Answers on Oceanography Flashcards

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What are the principal oceans of Earth? How to they compare in size, location, and depth?
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1.Pacific Ocean – largest, deepest 2.Atlantic Ocean – about half size of Pacific 3.Indian Ocean – slightly smaller than Atlantic; mostly in Southern Hemisphere 4.Arctic Ocean – about 7% size of Pacific; shallower than other oceans 5.Southern Ocean (Antarctic Ocean) – portions of Pacific, Atlantic, and Indian Oceans south of 50 degrees South latitude
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What percentage of Earth is covered by oceans?
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71%
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How does a sea differ from an ocean?
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smaller and shallower than ocean; composed of salt water; usually enclosed by land; directly connected to World Ocean (Mediterranean Sea)
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Name and locate the deepest ocean trench and describe its exploration by humans.
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Mariana Trench (Pacific Ocean) – deepest part of ocean (36,161 ft. below sea level) Visited by humans in 1960 in a deep-diving bathysphere. No mountain on Earth is taller than Mariana Trench is deep
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Who were some of the early explorers and what were some of their contributions?
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Mostly searching for new food sources -Pacific Navigators – Polynesians – great distances were challenging -Early European Navigators – Phoenicians (first western hemisphere), Greeks (followed the north star), Romans -Middle Ages – Arabs (dominant navigators in the Middle East), Vikings (established temporary settlements in North America), Chinese (Ming Dynasty)
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Who made one of the first scientific ocean explorations? What were some of his contributions?
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Captain James Cook – 3 scientific voyages between 1768 and 1779; created longitude, mapped previously unknown islands including Hawaiian Islands, died in Kona, Hawaii
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List and describe the systematic steps of the scientific method.
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1.Observation – Collection of facts 2.Hypothesis – preliminary explanation for observations or data (educated guess) Must be subject to testing and falsification, must be tested repeatedly and systematically 3.Testing – Development of observations 4.Theory – well tested, widely accepted explanation of some aspect of natural world that can incorporate facts, laws, logical inferences 5.Law – descriptive generalizations about behavior in natural world
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Distinguish between a hypothesis and a theory. Give some examples of each.
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hypothesis becomes a theory only after extensive testing. Examples: Big Bang, Plate Tectonics, Evolution
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What is the difference between a scientific laws and theories?
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Laws describe while theories explain
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Compare and contrast the protoearth and the modern Earth.
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Protoearth – more massive and larger than present Earth; molten; homogeneous
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Describe the process by which the protoearth formed a layered, internal structure. What is the basis for this layering?
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Density Stratification – protoearth formed a layered internal structure based on density (bombarded by meteorites)
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Distinguish between continental and oceanic crust. What is the composition of each?
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Oceanic crust – basalt (dense); Continental crust – granite (thicker, less dense)
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Describe the process that led to the formation of Earth’s early atmosphere. How was Earth’s early atmosphere different from the present atmosphere?
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Outgassing – process by which gases are expelled from Earth’s interior. Primordial atmosphere = Low density gases mostly water vapor (H2O) and CO2 with small amounts of H, CH4, NH3 and others
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What process led to the formation of Earth’s current oxygen-rich atmosphere?
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Photosynthesis
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Describe the formation of Earth’s oceans and discuss the origin of salts in ocean water.
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Water vapor from outgassing condensed and fell to Earth forming oceans about 4 billion years ago. Ocean Salinity – abundant acidic rainfall on surface dissolved compounds that when carried to ocean made it salty
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Discuss the implications of Stanley Miller’s 1952 experiment. What did he demonstrate?
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Demonstrated that UV radiation from sun (with an electric spark to simulate lightning) and H, CO2, CH4, NH3 and inorganic molecules from oceans may have combined to produce organic molecules such as amino acids (prebiotic soup)
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What is the age of the Earth and how was it determined?
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Radiometric dating of rocks determine Earth’s age to be 4.6 billion years old
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Describe Alfred Wegener’s hypothesis of Continental Drift.
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Super continent called Pangaea began breaking apart about 200 mya. Continents drifted to their present positions and broke through oceanic crust.
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List the evidence Wegener used to formulate his hypothesis.
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Evidence included puzzle-like fit of continents, matching fossils, matching rock sequences, matching mountain chains, climate evidence
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State the modern theory of Plate Tectonics.
