Delta vs. Submarine Fan

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Kelsey Johansen and Nathan Walker 10/24/2012 Period 8 Delta vs. Submarine Fan A delta is the product of sediment deposition at the mouth of a river which has condensed into land. River deltas form when a river carrying sediment reaches a body of standing water, such as a lake, ocean, or reservoir. When the flow enters the standing water, it is no longer confined to its channel and expands in width. This flow expansion results in a decrease in the flow velocity, which diminishes the ability of the flow to transport sediment and eventually deposits. Over time, this single channel will build into the beginnings of a delta (a deltaic lobe), pushing its mouth further into the standing water. As the deltaic lobe advances, the gradient of the river channel becomes lower because the becomes longer but has the same change in elevation. Often when the channel does this, some of its flow can remain in the abandoned channel. When these channel switching events occur a mature delta will gain a distributary network.Most river deltas are very large, intricate, and fan shaped (much like Harry Potter’s broom and various species of fan coral). Good examples of large deltas are located at the Mississippi river, Amazon river, Nile river, Ganges river, and Okavango river. They provide large tracts of build-able land and have flat or gently sloping areas with sand and gravel that are easy to excavate, mostly well drained-which are not prone to landslides or other geologic hazards. These areas are well suited for all scales of construction activity. Deltas contain vast amounts of sand and gravel, which are economically important as construction aggregate. Deltas are major sources of ground water for many a community-be it large or small. The list could be endless (almost) as to the benefits deltas have for
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