Sediment: Encyclopedia II - Sediment - Shores and shallow seas

Sediment - Shores and shallow seas

The second major environment where sediment may be suspended in a fluid is in seas and oceans. The sediment could consist of terrigenous material supplied by nearby rivers and streams or reworked marine sediment (e.g. sand). In the mid-ocean, living organisms are primarily responsible for the sediment accumulation, their shells sinking to the ocean floor upon death.

Marine environments also see the formation of bedforms, whose characteristics are influenced by the tides or currents.

The major areas for deposition of sediments in the marine environment include:

1. Littoral sands (e.g. beach sands, coastal bars and spits, largely clastic with little faunal content)
2. The continental shelf (silty clays, increasing marine faunal content).
3. The shelf margin (low terrigenous supply, mostly calcareous faunal skeletons)
4. The shelf slope (much more fine-grained silts and clays)

One other depositional environment which is a mixture of fluvial and marine is the turbidite system, which is a major source of sediment to the deep sedimentary and abyssal basins as well as the deep oceanic trenches.

Adapted from the Wikipedia article "Shores and shallow seas", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki