Physical Landscapes in the UK (UK Physical Landscapes (Highlands…
Physical Landscapes in the UK
UK Physical Landscapes
The UK has a diverse range of landscapes
The Northwest Highlands
Vale of york
Rockfall is the rapid, free-fall of rock from a steep cliff face. Rock fragments fall from the face of the cliff because of the action of gravity. This is made worse by freeze-thaw action loosening the rock. Bare, well-jointed rock is very vulnerable to rockfall - water enters the joint, freezes and expands, cracking the rock. A scree slope of fallen rock is formed at the bottom of the cliff.
Mudflow occurs on steep slopes over 10°. It's a rapid sudden movement which occurs after periods of heavy rain. When there is not enough vegetation to hold the soil in place, saturated soil flows over impermeable sub soil, causing great devastation and endangering lives.
Slumping: involves a whole segment of the cliff moving down-slope along a saturated shear-plane.
Slides: saturated weathered material moving down a slope under the influence of gravity
Abrasion: wearing away of cliffs by sediment flung by breaking waves.
Attrition: erosion caused when rocks and boulders transported by waves bump into each other and break up into smaller pieces.
Hydraulic Action: the process by which breaking waves compress pockets of air in cracks in a cliff. The pressure may cause the crack to widen, breaking off rock.
Longshore Drift: waves approaching the coast at an angle result in the gradual zig-zag movement of beach materials along the coast.
Coastal Land forms
Headland and bays
headlands are formed when the sea attacks a section of coast with alternating bands of hard and soft rock.
The bands of soft rock, such as sand and clay, erode more quickly than those of more resistant rock, such as chalk. This leaves a section of land jutting out into the sea called a headland. The areas where the soft rock has eroded away, next to the headland, are called bays.
Wave cut notch/platform
One of the most common features of a coastline is a cliff. Cliffs are shaped through a combination of erosion and weathering - the breakdown of rocks caused by weather conditions.
Soft rock, eg sand and clay, erodes easily to create gently sloping cliffs. Hard rock, eg chalk, is more resistant and erodes slowly to create steep cliffs.
Weather weakens the top of the cliff.
The sea attacks the base of the cliff forming a wave-cut notch.
The notch increases in size causing the cliff to collapse.
The backwash carries the rubble towards the sea forming a wave-cut platform.
The process repeats and the cliff continues to retreat.
Cave, arch, stack, stump
Caves occur when waves force their way into cracks in the cliff face. The water contains sand and other materials that grind away at the rock until the cracks become a cave. Hydraulic action is the predominant process.
If the cave is formed in a headland, it may eventually break through to the other side forming an arch.
The arch will gradually become bigger until it can no longer support the top of the arch. When the arch collapses, it leaves the headland on one side and a stack (a tall column of rock) on the other.
The stack will be attacked at the base in the same way that a wave-cut notch is formed. This weakens the structure and it will eventually collapse to form a stump.
One of the best examples in Britain is Old Harry Rocks, a stack found off a headland in the Isle of Purbeck.
EG: old harry rocks in dorset
A BEACH IS FORMED WHEN DEPOSITED MATERIALS CARRIED BY WAVES ARE ACCUMULATED IN A ZONE ALONG THE COAST. THE MATERIALS ON THE BEACH VARY IN SIZE FROM FINE SAND TO PEBBLES . THE WAVES SORT THESE MATERIALS ACCORDING TO THE WEIGHT. THE FINER SAND DEPOSITED NEARER THE SEA AND THE COARSER MATERIALS FURTHER INLAND.
Deposition of sand must take place quicker than the obstruction material is eroded to enable build up of sand.
There must be abundant supply of sand transported to the beach from longshore drift.
There must be a huge range between high and low tides so that when the tide subsides, a large area of land is exposed and can dry out to enable the wind to pick up the sediments.
The river channel may be widened or deepened allowing it to carry more water. A river channel may be straightened so that water can travel faster along the course. The channel course of the river can also be altered, diverting floodwaters away from settlements.
Altering the river channel may lead to a greater risk of flooding downstream, as the water is carried there faster.
Dams are often built along the course of a river in order to control the amount of discharge. Water is held back by the dam and released in a controlled way. This controls flooding.
Water is usually stored in a reservoir behind the dam. This water can then be used to generate hydroelectric power or for recreation purposes.
Building a dam can be very expensive.
Sediment is often trapped behind the wall of the dam, leading to erosion further downstream.
Settlements and agricultural land may be lost when the river valley is flooded to form a reservoir.
Formation of a waterfall:
The soft rock erodes more quickly, undercutting the hard rock.
The hard rock is left overhanging and because it isn’t supported, it eventually collapses.
The fallen rocks crash into the plunge pool. They swirl around, causing more erosion.
Over time, this process is repeated and the waterfall moves upstream.
A steep-sided gorge is formed as the waterfall retreats.
erosion – hydraulic action, abrasion, attrition, solution, vertical and
transportation – traction, saltation, suspension and solution
deposition – why rivers deposit sediment.