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38 Cards in this Set
- Front
- Back
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All forms of water: __% is what we drink |
97% 2.8% 0.03% |
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Oceans are important for five things: |
(1) Oceans influence climate: they store vast amounts of heat and moderate climate (3) Source of food: primary food chain source (4) Transportation medium (5) Resources: about half of all known elements present in oceans |
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Oceans cover __% of the globe |
71% |
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What is the average depth of the oceans? |
3,729 meters (12,234 feet) |
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What is the average depth of continents? |
840 meters (2,756 feet) |
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Passive Continental Margin |
Margins that consist of a continental shelf, continental slope, and continental rise. -They are not associated with plate boundaries and therefore experience little volcanism and few earthquakes |
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Continental Shelf |
The gently sloping submerged portion of the continental margin, extending from the shoreline to the continental slope. |
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Continental Slope |
The steep gradient that leads to the deep-ocean floor and marks the seaward edge of the continental shelf -Average 5 degree slope, carved by submarine canyons |
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Continental Rise |
The gently sloping surface at the base of the continental slope -Made of sediments derived by turbidity currents |
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Turbidity Currents |
A downslope movement of dense, sediment-laden water created when sand and mud on the continental shelf and slope are dislodged and thrown into suspension. -Happens under water; an important part of erosion |
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Turbidity currents cause submarine canyons and fans. What are submarine canyons and fans? |
It is a seaward extension of a valley that was cut on the continental shelf during a time when sea level was lower, or a canyon carved into the outer continental shelf, slope, and rise by turbidity currents. |
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Active Continental Margins |
Are usually narrow and consisting of highly deformed sediments. They occur where oceanic lithosphere is being subducted beneath the margin of a continent -Convergence, trenches, subduction zones, volcanic island arcs |
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Deep-ocean basin |
The portion of seafloor that lies between the continental margin and the oceanic ridge system. This region comprises almost 30% of earth's surface |
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Abyssal plain |
Very level area of the deep-ocean floor, usually lying at the foot of the continental rise. -It contains: terrigenous sediment (silt, mud) biogenous sediments (living things) hydrogenouis sediments (water, salt deposits) |
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__% of ocean water is made up of minerals, which makes it denser. It is mostly made of the mineral _____. |
3.3% Salt |
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Seamount |
An isolated volcanic peak that rises at least 1,000 meters (3,000 feet) above the deep-ocean floor -volcanoes under water are called guyots and seamount |
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Guyot |
A submerged flat-topped seamount. -volcanoes underwater are called guyots and seamount |
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Carol Atoll |
Carol atoll is a ring-shaped coral reef including a coral rim that encircles a lagoon partially or completely -they were used as airbases in WWII |
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Mid-ocean rift |
The rifts at the crests of ridges represent divergent plate boundaries -43,000 miles long |
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Rift Valley |
A long, narrow trough bounded by normal faults. It represents a region where divergence is taking place. -They are as deep and wide as the Grand Canyon |
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The 3 seafloor sediments are: |
(1) Terrigenous: Derived from land, whether sand close to margins or mud far at sea (2) Biogenous: Living things, calcareous and siliceous (3) Hydrogenous: Manganese nodules, metal sulfides near black smokers, evaporates |
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Composition of Seawater: __% sodium chloride __% magnesium chloride __% sodium sulfate |
2.3% 0.5% 0.4% 0.1% 0.07% |
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Thermocline |
-the layer of ocean water between about 300 meters and 1,000 meters, where there is a rapid change of temperature with depth is called the thermocline. -(thermo = heat, cline = slope) -thermocline is a very important zone in the ocean because it creates a vertical barrier to many types of marine life |
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T/F: high variation = no thermocline |
True |
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T/F: Low latitudes = thermocline at 500-1000 meters in depth (beyond photic zone), 70-80 degrees near surface, 32-40 degrees at depth |
True |
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Ocean currents |
they are driven by winds, changed by corolis effect, and forming giant gyres (huge, circular whirls of water/current within an ocean basin) |
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What are the world's 5 main gyres? |
North Pacific Gyre, North Atlantic Gyre (a clockwise rotation in the northern hemisphere), South Pacific Gyre, South Atlantic Gyre, Indian Ocean Gyre |
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coriolis effect |
because of earth's rotation, currents are deflected to the right in the northern hemisphere and to the left in the southern hemisphere |
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Waveheight |
the vertical (up/down) distance between trough and crest is called the waveheight |
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wavelength |
the horizontal (left/right) distance between successive crests (or troughs) is the wavelength. |
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Wave period |
the time interval between the passage of successive crests at a stationary point -the time it takes one full wave/one wavelength to pass a fixed position |
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T/F: Swells = waves of oscillation |
True |
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T/F: Surf zone = waves of translation |
True |
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Abrasion |
an erosion caused by wave impact and pressure is abrasion--the sawing and grinding action of the water armed with rock fragments. |
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wave refraction |
(refringere = to break up) -The bending of waves -this plays an important part in shoreline processes |
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Longshore transport (beach drift) |
When waves hit the beach, the sand travels in zig-zag motion -the transport of sediment (sand/pebbles) along the beach. |
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where does beach sand come from? |
the rivers |
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beaches are disappearing in america due to ____. |
dams in rivers |