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Lithosphere is divided into 3 plates. Divergent, Convergent, transform. Volcanism and earthquakes are the result of the plates.
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Describe the evidence on continents and the sea floor that supports the modern theory of Plate Tectonics. What is the most persuasive evidence?
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Paleomagnetism – most persuasive evidence. Apparent polar wandering (continental rocks). Magnetic anomalies on ocean floor (sea floor spreading)
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What is sea floor spreading and why is it an important piece of evidence supporting plate tectonics?
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formation of magma that rises to Earth’s surface and solidifies at a mid-ocean ridge.
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How did the work of Vine and Matthews confirm sea floor spreading?
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They examined a magnetic pattern on the sea floor which determined a new crust created at mid-ocean ridges
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Why does a map of worldwide earthquakes closely match the locations of worldwide plate boundaries?
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Most earthquakes occur along the edge of the oceanic and continental plates. **Earthquakes usually occur where 2 plates are running into each other or sliding past each other.**
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List the features found in the following type of plate boundary and give a geographic example: Divergent
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Sea floor spreading forms ridge crest fractures, which fill with molten material. *On continents rift or rift valleys form (e. g. East African rift- Red Sea)(spreading) continental rifting, splits landmasses into 2 or more smaller parts. mid ocean ridge, new ocean floor, shallow focus on earthquakes.
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List the features found in the following type of plate boundary and give a geographic example: Convergent Oceanic – Continental
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ocean plate is subducted, continental volcanic arcs generated, explosive andesitic volcanic eruptions. Example: Cascade Randge, Andes Mountains.
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List the features found in the following type of plate boundary and give a geographic example: Convergent Oceanic – Oceanic
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Forms volcanoes on ocean floor that merge as volcanic island arc (convergence), Denser plate is sub ducted, Deep trenches generated, Volcanic island arc generated -Ex. Aleutian Islands, Japan Arc
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List the features found in the following type of plate boundary and give a geographic example: Convergent Continental – Continental
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Often produces mountains (no subduction), Tall mountains uplifted Example: Himalayas, (India-Asia collision), Other possibilities Alps, Appalachians, Urals
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List the features found in the following types of plate boundaries and give a geographic example of each: Transform
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Oceanic transform fault- ocean floor only, Continental transform fault – cuts across, Transform faults occur between mid – ocean ridge segments * Plates slide past one another a.) No new crust created b.) No crust destroyed, *Most in oceanic crust, *Join two segments of mid ocean ridge, *Parallel motions of plates; same direction plates are spreading. Example: San Andreas Fault
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What are the differences between oceanic ridges and oceanic rises? Why do these differences occur? Give an example of each.
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Oceanic Rise – Fast spreading, Gentle slopes, East pacific. Oceanic Ridges – Slow spreading, Steep slopes, Mid Atlantic
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Distinguish between mantle plumes, and hot spots.
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Rising plume of mantle material forms hot spots.
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Describe how the occurrence and distribution of mantle plumes and hot spots supports the theory of Plate Tectonics.
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Rising plume of mantle material forms hot spot
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Explain the stages of coral reef development form fringing to barrier reef to atoll?
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Fringing reefs – develop along margin of landmass. Barrier reefs – separated from landmass by lagoon. Atolls – Atolls are a round reef with nothing in the middle and form on flanks of sinking volcanic islands.
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Who was the first scientist to explain atoll formation?
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Charles Darwin
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Anaerobic
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A bacteria that lives without oxygen.
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Heterotroph
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An organism that cannot make its own food.
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Mantle
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Thickest layer, made up of hot rock. has plasticity
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Nebular Hypothesis
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All bodies of the solar system are formed from the nebula (mainly hydrogen & helium)
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Photosynthesis
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A process by which plants use the sun’s energy to make food.
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Scientific Method
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A series of steps followed to solve problems including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions.
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Theory
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A hypothesis that has been tested with a significant amount of data
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Hypothesis
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(educated guess) A preliminary explanation for observations or data
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Autotroph
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An organism that makes its own food
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Evolution
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A change in a species over time
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Continental Crust
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Granite – Intrusive, igneous rock. Less dense, light colored. A solid, thicker layer.
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Oceanic Crust
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Basalt. Earths crust located under the ocean that is usually thinner.
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Isostatic
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Vertical movement of sections of Earth’s crust to achieve balance. rises or sinks due to loading or unloading
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Density Stratification
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The process by which matter became layered by density during Earth’s formation.
