Changes in the Earth and its Atmosphere

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  • Created by: Heather
  • Created on: 29-05-14 12:38
What are the three main layers of the Earth starting with the outermost and its properties/appearance?
Crust-Thin and rocky, -Mantle-Properties of a solid but can flow very slowly, -Core-Outer then Inner-Made from liquid nickel and iron,
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Where are the tectonic plates?
In the Earth's crust and upper part of the mantle,
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How often do tectonic plates move?
The move a few Cm each year
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What is continental drift?
The process where over millions of years, it allows continents to shift apart,
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Why do the tectonic plates move?
They move becuase of convection currents in the Earth's mantle which is driven by the heat produced from radioactive decay in the Earth,
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What are the three options of what could happen when tectonic plates meet?
-Plates push against each other, -Ride under the plate, -ride over the plate,
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What natural disasters might occur when these plates meet and what could form when the crust 'crumples'?
Earthquakes and volcanic eruptions happen at the boundaries between plates, -Crust may 'crtumple' to form mountain ranges,
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Wh proposed the idea of tectonic plates and continental drift?
Alfreed Weigner-A german scientist,
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What was Weigar's theory about how mountaisn formed?
He suggested mountains formed when the edge of a drifting continent collided with another, causing it to crumple and fold,
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Why did it take 50 years for Wegener's theory to be accepted?
As it was difficult to work out how whole continents could move
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What was Weignar's theory about how the continents were positionned like they are today and now how they were at the time of Pangaea?
In the time of Panaea, aroudn 200 million years ago, continents formed a single landmadd which began to crack and divide due to slow convection currents from the magna beneath. These currents formed the continent's positions like they are todays
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What are the two main types of tectonic plates?
-Oceanic plates which occur under oceans, -Continental plates form the land
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What happens if oceanic plates and continental plates meet and why?
Oceanic plates are pushed under continental plates are oceanic plates are denser,
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When tectonic plates meet, the Earths crust becomes unstable. What rises from the crust and why and what does it form?
Magma, molten rock, can rise from gthe surface as it is less dense that the crust so it rises through the weakened crust and forms a volcano,
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Why can;t scientists predict earthquakes or volanic eruptions?
-They can;t see beneath the crust to see the position of the tectonic plates, -We dont have the right equipment yet, -Scientisrs don't know when and where it could happen as the movements are so tiny,
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In the modern atmosphere, what are the two main gases and what percentage are they in the atmosphere?
Nitrogen-78%, oxygen-21%,
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Give two examples of the remaning 1% gases?
-Carbon dioxide, water vapour, noble gases like argon,
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What was in the early atmophere of the gases?
Mainly carbon dioxide but a small amount of water vapour, ammonia and methane,
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Where were theses gases formed from?
The gases given out by volcanoes as there was an intense volcanic activity on Earth's first existance,
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What two planets are thought to have atmosphere today which were similar to Earth;s early atmosphere?
Mars and Venus,
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What experiment was used to explain how life began on Earth?
Miller-Urey Experiment,
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Describe the Miller-Urey Experiment?
The two scientists sealed a mixrture of water, ammonia, methane and hydrogen in a sterile flask, -The mixture was heated to evaporate water to produce water vapour, -Electric sparks passed through the mixture of water vapour and gases=lightning,
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After a week, what was formed?
Amino acids were discovered,
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What theory did the Miller-Urey experimenmt support and what did it mean?
THe theory of a 'premordial soup' so the udea that complex chemicals needed for livign things to develop could be produced naturally,
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From Earth'd early atmosphere to today, how did oxygen levels increase?
Plants and algae carried out photosynthesis which uses the carbon dioxide in the atmosphere with water and sunlight to produce oxygen and glucose,
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From Earth'd early atmosphere to today, how did carbon dioxide levels increase?
-Photosynthses by plants used the carbon dioxide, -Dissolved in oceans, -Production of sedimentary rocks like limestone, -Production of fossile fuels from remains of dead plants,
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How do we seperate oxygen from nitrogen?
By fractional distillation of liquid air,
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How is the air liquified?
The water vapour is condensed. The carbon dioxide freezes as it has a lower melting/boiling point so its removed and oxygen and nitrogen is liquified,
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How is the liquified air seperated in the fractional distillator?
It is passed into the bottom of a fractionating column-Warmer ar rhe bottom and cooler at the top. Liquid nitrogen rises to the top and liquid oygen collects at the bottom,
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What is nitrogen used for?
-Freeze food, -Food packaged in gaseous nitrogen to increase shelf life, -Oil tankers use nitrogen to reduce chance of explosion,
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What is oxygen used for?
-Manufacture of steel and in medicine
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Other cards in this set

Card 2


Where are the tectonic plates?


In the Earth's crust and upper part of the mantle,

Card 3


How often do tectonic plates move?


Preview of the front of card 3

Card 4


What is continental drift?


Preview of the front of card 4

Card 5


Why do the tectonic plates move?


Preview of the front of card 5
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