Geographical Issues Flashcards
Where is the upper course
Closest to the river
Where is the lower course
Closest to the mouth
What is a long profile
Shows how the gradient changes over different courses
Cross profiel
Shows you waht the cross section of the river looks like
Discharge
The volume of water in a river measures in m3/sec of cumecs
How do waterfalls form
A waterfall occurs when more resistant rock lies over a layer of less resistant rock.
The river bedload swirls around at the foot of the waterfall, gradually eroding the river bed to form a plunge pool.
This results in the water for a eroding up stream forming A steep sided valley called a gorge.
Less resistant rock erodes more easily by abrasion and hydraulic action which.
Eventually the overhang of the more resistant rock collapses under its own weight.
The collapse of the less resistanr rock results in further erosion of the more resistant rock
How does river discharge increase
It increases downstream as tributary streams and ground water increases the amount of discharg. Also the dranage basin will increase in size.
How does channel width and depth increase
Discharge increases meaning higher velocity in and higher rate of erosion lateral and vertical
How does sediment particle shape change
Thanks to attrition the sediment becomes smaller and smoother which will increase as the river has more energy and velocity meaning more collisions of sediment
Vertical erosion
This depends the river valley making it reshaped. It’s dominant in the upper course of the river. High turbulence causes the sediment particles to scrape along the river bed causing intense downwards erosion
Lateral erosion
This widens the river during the formation of meanders. Is dominant in the middle and lower course
Upper course features
Rough channel sides and bed, Gradient is at its source by the source of water, low discharge, carries large, angular stones, resistent rock,steep sided valley, narrow and shallow river channel
Middle course features
Basin made of softer rock like sand stone,easily eroded, rounded and smaller rocks, river valley is wide and deep, discharge increases, less steep gradient,
Lower course features
Close to sea level, very wide and flat valley, high velocity, little friction, large discharge,sediment is very smooth and well rounded.
Active volcanoes shape the land of the UK
520 million years ago the UK used to be much closer to the plate Boundry than now. Active volcanoes form magma through the earths crust which called the form igneous rock.
Plate collitions shaping UK boundaries
Plate collisions cause the rock to be folded and uplifted forming mountain ranges. (Uplands) The igneous granite is hard and more resistant to erosion
The intense heat and pressure caused by plate collisions formed hard metamorphic rock in northern uk.
Plate movements UK position
Plate movements meant that 345 to 280mill years ago Britain was in the tropics and higher sea levels meant it was partly underwater. Carboniferous limestone formed in the warm shallow seas. This can be seen in in the south west of the uk
The youngest rocks in the UK are the chalk and clay is found in the south of England.
Granite (igneous)
- very resistent
- has lots of joints which aren’t evenly spread
- areas with fewer joints are weathered more slowly than the surrounding rock and stick out at the surface forming tors.
- Granite is impermable which creates morrlands
What are moorlands
Large areas of waterlooged land and acidic soil with low growing vegetation
Slate and schist (metamorphic)
- slate forms in layers creating weak planes in the rock.
- generally very hard and resistent to weathering but easily split into thin slabs.
- Schist has bigger crystals than slate and also splits easily into small flakes.
- they are often rugged upland areas.
- they are impermable, leading to waterlogged and acidic soils
Carboniferous Limestone (sedimentary)
- rainwater slowly eats away at it through carbonation weathering
- most weathering happens at joints in the rock (limestone pavements, cavers and gorges)
- Limestone is permable meaning it has areas of dry valleys and resurgent rivers.
It is formed from tiny shells and skeletons of the sea creatures
Chalk and clay
- chalk is harder than clay. It forms escarpments (hills) in UK lowlands and cliffsat the coast.
- one side is usually steep and other is more gentle
- chalk is permable
- clay is very soft and easily eroded
- forms wide flat valleys in UK lowlands
- it is impermable (streams,rivers,lakes)
Igneous rock
Formed when molten rock (magma) from the mantle cools down and hardens. The rocks forms crystals as it cools.
Sedimentary
Sedimentary rocks are formed when largest elements are come back together until they become solid rock.
