Terrace deposit
3572234
220863145
2008-06-21T23:44:27Z
Una Smith
3349439
image
[[Image:Manu riverbank.jpg|thumb|right|Terrace deposit above banks of the [[Manu River]], [[Peru]]]]
A '''terrace deposit''' is [[geology|geological]] term for a flat platform of land created alongside of a [[river]] or sea, where, at some time in the past, the river has cut itself a deeper channel. The former [[floodplain]] of the river is therefore at a higher point and is known as a terrace. Rivers can create a sequence of terraces over millennia as they erode away more material.
[[Image:Corte geomorfológico del Trabancos.gif|thumb|left|Terrace formation in cross section]]
Terraces are formed by [[rejuvenation_(river)|river rejuvenation]], when the river gains in [[gravitational potential energy]]. The terraces themselves are often made from fluvial material previously dumped by the river to create the earlier floodplain, These terrace deposits are broadly horizontal layers of [[gravel]], [[sand]] and finer sediments that can sometimes contain [[prehistoric]] [[archaeological]] finds.
Another notable source of stream terracing is the aggradation of legacy [[sediment]]s behind dams. These sediment deposits can accumulate very rapidly, in under 300 years, and can be observed to be in excess of five meters in height.
Here is a good example of a River Terrace: http://www.geographie.uni-erlangen.de/mrichter/gallery/photos/asia/images/river_terraces_near_kasbeki.jpg
==See also==
* [[Musashino Terrace]]
* [[Coastal sage scrub]]
* [[Table (landform)]]
{{geology-stub}}
[[Category:Landforms]]
[[Category:Geomorphology]]
[[Category:Archaeological features]]
[[de:Terrasse (Geologie)]]
[[es:Terraza aluvial]]
[[ja:河岸段丘]]
[[no:Terrasser (geologi)]]
[[zh:河階]]