Physical Geography Processes

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Oxbow Lake

1) The water travels fastest on the outside bend of the meander bend which causes erosion to take place through hydraulic action and abrasion. This creates a river cliff on the outside bend and a slip-off slope on the inside bend. The meander neck becomes narrower over time as erosion takes place on the river cliffs.

2) The meander neck becomes narrower over time as erosion takes place on the river cliffs.

3) During a period of flood, the water cuts through the meander neck causing the river to flow straight.

4) The river now flows straight which causes deposition to take place on the meander bend where the water has no energy. Over time, this causes the bend to become cut off from the rest of the river leaving an abandoned meander called an oxbow lake.

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The Greenhouse Effect

1) Incoming shortwave solar radiation heats the earth's surface.

2) Some solar radiation is reflected back out of the earth's atmosphere.

3) The earth warms up and emits longwave radiation into the atmosphere.

4) Some longwave radiation escapes out into space.

5) Other longwave radiation is absorbed by the greenhouse gases in the earth's atmosphere keeping the earth warm.

6) The enhanced greenhouse effect is caused by humans releasing large amounts of greenhouse gases into the earth's atmosphere which causes more longwave radiation to be absorbed into the atmosphere.

7) This causes global temperatures to increase resulting in global warming.

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Formation of a tropical storm

1) Hot seawater (27.5°c+) heats up the air above.

2) Warm moist sea air starts to rise in convection currents.

3) Rising currents of air from towering cumulonimbus clouds from which heavy rain falls.

4) Air is sucked in to replace the rising air.

5) A deep centre of low pressure is created.

6) Winds increase to hurricane force as the pressure gradient increases.

7) Air is sucked down in the centre to form an eye of calm and dry weather in the centre.

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Passage of a depression

1) Warm air from the tropics meets cold air from the poles. The warm air is less dense and so rises over the cold air.

2) As the air rises, it cools, condenses and forms stratus clouds.

3) The pressure gradient is gentle and so light rain is produced.

4) As the depression moves east, the warm sector passes over.

5) Here there is no air moving and so there are some clouds and sunny intervals.

6) At the cold front, cold air meets warm air. The cold air is denser and forces its way under the warm air creating a steep pressure gradient.

7) Here cumulonimbus clouds form producing heavy rainfall.

8) Depressions spiral in an anti-clockwise direction.

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Formation of a fold mountain

1) The rivers carry sediment and then the sediment accumulates on the seabed.

2) Geosyncline is filled with sediments compressed with rock. Sediment is built up in layers.

3) There is continued compression from plate movement. Due to pressure, the sediments are folded into fold mountains.

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Formation of a shield volcano

1) The two oceanic plates move apart.

2) As the plates move apart the magma rises to fill the gap.

3) The magma rises and cools and begins to build up.

4) The volcano erupts and spews out lava.

5) The runny, basic lava spreads out to form a volcano.

6) The volcano erupts regularly and non-violently.

7) An example is Mauna Loa.

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Formation of a composite volcano

1) As the two plates move towards each other, the oceanic plate is forced under the continental plate at the subduction zone.

2) The oceanic plate melts due to the friction/pressure and forms lava.

3) The lava rises through cracks in the rocks where it eventually erupts onto the surface to form a composite volcano.

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Formation of a supervolcano

1) A hot spot forms away from the plate boundary. This is due to the rising convection currents in the mantle. The pressure from the magma builds and begins to 'melt' the crust. The pressure causes the crust and land to be pushed up.

2) As the pressure increases, cracks are created in the crust. Through these cracks, gases escape.

3) The pressure from the mantle increases so much that the land and crust collapses. This creates a crater, called a caldera. This is the super volcano.

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Formation of an earthquake

1) The two plates  move against each other. This causes a build-up of pressure due to friction.

2) The pressure continues to build up until it is released because it is too much. The plate jolts upwards, releasing energy.

3) This energy causes seismic waves which cause the ground to shake in all directions.

4) The focus is the point where the waves start. The epicentre is the point on the surface directly above it.

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Formation of a waterfall

1) The river flows over hard and soft rock.

2) The less resistant soft rock is eroded first through hydraulic action leaving a dip.

3) Over time, a plunge pool is formed due to hydraulic action and causes splashback.

4) An overhang is formed from the hard rock which eventually falls into the plunge pool due to gravity. This deepens the plunge pool due to abrasion.

5) The waterfall retreats upstream leaving behind a steep sided valley called a gorge.

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Destructive Subduction

1) An oceanic plate moves towards a continental plate.

2) The more dense oceanic plate sinks beneath the continental plate.

3) This creates an ocean trench.

4) The oceanic plate melts in the subduction zone.

