1. River features – Upstream portion River Channel: small, narrow, rough and usually shallow. When rivers have to flow round obstacles of hard rocks in its path (spurs), it develops a winding course.

2. River features – Upstream portion

3. 1) Rapids: a series of short and fast-flowing turbulent falls of water along a part of the river. Water is relatively shallow.

4. River features – Upstream portion

5. Formation of rapids: River flows over an area of alternating bands of gently inclined resistant and less resistant rocks. Less resistant rocks are eroded faster. river flows swiftly when it flows over outcrops of resistant rocks.

6. River features – Upstream portion 2) Waterfalls Sudden fall of water along a course of a river. Water plunges down almost vertically and rapidly into a deep valley

7. River features – Upstream portion Formation of waterfall: forms when a river flows from a band of resistant rock to less resistant rock. band of resistant rock can lie horizontally, vertically or dip upstream less resistant rock that lies downstream will be eroded faster than the resistant one

8. River features – Upstream portion Formation of waterfall: differential erosion causes a change in gradient of river. over time, the river bed will be steepened. water plunges down almost vertically and rapidly as a waterfall.

9. River features – Upstream portion

10. Formation of waterfall (cont’d) when faulting causes land to be displaced, waterfalls can also form. One block of land will be uplifted relative to the adjacent block. This displacement causes a difference in height. Water cascades down the fault scarp.

11. River features – Upstream portion

12. 3) Plunge Pools A depression at the foot of a waterfall. This depression is excavated, enlarged and deepened by hydraulic action of the plunging water. Rock debris erodes the depression by abrasion to furthur enlarge and deepen it.

13. River features – Upstream portion 4) Gorges Deep narrow valleys with almost vertical sides.

14. River features – Upstream portion

16. 5) Potholes Depressions of different sizes in the river bed. Formed by river abrasion. Abrasive action especially effective in flood conditions

17. River features – Upstream portion

18. http://library.thinkquest.org/28022/