Component 2 Topic 4 - The UK's Physical Landscape Flashcards Preview

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Flashcards in Component 2 Topic 4 - The UK's Physical Landscape Deck (35)
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1
Q

How are igneous rocks formed?

A

Igneous rocks are formed when molten rock from the mantle cools down and hardens, forming crystals as it cools. These rocks are usually hard (e.g: granite).

2
Q

How are sedimentary rocks formed?

A

Sedimentary rocks are formed when layers of sediment are compacted together until they become solid rock. They come in 2 types:
Carboniferous limestone and chalk from fossils of sea creatures - limestone is hard but chalk is much softer.
Clays and shales are made from mud and clay minerals - very soft.

3
Q

How are metamorphic rocks formed?

A

Metamorphic rocks are formed when other rocks are changed by heat and pressure. The new rocks are very hard and compact (e.g: shale becomes slate which become schist).

4
Q

Give two ways tectonic activity shaped the UK landscape…

A
  • Active volcanoes forced magma through the earths crust which cooled to form igneous rocks (e.g: granite)
  • Plate collisions caused rocks to be folded and uplifted, forming mountain ranges, many of which remain as uplands (e.g: the Lake District)
  • Intense heat and pressure from plate collisions formed hard metamorphic rocks in northern Scotland and northern Ireland
  • Plate movements meant that 345-280 million years ago Britain was partially underwater (in the tropics) causing carboniferous limestone to form in the warm shallow seas (e.g: south west England)
  • The UK’s youngest rocks are found in south England (chalks and clays) which are easily erodible and form lowland landscapes. They formed in shallow seas and swamp when the Britain was in the tropics.
5
Q

Outline the characteristics of slate and schist…

A
  • Slate forms in layers creating weak planes of rock. It is generally very hard and resistant to weathering but it is easily split into thin slabs.
  • Schist has bigger crystals than slate and also splits easily into small flakes.
  • Slate and schist often form rugged upland landscapes. They are impermeable, which can lead to waterlogged and acidic soils.
6
Q

Explain how the UK landscape has been shaped by glacial periods…

A
  • Ice, which covered most of Britain during the glacial periods (at its best, most of Scotland, Ireland and Wales and northern England) eroded the landscape, forming large U-shaped valleys in upland areas (e.g: Lake District).
  • Glaciers deposited material as they melted. Landscapes formed by the deposition and glacial meltwater extend south of the ice sheets (e.g: large parts of east England covered in till (mixture of clay, sand and rocks).
7
Q

Give three physical processes that alter the landscape…

A
  • Weathering: The breakdown of rock into smaller pieces, it can be mechanical, chemical or biological.
  • Erosion: The wearing away of rock. During the last glacial period ice eroded the landscape to form valleys. Rivers and the sea constantly erode the landscape.
  • Post Glacial Processes: Melting ice at the end of glacial periods made rivers much bigger than normal, with the power to erode the landscape. The ice also left distinctive landforms when it melted (e.g: hanging valleys - little valleys that are left at a higher level than the main valley).
  • Slope Processes: Includes mass movements (e.g: rockfalls, slides, slumps and soil creep).
8
Q

Give an example of a lowland landscape. How have physical processes shaped this landscape?

A
  • The Downs and the Weald are a lowland landscape - chalk escarpments (the Downs) lie either side of a large flat area of clay (the Weald). The valley is flat.
  • Large rivers (on top of impermeable clay) erode the valley floor, widening it.
  • During glacial periods, the colder climate increased freeze-thaw weathering and glacial snow melt. This means that streams had much more water than they do today (more erosion back then).
9
Q

How does Forestry change the landscape?

A
  • There is very little natural woodland left (The UK used to be covered in deciduous woodland).
  • Coniferous (evergreen) forests have been planted for timber and the forests don’t look natural (planted in straight lines).
  • In some places, deciduous woodland is being replanted to return the area to its natural state.
10
Q

How does settlement change the landscape?

A
  • Settlements were usually built near natural resources (water sources, forests) or defendable/protected areas.
  • Land was paved over with concrete for roads and buildings (changed drainage patterns).
  • Some rivers were diverted through underground channels.
  • Some rover channels were straightened or had embankments built to prevent flooding.
  • Large cities which are ports or industrial areas (e.g: London, West Midlands, Portsmouth, Manchester) are much more urbanised.
11
Q

What does a river’s long profile show? What does a river’s cross profile show?

A
  • A river’s long profile shows you how the gradient (steepness) changes over the different coures (upper, middle and lower).
  • A river’s cross profile shows you what a cross section of the river looks like (shows channel width, depth etc.).
12
Q

Describe the cross profile of a river’s lower course…

A

In the lower course, a river has a very deep and wide channel. The surrounding valley will be mostly flat and very wide.

13
Q

What is the difference between vertical and lateral erosion?

A
  • Vertical erosion deepens the river valley (and channel) making it V-shaped. It’s dominant in the upper course of a river. High turbulence causes rough, angular particles to be scraped along the river bed, causing intense downward erosion.
  • Lateral erosion widens the river valley (and channel) during the formation of meanders. It’s dominant in the middle and lower courses of a river.
14
Q

Compare the sediment size and shape in a river’s upper and lower courses…

A
  • The lower course has very fine and well-rounded material, most of which is being carried by suspension or solution.
  • The upper course has large and angular stones being carried (resistant rock in highlands are eroded less).
15
Q

How does a river’s discharge change along its course?

