1.7 Changes In The Earth And Atmosphere Flashcards
What is the structure of the earth?
Crust
Mantle
Outer core
Inner core
How thick are each parts of the earth?
Crust: 10-200km thick
Mantel: 5800km thick
Outer core: 4200km thick
What state is each layer of the earth?
Crust - solid (oceanic or continental)
Mantle - neither solid nor liquid
Outer core - liquid
Inner core - liquid (molten nickel and iron liquid)
What is the crust and mantle together?
The lithosphere
What is the lithosphere broken into?
Tectonic plates
Who came up with a theory about tectonic plates and what was it called?
Alfred Wegner
Continental drift
What is continental drift?
The idea that a long time ago all the plates were joined together and had moved apart
Why did wegner think the tectonic plates were once together?
He saw the coast lines of south America and and West Africa had similar fossils and rocks
Why wasn’t continental drift excepted for so long?
Insufficient evidence
He suggested tidal waves or the earth rotation
How did people explain continental drift back then?
A land bridge
Was a reasonable explanation
How do tectonic plates actually move?
Convection currents in the mantle
How are convection currents caused within the mantle?
Radioactive decay generates heat within the mantle
What are the plate boundaries of tectonic plates?
Deconstructive
Constructive
Compressional
Conservative
What is a deconstructive plate boundary?
Oceanic and continental plate collide and the oceanic is sub-ducted below the continental
What is a constructive plate boundary?
The plates move away from each other
What is a compressional plate boundary?
To continental plates collide forcing them upwards creating fold mountains
What is a conservative plate boundary?
When two plates slide past each other
Why is it difficult for scientists to predict natural disasters?
You can’t see the movement, forces or pressure building up
They don’t know where or when it will be
What was the earths conditions like 4 billion years ago?
Intense volcanic activity releasing: Carbon dioxide Ammonia Methane Water vapour
What happened to the water vapour from the early atmosphere?
Condensed into the seas
What happened to the carbon dioxide from the early atmosphere?
Carbon dioxide dissolves in the seas
Algae evolved and photosynthesis took in CO2 and produced oxygen
Plants and trees evolved also photosynthesising
What happened to the ammonia from the early atmosphere?
In the soil oxygen and bacteria broke down the ammonia giving of Nitrogen
How was the ozone layer created?
Oxygen reacted with the lightening
What is the ozone layer? What destroys it?
A protective layer in the outermost atmosphere from harmful radiation from the sun
CFC’s not CO2
What is stored in sedimentary rocks?
Calcium carbonate
What is extracted from sedimentary rocks? What happens when burnt?
Crude oil
When burnt it releases the store of carbon - contributing to global warming
What are the percentages of gases in the atmosphere today?
Nitrogen - 78%
Oxygen - 21%
Other gases - 1% (CO2 - 0.03%)
What experiment was conducted to recreate early life atmosphere?
Miller-Urey experiment
Or
Primordial soup theory
What happened in the Miller-Urey experiment?
The boiled water in a flask
The water vapour was pumped round into a flask with CO2, methane and ammonia were present
They added electrodes (lightening effect)
It went through a condenser allowing amino acids to be collected
What did the Miller and Urey conclude from their experiment?
They created amino acids and amino acids are the proteins that lead to life
This is how life began
What does the experiment actually conclude?
How amino acids may have been created
Not how life came about
What is the air?
A mixture of gases
How could you separate the air?
They have different melting and boiling points
So turn them into liquids and use fractional distillation
Then turn them back into gases but now separated
Why is fractional distillation of air useful in industry?
Raw materials can be obtained
What has to be removed before fractional distillation of air and why?
CO2 and water vapour
They would be solids by -200 which would clog up the pipes
What two gases don’t separate completely?
Oxygen and Argon
What two gases don’t condense at -200 degrees?
Neon and helium
Their boiling points are -246 and -269
Why is the Miller-Urey experiment not 100% accurate?
They can’t know the exact amounts of gas back then and if there was a constant supply of lightening
