (Destruction of the Lithosphere)
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- Ocean-Continent
- Subduction
- Ocean-Ocean
- Subduction
- Continent-Continent
- Uplift of sediments
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Ocean-Continent collision
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- Continental Arc Trench Systems
- Melted lithosphere rises and forms a continental arc of volcanoes at the surface
- Andesite - Composition between continent and ocean material
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Ocean- OCean collision
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Island Arc Trench Systems
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Continent-Continent collision
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ex. Himalaya Mountains
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Ocean basins get ____ or are _____ in Convergent boundaries
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smaller, destroyed
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Transform Boundaries
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- Plates move past each other
- No material is created or destroyed
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Transform Boundaries must have
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- Transform faults
- Perpendicular to ridge axis
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Offsets between segments at spreading centers occur along...
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Transform Faults
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Fracture Zones
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Extend beyond the ridge axis
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Volcanic Islands in middle of plates caused by...
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- Hot Spots
- Magma chambers are close to the crust
- Plates move above it
- Hot Spot doesn't move as fast as plate
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Seamounts and table mounts
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- Volcanoes are formed near spreading center
- Fractures (cracks) allow lava to get to the surface
- Volcano dies in 30 mil. years
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Coral reef changes:
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Fringing reef
Barrier reef
Atoll
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Fringing reef
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coral needs shallow water; favorable temperature and salinity
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Barrier reef
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- Landmass starts to subside
- Cooling of lithosphere as it moves from spreading center
- Separated by a lagoon
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Atoll
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- No island-Volcano has subsided below sea level
- Reef contines to grow upward
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North America at equator ____ years ago, Pangea ___ years ago, Atlantic Ocean starts forming ____ years ago, India collies with Asia ____ years ago
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500 mil, 200 mil, 150 mil, 45 mil
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Bathymetry
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topography of the ocean
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How to collect number of depth measurements?
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Sound Reflection (Sonar) & Satellites
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Density differences between 2 layers cause
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energy reflected, energy transmitted to deeper layers
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____ causes sea level to rise or fall above bathymetric features
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Gravity
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____ leads to extra gravitational attraction on water, which leads to ____ sea levels (water bulges ___)
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Bathymetric high, Higher, upward
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Ship bathymetry vs. satellite bathymetry
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able to be more exact, see minor details
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Passive Margin
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- No seduction
- No plate boundary
- Wide shelves
- slope and rise built seaward
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Active Margin
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- Subduction
- Convergent plate boundary
- Tectonic movement
- Trenches offshore
- Narrow Shelf
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Largest areas on Earth's surface
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- Ocean Basins
- 45% of earth's surface
- Deep water depths
- 2nd coastal plain / Continental shelf
- 27% of earth's surface
- Low elevation- shallow water depth
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Smallest areas on Earth surface
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- Trenches
- 4% of earth's surface
- Mountains
- 8% of earth's surface
- Continental slopes
- 14% of earth's surface
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____ proves activity of turbidity currents in ocean
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Turbidity currents
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Turbidity currents
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cut canyons and form deep-sea fans
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Sea level rise and fall creates ____ sediment deposits in continental slope
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thick
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Highstand sea level
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Trapping on the shelf
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Lowstand sea level
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- Sediment to slope
- Active Caynons
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____ Heated subsurface seawater migrates through cracks in ocean crust
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Hydrothermal vents (30C-350C)
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Hydrothermal vents dissolved ___ precipitate to from ___ sulfide deposits
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metal, metal
- Chemosynthetic
- Able to survive without sunlight
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Types of continental margins _____ & ______
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active, passive
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Marine Provinces
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Areas of the ocean bottom classified by water depth, slope and process of formation
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Continental margins:
- Shelf
- Slope
- Rise
- Ocean basin
- aBYSSAL pLAIN
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- shallow, flat
- steeper slope
- base of slope
- REALLY FLAT
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Parts of Deep Ocean Basin
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- Ocean Basins (4000 m avg)
- Trenches and volcanic arcs
- Hydrothermal vents
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Why do we care about sediments in the ocean?
