Rivers landforms.

Question 1

Describe the formation of a waterfall.

Answer 1

• Bands of more resistant and less resistant rock.
• Less resistant erodes (hydraulic action and abrasion) quicker leaving a step.
• Water undercuts the less resistant rock creating an overhang.
• Overhand collapses.
• Rocks in plunge pool further erode it through abrasion and attrition.
• Waterfall retreats.
• Gorge.

Question 2

Describe the formation of a pothole.

Answer 2

• Hollow in river bed.
• Helicoidally flow carry rocks down the river.
• Rock stuck in hollow.
• The hollow is deepened by the process of attrition and abrasion.

Question 3

Describe the formation of a meander.

Answer 3

• Forms from a bend in the river.
• Helicoidal flow increases velocity on the outer bends (river cliff).
• Increased erosion (abrasion and hydraulic action).
• Inside bend (slip off slope) deposition occurs.

Question 4

Describe the formation of an ingrown meander.

Answer 4

• Established meander in place.
• Rejuvenation occurs (increase in energy due to a change in sea levels and isostatic lift).
• Vertical erosion depends the channel with stages of lateral erosion creating an asymmetric shape.

Question 5

Describe the formation of an entrenched meander.

Answer 5

• Established meander in place.
• Rejuvenation occurs (increase in energy due to a change in sea levels and isostatic lift).
• Vertical erosion occurs at a rapid rate over a long period creating a symmetric valley shape.
• With steep sided slopes on each side.

Question 6

Describe the formation of a ox-bow lake.

Answer 6

• Forms from a bend in the river.
• Helicoidally flow increases velocity on the outer bends (river cliff).
• Increased erosion (abrasion and hydraulic action).
• Inside bend (slip off slope) deposition occurs.
• Neck of meander continues to erode.
• Gap between two bends become closer.
• Water breaks through and cuts of the old meander.
• Leaving an ox-bow lake.
• Ox-bow lake evaporates leaving a meander scar.

Question 7

Describe the formation of a floodplain.

Answer 7

• Flat area of land either side of the river.

* Found in middle/lower course.

Question 8

Describe the formation of a delta.

Answer 8

• Lower course where the river meets the sea.
• Velocity decreases.
• Flocculation occurs when fresh water meets sea water and clay particles coagulate.
• Sediment is deposited in different layers (top set, bottom set and fore-set).
• Birds-foot: high velocity means that sediment is throw further out into the ocean.
• Cuspate and arcuate: Depending on the strength of long-shore drift.