A
  • In the upper course, discharge is low because the river channel is narrow and shallow (due to vertical erosion).
  • In the middle course, discharge increases as more streams join the main river.
  • In the lower course, discharge is at its highest because all the rivers/streams have joined the main river and the river is fastest flowing at this point.
16
Q

Describe the process of freeze-thaw weathering…

A
  • Freeze thaw weathering occurs when the temperature alternates above and below 0 degrees celsius.
  • Water gets into rock that has cracks, e.g: granite. When the water freezes it expands, putting pressure on the rock. When the water thaws it contracts, releasing the pressure on the rock.
  • Repeated freezing/thawing and pressure on the rock expands these cracks and causes the rock to break up.
17
Q

What is the difference between abrasion and attrition?

A
  • Abrasion: Eroded rocks picked up by the river scrape and rub against the channel, wearing it away. Most erosion happens by abrasion.
  • Attrition: Eroded rocks picked up by the river smash into each other and break into smaller fragments. Their edges also get rounded off as they rub together. The further material travels, the more it is eroded.
18
Q

Name two processes of transportation…

A
  • Traction: Large particles like boulders are pushed along the river bed by the force of the water.
  • Saltation: Pebble-sized particles are bounced along the river bed by the force of water.
  • Suspension: Small particles like silt and clay are carries along by the water.
  • Solution: Soluble materials dissolve in the water and are carried along.
19
Q

When does deposition occur?

A

Deposition occurs when the river slows down (loses velocity) because…

  • The volume of water in the river falls
  • The amount of eroded material in the water increase
  • The water is shallower, e.g: on the inside of a bend
  • The river reaches its mouth
20
Q

Where do waterfalls form? How do they form?

A
  • Waterfalls form in the upper course where the river flows over an area of hard rock followed by an area of soft rock.
  • The softer rock is eroded (by hydraulic action and abrasion) more than the hard rock, creating a ‘step’ in the river.
  • As water goes over the step it erodes more and more of the softer rock.
  • A steep drop os eventually created, which is called a waterfall
21
Q

What are interlocking spurs? How do they form?

A
  • In the upper course, vertical erosion creates steep sided V-shaped valleys.
  • The rivers aren’t powerful enough to erode laterally (sideways) - they have to wind around the high hillsides that stick out into their paths on either side.
  • The hillsides that interlock with each other as the river winds around them are called interlocking spurs.
22
Q

Where is the current fastest on a meander? What feature forms here?

A
  • The current is fastest on the outside of the bend because the river channel is deeper (less friction to slow the water down).
  • On the outside bend of a meander there is lots of erosion and so it forms an ox-bow lake over time.
23
Q

Name the landform created when a meander is cut off by deposition…

A

Ox-bow lakes

24
Q

What is a flood plain?

A

A flood plain is the wide valley floor on either side of a river which occasionally gets flooded.

25
Q

Outline the main features of a delta…

A
  • Deltas are low-lying areas where a river meets the sea or a lake.
  • As the river slows down when it meets the sea or a lake it deposits material that is being carried.
  • If not washed away, the material builds up and blocks the channel. This forces the channel to split up into lots of smaller rivers to get around the blockage called distributaries.
  • Eventually the material builds up so much that low-lying areas of land called deltas are formed.
26
Q

What do the contour lines on a map show?

A
  • Contour lines on a map (in orange) tell you the height of the land (in metres).
  • They also tell you the steepness of the land by how close together the lines are (the closer, the steeper).
27
Q

Give two pieces of map evidence for a waterfall…

A
  • Waterfalls are often marked on maps by the symbol for a cliff (black, blocky lines).
  • Waterfalls often occur near close contour lines (they are in the upper course).
28
Q

Give two pieces of map evidence for a river’s lower course…

A
  • Rivers in the lower course are wide (a thick blue line) and will likely meander.
  • There might be an ox-bow lake.
  • Very few, if any, contours that are far apart (the floodplain is flat low-lying land).
29
Q

Where are gorges formed? How do they form?

A
  • Gorges form in the upper courses of rivers where there is a waterfall (so there will also be an area of hard rock followed by soft rock).
  • The hard rock is eventually undercut by erosion and it becomes unsupported, causing it to collapse.
  • The collapsed rocks are swirled around at the foot of the waterfall where they erode the softer rock by abrasion, creating a deep plunge pool.
  • Over time, more undercutting causes more collapses. The waterfall will retreat (move back up the channel), leaving behind a steep sided gorge.
30
Q

Where do ox-bow lakes form? How do they form?

A
  • Ox-bow lakes form in the middle and lower courses (because meanders are in the middle/lower course due to deep sections of the channel).
  • Erosion causes the outside bends to get closer until there’s only a small bit of land left between the bends (called the neck),
  • The river breaks through this land (neck), usually during a flood and the river flows along the shortest course.
  • Deposition eventually cuts off the meander, forming an ox-bow lake.
31
Q

Explain how climate influences sediment load…

A
  • River’s in wetter climates have a higher discharge because there’s more water entering the river channel. Higher discharge increase the rate of erosion (more water = more eroding power) and therefore adds material to the river’s load as it erodes the river bed/banks.
  • Temperature in an area cam affect the amount of freeze-thaw weathering. More freeze-thaw weathering increases the chance of rockfalls occurring and adding to the river’s sediment load.
32
Q

Give two ways geology influences river landscape..

A
  • River’s flowing through areas of harder rock have a slower rate of erosion because these rocks are more resistant. Consequently, the river will have a lower sediment load.
  • River’s flowing through areas of softer rock have a faster rate of erosion because these rocks are less resistant. As a result, the river will have a higher sediment load.
33
Q

What is soil creep?

A
  • Soil creep is when soil particles move down a slope because of gravity. Its caused by expansion and contraction of the soil.
  • Water adds weight to the soil and makes it expand, causing it to move down the slope. When the soil dries out, it contracts. Soil creep can add lots of fine material to the river’s load.
34
Q

What is river discharge?

A

T

35
Q

What is lag time?

A

T