4.6 Landscapes And Processes Flashcards
What is meant by the long profile and cross profile of a river?
LP - It shows you how the gradient changes over the different courses.
CP - It shows you a cross-section of the river.
How does the river Eden’s landscape change along its long profile (upper/middle/lower)?
What are the reasons?
Upper - Steep gradient with V-shaped valleys. Steep sides. Narrow and shallow channel. Lowest river velocity and discharge. Biggest sediment size.
Middle - Medium steepness with gently sloping valley sides. Wider deeper channel.
Lower - Very wide with almost flat valley. Very wide and deep channel. Highest river velocity and discharge. Smallest sediment size.
It all depends on whether erosion or deposition is dominant and whether lateral or vertical erosion is dominant.
Compare hydraulic action with abrasion
Hydraulic action - water and air goes in cracks/rocks, pressure, cracks due to pressure, break off.
Abrasion - pebbles/ rocks, thrown and smashed, cliff side, smoother and erosion.
Define weathering
It is the process of rocks and other materials getting broken down.
Compare freeze thaw and biological weathering
Freeze-thaw weathering - water falls inside cracks and crevices in rocks, temperature goes under freezing, water freezes and expands, pressure, makes rock expand, sun comes back, heats up causing the ice to melt, rock shrinks, continues in a cycle.
Biological weathering - Animals and roots dig through the rock and soil, weakening joints, rocks crack, break off.
Compare traction with suspension transport
Traction - large particles like boulders are pushed along the river bed by the force of the water.
Suspension - small particles like silt and clay are carried along by the water.
Explain the stages and processes responsible for waterfall formation.
- A river flows over an area of hard rock followed by an area of softer rock.
- softer rock is eroded creating a step in the river.
- as the water goes over the step, it erodes the soft rock more and more.
- a steep rock is eventually created with a slowly enlarging plunge pool.
- hard rock is undercut by erosion and collapses.
- these repeats itself making the river retreat and create a gorge.
Explain the stages and processes responsible for v shaped valleys.
- River erodes downwards due to gravity, creating a gap.
- weathering causes the river sides to weaken and become like scree slopes.
- they are transported downwards and into the river steepening the river sides.
- the valley becomes v shaped.
Explain the stages and processes responsible for interlocking spurs.
- water flows in a river.
- hard rock obstructs it.
- river finds another way through the least resistant rock by traveling around the hard rock.
- interlocking pieces of land are created with a small river flowing between them.
Explain the stages and processes responsible for meanders.
- current on the outside of the river is fastest and has more erosion.
- current on the inside of the bend is slowest and has deposition.
- slowly, the outside of the bend is eroded further and further.
- the bend is enlarged and meanders are created.
Explain the stages and processes responsible for ox-bow lakes.
- they are created from meanders.
- erosion causes the outside bends to get closer.
- a small bit of land is left between the bends.
- the river breaks through the land.
- the river flows through the shortest route.
- deposition cuts of the meander.
- this creates an ox-bow lake.
Explain the stages and processes responsible for flood plains.
- the meanders become larger and larger.
- this means that they eventually erode far enough to reach the valley edge.
- the meanders erode them as well widening the river valley.
- the space they created is the floodplain.
Explain the stages and processes responsible for levees.
- when the river floods, it goes onto the floodplain.
- friction slows the river down.
- the biggest sediment is dropped first so it is closer to the actual river.
- the smallest sediment is carried the furthest.
- the biggest sediment will form the levee which is a natural embankment on the side of the river.
Explain the stages and processes responsible for deltas.
- river loses velocity when it reaches another body of water.
- it deposits lots of sediment faster than it can be eroded away.
- sediment builds up in a fan-shaped delta.
- river splits into many smaller channels called distributaries.
Explain two ways climate, geology and slope processes change the river landscape.
- rivers flowing through areas of hard rock have slower erosion so it will have gentle sloping valleys.
- vertical erosion in rivers causes steep valleys so soil creep and mass movement is more common.
