Oceanography Exam #1 – Flashcards
Unlock all answers in this set
Unlock answersquestion
Oceanography
answer
Study of the water of the oceans, the life in it, and the Earth beneath it.
question
Four Sub-disciplines of Oceanography
answer
Geological, Chemical, Physical, Biological
question
Ocean covers __% of Earth's surface, and contains __% of Earth's water.
answer
71, 97
question
The ocean and its ____ ____ control ____ ____.
answer
Stored Heat, Global Climates
question
The ocean is important for...
answer
...commerce, transportation and recreation.
question
Ocean Resources
answer
Water, Food, Minerals, Energy, Space
question
Human Habitation in Coastal Zone
answer
3.2 Billion People Worldwide, 80% of US Citizens, 8 out of 10 Largest Cities, 3,600 people move to coast each day.
question
The Four Principal Oceans (+1)
answer
Pacific, Atlantic, Indian, Arctic, (+Southern/Antarctic)
question
Average Ocean Depth
answer
~3,796 Meters
question
Average Elevation of Land
answer
840 Meters
question
Deepest Part of Ocean
answer
Mariana's Trench at 11,022 Meters Deep.
question
Highest Mountain
answer
Mount Everest at 8,850 Meters High.
question
Total Maximum Relief on Earth
answer
19,872 Meters
question
Early Period
answer
Up to ca 1400 CE (Includes Middle Ages); First Used as Food Source, Migration/Trade by Vikings, Phonecians, Chinese, and Micronesians; Later by Romans & Greeks for Political/Military Reasons
question
Early Period Accomplishments
answer
First Maps, Magnetic Compass, Size/Shape of Earth, System of Latitudes, Tides
question
Middle Period
answer
ca 1400-1800 CE (Age of Discovery); Exploration/Mapping by Western Man, Used for Trade/Colonialism/National Security, No Academic Study.
question
Middle Period Names
answer
Henry the Navigator, DeGamma, Magellan, Drake, Cook, Henry Hudson, Columbus
question
Middle Period Accomplishments
answer
Accurate Maps of Worlds & Oceans, Sextant, Chronometer, System of Longitude, Mercator Projection Maps, Notes on Local Biota.
question
Modern Period
answer
ca 1800 CE to Present; Primary Motivation Still Economic and Political, Includes First Systematic Scientific Studies
question
Modern Period Accomplishments
answer
1777: Ben Franklin's Map of Gulf Stream; 1807: US Coast and Geodetic Study (NOAA); 1830: Voyage of the Beagle, Darwin; 1872: Voyage of the HMS Challenger (First Purely Scientific Oceanographic Study)
question
Pacific Ocean
answer
Largest (width half circumference of Earth), nearly circular, deepest (greatest average depth because of many deep trenches), coldest and least salty, and numerous islands and volcano.
question
Atlantic Ocean
answer
Second largest, "S" shaped, shallower (large central ridge, average depth 3310 m), saltier than average; Mediterranean water.
question
Indian Ocean
answer
South of Tropic of Cancer, roughly symmetrical (more or less circular), smallest of the three main oceans.
question
Arctic Ocean
answer
Almost enclosed by land, nearly all above the Arctic circle, dominated by ice, largest connection with Atlantic/major influence on Atlantic.
question
Southern/Antarctic Ocean
answer
Defined by a set of physico‐chemical oceanographic parameters that distinguish the Antarctic water mass from the other water masses.
question
Universe Origin
answer
13-15 Ga; Big Bang Theory
question
Solar System Origin
answer
~5 Ga; Condensation of Solar Nebulae
question
Earth Origin
answer
~4.5 Ga; several hypothesis; most involve condensation and collapse of part of the solar nebulae, era of impacts; then fractionation/ differentiation, degassing, cooling.
question
Atmosphere Origin
answer
Ongoing; original atmosphere lost; atmosphere continually evolves as a result of degassing, abiotic and biotic processes; earliest known atmosphere much different from current.
question
Oceans Origin
answer
About 4.0 Ga (Billion Years Ago)
question
Oldest Fossils
answer
3.5 Ga (Billion Years Ago)
question
Oldest Rocks on Earth
answer
3.99 Ga (Billion Years Ago)
question
Oldest Ocean Floor
answer
200 Ma (Million Years Ago)
question
Continental Margin
answer
Submarine Extensions of the Continents
question
Deep Ocean Basins
answer
Deep ocean floor, fundamentally different from the continents.
question
Mid-Ocean Ridge/Oceanic Ridge
answer
Submarine mountain range; MOR
question
Continental Margin Features
answer
(From On Shore to Off Shore) Continental Shelf, Shelf Break, Continental Slope, Continental Rise
question
Continental Shelf
answer
Extends from shoreline to shelf break, shallow/lowrelief/gently sloping (~1-2º), similar topography to adjacent coast, average width 70 km but up to 1,500 km, average depth of shelf break 135 m
question
Continental Slope
answer
Steeply sloping area extending seaward from shelf break to deep ocean floor; average 4º slope; depth range ~200 m to ~3,000 m; submarine canyons cut into slope by turbidity currents (mixture of seawater and sediments, move under influence of gravity, erode canyons, deposit sediments at base of slope)
question
Continental Rise
answer
Transition between continental margin and deep ocean; composed of aggregated sea fans; turbidite deposits (graded bedding, submarine fans); distal end of submarine fans become abyssal plains
question
Features of Deep Ocean Basin
answer
Abyssal Plains, Volcanic Peaks, Ocean Trenches, Volcanic Arcs
question
Abyssal Plains
answer
Flattest places on Earth (<1º), very deep (Average Depth: 4,500-6,000 m); depositional surfaces extending seaward from base of continental rise; sediment comes from suspension settling of very fine particles; sediments cover ocean crust irregularities.
