Rivers

Question 1

Formation of a v-shaped valley

Answer 1

• River in upper course
• Vertical erosion (hydraulic action and abrasion)
• Deep notch in landscape exposes sides to freeze thaw
• sides get weak and fall into the river (further abrasion)
• Rocks transported downstream
• V-shape valley is formed weaving around interlocking spurs

Question 2

Formation of a meander

Answer 2

• Middle/Lower course
• Lateral erosion
• River has deep and shallow parts
• River fastest on outer bend eroding it making it deeper (hydraulic action + abrasion). Forms River cliff.
• River is slowest on inside of the bend making it shallower (deposition- dropping of the load). Forms river cliff

Question 3

Formation of waterfall

Answer 3

• Upper course
• Water flows over bands of hard and soft rock
• Soft rock eroded quicker than hard
• Erosion creates a plunge pool where the water hits, undercutting the hard rock (hydraulic action + abrasion)
• Hard rock collapses leaving waterfall and a steep sided gorge

Question 4

Formation of ox bow lakes

Answer 4

• Middle/Lower course meanders
• Deposition on inside of bend due to slow current
• Erosion (hydraulic action + abrasion) on the outside of bend due to fast current.
• Neck gets narrower as river cliffs meets
• When river has power it takes shorter route over the neck.
• Deposition eventually blocks of the meander bend from the main river leaving an ox-bow lake

Question 5

Formation of leeves

Answer 5

• Levees are natural embankments
• Middle/ lower course
• Times of low flooding river deposits on the river bed raising its height.
• Times of flood river flows over the edge and deposits heavy material on the side of the river.
• Each flood builds up the levees.