C1.7 Our Changing Planet Flashcards
What are the layers of earth?
Inner core
Outer core
Mantle
Crust
How thick is the crust?
6-35 km
How thick is the mantle?
3000km
How thick is the core?
3500km
What’s the crust?
Rocky outer layer beneath your feet. It’s where we get our minerals.
What’s the mantle?
Semi-liquid, very high temperatures
The cooler section near the crust is less mobile than the hotter section next to the core. It has properties of a solid but can flow very slowly.
What’s the core?
The layer at the centre of the earth. This layer is divided into two sections: the liquid outer core and the solid inner core. It’s a mixture of magnetic metals: nickel and iron.
What are Seismic waves?
S waves which only travel through solids and P waves travel through the earth and are refracted when they pass through a medium.
These are how they know what’s in the earth and the layers.
S-waves are transverse and P-waves are longitudinal
Both waves can be detected in an earthquake
How much do continents move per year?
A couple of centimetres
Who’s Alfred Wegener?
Discovered the theory of plate tectonics, continental drift in 1911. It took over 20 years to be accepted.
How is convection formed in earth?
The earths radioactive core releases large amounts of heat energy, which heats the rock in the lower mantle. It becomes less dense and rises.
The warmer rock in the lower mantle begins to rise, while the cooler rock in the upper mantle sinks. This movement of rock means that circulating convection currents are formed within the mantle.
As the mantle heats up, energy transfer from the convection currents causes the earths crust to heat up. This heating drives the movement of the tectonic plates and causes the continents to move a few centimetres each year.
How are earthquakes formed?
When the boundaries meet, huge stresses build up.
These forces make the plates buckle and deform which can create mountains.
If the plates suddenly slip past each other, earthquakes may form.
Why don’t scientists know when earthquakes will occur?
They don’t know what happens under the crust
Don’t know where forces and pressures build up
Don’t know the sizes of the forces
Don’t know when the sizes reach their limit
What are the gases in our atmosphere and the percentages of them?
Oxygen - 21%
Carbon dioxide - 0.04%
Nitrogen - 78%
Argon - 0.9%
When did the earth form?
4.5 billion years ago
What happened 4 billion years ago?
There was a lot of volcanic activity and release nitrogen, CO2 and water which make a dangerous atmosphere
What happened 3.4 billion years ago?
Tiny photosynthesis bacteria are everywhere. They give out oxygen and waste gas. The concentration of oxygen was 0.001%
What happened 600 million years ago?
0.21% of oxygen and bacteria was thriving more.
What happened 400million years ago?
Land plants start to appear and produce more oxygen - 2.1%
How long has the oxygen level stayed the same?
200 million years
What are amino acids?
Any of a large number of compounds found in living cells contain carbon, oxygen, hydrogen and nitrogen and come together to form proteins.
What’s the primordial soup theory?
It states that billions of years ago the earths atmosphere was rich in nitrogen, hydrogen, ammonia and methane. Lightning struck, causing a chemical reaction between the gases, resulting in the formation of amino acids. The amino acids collected in a ‘primordial soup’ - a body of water out of which life gradually crawled. The amino acids gradually combine and make organic matter.
What and when was the Miller-Urey Experiement?
1953
They combined water, hydrogen, methane and ammonia. They sparked them (like lightening). This formed amino acids which is the block of living things. They found out how life on Earth supposedly started. They found 11 amino acids and in 2008 scientists analysed it again and found 22 amino acids.
Why don’t some people agree with the Miller Urey experiment?
People believe oxygen was present before the time and Miller and Urey didn’t use oxygen.
No one knows exactly what the atmosphere was like.
There might not have been continuous lightening.
What’s the Murchison Theory?
In 1969 a meteorite fell from the sky above Australia. It weighed over 100kg
We have identified over 70 amino acids on the fragments
Therefore the acids could have come from space, extraterrestrial seeding.
What are volcanic vents?
From volcanoes there was the correct environment for amino acids to form.
Where has carbon dioxide gone?
Locked up in sedimentary rock, such as limestone and fossil fuels.
Absorbed by plants for photosynthesis.
Dissolved in the oceans.
What happened to methane and ammonia?
They reacted with oxygen.
Methane+oxygen->carbon dioxide+water
Ammonia+oxygen->nitrogen+water
What do we use nitrogen for?
Make ammonia
Inert(Unreactive)- used in food
Packaging
Used to cool things
What do we use argon for?
Very inert (Unreactive) Light bulbs
What do we use oxygen for?
Hospital - breathing
Welding - binding metals
What do we use co2 for?
Stage shows- dry ice
Cools things
Draw the carbon cycle.
Look it up :)
Animals in the middle Fossil fuels to the right Carbon dioxide at the bottom Plants to the left Dead organisms at the top
What’s carbon capture?
Instead of being released into the atmosphere, carbon dioxide is capture at power stations and compressed. The CO2 is pumped through a network of pipelines. It’s then pumped down through the well into porous rock which previously held gas deep beneath the sea bed. The CO2 filters into the porous sandstone reservoir, filling the ring spaces which once held natural gas. It is trapped from escaping by the layers of solid rock above.
What’s a tectonic plate?
The sections of the earths crust
