Term
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Definition
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Term
| What is the dominant feature of the ocean floor? |
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Definition
the mid-ocean ridge system
other major: deep ocean trenches |
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Term
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Definition
| the boundary between the continents and the deep ocean basins |
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Term
Three components of
the continental margin |
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Definition
continental shelves
continental slope
continental rise |
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Term
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Definition
submerged upper part of continental margin
shoreline to shelf break |
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Term
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Definition
steeper part of continental margin
outer edge coincides with geologic edge of the continents |
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Term
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Definition
starts at the base of the continental slope, and eventually connects with the deep sea floor
large apron of sediment
rises are broad and less rugged |
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Term
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Definition
| former areas of the continental shelf that are now exposed above sea level |
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Term
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Definition
cut through the continental shelves and slopes
similar to rift valleys in morphology
associated with large river systems
probably formed as river valleys when seal level was much lower |
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Term
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Definition
continuous elevated zone on all major ocean basins
has steep-sided central rift valley, site of:
basaltic volcanism
shallow focus earthquakes
hydrothermal vents
ridges are relatively narrow and rugged |
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Term
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Definition
areas of low rolling topography
many appear to e extinct volcanoes covered by sediment
cover 80% of pacific basin and much of indian ocean |
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Term
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Definition
extensive, flat areas of the sea floor
occur at the base of the continental rises
areas of thick deposits of sediment that has buried original topography |
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Term
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Definition
narrow elongated zones of rugged topography with steep ridges and valleys
extensions of transform faults from the mid-ocean ridges
parallel eachother |
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Term
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Definition
deepest parts of the ocean floor
relatively narrow, but long
usually associated with volcanic arcs |
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Term
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Definition
isolated portions of the ocean floor that stand a kilometer or more above their surroundings
found in all ocean basins
can be microcontinents or associated with volcanic activity |
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Term
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Definition
more than half the world's water
deepest
bounded by active continental margins,
including trenches and volcanoes
islands abundant
numerous marginal seas
few rivers empty into pacific |
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Term
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Definition
relatively narrow,
bounded by parallel continental margins
greatest extent is in N-S direction
many rivers drain into Atlantic
highest salinity
due to high sediment transport and surface runoff
few islands
several marginal seas
Arctic Ocean is an extension of the Atlantic Basin |
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Term
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Definition
shortest in N-S extent
esentially straddles equator
intermediate depth
few islands or marginal seas
proximaty of continents leads to rapidly changing climatic conditions from summer to winter (monsoons)
3 of largest rivers empty, supplying significant sediment |
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Term
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Definition
large ocean-bottom depressions near continents
separated from open ocean by submarine ridges or islands |
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Term
| 3 Types of Marginal Ocean Basins |
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Definition
those associated with volcanic island arcs
basins that lie betwen continents
long, narrow basins surrounded by continent |
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Term
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Definition
found along coastal areas surrounding atlantic ocean
experience very little volcanic activity and few earthquakes
includes continental shelf, slope, and rise |
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Term
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Definition
occur where oceanic lithosphere is being subducted beneath the edge of a continent
narrow margin
sediments from ocean floor are scraped from the descending plate and added to the continental crust as an accretionary wedge
common around Pacific Rim, parallel deep ocean trenches |
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Term
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Definition
| the measurement of ocean depths and the carting of the topography of the ocean floor |
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Term
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Definition
| method used by oceanographers to visualize land and ocean relationships; terrain relief |
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Term
| lithogenous/terrigenous sediment |
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Definition
material derived from the continents or associated with oceanic volcanism (clay, silt)
transported to oceans by rivers, glaciers, and wind
sedimentation rates variable
found close to source |
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Term
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Definition
derived from biological activity; remains of plants and animals
(shells, bone, teeth)
distribution controlled by:
biological productivity in surface waters
dilution by other sedimenet types
chemical dissolution
destruction by scavengers or burrowing organisms |
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Term
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Definition
formed from seawater through chemical reactions (nodules and crusts)
both marine and freshwater
form in areas of low sedimentation rates or areas of net erosion
produce particles, concretions, crusts, or coatings |
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Term
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Definition
| fine dust and small particles that fall into the ocean from space (tektite) |
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Term
| Ocean sediments are usually classified according to ___ |
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Definition
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Term
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Definition
sediment deposited under conditions that no longer exist
for example, fluvial sediments deposited on the current continental shelves during the last glacial age when sea level was lower |
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Term
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Definition
sediment contains more than 30% of skeletal (shells or bone) debris
two types:
silicerous: silica shells
calcareous: CaCO3 shells |
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Term
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Definition
lithogenous sediment
color due to coating of oxidized iron |
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Term
| kinds of lithogenous sediment |
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Definition
deep-sea muds or red clay
terrigenous sediment: land
glacial marine
relict sediment |
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Term
what processes control the distribution of
biogenous sediments? |
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Definition
biological productivity in surface waters
dilution by other sediment types
chemical dissolution
destruction by scavengers or burrowing organisms |
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Term
| why study ocean sediments? |
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Definition
ocean is a site of deposition
generally undisturbed
deposited under slowly changing conditions
retain organized record of earth history
explain past climates
explain evolution of life
economically important resources
oil, natural gas, minerals |
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Term
| what affects the global distribution of marine sediments? |
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Definition
proximity to source areas
water temperatures
that favor the growth of certain marine organisms |
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Term
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Definition
material transported to the oceans by rivers or wind
transport affected by particle size. particle shape, ocean currents
the smaller the particle, the slower the settling rate |
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Term
| rates of settling of sand, silt, clay |
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Definition
sand - fastest 4 km/1.8 days
silt - 4 km/185 days
clay - 4 km/50 years |
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Term
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Definition
wind
turbidity currents along bottom
rivers - continental margins only |
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