Upload
others
View
21
Download
0
Embed Size (px)
Citation preview
Distinctive Landscapes Revision Guide What makes a landscape distinctive?
Physical Mountains, lakes and valleys etc
Biological Trees and Grass etc
Variable (temporary) Weather and seasons etc
Human Buildings and farm land etc
Uplands and Lowlands
Uplands including mountainous areas like the Grampians and Pennines are mainly found in the North and West, particularly Scotland, Wales and norther England Lowlands include flat and rolling landscapes like the Cotswolds and South Downs, are found mainly in England in the south and east. Upland Country: Andorra Lowland Country: Netherlands Glaciation
Glaciation (large scale ice) occurred in the UK at different times, the Red
line indicates the limits of the Devensian ice age 10 000 years ago
The blue line indicates the limits of the Anglian (biggest) ice age 500 000
years ago
Features of glaciated landscapes
Impact of glaciation in the South Downs
Geology
Igneous rock is formed through the cooling and solidification of magma or lava. Igneous rock may form with or
without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic)
rocks. This magma can be made from partial melts of existing rocks in either a planet's mantle or crust.
Sedimentary rocks are types of rock that are formed by the
deposition and subsequent cementation of that material at the
Earth's surface and within bodies of water. Sedimentation is the
collective name for processes that cause mineral and/or organic
particles to settle in place. The particles that form a
sedimentary rock by accumulating are called sediment. Before
being deposited, the sediment was formed by weathering and
erosion from the source area, and then transported to the place of deposition by water, wind, ice, mass movement
or glaciers.
Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which
means "change in form". The original rock is subjected to heat (temperatures greater than 150 to 200 °C) and
pressure (1500 bars), causing profound physical and/or chemical change. The original rock may be a sedimentary
rock, an igneous rock or another older metamorphic rock.
How can soil influence a landscape?
Weathered Rocks + Organic Material + Water = Soil
Deep soil is easier to farm, it is often in low-lying areas. The
most productive soils in the UK are found in the East Anglian
Fens.
Parent Material: The underlying geological
material from which the soil is made
Periglacial means, that an area next to an
icesheet that is subjected to repeated
freezing/thawing
Gradient Steep ground tends to have thin soil because of accelerated erosion due to gravity and less vegetation to hold the soil together Drainage The rocks (geology) below the soil determines if the soil drains well or not. Where water remains on the surface you can often find moors and heathland as the soil has turned into peat. Peat is partially decomposed organic matter that creates boggy landscapes
Where in the UK can you find moors and heathlands, Exmoor, Dartmoor, Peak District
Contrasting Rock Types
Chalk Granite
Formation Formation: A type of limestone, a sedimentary rock formed in layers, or strata, on the seabed. Later, the strata were folded and pushed up to form new land above sea level.
Formation: An igneous rock found where molten rock cools down slowly below Earth’s surface. Because it cools slowly the crystals are large
Composition Composition: Made from calcium carbonate from the shells of tiny sea creatures that sank to the bottom of the ocean
Composition: Crystals are made from quartz (colourless), feldspars (White or pink) and mica (silver or black)
Properties Properties: Unlike other types of limestone, this is a soft and crumbly rock, so it is easily weathered and eroded. It is also permeable, so water drains through it.
Properties: A very hard rock that weathers and erodes slowly. It can be used to make kerbstones. It is also impermeable, so water down not pass through it.
Soils and Farming
The soil on this rock type is alkali, quite fertile and well drained. It is ideal for growing grass and also suitable crops.
The soil on this rock type is acidic and not very fertile. Often it is also waterlogged and so not good for growing crops
Uses This rock can be used to write on a blackboard
It’s a very hard rock used for making kitchen worktops
Found Found in the South Downs of England. Here they create the famous White Cliffs of Dover.
Found in the Cuilin Hills on the Isle of Skye in Scotland and also Dartmoor in Devon. It’s hard to believe that Devon used to be volcanic.
Landscape Often forms gentle rolling hills.
Often forms dramatic looking mountain landscapes
Weathering and Erosion
Erosion types
Attrition Abrasion Hydraulic Action Corrosion
Rocks carried by water are reduced in size as they collide with each other.
The water throws sand and pebbles against the river banks, causing them to wear away.
This is the sheer weight and impact of the water against the river banks. Air trapped in cracks in the river bank is suddenly compressed by the force of the water, which increases the pressure on the soil of the river banks.
This is the chemical action of river water on the river banks. Minerals in the rocks and soil are dissolved by river water.
