Oceanography Ch. 1-4 Exam – Flashcards

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Pacific Ocean
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Deepest and largest ocean
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Atlantic Ocean
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Second largest ocean; separates the Old World from the New World
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Indian Ocean
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Slightly smaller than the atlantic ocean but has the same average depth; mostly in the southern hemisphere
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Arctic Ocean
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Smallest and shallowest ocean; has a permanent layer of sea ice
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Antarctic or Southern Ocean
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Ocean that connects the pacific, atlantic and indian oceans; south of about 50 degrees south latitude
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Ocean versus Sea
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Smaller and shallower than oceans, salt water, enclosed by land
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Phoenicians
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The first Mediterranean people known to have developed the art of navigation
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Eratosthenes
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Determined the Earth's circumference in 200 B.C.
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Ptolemy
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Produced a map of the world in about 150 a.d. that represented the extent of Roman knowledge at that time (first world map)
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Ptolemy
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Overestimated the size of Asia which later caused Christopher Columbus to believe he has encountered parts of Asia rather than a new world
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Oceanography
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Literally the description of the marine environment; the scientific study of all aspects of the marine environment; also called marine science
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Geological oceanography
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The study of the structure of the sea floor and how the sea floor has changed through time; the creation of the sea floor features; and the history of sediments deposited on it
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Chemical oceanography
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The study of the chemical composition and properties of seawater, how to extract certain chemicals from seawater, and the effects of pollutants
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Physical oceanography
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The study of waves, tides and currents, the ocean-atmosphere relationship that influences weather and climate, and the transmission of light and sound in the oceans
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Biological oceanography
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The study of the various oceanic life-forms and their relationships to one another, their adaptations to the marine environment and developing sustainable methods of harvesting seafood
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Scientific Method
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Observation, hypothesis, testing and modification of hypothesis, theory
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The Nebular hypothesis
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States that all bodies in the solar system formed from an enormous cloud composed mostly of hydrogen and helium, with only a small percentage of heavy elements
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Universe
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The huge space which contains all of the matter and energy in existence
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Galaxy
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One of billions of systems, each a giant collection of gas, dust and billions of stars
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Stars and suns
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High temperature bodies; one has planetary systems and the other does not
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Proto-earth
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Looked very different from Earth today It was larger, there were no oceans and no life Thought to be homogenous, which means that it had a uniform composition throughout It changed as its heavier constitutions sank toward the center to form a heavy core
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Fusion
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Contracted masses reach high temperatures causing hydrogen to combine in the sun
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Thermonuclear fusion
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Occurs when temperatures reach tens of millions of degrees and hydrogen atoms combines to form helium atoms, releasing enormous amounts of energy
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Solar Wind
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Electrical particles emanating from the sun; blows light elements away from the inner planets; caused planets to contract
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Radioactive heat
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Internal warming of each planet
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Density
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Mass per unit volume; measure of how heavy something is for its size
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Density stratification
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Elements segregated according to their densities (layered earth); high density materials move to the center (core), lower density materials move to the surface
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How long ago did solid Earth form?
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4.6 billion years ago
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Chemical composition
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Crust, mantle and core
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Crust
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Extends from the surface to an average depth of about 30 kilometers (20 miles) It is composed of relatively low density rock, consisting mostly of various silicate minerals (common rock forming minerals with silicon and oxygen)
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Mantle
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Immediately below the crust and occupies the largest volume of the 3 layers and extends to a depth of about 2885 kilometers (1800 miles) It is composed of relatively high density iron and magnesium silicate rock
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Core
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Forms a large mass from 2885 kilometers (1800 miles) to the center of Earth at 6371 kilometers (3960 miles) It is composed of even higher density iron and nickel
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Physical properties
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Earth is composed of five layer: the inner core, the outer core, the mesosphere, the asthenosphere, and the lithosphere
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Lithosphere
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Earths cool, rigid, outermost later It extends from the surface to an average depth of about 100 kilometers (62 miles) and includes the crust plus the topmost portion of the mantle Covers entire Earth surface (on land and under the ocean) "floats" on top of the asthenosphere It is brittle, meaning it will fracture when force is applied to it (a physical property of earth)
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Asthenosphere
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Plastic, meaning that it will flow when a gradual force is applied to it It extends from about 100 kilometers to 700 kilometers (430 miles) below the surface, which is the base of the upper mantle At these depths it is hot enough to partially melt portions of most rocks (a physical property of earth)
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Mesosphere
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Extends to a depth of about 2885 kilometers (1800 miles) which corresponds to the middle and lower mantle; rigid because of the increased pressure at these depths (a physical property of earth)
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Inner core
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Liquid and capable of flow (a physical property of earth)
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Outer core
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Rigid and does not flow(a physical property of earth)
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Oceanic crust
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Crust that underlies the ocean basins and is composed of the ingenious rock basalt, which is dark colored and has a relatively high density of about 3 grams per cubic centimeter
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Continental crust
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Crust that is composed mostly of the lower density and lighter colored igneous rock granite
