C1 Earth and Atmosphere

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who was Alfred Wegener
scientist with theory of continental drift
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what was the initial theory of the earths structure at that time
there were land bridges that linking the continents enabling animals to cross
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what did Wegener suggest it was
continental drift
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what did he realise between south america and africa
their coastlines seemed to match like pieces of a jigsaw
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what else supported his theory
matching layers in the rocks in different continents, fossils were found in the 'wrong' places
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when did he publish his theory
1915
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what did he suggest the continents started as (when)
300 million years ago there was just one super continent called Pangea which broke and moved apart
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what was the main reason his theory was disregarded
Wegeners explanation of how the drifting happened
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what did he use and what did this cause
inaccurate data in his calculations meaning he made wild predictions about how fast the continents ought to be moving apart
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what happened in 1950+
investigations of the ocean floor took place, finding new evidence to support Wegeners theory
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what is the structure of the earth
the earths crust is made of several chunks called tectonic plates which move about, colliding chunks push the land up and form mountains
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how thick is the crust
between 5km-50km
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what surrounds the crust
the atmosphere
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what is below the crust
the mantle
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what are the properties of the mantle
properties of a solid but can flow very slowly
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what causes convection currents in the mantle
radioactive decay takes place producing heat causing the mantle to flow in convection currents
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what is the core suspected to be made from
iron and nickel
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what are tectonic plates
big rafts that 'float' on the mantle
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how do they move
convection currents in the mantle cause them to drift
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on average how much do they move every year
a few cm
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what are the 2 features that occur at plate boundaries
volcanoes and earthquakes
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way of predicting volcanoes
molten rock rises up into chambers near the surface causing the ground surface to bulge slightly
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how can this be a false alarm
the molten rock cools instead of erupting
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a way to predict an earthquake
strain in underground rocks
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how is this very unaccurate
cant say when it is exactly going to happen
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phase 1:
volcanoes gave out gases
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phase 1:1
it was so hot any atmosphere boiled away into space
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phase 1: 2
it cooled down and a thin crust formed but volcanoes continued to erupt
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phase 1: 3
the volcanoes gave out a lot of gas
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phase 1: 4
early atmosphere was mostly CO2 with virtually no oxygen, small amounts of methane and ammonia
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phase 1: 5
oceans formed when the water vapour from the volcanic eruptions condensed
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phase 2:
green plants evolved and produced oxygen
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phase 2: 1
green plants and algae evolved
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phase 2: 2
a lot of early CO2 dissolved into the oceans and the green plants and algae absorbed some and produced O2 by photosynthesis
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phase 2: 3
plants+algae died and buried under layers of sediment, along with skeletons of organisms, carbon and hydrocarbons became locked up in sedimentary rocks as insoluble carbonates
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phase 2: 4
when we burn fossil fuels today the locked up carbon is released
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phase 3:
ozone layer allows evolution of complex animals
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phase 3: 1
the build up of oxygen in the atmosphere killed off organisms but allowed more complex organisms to evolve
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phase 3: 2
the oxygen created the ozone layer which blocked harmful rays from the sun
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phase 3: 3
virtually no CO2 left now
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what was the earths surface originally
molten
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2 ways CO2 decreased
dissolved in oceans, plants used it for photosynthesis
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what is the primordial soup theory
one theory of how life was formed
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what does the primordial soup theory suggest the earths atmosphere was made from
nitrogen, hydrogen, ammonia and methane
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what caused a chemical reaction to take place between these gases
lightning
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what did the reaction form
amino acids
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where did the amino acids collect
in a 'primordia soup', a body of water
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what did the amino acids gradually combine to produce
organic matter
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what did this organic matter eventually evolve into
simple living organisms
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when was the Miller Urey experiment
1950s
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what was the Miller Urey experiment
sealed the same 4 gases in their apparatus, heated them and applied an electrical charge for a week
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what was created
amino acids
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why wasnt it perfect
not as many amino acids as there are on earth were created
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during the fractional distillation of air what happens first
air is filtered to remove dust
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name two molecules that are removed
carbon dioxide and nitrogen
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what is the air cooled to and why
-200 degrees Celsius to condense the air (make it a liquid)
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what molecule comes out as a gas
nitrogen
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what molecules come out as a liquid and why
oxygen and argon, they have a higher boiling point than nitrogen
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what happens to the liquid air as it enters the column
its heated slowly
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name a problem with CO2
causes global warming, a type of climate change
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name a natural store of CO2 + a problem + side effect
oceans are a natural store as they absorb CO2 from the atmosphere, the extra CO2 we are releasing makes them too acidic, this kills coral and shellfish and also means in the future they wont be able to absorb any more CO2
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Card 2

Front

what was the initial theory of the earths structure at that time

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there were land bridges that linking the continents enabling animals to cross

Card 3

Front

what did Wegener suggest it was

Back

Preview of the front of card 3

Card 4

Front

what did he realise between south america and africa

Back

Preview of the front of card 4

Card 5

Front

what else supported his theory

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