5) The lighter molten rock rises to the surface and creates composite volcanoes.

6) Continental crust is crumpled, forming fold mountains.

7) An example of this is the Andes (SA, Nazca plate).

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Destructive Collision

1) The two continental plates meet each other.

2) They collide rather than one sinking beneath the other.

3) Here, earthquakes can occur but volcanoes do not.

4) Fold mountains often form here.

5) An example of this is where the Indian plate collided with the Eurasian plate to form the Himalayas.

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1) The two tectonic plates move apart.

2) Magma is injected in between the two plates.

3) Shield volcanoes form at the surface.

4) These volcanoes are not very dangerous or explosive.

5) Small earthquakes are common.

6) They are produced by the movement of rising magma.

7) They are more like small earth tremors.

8) An example of this is where the NA plate moved away from the Eurasian plate to form the Mid-Atlantic ridge.

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1) The two tectonic plates move alongside each other.

2) The boundary between the two plates is a fault.

3) There are no volcanoes at conservative plate margins, and no lava has erupted.

4) Sometimes the plates can not move past each other and get stuck.

5) Pressure builds up until the plates give way.

6) The produces large, destructive earthquakes.

7) An example of this is the San Andreas Fault.

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Formation of a tsunami

1) Convection currents within the mantle move two plates towards each other, building up pressure causing an underwater earthquake.

2) One plate jolts up causing vertical displacement of the water and large waves to form. The water splits into a series of waves which travel towards land.

3) As the waves approach the land, the wave height increases due to friction on the seabed. As the speed decreases the height increases. A tsunami is formed and causes devastation when it hits the land.

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Convection Currents and plate comparison

1) Convection currents within the mantle move the tectonic plates.

2) This means that sometimes the plates move with each other and sometimes they move apart.

3) The Earth's mantle heats the magma which rises up and cools down when it reaches the core.

4) These are called convection currents.

Oceanic crust:

  • Newer
  • Denser
  • Can sink
  • Can be renewed and destroyed

Continental crust:

  • Older
  • Less dense
  • Cannot sink
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Erosion and transportation

Hydraulic action: the force of the water hitting the bed and banks of the river.

Abrasion: the load carried by the river hits the river bed and banks, causing material to break off.

Attrition: Stones and boulders carried by the river knock against each other, causing bits to fall off and reduce in size.

Solution: Rocks and minerals slowly dissolve in river water.

Traction: large boulders roll along the river bed.

Saltation: smaller pebbles are bounced along the river bed, picked up and then dropped as the flow of the river changes.

Suspension: the finer sand and silt-sized particles are carried along with the flow, giving the river a brown appearance.

Solution: minerals, such as limestone and chalk, are dissolved in the water and carried along in the flow, although they cannot be seen.

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Areas closest to the equator have higher temperatures because:

1) The sun's rays have less distance to travel at the equator than the poles so more energy to heat.

2) The angle of the sun is also more direct at the equator.

3) The surface area is smaller at the equator, so more energy is transferred.

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The land is solid and heats up/cools down quickly.

Water is a liquid so heats up/cools down slowly.

Summer: The sea/ocean takes longer to warm up than the land in the summer. So areas inland are hotter in summer than coastal areas.

Winter: The sea/ocean takes longer to cool down than the land. So coastal area are warmer in the winter than areas inland.

The UK is surrounded by water so does not feel the extremes of heat like areas in the centre of the European continent.

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Altitude - this means the height above sea level.

The higher up you go from sea-level the colder it becomes. 1°c for every 160m in height.

This is because there is less oxygen and oxygen holds the heat from the sun.

Altitude also affects the precipitation amounts.

Mountains and hills force air to rise over them, as they do the air gets colder and water vapour condenses to form stratus clouds.

Once passed the mountains, air sinks and warms as it reaches the surface. Any water evaporates so no clouds and dry air - a 'rain shadow'.

West of the UK is wetter because of relief rainfall. Lots of mountain ranges.

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Ocean currents move around the globe. They can be cold or warm. 

Our ocean current is a warm body of water which comes from the Carribean (North Atlantic Drift).

This brings mild air to the UK, making out climate warmer than it would be for the same latitude. Especially important in winter.


The UK lies in a zone of low pressure where air rises. Air is rising and cools so it forms clouds and rain.

The PREVAILING WIND is the most common wind and this is from the SW in the UK bringing tropical (warm) air to the UK.

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River Courses


  • Abrasion + attrition
  • Vertical
  • V-shaped valley


  • Attrition + hydraulic action
  • Vertical + lateral
  • U-shaped valley


  • Hydraulic action + solution
  • Lateral
  • U-shaped valley
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