oceanography Oceanography (), also known as oceanology, sea science, ocean science, and marine science, is the scientific study of the ocean, including its physics, chemistry, biology, and geology. It is an Earth science, which covers a wide range of to ...

, terrigenous sediments are those derived from the erosion of rocks on land; that is, they are derived from ''terrestrial'' (as opposed to marine) environments. Consisting of

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

, mud, and

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension (chemistry), suspension with water. Silt usually ...

carried to sea by

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

s, their composition is usually related to their source rocks; deposition of these sediments is largely limited to the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an islan ...

. Sources of terrigenous sediments include volcanoes, weathering of rocks, wind-blown dust, grinding by glaciers, and sediment carried by rivers or icebergs. Terrigenous sediments are responsible for a significant amount of the salt in today's oceans. Over time rivers continue to carry minerals to the ocean but when water evaporates, it leaves the minerals behind. Since chlorine and sodium are not consumed by biological processes, these two elements constitute the greatest portion of dissolved minerals.

Quantity

Some 1.35 billion tons, or 8% of global river-borne sediment (16.5-17 billion tons globally), is transported by

Ganges The Ganges ( ; in India: Ganga, ; in Bangladesh: Padma, ). "The Ganges Basin, known in India as the Ganga and in Bangladesh as the Padma, is an international which goes through India, Bangladesh, Nepal and China." is a trans-boundary rive ...

- Brahmaputra river system annually according t
decades old studies
it is unquantified how much variance year to year as well as the impact modern humans have on this amount by holding back sediment in dams, counteracted with increased development of erosion patterns. Wind born sediment also transports billions of tons annually, most prominent in Saharan dust, but thought to be substantially less than rivers; again, variance of year to year and human impacts of land use remain unquantified on this data. It is well known terrain influences climate conditions, and erosive processes slowly but surely modify terrain along with tectonic causes, but all encompassing studies have been lacking on a global scale to understand how these ''shape of land and sea'' factors fit in with both human induced

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

and natural climate variability.

References

Cited

* Sedimentary rocks Sedimentology Marine geology Oceanography {{Ocean-stub

Quantity

See also

References

Cited