- Created by: Sean Duckworth
- Created on: 29-05-11 12:56
3 types of rock- Igneous formed when magma cools and hardens, eg granite- Sedimentary are formed when sediment compacts together due to lithification, eg chalk- Methamorphic rocks are formed when a different type of rocks changes due to heat and pressure, eg marble.
3 types of wetahering- physical- freeze thaw weathering- water gets in to cracks in rocks and freezes and expands the crack when thawed.- Exfoliation- surface layers of rocks heats up quicker than inner so it peels off.- Chemical weathering- carbonation- rainwater is a weak carbonic acid, carbonic acid reacts with rocks that contain calicium carbonate, eg carboniferous limestone, therefore the rocks are dissolved by rainwater.
Granite has many cracks which arent evenly spread out, weathering occurs quicker in the cracks pushing up the parts with no cracks.
Chalk and clay Escarpments
Clay is eroded quicker than chalk,so the chalk is left sticking up, forming an escarpment.
Continental crust- thicker and less dense- Oceanic crust- thinner and more dense.
3 types of plate margins- destructive plates- moving towards each other- the denser oceanic crust is pushed down into mantle causing a volcano etc- Constructive margins-moving away from each other- magma rises to fill the gap and colls to form a new crust- Conservative margins- moving side by side at different speeds.
Fold mountains- found at destructive plate margins. the sedimentary rocks that have built up between them is folded and pushed up to form mountains, eg Alps.
Volcanoes- Found at destructive and constructive plate margins. @ destructive plates- the oceanic plate (which is more dense) goes under the continental plate into the mantle where it is melted and destroyed- a pool of magma forms and it rises through cracks in the crust called vents- @ constructive plates margins- the magma rises to fill the gap created by the plates moving away from each other.-Composite volcanoes are found at destructive margins- Shield volcanoes are found at constructive margins.
Supervolcanoes- Much bigger than standard volcanoes, form over hotspots, eg yellowstone national park, USA. - they are flat, they cover a large area, and have a caldera.
Earthquakes- Earthquakes are caused by the tension that builds up at all three types of plate margin.- When tension builds, the plates eventually jerk past each other sending out shockwaves (vibrations) . these vibrations are the quake, the focus of the earthquake is the pointin the earth where the quake starts- the epicentre is point on the earth surface above the focus.
Earthquakes can be measured using two different scales- richter scale and mercali scale- mercali is in roman numerals and measures the effects of the earthquake, its a scale of 1-12, the richter scale neasures the magnitude of the quake, its a scale of 1-10.
Restless Earth eartquake case study
Earthquake case study
Kobe- In japan, 1995, 7.2 richter scale,- short term effects- 6000 dead, 40,000 injured 30,000 homeless, water shortage- preparedness- the buildings were generally well built which shortened deaths- however old wooden houses burned down in fires, rescue teams were slow, Japan refused foreign support and hospitals were overcrowded.- (example of eathquake in MEDC)
Haiti- 2010- 7.0 richter scale, 200,000 dead- The houses were built very poorly and were built on uneven foundations such as hills- the epicentre was only 10 miles away from port au prince which is very over populated,early warning systems were not put in place- (example of earthquake in MEDC)