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Earths Core
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The extremely hot and dense center of the earth, which is believed to be composed of iron and nickel
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Crust
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Earth’s outermost layer. Basaltic/Granitic Rock
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Protoearth
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The protoplanet Earth- was much larger than today’s earth and didn’t contain life or water. Was homogenous and was bombarded by meteorites. One theory states that the Moon was born after Protoearth collided with a planet.
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Granite
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A usually light colored igneous rock that is found in continental crust
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Density
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Mass per unit volume
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Basalt
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A dark, dense, igneous rock with a fine texture, found in oceanic crust
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Outgassing
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the process by which water vapor and other gases and compounds are brought to Earth’s surface by volcanism and released into the atmosphere
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Lithosphere
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A weak, cool, rigid layer made up of the uppermost part of the mantle and the crust. Thinner in oceans and thicker on continents.
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Asthenosphere
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The solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it
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Define bathymetry
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The measurement of depth of water in oceans, seas, or lakes.
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Name the techniques used by early ocean navigators to estimate ocean depth.
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Echo Soundings & Precision depth recorder
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Name some modern techniques used to map the ocean floor.
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Multi beam sounders, side scanning sonar, Satellite Mapping,
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Describe the differences between Passive and Active continental margins. List and describe the features associated with each type. Explain how these features relate to plate tectonics.
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Passive: not close to plate boundary; lack major tectonic activity; wide continental shelf, continental slope, continental rise. Active Margins – associated with plate boundaries; high degree of tectonic activity
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Differentiate between continental shelf and continental slope. Which has the steeper gradient?
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Continental shelf – flat zone (gentle slope) from shoreline to shelf break (deep ocean basin); Continental slope- steep gradient; beyond the shelf break where deep ocean basins begin
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What are turbidity currents and what type of deposits do they generate?
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move under the force of gravity, graded bedding. underwater avalanches; sediment from continental shelf
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Explain what graded bedding is and how it forms.
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material that settles out and larger particles on the bottom smaller ones stay on top
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How are submarine canyons created?
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formed by turbidity currents which carve out the submarine canyons in the continental shelf.
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What are some differences between a submarine canyon and an ocean trench?
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submarine canyons – deep, narrow, v-shaped; carved by turbidity currents. Ocean Trenches: convergent boundaries; deepest part of oceans; most in Pacific; example Mariana Trench
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What are abyssal plains and describe the process by which they are formed.
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is the end result of spreading of the seafloor basaltic material reaches the surface at mid-ocean ridges it forms new oceanic crust.
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What is the origin of the various volcanic peaks of the seamounts?
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below sea level
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What is the origin of the various volcanic peaks of the table mounts?
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below sea level
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What is the origin of the various volcanic peaks of the abyssal hills?
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above sea level
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What is the origin the various volcanic peaks of the sea knolls ?
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above sea level
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Where are the majority of the world’s earthquakes and active volcanoes located?
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Pacific Ring of Fire
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Describe characteristics and features of the mid-ocean ridge.
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Earth’s longest mountain chain; entirely volcanic; basaltic lava; divergent plate boundary
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List and describe the different type of hydrothermal vents. What is the water temperature associated with each type?
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Warm Water Vents: lowest temperature; clear water (86 degrees). White Smokers: Intermediate temp. White water (light compounds) (86-662 degrees). Black Smokers: highest temp. Black water; metal sulfides (Fe, Ni, Cu, Zn) 662 degrees
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Name the three basic types of oceanic islands. Describe the origin and name an example of each type.
answer

hot spots – form at one time, hawaiian islands. volcanic activity – Ascension island among the mid-atlantic ridge (iceland). Island arcs – Convergent plate boundaries – aleutian islands, Japan forms at the same time because of subduction and bc they move away from the hot spot.
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Abyssal clay
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fine-grained sediment
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Radiolarian
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protozoans; hard shells made of silica (glass)
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Quartz
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A very hard mineral composed of silica
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precipitate
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A solid that forms and settles out of a liquid mixture
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phosphorite
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phosphates, fertilizers
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phosphate
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useful as a fertilizer
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petroleum
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mainly from continental shelves
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pelagic deposit
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Sediments cover about 3/4 of the sea floor. Lithogenous sediment- found in deep ocean basins and are fine grained
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paleoceanography
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study of how ocean, atmosphere, and land interactions have produced changes in ocean chemistry, circulation, biology, and climate
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ooze
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accumulates when rate of deposition exceeds rate of dissolution (to leak out slowly)
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neritic deposit
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lithogenous sediment, may contain biogenous sediment, on continental shelves and shallow water near islands.
