GCSE Geography Edexcel B REVISION – UNIT 1 Dynamic Planet
Ms Mansell 2010
UNIT 1 : DYNAMIC PLANET
Atmosphere Biosphere Geosphere The layers of gases/air around us. The very thin layer of living things on the crust. The rocks of the crust and deeper towards the core.
How are we damaging each of the spheres?
Atmosphere releasing CO2 into. Hydrosphere using too much water in some areas Biosphere deforestation (chopping down the trees) animals extinct. Geosphere using up fossil fuels
The layers of the earth…
The lithosphere (which is solid) is split into tectonic plates. These move slowly (2-5cm/yr) on top of a layer called the asthenosphere (which is like porridge) CONTINENTAL CRUST = land, low density, thick. OCEANIC CRUST = under the oceans, thin, dense.
Meteorites give us a clue as to what the core is like.
How do we know that the inside of the earth is hot?
lava from volcanoes hot springs, geysers
Heat from the inside of the earth. Produced by the radioactive decay of uranium etc in the core and mantle. As heat rises from the core it creates convection currents in the liquid outer core and mantle. These convection currents move the tectonic plates on top of them. PLUMES = where heat moves to the surface e.g. hotspots like Hawaii.
Ms Mansell 2010
The earth is surrounded by an invisible magnetic field –made by the outer core – protects the earth from harmful radiation from space/the sun.
The continents were once all joined together – Pangea. How do we know this? Identical fossils and rocks have been found in western Africa and Eastern South America for example. Today the lithosphere is split into 15 tectonic plates. Where 2 plates meet together = plate boundary.
Constructive plate boundary…
Where two oceanic plates are moving apart from each other. New oceanic crust is forming constantly in the gap created. The magma is injected between the two plates. As it cools it forms new oceanic crust. The magma is runny. Shallow sided volcanoes form. HAZARDS: Small earthquakes are formed by friction as the plates tear apart. Volcanoes that are not very explosive/dangerous. Examples are Iceland – the Mid Atlantic Ridge
Convection currents from the mantle bring magma towards the surface. Magma is forced between the plates, cools and forms new oceanic crust.
Destructive plate boundary…
Where an oceanic plate meets a continental plate. They are moving towards each other. The denser oceanic plate is subducted beneath the less dense continental plate. HAZARDS: very destructive earthquakes tsunami very explosive, destructive volcanoes which cool to be steep sided. Examples are Andes mountains, Peru, Chile.
Conservative plate boundary…
Formed where two plates are sliding past each other. HAZARDS: destructive earthquakes small earth tremors daily. no volcanoes Example is San Andreas Fault, California
A type of destructive boundary where two continental plates move towards each other. As they meet they push upwards forming mountain ranges e.g. Himalayas.
Ms Mansell 2010
HAZARDS: destructive earthquakes landslides volcanoes are rare
Volcanic Explosivity Index (VEI)
Measures the destructive power of a volcano on a scale from 1 to 8.
Pyroclastic flows – deadly clouds of hot ash and gas. Landslides Lahars – volcanic mudslides Lava flows Ash builds up on the roofs of houses buildings collapse. Acid rain is created.
NAMED EXAMPLE: Sakurajima, Japan
Stratovolcano/ composite volcano (steep sided) Destructive plate boundary
Can erupt 200 times a year. ADVANTAGES OF THE VOLCANO 40% of the land is fertile, volcanic soil can grow rice and tea. Hot springs are a tourist attraction. Sheltered bay is good for the fishing industry.
DISADVANTAGES OF THE VOLCANO 7000 people live at the base (are...
Please join StudyMode to read the full document