Science chapter 19 the oceans and the seas
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Created by:
studydog6624 Plus on March 26, 2012
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45 terms
Terms | Definitions |
|---|---|
 Sea | A large body of salt water partially or near completely enclosed by land |
| Echo sounding | A form of sonar used to measure water depth beneath the vessel.Echo sounders measure the time it takes for sound waves to travel to the ocean floor and back and assumes a constant speed of sound through the water to obtain the distance. |
| Continental shelf | The submerged edge of a continent extending from the coastline to some distance offshore.It is characterized by having gentle slopes and similar geological formations and topography to the adjacent land. |
| Continental slope | The relatively steep drop-off from the continental shelf into the deep ocean basin |
| Submarine canyon | A canyon that occurs on the ocean floor, often on the continental slope |
| Continental rise | The sea bottom at the foot of the continental slope, consisting of sediments washed down the slope form the continental shelf above.The slope angle of the continental rise is less steep than that of the continental slope |
| Abyssal plain | The flat,deep sea floor of an ocean basin |
| Seamount | Any submerged mountain-like structure on the sea bottom; most are extinct volcanoes |
| Guyot | A submarine mountain that has a flat top |
| Trench | A deep canyon in the sea floor.Trenches seem to be associated with subduction at the margins of oceanic plates |
| Island arc | A long,curved chain of volcanic islands that lines the oceanic margin of a tectonic plate |
| Coral reef | A massive marine geological feature made up of calcium carbonate secreted by colonies of coral polyps in relatively shallow tropical waters and near continents and islands. |
| Fringing reef | A coral reef along a coast line that is in contact with the shore.Generally, it has only a very narrow lagoon or none at all. |
| Barrier reef | A coral reef located away from the shore that creates a lagoon between the reef and the shore. |
| Atoll | A ring of low coral islands and reefs surrounding a central lagoon that is in most cases built on a submerged volcano. |
| Residence time | Another name for an erosional mountain,such as a mesa,butte,monadnock,horn,and so forth. |
| Desalinate | The removal of salt and minerals form seawater to produce fresh,drinkable water |
| Reverse osmosis | A method of desalinization in which seawater is pumped at high pressure against a special membrane that allows water molecules to pass through but prevents the salt and other particles from crossing over |
| Tide | A periodic fluctuation in sea level that is caused by the gravitational forces of the moon and the sun as well as by the inertia of the waters on the rotating earth. |
| Spring tide | A unusually high tide that occurs when the sun,earth, and moon are lined up, either at new moon or at full moon |
| Neap tide | A lower-than-usual tide that occurs when the sun,earth, and the moon form a right angle and cause the sun's gravity to work agianst the moon's gravity.Neap tides occur twice each month, at the first and third quarters of the moon |
| Sea level | The level of the sea at a particularly time.Sea level thus changes with the rising and falling tides.The term is often used interchangeably with mean sea level. |
| Mean sea level | The average local sea level between high and low tide determined over the course of years |
| Crest | The peak or apex of a wave |
| Trough | The lowest part of a waveform |
| Wave height | The vertical distance between a wave's crest to the next wave crest. |
| Wave base | The water depth to which a wave disturbance equal to half the wavelength below the still-water level. |
| Breaker | A water wave in which the top falls over on the forward side of the wave.AS wave becomes unstable and produces a breaking wave when its height is more than or 1/7 or 0.143 of its length |
| Longshore current | A current that flows parallel to the shore and is caused by waves that approach the shore at an angle |
| Rip current | Rapid currents flowing outward to sea from indentations long a shore on which large waves are breaking.These currents are also called undertow |
| Sea cave | A cave formed by erosion of a cliff face by waves |
| Sea arch | A coastal erosional formation resembling a natural bridge that was caused by wave erosion of a sea cave through a narrow headland |
| Stack | A mass of rock that wave erosion has isolated from the shore, often formed by the collapse of a sea arch |
| Spit | A narrow sand formation deposited by waves and currents that extends out from a headland, often across the mouth of a bay or inlet |
| Bay barrier | A spit that extends across the mouth of a bay, closing it to the sea |
| Hook | A sand formation extending from a headland, deposited by waves and currents, which contains a sharp bend |
| Barrier island | An island formed when waves deposit sand across the mouth of a bay or along a coastline but has no connection with the mainland |
| Tombolo | A wave-deposited sandbar that connects islands with each other or with the mainland |
| Gyre | A large,closed-loop surface current in an ocean basin formed under the influence of prevailing winds and the Coriolis effect.Gyres flow clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere |
| Ekman spiral | a complex interaction on the surface of the sea between wind, rotation of the earth, and friction forces |
| Salinity | Describes the relative amount of salts dissolved in water.Highly saline water,as found in salt lakes or the Dead Sea, contains a relatively large amount of dissolved salts.Fresh water from snowfield runoff has very low salinity.Seawater salinity varies midway between these extremes |
| Thermohaline current | A deep ocean current caused by differences in temperature or salinity between large masses of ocean water |
| Density | The amount of matter contained in a single volumetric unit of a substance |
| Turbity current | A fast subsurface density current caused by the weight of large amounts of suspended sediment. Such flows are believed to res;ult in erosion o f the continental slope. |
| Upwelling | The rising to the surface of cold, nutrient rich water from the depths of the ocean; often occurs when prevailing winds blow surface waters away, allowing deeper waters to rise and take their place. |
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