Types of Weathering
Chemical Biological Physical Chemical weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic.
Where does it occur?
These chemical processes need water, and occur more rapidly at higher temperature, so warm, damp climates are best. Chemical weathering (especially hydrolysis and oxidation) is the first stage in the production of soils. How does it occur? Solution - removal of rock in solution by acidic rainwater. In particular, limestone is weathered by rainwater containing dissolved CO2, (this process is sometimes called carbonation). Hydrolysis - the breakdown of rock by acidic water to produce clay and soluble salts. Oxidation - the breakdown of rock by oxygen and water, often giving iron-rich rocks a rusty-coloured weathered surface.
Trees put down roots through joints or cracks in the rock in order to find moisture. As the tree grows, the roots gradually prize the rock apart. Even the tiniest bacteria, algae and lichens produce chemicals that help break down the rock on which they live, so they can get the nutrients they need.
Many animals, such as these Piddock shells, bore into rocks for protection either by scraping away the grains or secreting acid to dissolve the rock.
Physical weathering is caused by the effects of changing temperature on rocks, causing the rock to break apart. The process is sometimes assisted by water. There are two main types of physical weathering:
Freeze-thaw occurs when water continually seeps into cracks, freezes and expands, eventually breaking the rock apart.
Exfoliation occurs as cracks develop parallel to the land surface a consequence of the reduction in pressure during uplift and erosion.
Where does it occur?
Physical weathering happens especially in places where there is little soil and few plants grow, such as in mountain regions and hot deserts.
How does it occur?
Either through repeated melting and freezing of water (mountains and tundra) or through expansion and contraction of the surface layer of rocks that are baked by the sun (hot deserts).
How have humans impacted on uplands?
Human activities Features Why they’re in the uplands
Wind farms Multiple wind turbines to generate electricity
Exposed Wind Hills
Hunting For deer and grouse Space
Tourism Walking/mountain biking
Views Peace
Pastoral farming Sheep grazing Good use of hills as sheep can graze there
Forestry Coniferous It changes the landscape
Well drained land
Hydro Elecric Power Provides electricity Creates a reservoir Changes the landscape and natural rivesr course
Gravity and the water cycle make it ideal for HEP
Arable Farming Happens in the valleys Crops
The most fertile soil in the uplands
How have humans impacted in lowlands?
Feature Impact
Urbanisation Urbanisation increases flood risk as the land becomes impermeable, it also increases water, air and soil pollution
Dairy Farming Dairy farm land reduces tree cover as cattle need space to graze. Water pollution can be high if waste isn’t properly disposed of
Arable Farming Arable farms (crops) take up lots of space and require access by heavy machinery which can be noisy
Roads Roads increase traffic flow. This increases the visual, noise and pollution impacts of the area.
Housing Housing is popular on lowland areas as its easier to build on than uplands. Construction leads to higher population densities and requirements of services
Industry Industry varies in lowland areas. Can include retail or manufacturing.
What is an EIA? Environmental Impact
Assessment
Agents of Change – Rivers
Main processes of transportation
Type Size of sediment (dependent on velocity of river or sea)
Description
Traction Large stones/boulders
Boulders are the largest sized material to be transported by coastal
processes. They are transported by being rolled along the river bed; a
process called traction. Boulders are too large and too heavy to be
picked up by the river’s current.
Saltation Smaller pebbles Smaller sediments can be picked up by the water for short periods of
time and move by bouncing along the river bed. This process is called
saltation.
Suspension Sand Many of the smallest sediments are carried in suspension. This means
that the sediment travels above the river bed within the water. The
smallest sediments, such as sand, are lightest and can therefore be
carried by the energy of the water.
Solution Tiny particles Minerals in rocks are dissolved by reacting with river water and
carried in solution. These minerals are not visible within the water.
Minerals enter the river when the water come into contact with rocks
of the bank and bed. Lime from chalk and limestone rocks is often
carried in solution.
Depositional landforms
Spit Deposited material in a line extending from a change in direction of the coastline. Caused by longshore drift and deposition
Bar A spit that continues along and makes contact with land again
River Beach
Beach on the inside bend of a river meander where material is deposited by the slower flowing water
Moraine Sediment deposited a the edge of a glacier by the ice
Tombolo A spit that joins an island
Delta Sediment deposited in a wide fan shape at the mouth of a river when the river’s velocity slows down and can no longer transport the sediment load
Flood plain Flat land to the side of a river channel where material is deposited during a flood. This occurs when the river breaks its banks, loses energy and the transported material is deposited. It leaves a highly fertile layer ideal for farming.