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Isostatic adjustment
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The vertical movement of crust and is the result of the buoyancy of earth's lithosphere as it floats on the denser, plastic like asthenosphere below (ex: heavier ships sink deeper in water)
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Archimedes' Principle
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A floating body displaces a volume of water equal to its own weight
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Stanley Miller's Experiment
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Suggested that life most likely originated in the oceans
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Theory of evolution
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Groups of organisms adapt and change with the passage of time, causing descendants to differ morphologically and physiologically from their ancestors
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Heterotrophs
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Earliest forms of life, require an external food supply, which was abundantly available in the form of nonliving organic matter on the ocean around them
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Autotrophs
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Can manufacture their own food supply (photosynthesis), evolved later (after heterotrophs)
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Anaerobic bacteria
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Live without atmospheric oxygen They may have been able to derive energy from inorganic compounds at deep water hydrothermal vents using a process called chemosynthesis (after autotrophs)
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Photosynthesis
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Plant and algae cells capture energy from sunlight and store it as sugars, releasing oxygen gas as a by product
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Cellular respiration
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Animals who consume the sugars produced by photosynthesis combine them with oxygen, releasing the stored energy of the sugars to carry on cellular tasks important for various life processes
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The great oxidation event
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Earth's atmosphere became oxygen rich about 2.45 billion years ago and fundamentally changed Earth's ability to support life; most anaerobes died out
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Half-life
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The time required for one-half of the atoms in a sample to decay to other atoms
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The geologic time scale
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Lists the names of the geologic tim periods as well as important advances in the development of life forms on earth
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Alfred Wegener
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The first person to advance the idea of mobile continents in 1912
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Sir Edward Bullard
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Used a computer program to fit the continents together; he achieved the best fit by using a depth of 2000 meters below sea level
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Paleomagnetism
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The study of earths ancient magnetic field
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The mid-ocean ridge
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A continuous underwater mountain range that winds through every ocean basin in the world and resembles the seam on a baseball; results from sea floor spreading along the divergent plate boundaries
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Why do plates move?
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Thermal convection
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Earthquakes
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Sudden releases of energy caused by fault movement or volcanic eruptions Largest ones occur along trenches, reflecting the energy released during subduction
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Slab pull
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Generated by the pull of the weight of a plate as it sinks underneath an overlying plate, pulling the rest of the plate behind it
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Slab subduction
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Created as a subducting plate drags against the volcanic mantle causing the mantle to flow in toward the subduction zone, thereby sucking in nearby plates
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Divergent plate boundaries
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Occur where two plates move apart, such as long the crest of the mid-ocean ridge, where sea floor spreading creates new oceanic lithosphere
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Convergent boundaries
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Where two plates move together and collide- usually result in the destruction of ocean crust as one plate plunges below the other and is remelted in the mantle
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Transform boundaries
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The movement of one plate past another
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Divergent plate boundary features
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Mid-ocean ridge, volcanoes, young lava flows (sea floor spreading) Rift valley; volcanoes; young laval flows (continental rifting)
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Convergent plate boundary features
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Trench, volcanic arc on land (subduction) Trench, volcanic arc as islands (subduction) Tall mountains
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Transform plate boundary features
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Faults
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Hot Spots
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Areas of intense volcanic activity that remain in more or less the same location over long periods of geologic time and are unrelated to plate boundaries Causes nearly all volcanoes
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Seamounts
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Many areas of the ocean floor contain tall volcanic peaks that resemble some volcanoes on land
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Tablemounts or guyots
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Some volcanoes are flat on top-unlike anything on land
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Fringing reefs
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Initially develop along the margin of a landmass where the temperature, salinity and turbidity (cloudiness) of the water are suitable for reef building corals Associated with active volcanoes whose lava flows down the flanks of the volcano and kill the coral First step of coral reef development
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Barrier reef stage
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Landmasses start to subside, cooling of lithosphere as it moves from spreading center reef builds upward to stay shallow separated by a lagoon second stage of coral reef development
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Atoll stage
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Comes after a barrier reef around a volcano continues to subside and coral reef builds up toward the surface
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Paleography
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The study of historical changes of continental shapes and positions
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Continental accretion
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Continents are thought to add material through this process
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The Wilson cycle
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Uses plate tectonic processes to show the distinctive life cycle of ocean basins during their formation, growth and destruction over many million years
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Bathymetry
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The measurement of ocean depths and the chartering of the shape, or topography of the ocean floor
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The fathom
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The standard unit of ocean depth (1.8 meters)
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An echo sounder
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Sends a sound signal called a ping from the ship downward into the ocean, where is produces echoes when it bounces off any density difference lacks detail and often gives an inaccurate view of the relief of the sea floor most of our knowledge of ocean bathymetry has been provided by this
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Passive margins
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Type of continental margin: embedded within the interior of lithospheric plates and are therefore not in close proximity to any plate boundary; They usually lack major tectonic activity such as large earthquakes, eruptive volcanoes, and mountain building; They are usually produced by rifting of continental landmasses and continued sea floor spreading over geologic time
