features of erosion

• how do cracks grow into caves?


  by hydraulic action and abrasion
• what is a GEO?


  A LARGE CRACK, OPENED UP BY HYDRAULIC ACTION
• when is a natural arch formed?


  when the cave breaks through the headland
• when is a stump formed?


  when the stack is eroded
• when is a tall rock stack (REMANENT) dformed?


  when the arch is eroded and collapses
• what are BARS?


  Spits that extend across an estuary linking two headlands

  Low river flow fails to carry deposits offshore

  River water simply flows under/through the shingle beach

  EG SLAPTON LEY IN DEVON
• How are bars/barrier beaches formed?

  1. Sometimes LSD will cause a SPIT to GROW ALL THE WAY ACROSS A BAY
  2. If this happens then the spit is called a BAR
  3. The BAR CONNECTS TWO HEADLANDS AND THE water trapped behind is called a LAGOON
  4. This will eventually be FILLED BY DEPOSITION
• What is a TOMBOLO?


  A shingle or sand ridge that connects an island to the mainland
• give a point about tombolos?


  may be covered at high tides so drive carefully!1111111
• What are offshore bars aka?


  sandbars
• what are offshore bars?

  submerged or partially submerged ridges of sand or coarse sediment

  Deposited by the strong backwash from destructive wavers
• Why are sandbars only visible at low tide?

  these usually low below sea levels, becoming visible only at low tide
• what do sandbars act as?

  temporary sediment stores or more permanent sediment sinks
• what do sandbars/offshore bars ABSORB?


  ABSORB WAVE ENERGY
• If offshore bars become larger and more permanent, what may happen>?


  they may be exposed at both low AND high tide. They then become BARRIER ISLANDS
• Give the order of size from smallest to largest of coves?


  GEO --> COVE --> BAY