diagrams/formations

Ox-bow lake formation

• Outer Bend ➡ Faster water flow ➡ Erosion (abrasion, hydraulic action)

• Inner Bend ➡ Slower water flow ➡ Deposition (sand, rocks)

• Continuous erosion ➡ Meander neck narrows

• Flood ➡ Water cuts through meander neck (faster route)

• Original meander sealed ➡ Oxbow Lake formed

• Oxbow Lake ➡ Gradually fills ➡ Becomes bog (vegetation, sediment)

  

formation of waterfall

• Water flows over hard rock and soft rock. Hard rock resistant erosion → the soft rock gets eroded faster

• Hydraulic action & abrasion erodes the river bed more.

• force of water undercuts the hard rock forming an overhang

• plunge pool is formed at the foot of the river → to the sheer impact of the water.

• After some time, the undercut area has no more support for overhang of hard rock → collapses into the plunge pool.

• Pieces of the overhang erode plunge pool.

• The waterfall now retreats upstream, forming a gorge (deep and narrow valley)

  

formation of spit

• prevailing winds blow at an angle

• swash moves beach material towards direction

• backwash drags sediment perpendicular to angle

• zig-zag motion → longshore drift

• spit formed → material depositing at change in coastline direction

• recurved end form when wind approach in different direction

  

formation of cliff cave arch stack stump

• Cliff ➡ Erosion (hydraulic action, abrasion) ➡ Rock layers exposed
  Cave ➡ Erosion on weak rock ➡ Undercutting at base of cliff
  Arch ➡ Cave on both sides of headland ➡ Erosion breaks through ➡ Arch formed
  Stack ➡ Collapse of arch ➡ Sea erodes base ➡ Stack formed
  Stump ➡ Stack collapses ➡ Sea erosion ➡ Stump remains