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Tells us about climate change and earth's past, present, and future
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Methods of retreiving sediments from seafloor:
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- Dredge: metal net to scoop up rocks
- Gravity corer
- Rotary drilling
- Piston corer
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Classifications of marine sediments
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- Lithogenous ( Land & volcano)
- Biogenous (organism)
- Hydrogenous (water)
- Cosmogenous (outter space)
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Lithogenic Sediments
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- Pre-existing rock, on the continents or volcano
- Transport to ocean through water/air
- Most deposited on Margins
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Sources of Lithogenous sediment
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Rivers, wind glaciers, gravity slides
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Composition of Lithogenous sediments
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- Primarily Quartz
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Classifcation by sediment texture
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- Grain size important in moving sediment
- Erosion
- Transport
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____ the particle, sooner it'll settle. Size is more important than ____
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larger, density
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Well sorted
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- all grain is the same size
- many transport events before deposition
- Ex. Beaches or sand dunes
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Poorly sorted
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- Few transport events
- Many grain sizes can be moved
- Ex. Glacial deposits
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Grain shape; ____ = less weathered,
____ = more weathered
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angular and jagged, rounded
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Where are lithogenous sediments found?
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- Neritic (near shore to edge of continental shelf)
Beaches, Shelf, Glacial
- Pelagic (deep ocean)
Abyssal clay, Volcanic ash, dust, Deep ocean currents
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World-wide sediment discharge
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- 20 billion metric tons per year
- 80% from Asian rivers
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Thickest sediments are found near the ____ ______
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Passive Margins
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Biogenous sediment
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- Macroscopic (shells)
- Microscopic
- shells from microscopic algae
- OOZE (if sediment is .30% biogenic material)
- Not all organisms leave a trace
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Major building blocks "bones" for plankton shells
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Calcium Carbonate, Silica
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Carbonate organisms
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- Calcium carbonate
- Coccolithophores photsynthesize
- Smaller than diatoms (silica); form chalk deposits
- Diatoms - photosynthesizers
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Distribution of biogenous sediments
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- Most common as pelagic deposits
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Factors controlling sediment distribution and composition
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- Productivity
- Destruction (dissolution)
- Dilution
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Where are Biogenous sediments found?
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- Neritic: biogenous material overwhelmed by lithogenous sediment
- Pelagic: oozes (contain at least 30% biogenic material
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Calcareous ooze:
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At least 30% carbonate shells
- preserved in water <4500 m
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Conditions that cause calcite to dissolve
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- Low temp
- Higher pressure
- Higher CO2
- Low pH(more acidic)
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Lysocline
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Depth at which carbonate shells start to dissolve
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_____ ____ ____in ocean, little carbonate material settles and survives below 4500m
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Calcite compensation depth
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Where are Carbonate oozes common?
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Ridges (Mid-ocean ridges)
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How do sea floor sediments record surface ocean conditions?
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- microscopic test sink slowly 10-50 years
- Most biogenous bodies are turned into fecal pellets and fall to seafloor in 10-15 days
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Marine sediments record ocean surface conditions
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Temperature
Nutrient supply
Abundance of marine life
Ocean current patterns
Volcanic eruptions
Change sin climate
Movement of tectonic plates
etc.
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Hydrogenous sediment
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- Derived from dissolved material in water
- Maganese nodules - Mn and Fe
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Other hydrogenous sedimnets
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- Phosphates
- Evaporites
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Mixtures of marine sediments
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Typically one sediment type dominates in different areas of the sea floor
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Global distribution of neritic (near shore) and pelagic (open ocean) surface sediments
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- 48% calcareous ooze
- 38% abyssal clay
- 14% siliceous oozee
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Study Guide: Exam 4