River Landscapes in the UK 1 (Erosion (Hydralic action (This is the sheer…
River Landscapes in the UK 1
This is the sheer power of the waves as they smash against the cliff. Air becomes trapped in the cracks in the rock and causes the rock to break apart.
This is when pebbles grind along a rock platform, much like sandpaper. Over time the rock becomes smooth.
This is when rocks that the sea is carrying knock against each other. They break apart to become smaller and more rounded.
This is when sea water dissolves certain types of rocks. In the UK, chalk and limestone cliffs are prone to this type of erosion.
How are the made?
New deposition seals off the ends and the cut-off becomes an oxbow lake that will eventually dry up.
The river continues on its straighter path and the meander is abandoned.
Often during a flood the river will cut through the neck.
Continual erosion and deposition narrows the neck of the meander.
The river flows slowly on the inside bends and deposits material so its course is changing.
The river flows faster on the outside bends and erodes them.
The river is eroding laterally (from side to side).
The river is meandering across the valley.
How are they made?
The meander will migrate downstream and change shape over time.
Continuous erosion on the outer bank and deposition on the inner bank forms a meander in the river.
Water moves slowly on the inside of the bend and the river deposits some load, forming a river beach/slip-off slope.
The river erodes the outside bends through corrasion, corrosion and hydraulic action.
Water moving faster has more energy to erode. This occurs on the outside of the bend and forms a river cliff.
The river starts to flow from side to side in a winding course but still in a relatively straight channel.
Water twists and turns around stones and other obstructions resulting in areas of slower and faster water movement.
Transportation in a river
Large boulders and rocks are rolled along the river bed.
Small pebbles and stones are bounced along the river bed.
Fine light material is carried along in the water.
Minerals are dissolved in the water and carried along in solution.
A river’s profiles
A cross profile shows a cross-section of a river’s channel and valley at a certain point along the river’s course.
A long profile is a line representing the river from its source (where it starts) to its mouth (where it meets the sea). It shows how the river changes over its course.
When the river loses energy, it drops any of the material it has been carrying. This is known as deposition.
Factors leading to deposition:
At the end of the river's journey, at the river's mouth
When the volume of the water decreases.
vertical and lateral erosion on a river
The wearing away of a landscape when a river erodes sideways.
As a river flows into the middle course, there is some vertical erosion but more lateral erosion. The channel is wider and deeper as a result.
When the land is eroded or worn away in a downward direction, e.g. a river that is high up will erode vertically becuase the gravity pulls the water downwards.
As a river flows downhill there is an increase in vertical erosion. The channel is shallow and narrow because there is not a lot of water in the channel.
Interlocking spurs, waterfalls & gorges
A deep valley caused by the wearing back of a waterfall
Oftern occur where the river crosses a band of harder rock
Where a river winds between ridges