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Lithogenous sediment is also common at the poles where thick ice cover can limit primary production, and glacial breakup deposits sediments along the ice edge. [1] Coarse lithogenous sediments are less common in the central ocean, as these areas are too far from the sources for these sediments to accumulate.
In oceanography, terrigenous sediments are those derived from the erosion of rocks on land; that is, they are derived from terrestrial (as opposed to marine) environments. [1] Consisting of sand , mud , and silt carried to sea by rivers , their composition is usually related to their source rocks; deposition of these sediments is largely ...
Sediment is a solid material that is transported to a new location where it is deposited. [1] It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles.
Terrigenous (also lithogenous) describes the sediment from continents eroded by rain, rivers, and glaciers, as well as sediment blown into the ocean by the wind, such as dust and volcanic ash. Biogenous material is the sediment made up of the hard parts of sea creatures, mainly phytoplankton, that accumulate on the bottom of the ocean.
The continental shelves are covered by terrigenous sediments; that is, those derived from erosion of the continents. However, little of the sediment is from current rivers; some 60–70% of the sediment on the world's shelves is relict sediment, deposited during the last ice age, when sea level was 100–120 m lower than it is now. [21] [11]
Pelagic sediment or pelagite is a fine-grained sediment that accumulates as the result of the settling of particles to the floor of the open ocean, far from land. These particles consist primarily of either the microscopic, calcareous or siliceous shells of phytoplankton or zooplankton ; clay -size siliciclastic sediment ; or some mixture of these.
The two primary types of ooze are siliceous, which is composed primarily of silica (SiO 2), and calcareous or carbonate, which is mostly calcium carbonate (CaCO 3). [1] In an area in which biogenous is the dominant sediment type, the composition of microorganisms in that location determines to which category it is classified.
Breccia is composed of coarse rock fragments held together by cement or a fine-grained matrix. [5] Like conglomerate, breccia contains at least 30 percent of gravel-sized particles (particles over 2mm in size), but it is distinguished from conglomerate because the rock fragments have sharp edges that have not been worn down. [6]