GCSE Edexcel A

1. Revision: Physical World Rivers

4. Methods of Erosion

10. River Structure

12. Upper Course Also known as ‘Torrent’ or ‘Youth’ stages Interlocking Spurs In the Upper Course, the river is fast flowing, but there is little water and load. The river is often called a stream and does not have the erosive power to remove the hillsides (spurs), but erodes downwards instead. EROSION TYPE: Vertical and Headward

13. Upper Course:Interlocking Spurs

14. Interlocking Spurs River channel

15. Upper Course: Potholes Potholes Boulders broken off by erosion that sit on the river bed create swirling eddy currents as the water flows past as the river is not strong enough yet to move the boulders by TRACTION. These eddies swirl the boulder round and erode a pothole in the river bed by ABRASION. EROSION TYPE: Vertical (by EDDY CURRENTS)

16. Upper Course: Waterfalls & Gorges Waterfall and Gorge 1 (OBLIQUE AERIAL VIEW) EROSION TYPE: Vertical and Headward

17. Upper Course: Waterfalls 2 Waterfall and Gorge 2 (PROFILE VIEW) EROSION TYPE: Vertical and Headward

18. Meanders

19. Middle Course: Meanders Meanders are formed because the current swings to the outside of a bend and concentrates the erosion there. Deposition occurs on the inside of the bed where there is not enough energy to carry load. EROSION TYPE: Lateral Also known as the ‘Mature’ stage Meanders 1 (Aerial View)

20. Middle Course: Meanders 2 Meanders 2 (Profile View / Cross Section X - Y) EROSION TYPE: Lateral This cross section clearly shows the eddy current (near ’X’) formed by the velocity of the river being concentrated on the outside of the bend. These UNDERCUT the bank causing the formation of a RIVER CLIFF. On the inside (NEAR ‘Y’), a SLIP-OFF-SLOPE is formed where current is too slow to carry any load.

21. Middle Course: Ox-bow lake Ox-Bow Lake 1 (Aerial View) EROSION TYPE: Lateral Ox-bow lakes are formed when two meander RIVER CLIFFS are being eroded towards each other. These will eventually meet, causing the river to then flow across the bottom of the diagram.

22. Middle Course: Ox-bow lake 2 Ox-Bow Lake 2 (Aerial View)

23. Lower Course: Levees Leveés and Raised Beds 1 (Front View) DEPOSITION FEATURE: no erosion in the Lower Course Leveés are formed when rivers flood. The river water overflows the banks of the river and immediately slows down due to friction with the FLOODPLAIN. This drops the larger particles first, building up a raised river bank called a LEVEÉ.

24. Lower Course: Levees 2 Leveés and Raised Beds 2 (Front View) DEPOSITION FEATURE: no erosion in the Lower Course Raised beds form in the Summer months when the river volume and energy are low and load is dropped onto the river bed. The bed raises up and the capacity of the river reduces, causing flooding in the winter. This in turn builds up the leveés and the whole process raises up the level of the river in the landscape.

25. Lower Course: Deltas Delta (Aerial View) This deposition feature is one of the largest. When the flowing river hits the non-flowing sea, energy is suddenly lost. This causes all of the load in the river to drop in the river MOUTH. This builds up over time to create a delta – an area of land. The river divides into DISTRIBUTARIES to continue to the sea, which is now some way away from its original meeting point.