Distinctive Landscapes Flashcards
Define a landscape
A landscape comprises of all the visible features of an area of land. It can contain both natural features and man made features.
What is the difference between a built up and ‘natural’ landscape?
Where there are more human than physical elements visible
in a landscape we use the term ‘built landscape’ to describe
It. Whereas areas dominated by physical elements are known as
‘natural landscapes’.
Explain the distribution of the main upland, lowland and glaciated landscapes in the UK.
The bulk of our upland areas above 250m are found in the North and West of the UK in areas of old volcanic and metamorphic rocks. Lowlands are found along coastal fringes and further south, in areas of more sedimentary geology.
Upland areas are mainly found in:
Scotland - The Northwest Highlands, the Cairngorm Mountains, the Grampian Mountains and the Southern Uplands. Ben Nevis is the UK’s highest peak and is found in the Grampian Mountains.
England - The Pennines, Lake District, Dartmoor and Exmoor. Scafell Pike is the highest mountain in England and is found in the Lake District.
Wales - Snowdonia and the Brecon Beacons. Snowdon is the highest mountain in Wales and is found in Snowdonia.
Lowland areas can be found in the following places:
Lincolnshire
The Fens in East Anglia - they are the lowest place in the UK
the Midlands
the London Basin
the Vale of York
Our glaciated landscapers are found in the Northwest highlands, the Grampian Mountains in Scotland, the lake district in England and Snowdonia in Wales.
Southern UK was not affected by glaciers, all of Scotland was. Why we get glaciated landscapes in places such as the Lake District (U shaped valleys)
Explain the characteristics of the lowland and upland areas which make them distinctive, including:
○ geology
○ climate
○ human activity
Lowland areas tend to be formed of sedimentary rocks like sandstones and clays, and experience milder temperatures and less rainfall.
Upland areas are high above sea level. They are often mountainous. They usually consist of
igneous rocks, and experience lower temperatures, high rainfall, and are windy.
Explain the three types of weathering
Physical/mechanical weathering is caused by temperature changes, especially on mountains. Larger temperature variations between day and night can lead to freeze-thaw weathering.
Chemical weathering: rain dissolves with sulphur dioxide in the air, forming weak acid. Rain water is naturally acidic which can cause chemical weathering in rock such as limestone.
Biological weathering: This type of weathering is caused by plants or animals. Tree roots can force their way into rocks, splitting them apart. Smaller plants like moss grow on the surfaces of rock, slowly making it crumble. Even animals burrow into softer rocks and people can have an effect with their trampling feet
In what ways have humans influenced the landscape?
Building dams + canals - straightening of rivers removing rivers natural movement such as meanders, deforestation - change of land use - from woodland to either farming areas or for residential or industrial use. Industrialisation, roads being built for transport, hunting for food, farming for crops.
Describe the different types of erosion
Hydraulic action:
The power of the waves crashing into the rock river banks forces water and air into small cracks, this creates huge pressure in these cracks forcing them wider apart.
Abrasion:
This is when sediments are ground against each other on the bed and banks, making the sediment smaller, rounder and more smooth.
Attrition:
Collision of rocks into one another wearing them down and making them smoother and rounder.
Solution:
Sediment which is dissolved and transported in the river
Describe the different types of transportation
Traction:
Heavy material is rolled along the river bed
Saltation:
Material is bounced along the river bed
Suspension:
When smaller material is light enough to be carried in the flow of the river itself
Solution:
Minerals which are dissolved within the water itself are transported within the flow of the water
Explain why deposition occurs
When there are lower levels of GPE, there is less energy for converting GPE into kinetic energy so a river eventually slows down. - Note that a river increases in efficiency downstream so this can counteract the issue until the very end of the rivers course
Inside bend of a meander – slow flowing reduces capacity of a river to transport sediment, so heaviest sediment is deposited.
Shallow water - This is because the shallow water causes a drop in the speed at which the water flows due to more water (as a proportion) in contact with the bed/banks/air and thus friction is higher.
Obstacles! Large boulders act as an obstacle and can trap sediment behind it when flow is reduced.
