UK Physical Landscape PDF

UK Physical Landscape Rock Formation: - Igneous Rocks = Formed when molten rock from the mantle cools down and hardens - Sedimentary Rock = Formed when layers of sediment are compacted together after millions of years - Metamorphic Rocks = Formed when other rocks are chan...

UK Physical Landscape Rock Formation: - Igneous Rocks = Formed when molten rock from the mantle cools down and hardens - Sedimentary Rock = Formed when layers of sediment are compacted together after millions of years - Metamorphic Rocks = Formed when other rocks are changed by heat and pressure making them harder and more compact. Impact of glaciation: - Ice was able to erode the landscape, carving out large U-shaped valleys in upland areas such as the Lake District. - They also deposit lots of material as they melt specifically on the eastern side. Human Impact on the Landscape: - Agriculture: People have cleared the land of forest to make space for farming. Hedgerows and walls have been put in to mark out fields - Forestry: This is the management of woodland areas that can be used for timber, recreation and conservation. Coniferous forests have been planted for timber and the trees are often planted in straight lines making the forests look unnatural. - Settlement: Land was concreted over for roads and buildings which affected drainage patterns. Some rivers were diverted through underground channels and some rivers were straightened or had embankments built to prevent flooding. Weathering: - Physical: - Freeze thaw weathering occurs causing water to get into the cracks of rocks. The water expands which puts pressure on the rock. When water thaws it contracts. Repeated freezing and thawing widen the cracks and cause the rock to break up. - Mechanical: - Break down of rock without changing its chemical composition - Salt weathering is when the sea water gets into the cracks in the rock. When the water evaporates, salt crystals form. As the salt crystals form they expand which puts pressure on the rock. - Chemical: - Carbonate weathering: Seawater and rainwater have carbon dioxide dissolved in them which makes them weak carbonic acids. Carbonic acid reacts with rock that contains calcium carbonate. - Biological: - Plant roots break down rocks by growing into cracks on their surfaces and pushing them apart. Coasts Factors affecting rates of erosion along the UK coastline: Hydraulic action Waves crash against the rock and compress air in the crack. This puts pressure on the rock. Abrasion Eroded particles in the water scrape and rub against the rock, removing small pieces. Attrition Eroded particles in the water smash into each other and break into smaller fragments. Their edges also get rounded off as they rub together. Coastlines: Discordant coastline: ALternating bands of hard and soft rock at tight angles to the coast. COncordant coastline: Alternating bands of hard and soft rock but parallel to the coast. Types of Rocks: Hard rocks are more resistant so it will take longer for them to be eroded and weathered. Soft rocks are less resistant. Engineering Strategies: Hard Engineering: Defence What it is Benefits Costs Sea Wall A wall made from concrete Prevents erosion Creates a strong which reflects waves back of the coast and backwash which to the sea acts as a barrier to erodes under the prevent flooding wall. Expensive and hard to maintain Groynes Wooden or stone fences Creates a wider They starve that are built at right angles beach which slows beaches further to the coast. the waves. This down the coast, They trap material gives greater making them transported by longshore protection from narrower drift. flooding. Cheap Soft Engineering: Defence What it is Benefits Coasts Beach Sand and shingle It creates a wider Taking material Replenishment from elsewhere or beach which slows from the seabed from lower down the waves and can kill organisms. the beach are gives greater It can be added to the protection. expensive and has upper parts of the to be repeated beaches over and over again. Slope Slopes are It prevents mass Expensive and stabilisation reinforced by movement by often hard to inserting concrete increasing the install. nails into the strength of the ground and slope. covering the slope with metal netting Strategic Removing existing Over time the land Many people may Realignment defence and will become disagree with allowing the land marshland which what land is behind to flood. reduces flooding allowed to flood. and erosion and also creates habitats. Rivers Course Gradient Characteristic Upper Steep V-shaped valleys, steep-sided, narrow, shallow channels, vertical erosion, low discharge, low velocity, large and angular stones. Middle Medium Gently sloping valley sides, wider, deeper channels, lateral erosion, increase in discharge and speed, smaller and rounded sediment load. Lower Gentle Very wide, almost flat valley, deep