Formation of fluvial landforms
Upper Course: EROSIONAL LANDFORMS
Waterfall – A sudden drop along the river course when water flows over a band of resistant rock
(hard rock) on top of less resistant rock (soft rock)
1. Soft rock is eroded more quickly than hard rock
2. Hard rock is undercut, forming an overhang
3. Abrasion (the eroded material against the
bottom of the waterfall)and hydraulic action
(force of the water) creates a plunge pool
4. Over time, the plunge pool gets bigger which
increases the size of the overhang. Eventually
the hard rock is no longer supported and
collapses
5. This process continues and the waterfall retreats
upstream
6. A steep-sided valley is left where the waterfall
was. This is called a gorge
Examples of waterfalls:
A) Victoria Falls, Zimbabwe/Zambia (1,708m across, 108m high)
Human uses for waterfalls:
- Hydroelectricity can be produced (e.g.
Niagara Falls)
- Fishing
- Waterfalls are fast moving leading to
water purification
- Fast moving water oxygenates the
environment which provides a suitable
B) Niagara Falls, USA/Canada environment for fish and other marine
animals to thrive
- However, in less developed countries
like Zimbabwe/Zambia, waterfalls
could be a big hindrance to trade since
goods cannot be transported on ships
when the rivers are not navigable
Upper Course: EROSIONAL LANDFORMS
Waterfall – A sudden drop along the river course when water flows over a band of resistant rock
(hard rock) on top of less resistant rock (soft rock)
1. Soft rock is eroded more quickly than hard rock
2. Hard rock is undercut, forming an overhang
3. Abrasion (the eroded material against the
bottom of the waterfall)and hydraulic action
(force of the water) creates a plunge pool
4. Over time, the plunge pool gets bigger which
increases the size of the overhang. Eventually
the hard rock is no longer supported and
collapses
5. This process continues and the waterfall retreats
upstream
6. A steep-sided valley is left where the waterfall
was. This is called a gorge
Examples of waterfalls:
A) Victoria Falls, Zimbabwe/Zambia (1,708m across, 108m high)
Human uses for waterfalls:
- Hydroelectricity can be produced (e.g.
Niagara Falls)
- Fishing
- Waterfalls are fast moving leading to
water purification
- Fast moving water oxygenates the
environment which provides a suitable
B) Niagara Falls, USA/Canada environment for fish and other marine
animals to thrive
- However, in less developed countries
like Zimbabwe/Zambia, waterfalls
could be a big hindrance to trade since
goods cannot be transported on ships
when the rivers are not navigable