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nannoplankton
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(coccolithospore) Photosynthetic algae, individual plates from dead organisms
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microscopic biogenous sediment
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Must use a microscope to see. Organisms create tiny shells called tests, which sink to the bottom of the ocean and form biogenous sediment. mainly algae and protozoans.
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manganese nodule
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under a microscope. found in deep sea floor (abyssal plains), hydrogenous sediment, Fist-sized lumps of manganese, iron, and other metals
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macroscopic biogenous sediment
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large enough to be seen without a microscope, shells, bones, teeth
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lysocline
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The depth in the ocean in which the pressure is high enough and the amount of carbon dioxide in deep ocean water great enough to begin dissolving calcium carbonate.
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lithogenous sediment
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(terrigenous) eroded material carried by wind, glaciers, and gravity, on continents.
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limestone
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hydrogenous sediment, CaCO3
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gas hydrate
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a gas; such as methane, trapped in a lattice-like structure of water molecules
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foraminifera
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(Microscopic zooplankton) One of a group of tiny single-celled organisms that live in surface waters and whose secretions and calcite shells account for most of the ocean’s carbonate sediments.
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evaporite mineral
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A hydrogenous sediment Minerals form when seawater evaporates in restricted ocean. Halite (common table salt) and Gypsum, high evaporation rates.
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diatomaceous earth
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a light soil consisting of siliceous diatom remains and often used as a filtering material
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diatom
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class of algae with silica tests which contain a single cell
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cosmogenous sediment
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derived from outer space (meteorite, space dust)
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coccolithospore
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photosynthetic, microscopic, made up limestone (calcite), live mainly on the surface
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chalk
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A type of limestone; a powdery, fine-grained rock composed of almost pure calcite.
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carbonate
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CO3
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calcium carbonate
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CaCO3
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calcite compensation depth (CCD)
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depth where CaCO3 produced can dissolve. rate at which the shells dissolve
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calcareous ooze
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50% of shallow oceans with warm surface water, mostly the hard remains of cocci, forminfera containing calcium carbonate
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biogenous sediment
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Sediment that is made up of the skeletons and shells of marine organisms.
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algae
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photosynthetic, biogenous sediment
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Fathom
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standard unit of the ocean depth
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Echo Soundings
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or fathomer, reflection of sound signal; lacks detail, may provide inaccurate view of sea floor
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Precision Depth Recorder (PDR)
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1950’s good resolution; reliable sea floor maps; confirmed sea floor spreading, focused on high frequency sound beam
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Multibeam echo sounders and side scan sonar
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precise pictures of ocean floor; computer generated sea floor maps
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Satellite mapping
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detect irregularities in height of ocean surface caused by gravitational attraction of sea floor features, indirectly reveal bathymetry
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Seismic reflection profiles
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air guns, strong, low frequency sounds, details ocean structure beneath the sea floor, structure of rock layers beneath sea floor; used in oil, gas, and mineral exploration
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Hypsographic curve
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relationship between height of land and ocean depth
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HMS Challenger
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(1872) – first systemic measurements
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What is the difference between oceanic ridges and oceanic rises?
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ridges=steep, slow with rugged slope. rises= gently sloped, rapid, less rugged
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Describe features of the mid-ocean ridge.
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caused by the divergent movement of plate tectonics and it is characterized by spreading sea-floor,shallow earthquakes and rising magma. (Mid-Atlantic ridge.)
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Hydrothermal vent
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unusual ecosystems; sea floor hot springs, foster unusual deep-ocean ecosystems able to survive without sunlight.
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What is one example of a passive margin?
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East coast of the US. Florida
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What are 2 examples of an active margin?
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Western South america (nazca plate) and cascades
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Name two types of active margins.
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Convergent and transform margin
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Describe the features of a convergent active margin
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continental volcanic arc, narrow shelf, steep slope, offshore trench, oceanic trench
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Transform active margin
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associated with transform plate boundaries. Linear islands, banks, and deep basins close to shore (less common)
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What is an example of a transform active margin
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coastal California along the san andreas fault
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Continental borderland
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islands, shallow banks, deep basins, transform active margins (san andreas fault)
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Example of a volcanic arc
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japan, aluetian islands
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example of a ocean trench
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mariana trench
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example of continental arcs
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cascades, andes mountains
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Oceanic crust is dense and composed of rock _____ while continental crust is less dense and composed of rock _____.