How is the most sedimentary rock formed
As Fish and coral die their skeleton fall, weight crushed those beneath compacting to rock, calcium carbonate in the rocks cemented them together, sand was then laid down on top of this, these layers and a strata.
How is metamorphic rock formed
They are formed when other blocks are changed by heat and pressure. New rock becomes harder and more compact
Physical processes
Weathering, erosion, post glacier river processes, slope processes
How are physical processes affected by climate (freeze thaw weathering)
For example a cold climate increases the likelihood of Freeze thaw weathering weathering and wet climate increases the number of streams and rivers
Weathering
Weathering is the breakdown of rocks into smaller pieces. It can be mechanical chemical or biological
Erosion altering physical landscapes
Wears away rock. During the last glacial period Ice eroded the landscape. Rivers and the sea now constantly around the landscape
Postglacial with the processes
Melting ice at the end of glacier period made rivers much bigger than normal with more power to erode the landscape. The ice also left distinctive landforms when it melted e.g. hanging valleys, misfit streams and u shape valleys
Slope processes
Including mass movements such as rockfalls, slides, slumps and soil creep
Soils such as sandstone and clay can absorb large amounts of moisture and become saturated – they can move down the slope
Agriculture changing landscape
People have cleared the land of forest to make space for farming. Overtime hedges grow and walls have been put in to mark out fields. Different landscapes are best for different types of farming
How has forestry changed landscape
Forestry is the management of areas of woodland they can be used for timber, recreation or conservation. The UK are used to be covered in deciduous woodland. Coniferous forests have been planted for timber (often planted in straight lines making them not look natural) Where areas are felled the landscape is left bare.
In some places deciduous woodland it’s been replanted to try return the area to more natural state.
Settlements changeing landscape
Sime settlements have been developed early so reasons such as britain points over rivers and the availability of resources.
Settlements now have concrete over the roads and buildings which affected surface run-off.
Some rivers have channels straightened or embankments built to prevent flooding.
Tees exe line
Line that seperates the main rock types in the UK
Scree (slope processes)
Scree consists of angular rock pieces created by freeze-thaw weathering. Scree fragments are unstable and move easily during rockfalls, increasing dangers for walkers.
Landslides
Rain adds to the weight of weathered rocks so it slides easily
The Lakes district is the Uk’s wettes region (over 2000mm per year).
Effects of ice age upland
Glacial process happened 12,000 years ago
As ice moved through the upland landscape it eroded huge areas to create U-shaped valley. These had steep sides, flat bottoms and hanging valleys.
Post Glacial River Processes (water on land)
rivers in the upland areas are fed by rainwater so the rivers are very small relative to their valleys. We call these misfit streams.
The Downs and the Weald
The Downs and the Weald are lowland landscapes. They are chalk escarpments that lie either side of a large, flat area of clay. The valley is flat (with some small hills). Glacial melt water eroded large amounts of sedimentary rock leaving this distinctive lowland landscape in South East England.
Effects of ice age low land
During glacial periods the gaps in the chalk froze making it impermeable. When seasonal snow melt occurred, it couldn’t infiltrate into the chalk and instead ran over the top and eroded the valleys. Now the water runs underground through the chalk and the rivers can’t be seen
Post glacial river processes lowland
The UK climate is very wet. Heavy rain can lead to flooding. When rivers flood the overflowing water carries sediment and deposits silt on the valley floor forming a flood plain (very fertile).
Sheep Farming
They have influenced everything from:
- the stone walls to keep them penned in
- As a source of income from sheep farming and grazing.
- As such the sheep have grazed all the vegetation and prevent shrubs and trees from growing
- Winter hay is stored in the barns on the fells so farmers lived near their animals. This led to a dispersed settlement pattern
Lowlands geology affects agriculture
The area’s geology is mainly sand and clay which were deposited by glaciers, this produces fertile soil for arable (crop) farming but no solid materials for building walls as the rock was chalk. As a result, large villages are found around large farmland. Also less than 12% of the UK’s trees remain to make way for large farmlands
Freez-thaw weathering
Freez-thaw weathering is a process where water from rain freezes in the cold upland climates whilst inside cracks of valley walls. The ice expands the crack as it freezes by roughly 9% in size which slowly breakes the rock down. Over many days the rock eventualy breaks down.