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140:. Paleosols can serve as bounds for overbank depositional sequences or alternate with overbank deposits where flooding is episodic. Paleosols tend to show more maturity at a greater distance from the channel, where there is less sediment flux. The degree of soil horizon development can be used as a proxy for this process.
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Natural levees are sloped deposits which form on the banks of channels during flooding events, serving as barriers to future floods. The slope of a levee is primarily a function of its grain size. Levees tend to be steeper when they first form and are close to the channel, then gradually level out as
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Overbank deposits are climate-dependent. Of course, the frequency of floods has a major impact on overbank deposits. The controls on flood frequency are complex, but rainfall frequency is a major contributing factor. In humid environments, crevasse channels may empty into long-standing lakes or
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Floodplains are far wider than the channel they border, reaching widths of up to 100 kilometers, and their length is 10 times that. They are thin and roughly planar in shape. Unlike channel bars, which often build horizontally, overbank deposits build vertically.
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Overbank deposits are fine-grained and accumulate vertically. The disturbance of adjacent environments during flooding events leads to deposits containing terrestrial organic debris such as plant matter, and the intervening dry periods allow subaerial
152:), former floodplains can be stranded far from their former channel. They can be covered by new overbank deposits, cut by a channel, eroded completely, or converted into non-fluvial terrestrial deposits like soils.
54:, away from faster flow, the sediment is typically fine-grained. An overbank deposit usually consists primarily of fine sand, silt and clay. Overbank deposits can be beneficial because they refresh valley soils.
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Collinson, J.D. 1986. Alluvial
Sediments. In: H.G. Reading, editor, Sedimentary environments and facies, 2nd edition; Section 3.6: Inter-channel areas. Blackwell Scientific Publishing, Oxford; p. 41-43.
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and can have many of the features that larger fluvial bodies possess, like levees. A crevasse-splay sequence typically begins with an erosive base, followed by the deposition of coarse
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Crevasse-splay deposits form during flooding events when a river cuts a levee to form a smaller channel away from the main channel. These crevasse channels are essentially miniature
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pattern when viewed in cross-section. Crevasse channels are ephemeral, and their deposits commonly show terrestrial or desiccation features near the top such as
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Cazanacli, Dan; Smith, Norman D. (1998). "A study of morphology and texture of natural levees—Cumberland
Marshes, Saskatchewan, Canada".
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by roots and burrowing animals. Notable sub-environments within the floodplain include natural levees and crevasse splays.
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of a river or stream by flood waters that have broken through or overtopped the banks. The sediment is carried in
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marshes, whereas in arid environments any drainage areas can dry up between flooding events.
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Overbank deposits can also be referred to as floodplain deposits. Examples include natural
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sediment and transitioning to finer suspended sediment as energy decreases, resulting a
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Because overbank deposits often overlie areas that are normally exposed to
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Rivers and floodplains : forms, processes, and sedimentary record
199:"Definition of "overbank deposit" by Robert Michael Pyle: Home Ground"
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349:(5th ed.). Upper Saddle River, N.J.: Pearson Prentice Hall.
455:"Architecture of Miocene Overbank Deposits in Northern Pakistan"
136:, they can bury soils, allowing those soils to be preserved as
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Soils of the past: an introduction to paleopedology
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96:they grow and their grain size decreases. In the
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23:Example of overbank deposit, Price River, Utah
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347:Principles of sedimentology and stratigraphy
323:: CS1 maint: multiple names: authors list (
471:10.1306/D4267F46-2B26-11D7-8648000102C1865D
453:Willis, B. J.; Behrensmeyer, A. K. (1994).
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144:Controls on depositional system evolution
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295:. Oxford, UK: Blackwell Pub.
148:When a river changes course (
416:Retallack, Greg J. (1990).
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519:10.5194/hess-11-1405-2007
424:. Boston: Unwin Hyman.
291:S., Bridge, J. (2003).
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174:Deposition (sediment)
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110:distributary systems
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510:2007HESS...11.1405S
392:1998Geomo..25...43C
345:Boggs, Sam (2012).
225:"Overbank Deposits"
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209:2013-10-21
185:References
134:weathering
124:or roots.
48:suspension
44:floodplain
36:geological
479:1527-1404
365:666878065
319:cite book
158:Tectonism
138:paleosols
122:mudcracks
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311:49672174
168:See also
150:avulsion
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29:overbank
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