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Active margins
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Type of continental margin: associated with lithospheric plate boundaries and are marked by a high degree of tectonic activity; There are two types: convergent which are associated with oceanic-continental convergent plate boundaries and transform which are associated with transform plate boundaries
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The continental shelf
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A generally flat zone extending from the shore beneath the ocean surface to a point at which a marked increase in slope angle occurs, called the shelf break
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The continental slope
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Lies beyond the shelf break is where the deep ocean basin begins
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Submarine canyons
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Narrow but deep submarine valleys that are V-shaped in profile view and have branches or tributaries with steep to overhanging walls; They are the base of the continental slope
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Turbidity currents
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Responsible for carving submarine canyons; They are underwater avalanches of muddy water mixed with rocks and other debris
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The continental rise
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A transition zone between the continental slope and the deep-ocean floor comprised of a huge submerged pile of reprise
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Abyssal plains
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Extending from the base of the continental rise into the deep-ocean basins are flat depositional surfaces with slopes of less than a fraction of a degree that cover extensive portions of the deep-ocean basins
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Abyssal hills or sea knolls
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Volcanic features that are less than 1000 meters tall; They are one of the most abundant features on the planet and cover a large percentage of the entire ocean basin floor
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Hydrothermal vents
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Sea floor hot springs created when cold seawater seeps down along cracks and fractures in the ocean crust and approaches an underground magma chamber
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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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A transform fault
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A seismically active area that offsets the axis of the mid-ocean ridge; occur between offset segments of the mid-ocean ridge; two lithosphere plates are moving in opposite directions
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A fracture zone
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A seismically inactive area that shows evidence of past transform fault activity; occur beyond segments of the mid-ocean ridge; there is no relative motion because the parts of the lithospheric plate are moving in the same direction
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Paleoceanography
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The study of how the ocean, atmosphere, and land have interacted in the past to produce changes in ocean chemistry, circulation, biology, and climate
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Lithogenous sediment
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Sediment derived from preexisting rock material that originates on the continents or islands from erosion, volcanic eruptions, or blown dust (ex: beach sand)
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Quartz
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One of the most abundant, chemically stable, and durable minerals in earth's crust composed of silicon and oxygen in the form of SiO2- the same composition as ordinary glass; It is a major component of most rocks
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Sorting
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A measure of the uniformity of grain sizes and indicates the selectivity of the transportation process; The texture of lithogenous sediment also depends on this
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Neurotic deposits
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Marine sedimentary deposits that are found on continental shelves and in shallow water near islands; (nearshore) These deposits are generally coarse grained
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Pelagic deposits
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Marine sedimentary deposits that are found in the deep-ocean basins and are typically fine grained
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Biogenous sediment
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Sediment derived from the remains of hard parts of once living organisms
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Macroscopic biogenous sediment
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Type of biogenous sediment that is large enough to be seen without the aid of a microscope and includes shells, bones, and teeth of large organisms
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Microscopic biogenous sediment
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Type of biogenous sediment that contain particles so small they can be seen well only through a microscope; they can produce tiny shells called tests that begin to sink after the organisms die and continually rain down in great numbers onto the ocean floor
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Ooze
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It is fine-grained lithogenous clay that is deposited along with biogenous tests in the deep ocean
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Algae
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Primarily aquatic, eukaryotic, photosynthetic organisms, ranging in size from microscopic single cells to very large organisms like giant kelp
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Protozoans
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Any of a large group of single celled, eukaryotic, usually microscopic organisms that are generally not photosynthetic
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Silica
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In biogenous ooze and comes from microscopic algae called diatoms and protozoans called radiolarians
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Diatoms
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Type of silica that photosynthesize, so they need strong sunlight and are found only within the upper, sunlit surface waters of the ocean; most are free-floating or platonic
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Radiolarians
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Microscopic single-celled protozoans, most of which are algae planktonic; They often have long spikes or rays of silica protruding from their siliceous shell; They do not photosynthesize but rely on external food sources such as bacteria and other plankton
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Coccolithophores
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Calcium carbonate organisms that are single-celled algae, most of which are planktonic; They produce thin plates or shields made of calcium carbonate ; They photosynthesize, so they need sunlight to live They are really, really small so they are often called nannoplankton
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Foraminifers
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Single-celled protozoans, many of which are planktonic, ranging in size from microscopic to macroscopic; They do not photosynthesize, so they must ingest other organisms for food; They produce a hard calcium carbonate test in which the organism lives
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Productivity
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Determines the distribution of biogenous sediment; the number of organisms present in the surface water above the ocean floor
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Destruction
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Determines the distribution of biogenous sediment; occurs when skeletal remains (tests) dissolve in seawater at depth
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Dilution
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Determines the distribution of biogenous sediment; occurs when the deposition of other sediments decreases the percentage of the biogeneous sediment found in making deposits
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Stromatolites
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Locate structures consisting of fine layers of carbonate that form in specific warm, shallow water environments
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Hydrogenous sediment
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Sediment derived from the dissolved material in water
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Manganese nodules
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Rounded, hard lumps of manganese, iron, and other metals; important for making high-strength steel alloys
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Cosmogenous sediment
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Sediment derived from extraterrestrial sources
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