channel, high velocity, very large discharge, fine and well-rounded material Transportation: Traction: Large particles like boulders are pushed along the river bed by the force of water. Suspension: Small particles like silt and clay are carried along the water Saltation: Pebble-sized particles are bounced along the river bed. Solution: Soluble materials dissolve in the water. River Landforms: Waterfall and gorges: - The river flows over an area of hard rock followed by an area of softer rock. - Softer rock is eroded by hydraulic action and abrasion - As the water goes over the step it erodes more and more of the softer rock. - A steep drop is eventually created, which is called a waterfall. - Hardrock is eventually undercut and it becomes unsupported and collapses. - Collapsed rocks are swirled around causing erosion and then forming a plunge pool. - Over time due to more undercutting, the waterfall will retreat leaving a steep-sided gorge. Interlocking Spurs: - Vertical erosion occurs causing steep-sided valleys. - Rivers are not powerful enough to erode laterally so they go around the hills that stick out into their path. - The hillsides that interlock with each other as the river winds around them are called interlocking spurs. Meanders: - The current is faster on the outside of the bend because the river channel is deeper. - So more erosion takes place on the outside of the bend, forming river cliffs. - The current is slower on the inside because the river channel is shallower - So eroded material is deposited in the inside of the bend. Oxbow lakes: - Erosion on the outside bend causes the outside bends to get closer until there is only a little bit of the land left called the neck. - River eventually breaks through usually during a flood. - The river decides to flow along the shortest course of the river. - Deposition eventually cuts off the meander forming an oxbow lake. Flood Plains: - A wide valley floor on either side of a river which occasionally gets flooded. - The water deposits the eroded material that it’s transporting making the flood plain higher. - Meanders migrate downstream, flattening out the valley floor. - The deposition that happens on the slip-off slope of meanders also builds up the flood plain. Levees:  - During a flood, material is deposited across the whole flood plain. - The heaviest material is deposited closes to the river channel, because it gets dropped first. - Over time deposited material forms levees along the edge of the channel. Deltas: - Rivers are forced to slow down when they meet the sea or a lake causing them to deposit the material they were carrying. - If the sea doesn’t wash away the material, it builds up and the channel gets blocked. - Creates distributaries. - Eventually, the material builds up so much that low-lying areas of land called deltas are formed. River landscapes and sediment load: Climate A wetter climate means more river discharge. More discharge leads to more erosion due to a greater volume of water causing more power. Forms V-shaped valleys and a wide flat flood plain in the lower course. Increase in transportations Weathering increases the river's sediment load and can affect the shape of the landscape. Geology Landscapes with more resistant rock tend to have steeper valleys due to more erosion Less resistant rocks have a gently sloping valley side. Slope Vertical erosion by rivers makes valley sides steeper, increasing the Processes movement of material down the slopes. A mass movement can add large amounts of material to the river's load. Soil creep is when soil particles move down a slope because of gravity. It causes the expansion and contraction of soil. Physical and human reasons for flooding: Physical: - Intense rainfall can increase the surface runoff because it also increases the river discharge. - Impermeable rock means that water cannot infiltrate so there is more runoff. - Snowfall is also common so when it melts it can add lots of water to the river channel in a short space of time. Human: - Lots of development of floodplains can affect the flood plain’s ability to absorb and store flood water.  - Deforestation leads to little infiltration of rainfall leading to high surface runoff. - Drainage ditches mean water flows rapidly to the river channel. River Management: Flood Walls - Holds more water for the river, but can be expensive and can block the view. Embankments - Stops river flowing into built-up areas during a flood, protecting buildings and infrastructure on the flood plain. They are expensive and there is a risk of flooding and breakage. Flood Barriers: Stop flooding from storm surges or very high tides.Very expensive and hard to maintain. Flood plane retention: Helps slow floodwaters down and maintain the flood plain’s ability to store water. Cheap. River restoration: Less risk of flooding downstream because discharge is reduced. Looks natural.