Flashcards
Geography- Restless Earth
Cards in this deck (29)
- 1Describe the structure of the earth.The hottest part is the inner core and it gets cooler as you move towards the crust.
It is solid in the core, semi solid in the outer core and liquid in the mantle. - 2What are the two types of tectonic plates?Oceanic- Heavy and dense
Continental- Lighter and less dense - 3What is a constructive plate boundary?When the two plates move away from each other. e.g. north american and eurasion
- 4What is a destructive plate boundary?When two plates move towards each other
eg. Nazca and South American plates - 5What is a conservative plate boundary?When two plate slide past each other.
- 6How are composite volcanoes formed?They are formed at destructive plate margins. The oceanic plate( e.g. nazca plate) is dense and therefore forced under the less dense continental plate ( e.g. south american plate), this is then melted by the magma in the mantle ( the subduction zone). This new liquid magma then rises, piercing the earths crust and creating composite volcanoes.
- 7How are shield volcanoes formed?As the plates move away from each other the gap is filled with magma rising from the mantle, due to convection currents, this creates the shield volcano.
- 8What are the features of a composite volcano?.Viscous lava due to high silica content (this travels short distances)
.Steep slopes
.Violent explosive eruptions due to a lot of pressure and friction
.Irregular eruptions e.g. the anders - 9What are the features of a shield volcano?.Runny lava due to low silica content (this flows long distances)
.Gentle slopes and wide base
.Little violence, lava only
.Frequent eruptions e.g. iceland - 10What happens at a conservative plate margin?The plates move in the same direction, but one moves slightly faster e.g. north american v pacific
therefore friction and pressure builds up along the fault line until one jerks past the other, releasing pressure and causing an earthquake - 11How are fold mountains formed?They form along destructive plate boundaries. over millions of years sediment (geosyncline) that has accumulated on the sea bed,is compressed into sedimentary rocks. When the plates suddenly move towards each other, the sedimentary rocks are forced upwards into a series of folds.
- 12What are ocean trenches?They occur at destructive plate boundaries e.g. nazca and south american
It is a deep area of water found at the subduction zone, they are very deep at 5000- 10000m below sea level. - 13Why is there low population density up in fold mountains?.it is hard to grow food for living as the cold windy climate means the soil is infertile most of the time, ( theres only a short growing period).
.There is steep relief and so little flat land for houses or farming
.Its hard to create transport, communication links and build roads. - 14Why are there some settlements in fold mountains on the valley floor?.The physical conditions are more favourable
.The relief is flatter for farming and building
.Warmer, so longer growing season
.Soil is more fertile
. easier to build infasructure - 15What is a volcano?A cone shaped mountain, formed by eruptions of magma
- 16What comes out of a volcano?.Lava
.Gas
.Smoke/steam
.Ash/Dust - 17Where are volcanoes found?They are found along tectonic plate boundaries. They are found along the mid-atlantic ridge, the west coast of north and south america and the pacific ring of fire.
- 18Why are volcanoes cone shaped?Each time a volcanic eruption takes place, a new layer of lava is added to the surface of the volcano. as more lava accumulates close to the crater during each eruption, a cone shaped mountain is formed.
- 19Why does a secondary cone develop in composite volcanoes?Due to a build up of pressure on the main vent.
- 20What are the primary effects of volcanic eruptions?.People are killed/injured
.Buildings are destroyed
.Communications/infrastructure is disrupted e.g. electricity, gas, pipes - 21What are the secondary effects of a volcanic eruption?.Shortage of drinking water, as pipes have cracked.
. contamination of water, leading to spread of diseases e.g. cholera
.Shortage of food as farmland is destroyed
.shortage of shelter as buildings have collapsed.
.Loss of family and friends, causing stress and depression
.Economic problems - 22What can happen if a volcano erupts without warning?.People can be hit with rocks
.Suffocated by poisonous gases
. Buried in mudflows - 23How can volcanic eruptions be predicted?. small earthquake shock waves
.increased emissions of Sulfur dioxide
.A change of shape around the crater
.Satellites to check for infrared radiation
Poor countries cannot afford this equipment therefore damage is usually worse as it is harder for them to predict one. - 24Why do people live near active volcanoes?. After the lava weathers, the soils are some of the most fertile in the world for growing crops.
.Tourism- spectacular scenery, mud pools, bath in hot springs, watch geysers, lots of jobs created.
.Valuable for minerals eg. mining
.hot water can generate electricity e.g.. geothermic electricity in Iceland which is renewable and sustainable. - 25What is an earthquake?Vibrations in the earths crust which shake the grounds surface after pressure has built up, and is released between 2 plates.
- 26What is a richter scale?It is a log scale (1-10), 7 is 10x stronger than 6, 100x stronger than 5, and 1000x than 4.
A seismograph measures this. - 27What physical factors result in severe damage?.High magnitude earthquakes
.Shallow focus near the surface
.Soft rocks, as they vibrate more - 28What human factors result in severe damage?.High population density
.Self built homes
.Lack of emergency procedures and poor
emergency responses. - 29What makes a building earthquake resistant?.Cross bracing, this is reinforced walls using two steel beams.
.Deep foundations made out of rubber, to absorb shock waves
. shutters on windows to stop falling glass hitting people below
.wide base so theres a low centre of gravity.
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- GCSE geography Flashcards on Geography- Restless Earth , created by Nicole McNally on 28/03/2016.
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- Nicole McNally
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