Which, if any, of the types of processes or landscapes presented in this unit\'s
ID: 299895 • Letter: W
Question
Which, if any, of the types of processes or landscapes presented in this unit's chapters have you experienced personally? Describe the location and the physical geography of the landscape. What were your reactions or impressions of these phenomena?
Fluvial Landscape – a landscape created by rivers and their tributaries.
Tributary – a small river or stream which joins to a larger one.
River or drainage basin – an area drained by a single river together with all of its tributaries.
Confluence – where 2 or more streams, rivers or tributaries join together.
Watershed – The boundary line between different river/drainage basins. (Sometimes these are referred to as Catchment areas)
Source – The starting point of a river or stream. (watercourse) – This maybe a spring or just an area of boggy/marshy land.
Channel – the space between the banks of the watercourse in which the river flows, and may vary form a few meters to hundreds of kilometres.
Mouth – the point at which the river enters the sea or a lake.
Delta – the mouth of a river that splits into many channels (or distributaries) e.g. The River Mississippi or the River Nile.
Long Profile – the cross-section of a rivers course from its source to its mouth.
Cross Profile – a section across the valley of the river at any given point.
Explanation / Answer
Once i have travelled to the near places of Mississippi delta few years back. It was an amazing experience to travel by the roads of one of the world's largest delta. Although the whole view of delta could not be appreciated from a small part of the delta i.e nearby places of greenvile but the view of Atchafalaya River and the places nearby can amaze any person by the flood plains formed during intense flooding by the river where it meets the Gulf of Mexico. Like any great delta , huge amount of sediments are carried to the river mouth which outpaces the effect of waves or tides from the sea and so this is called a River Dominated Delta. The Mississippi delta is known to be the 7th largest delta of the world which formed nearly 100 million years ago during the Cretaceous time when the river started focusing it sediment deposition into the ocean and from then protrudation of the river channel started. During the starting of cenozoic era and end of the cretaceous several other smaller rivers joined the delta helping it to spread its sediments to more vast areas. Presently if we see the delta from a height ,we can see the distributaries branching out in all directions forming a Bird's foot structure. Prior to the 90's the river avulsed or abundant its course to flow in a shorter route to the sea every 1000 years. Rivers in most of the delta abunant its earlier course in search of new shorter course because and the avulsion may also be due to blockage of the river by its own sediment deposits. Louisiana coastline and a millions acres of coastal wetland formation was influenced by the several delta lobes of Mississippi river delta. With the avulsion of river, the flow of freshwater and sediment also changes which resulted in variety of landscape and there are periods of land loss and land building in different parts of delta. The lobe formed near the new orleans was probably the largest volume of sediment deposited. This whole process of delta formation could be termed as delta cycle. This is a dynamic process in which river carries sediment and deposits at its mouth forming a delta lobe. Then the river abandons that lobe seeking shorter paths and then forming other lobes. The lobes abundant by river generally experiences subsidence due to degradation by sea forces which distribute the sediments and sands to form barrier bars. Louisiana coastline was evidenced by bays ,coastal wetland and barrier islands due to avulsion by the river in past.
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