question
Volcanic Features
answer
Ocean crust that pokes through sediment cover; below sea level: seamounts, tablemounts or guyots at least 1.0 km above sea floor & abyssal hills or seaknulls less than 1.0km; above sea level: volcanic islands (Bermuda, Canary Isles, etc)
question
Ocean Trenches
answer
Linear, narrow, steep-sided, V-shaped depressions in the sea floor; deepest parts of ocean (>6,000 m); Mariana Trench at 11,022 m; majority in Pacific Ocean; Atlantic has 2 & Indian has 1; associated with subduction zones.
question
Volcanic Arcs
answer
Curved/arched chain of volcanic mountains; always on landward side of ocean trench; Island Arc-Chain of Islands (Japan, Phillipines) & Continental Arc-Volcanic Mountain Ranges (Andes, Cascades)
question
Mid-Ocean Ridge
answer
Longest mountain range on Earth circling the globe like the lines on a baseball; mostly transverses the middle of ocean basins; on average 2.5 km above sea floor with highest peaks about 2 km below sea level; wholly volcanic with basaltic lava; contains a central down-dropped rift valley; aka East Pacific Rise in Pacific Ocean and Mid Atlantic Ridge in Atlantic Ocean.
question
Oceanic Ridge
answer
Prominent rift valley; steep, rugged slopes; concave up
question
Oceanic Rise
answer
Gentler, less rugged slopes; sides are convex up
question
Features of Mid-ocean Ridge
answer
Central rift valley, faults and fissures; sea-mounts; pillow basalts; hydrothermal vents (deposits of metal sulfides, unusual life forms); fracture zones and transform faults
question
Transform Faults & Fracture Zones
answer
Long linear zones of weakness, cracks; offset axes of mid-ocean ridges; TF ocean floor on either side moves in opposite directions; FZ extensions of transform faults (aseismic, doesn't move, no earthquakes)
question
Pillow Lava
answer
Forms when hot lava comes into contact with cold sea water and quickly cools; basalt composition
question
Hydrothermal Vents
answer
Heated subsurface seawater migrates thru cracks in ocean crusts; Warm Water Vents 30ºC/86ºF but 350ºC; dissolved metals precipitate to form metal sulfide deposits; unusual biological communities (able to survive without sunlight, archaebacteria and bacteria oxidize hydrogen sulfide gas to provide food)
question
Pacific Ocean Floor
answer
Many large trenches; many oceanic islands, seamounts, guyots; few, poorly developed abyssal plains; narrow shelves, no continental rises; many island arcs; East Pacific Rise; marginal seas
question
Atlantic Ocean Floor
answer
Few oceanic islands, seamounts, guyots; large, central oceanic ridge; large, extensive abyssal plains; few trenches (Puerto Rico, Sandwhich); wide shelves, and extensive continental rises, Passive Margin; large marginal seas (Gulf of Mexico, Mediterranean, North, Caribbean)
question
Indian Ocean Floor
answer
Marginal seas (Red Sea, Persian Gulf, Bay of Bengal); Mid Indian Ridge, symmetrical, Y shaped, one branch in Red Sea, others connect with MAR and EPR; large abyssal plains and submarine fans; java trench
question
Arctic Ocean Floor
answer
Covered by ice & difficult to study; series of three oceanic ridges running N to S; relatively shallow
question
Density
answer
Fundamental property of matter that is important in one way or another to almost all aspects of oceanography; D=m/v or gm/cc; inversely proportional to temperature; less dense floats
question
Earth's Internal Structure
answer
Determined by seismic waves, rock samples from deep drilling, rock samples from deep earth, bulk chemical analyses
question
Crust
answer
5-60 km thick
question
Oceanic Crust
answer
dark colored, basaltic composition, avg density 3.0 gm/cc; avg thickness 6 km
question
Continental Crust
answer
light colored, granitic composition, avg density 2.7 gm/cc, avg thickness 35 km
question
Mantle
answer
2900 km thick, Iron & Magnesium rich minerals, avg density 5.5 gm/cc, density of uppermost mantle 3.0-3.3 gm/cc
question
Core
answer
3500 km thick, iron-nickel alloy, fluid/plastic outer core, solid/rigid inner core
question
Lithosphere
answer
100 km thick, rigid/brittle/breaks under stress, all crust and small portion of upper mantle, avg density 2.9-3.0 gm/cc
question
Asthenosphere
answer
600 km thick, plastic/ductile/bends or flows under stress but breaks when shocked; includes upper 1/4 of mantle; avg density 3.1-3.3 gm/cc
question
Mesosphere
answer
2200 km thick; more or less rigid down to outer core
question
Mohorovicic Discontinuity "MOHO"
answer
boundary between crust and mantle
question
Isostasy
answer
A condition of flotational equilibrium among various units of the lithosphere "floating" in the asthenosphere, Application of Archimedes Principle to the lithosphere and asthenosphere, Less dense materials float higher than more dense materials.
question
Relative Time
answer
...