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basalt, granite
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Plate tectonics is an example of a scientific ____ which is well tested, widely accepted.
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theory
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Lithosphere is sub ducted into the mantle at ______ plate boundaries.
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convergent
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__________ is the most persuasive evidence for plate tectonics.
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paleomagnetism
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The cool, rigid, solid outer portion of earth consists of the crust and upper mantle is known as the _________ which rides on a weak, plastic layer in the upper mantle known as the ________.
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Lithosphere, asthenosphere
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Iceland is located over the mid atlantic ridge which is a _____ plate boundary.
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divergent
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Many lines of evidence supported the hypothesis of ________________ but the inability to provide plausible mechanism caused most 20th century geologists to reject the idea.
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Continental drift
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The san Andreas fault in california is a _________.
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continental transform fault
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The ________ depicts stages of ocean basin evolution
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wilson cycle
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Mid ocean ridge
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divergent plate boundaries, volcanic magma rises creating new crust
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hot spot
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magma rises, intense volcanoes, associated with plate boundaries
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What is the difference in spreading rates of mid ocean ridges and a mid ocean rise?
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mid ocean rise is at a fast pace and is flat. mid ocean ridge is a slow, rigid, solid and tall.
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List the origin and characteristics of the four types of marine sediment.
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Lithogenous, biogenous, hydrogenous, cosmogenous
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How does lithogenous sediment originate? Where is most of it found?
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eroded material from continents carried to the oceans by streams, glaciers, wind and gravity. found around continental margins
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What is mineral that makes up most lithogenous sediment?
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Quartz (SiO2)
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Differentiate between sediment types found in neritic and pelagic deposits?
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Neritic is near shore, close to land, shallow water, deposited quickly. Pelagic is farther shore, deeper water and is finer sediment, deposited slowly
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How does biogenous sediment originate?
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from remains of hard parts of once living organisms
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Explain the difference between macroscopic and microscopic biogenous sediment and give and example of each.
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macro- large enough to see without microscope, shells, bones, teeth. micro- tiny shells called tests accumulate to form ooze
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Define ooze.
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algae and protozoans
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What is the most common type of pelagic deposit?
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abyssal clay (red from iron)
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What type of organism is a diatom?
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photosynthetic algae (plankton)
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If siliceous ooze is constantly dissolving in sea water, how can deposits of it accumulate on the sea floor?
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Ooze accumulates when rate of deposition exceeds rate of dissolution
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Discuss the distribution of biogenous sediments in neritic and pelagic environments including carbonate deposits such as limestone and stromatolites, siliceous ooze, and calcareous ooze.
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limestone contains fossil shells, stromatolites are fine layers of carbonate in warm, shallow high salinity oceans.
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Outline the relationship between the calcite compensation dept (CCD) and the formation of calcareous oozes.
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they both dissolve with warm ocean water
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Manganese Nodules
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very slow rates, not sure why hey are not buried on seafloor, fist sized lumps of manganese, iron and other metals
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Define cosmogeneous sediment and discuss the origin cosmogenous sediment.
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Macroscopic meteor debris
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what controls this distribution of pelagic and neurotic sediments?
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depth of water and sea floor features
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List some commercially important resources provided by ocean sediments.
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petroleum, gas hydrates, sand and gravel, evaporite salts, etc.
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Distinguish between calcareous and siliceous oozes.
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Calcareous=CaCoO3 Silicous=SiO2
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Lithogenous
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derived from land, produced by weathering: breaking of rocks into smaller pieces
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biogenous
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derived from organisms
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hydrogenous
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derived from water
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cosmogenous
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derived from outer space
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Neritic: What are the different mechanisms that transported the sediment and the energy conditions under which they were deposited?
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Beach deposits- wave deposited (quartz). Continental shelf- relict sediments. Turbidite- Graded bedding. Glacial- high latitude, ice rafting.
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Pelagic
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slowly on deep ocean floor, volcanic ash, wind-blown dust
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What is the composition of diatoms?
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silica
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Neritic covers about _____ of he sea floor.
answer

1/4
question

Pelagic sediments cover about _____ of the sea floor.
answer

3/4

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