Agents of change - coastal
1. Longshore drift
Mass Movement Types
Mass Movement Type
Features Picture
Rock Slide Failure occurs along a particular geological boundary within the cliff
Rotational Slumping
Occurs on softer rocks
The base of the cliff moves and the rest of the material slumps down
Frequent on the East Coast
In 2012 and 2015 people were killed in Devon by this type of mass movement
Constructive waves have a
stronger swash than backwash
and are likely to build up the
sediment on the beach
Destructive waves have a
stronger backwash than swash
and are likely to erode the
sediment on the beach
[Cite your source here.]
Coastal Landforms
1. A concordant coastline with where the rocks lie parallel to the coastline and is likely to include coves.
2. A discordant coastline is where the rocks like at 90 to the coastline and is likely to include headlands and
bays
The erosion of a headland
Headland– a ridge of hard, resistant rock sticking out into the
sea. It is subjected to erosion especially by destructive waves.
Hydraulic action and abrasion and the dominant erosive
forces.
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.
Formation of a spit
Formation of a Tombolo
Tombolos are created through the process of longshore drift. A tombolo is formed where the spit continues
to grow until it reaches an island, forming a link with the mainland, just like bridges.
Dorset Coastal Landform Case Study
Geology
Portland Stone- 150 million years old
• Limestone Made up of shells laid down in a calm shallow sea
• Strong and hard rock
Purbeck Beds - 147 million years old
• Made up of clays, shales, mudstones and limestone containing many fossils and crushed shell beds
Wealden Beds - 140 million years old
• Made up of sand, marl, clay and grit
• Soft and easily eroded
Greensand - 125 million years old
• Made up of layers of sandstone deposited in a shallow sea
• Well drained, soft rock and easily eroded
Chalk - 97 million years old
• Made up of trillions of minute marine organisms deposited slowly in a clear shallow sea
• Considered a soft rock but is resistant to erosion by the sea
Landforms
Lulworth Cove
Stair Hole
Durdle Door
Climate
5th February 2014 there was a big storm which caused:
• The Railway at Dawlish was left hanging
• Large rock fall at West Bay
Climate change
• Higher Sea Levels
• Warmer atmosphere = more intense storms
• More rainfall = more weathering and mass movement
Human Activity
High levels of tourism
High levels of coastal management
Geomorphic Processes
Rock Type Weathering Erosion
Portland Stone Limestone Limestone and chalk are
made of a mineral called
calcium carbonate. When
acidic rainwater falls on
limestone or chalk, a
chemical reaction
happens. New soluble
substances are formed in
the reaction. These are
washed away and the rock
is weathered.
Very slow, therefore the
Portland Stone acts as a
barrier to protect the rocks
behind it on the Dorset
Coastline
Purbeck Beds Limestone As above As above
Wealdon Beds Clay Clay weathers quickly, it is
subjected to chemical,
physical and biological
weathering
Very soft so easily erodible by
all types of erosion but
specifically hydraulic action
and abrasion
Greensand Sandstone Has a very low resistance
to weathering so is easily
weathered. It is porous
and holds lots of water so
is very vulnerable to
wetting/drying and
freeze/thaw action
More resistant than Clay
Chalk Chalk Much more resistant to
weathering
Much more resistant to
erosion by the sea
Coastal Management
Soft engineering is using strategies to work with natural processes. They are no physical barriers. Examples
including managed retreat and planting
Hard engineering is construction of physical barriers out of concrete, rock, metal or wood. Groynes and Sea
Walls are examples.
The courses of a River
Upper course of a river
V Shaped Valley
Waterfall
Gorge Formation
A gorge is left behind when a waterfall retreats. A gorge is a valley with
almost vertical sides that has been carved out by the river and
waterfall.
Upper and Middle Course
Meanders are large ends in the river and are
found in the middle/lower course of the river.
The river often takes on a “snake-like”
appearance if viewed from the air.
Water flows more quickly around the
outside of a meander (shown by the arrow)
A riffle is an area of shallow water,
where water travels more quickly.
The river starts to bend where the
water is shallower, at the riffle.
The meander is now s-shaped and
water is deepest on the outside of the bend.
Oxbow Lake
An oxbow lake is a U-shaped body of water that forms when a wide meander from the main stem of a river is cut off,
creating a free-standing body of water.
Levees
A levee, levée, is an elongated naturally occurring ridge or artificially constructed fill or wall, which regulates water
levels. It is usually earthen and often parallel to the course of a river in its floodplain or along low-lying coastlines.