With reference to processes of erosion and to processes of deposition, examine three ways in
which rivers shape the Irish landscape.
Name:
Waterfalls
Description:
This is a feature of river erosion found in the upper course of the river. It
is a steep or vertical fall in the flow of the river channel. The height of waterfalls can vary and
the speed of water is high.
Example:
Powers court Waterfall Co. Wicklow
Explanation and Processes:
Waterfalls generally form where the channel is sloping and consists of differing rock types.
Hard rock and soft rock lie beside each other. The soft rock is eroded quicker due to hydraulic
action when the power of flowing water will loosen and dislodge rocks. The load will collide and
erode the riverbed through abrasion and the softer rocks which are vulnerable the impact of
chemicals will be dissolved in a process called solution. The effect of these erosional processes
is to lower and deepen the level of the soft rock bed to below the hard rock. At the point where
the water hits the lower soft rock level a plunge pool may form undercutting the hard rock,
which will eventually collapse forming a waterfall.
Diagrams
Approaching the Physical Question
Remember the layout
Name
Explanation/Processes
Description
Diagrams
Example
o When explaining how a feature was formed name and describe the process involved as
shown below for a feature of erosion or deposition.
o Use pencil for large clear well labeled diagrams.
o Know 2 features of erosion and 2 features of deposition very well
Process of River Erosion.
1. Hydraulic Action. This is caused by the force of moving water. By rushing into cracks, the
force of moving water can sweep out loose material or help to break solid rock.
2. Abrasion or Corrosion This is the wearing away of the banks and the bed of a river by its
load. A river has its greatest erosive power during times of flood. Pebbles are whirled around by
eddies in hollows so cutting potholes.
3. Attrition As a river carries its load, the particles are constantly in collision with each other
and with the bed of the river. These particles are getting smaller in size, because of this;
boulders and pebbles in a river are always rounded and smooth in appearance.
4. Solution this is a chemical erosion process whereby a river dissolves such as limestone and
chalk as it flows across their surface.
Processes of River Deposition
Rivers drop their load when they loose their energy, which is likely in the middle and lower
courses. The heaviest part of the load, bed load is deposited first. Lighter finer material is
carried further in suspension and may be deposited over the flood plain during times of flood or
in the channel of a river as it nears the mouth some may help infill an estuary or form a delta.
The dissolved material is carried out to sea.