meander

• a meander is an example of erosion and deposition
• meander

  a bend in the river
• where are meanders found?

  in the middle and lower courses, eg the river severn, including shrewsbury on the inside of a bend and at arlingham
• characteristics of a meander inside bank:

  • curved, beach like feature
  • very gentle, convex slope (called a slip off slope with a point bar as it enters the river)
  • sediment consists of sand, gravel and pebbles that are smoothed and rounded by attrition
  • vegetation begins to grow furthest from the water
  • flow is slow and water is shallow
• characteristics of a meander outside bank:

  • a steep drop down into the river (usually termed as a river cliff)
  • can be several metres high
  • composed mostly of bare earth
  • loose material at base
  • flow is fast and water is deeper
• stage 1

  to begin with, water flows over shallow areas (riffles) and flows faster through deeper sections (pools), this sets in motion helocoidal flow that corkscrews across from one bank to the other which starts the erosion and deposition process.
• stage 2

  fast flowing water on the outside bend causes lateral erosion through abrasion and hydraulic action, making it deep, as the flow corkscrews round to the next inside bend, the flow slows due to friction and deposits its load. this creates an asymmetric profile
• stage 3

  on the inside bend, the river is forced to slow down, this encourages deposition and creates a river beach or slip off slope. the current is slower and with the deposition, shallower than the outside bend
• stage 4

  on the outside bend, the force of the water (hydraulic action) and the process of abrasion undercuts the banks creating deep water, a fast current and a steep river cliff
• stage 5

  on the outside of the bend, the river flows quicker and so erodes the outside bend faster
• what is this landform?

  its a meander