Tidal areas near the mouth – water slows down and deposition occurs - GPE gone, kinetic energy slowly runs out.
Explain the formation of headlands and bays
Headlands and bays form most often in discordant
geology where the bands of resistant and less resistant
rock run at right angles or perpendicular to the
coastline. The bands of rock are subject to differential
erosion rates. The geology that experiences fastest
erosion is the less resistant geology. Processes such as
hydraulic action and abrasion erode these rocks
quickly pushing the coastline back to form a feature called a bay. This normally takes a
semi-circular shape due to wave refraction. The land behind it is normally low and close to sea level because this less resistant rock would have been weathered over thousands of years (freeze-thaw, biological weathering etc). The resistant bands of rock are not eroded as quickly and so stick out into the sea forming headlands. These headlands often have
wave-cut notches and platforms as they are eroded at their base. The headlands encourage wave refraction, which concentrates the force of the waves onto the sides of the headland which can lead to caves, arches, stacks and stumps forming.
Explain the formation of cave, arches, stacks and stumps
Wave refraction concentrates the power of the waves onto the sides of the headland. Erosion exploits the lines of weakness in the side of the headland. Hydraulic action, abrasion and solution attack the rocks. Eventually, a small feature called a cave forms. Over time the cave is widened by hydraulic action, abrasion and solution. Storm waves, in particular, contribute to the width and height of the cave, increasing until it forms an arch, again the erosion processes continue. Eventually, likely in extreme storm conditions, the top of the arch is left unsupported and, having been weakened by weathering. It collapses under gravity. This leaves a stack of rock separated from the main headland. The stack is exposed to the open sea and the waves erode its base. Eventually, the base will become very thin and unable to support the weight of rock above. The bottom of the stack will collapse under gravity leaving a small stump.
Explain the formation of a beach
Material is brought onshore by swash in the direction of the prevailing wind.
With constructive waves (which deposit more material than they remove) as they move up the beach the energy is lost due to the level of friction experienced whilst going over the beach, as well as the volume of water decreasing due to percolation.
At the top of the swash’s reach the sediment is deposited, this creates a berm which runs the length of the beach. This is crested because the swash has no longer got sufficient energy to carry the heaviest material back down the beach in backwash.
As backwash moves back down the beach it deposits material as graded deposition. Graded deposition is when the larger heavier material (at the berm) to the smaller (closest to the coastline)
Overtime, as more material is deposited than is removed, the beach builds up over time.
Explain the formation of a spit.
A spit is an extended stretch of sand or shingle jutting out into the sea from the land. Spits occur when there is a change in the shape of the landscape. As sediment is carried in the swash of a wave at an oblique position to the beach following the direction of prevailing winds, the wave will lose energy and crash, the backwash of the wave (destructive in particular) pulls back sediment at a right angle to the beach, this is called longshore drift - which slowly transports sediment up the beach in a zig-zag pattern. When there is a change in the shape of the coastline, deposition occurs. A long thin ridge of material is deposited. This is the spit. Waves cannot get past a spit, therefore the water behind a spit is very sheltered. Silts are deposited here to form salt marshes or mud flats.
Explain the formation of a waterfall
A waterfall is a sudden drop along the river course. It forms when there are horizontal bands of resistant rock (hard rock) positioned over exposed, less resistant rock (soft rock).
The soft rock is eroded quicker than the hard rock and this creates a step.
As erosion continues, the hard rock is undercut forming an overhang.
Abrasion and hydraulic action erode to create a plunge pool.
Over time this gets bigger, increasing the size of the overhang until the hard rock is no longer supported and it collapses.
This process continues and the waterfall retreats upstream.
A steep-sided valley is left where the waterfall once was. This is called a gorge.
Explain how v-shaped valleys are formed
In the upper course the river has the most GPE, this leads to high levels of vertical erosion through hydraulic action and abrasion. As the river cuts downwards, it leaves behind steep sided valley walls. Overtime, the walls are weathered, in the upland areas of the UK this is often through freeze thaw weathering. This weakens the rock and eventually leading the material to landslide down the valley sides into the river, increasing the erosive potential of the river.
