Landing , landing , gravel or aggradation describes the natural deposition of mineral sediments (especially gravel , sand and silt ) as the initial process for the creation of flat, relatively well drained landscapes. The sediments were transported by flowing water over a certain distance into the landfall area (deposit area; geol .: deposit area). One therefore speaks of allochthonous material .
Landing can also include the increasing shallowness and eventually drying out of water or parts of water. This special form is in contrast to silting , which occurs through the deposition of predominantly organic (autochthonous) material from the water itself (in its pure form only occurs in standing inland waterways). However, when bodies of water or parts of bodies of water fall dry, landfall and siltation often work together.
Landings often take place in the area of already existing lake and river banks and on flat coasts , but can also lead to the formation of islands. In river valleys, the deposition of allochthonous sediments is usually referred to as agglomeration or, if it is relatively coarse sediment, as gravel and is related to changes in the flow velocity, which in turn depend on the water flow and the gradient. For example, due to periodic floods and the associated deposition of the sediment load in the flooded areas, vast alluvial plains are raised over the course of centuries to thousands of years. River terraces can be created in the interplay of erosion and flooding . The sliding slopes of meandering rivers are also created by landing.
The drying up of bodies of water or parts of bodies of water due to landing is usually the beginning of an allogeneic (caused by external influences) biological succession . At the same time, the uppermost sediment layers are converted into soil . Examples of such landfall areas are floodplains and marshes . The latter develop from sediment mud flats and in estuary deltas .
- M. Schaefer: Dictionary of Ecology . Jena, Gustav Fischer, 1992. ISBN 3-8252-0430-8
- Christiane Martin, Manfred Eiblmaier (Ed.): Lexicon of Geosciences. In six volumes, Spektrum Akademischer Verlag, Heidelberg [et al.] 2000–2002.