Chapter 7 - Our Changing Planet Flashcards
Why do tectonic plates move
Because of convection currents in the mantle beneath them. The convection currents are caused by energy released by the decay of radioactive elements heating up the mantle
What happens when the plates meet
Huge forces build up. Eventually the rocks give way, changing shape or moving suddenly causing earthquakes, volcanoes or mountains to form.
Why can scientists not predict when and where earthquakes will happen
They do not know enough about what is happening Inside the earth to predict when it will happen
What was Alfred Wegener’s idea and why did other scientist not accept his ideas
The idea of continental drift. He could not explain why the continents moved
What did the early atmosphere consist of
Carbon dioxide, water vapour and nitrogen, with traces of methane and ammonia as the surface was covered with volcanoes
Describe the process of what happens in the early earth
As the earth cooled most of the water vapour condensed to form the oceans. Bacteria, algae and plants evolved. Algae and plants used carbon dioxide for photosynthesis and this released oxygen. As the number of plants increase, the amount if carbon dioxide decreased and the amount of oxygen increased
What was the Miller Urey experiment
They used a mixture of water, ammonia, methane and hydrogen and a high voltage spark to simulate lightning. They found that amino acids, the building blocks for proteins had been produced.
How did carbon end up in plant and animal remains as sedimentary rocks and fossil fuels
Animals ate the plants and much of the carbon ended up in plant and animals remains.
How were insoluble carbonate compounds formed
Carbon dioxide dissolves in the oceans and the carbonate compounds were deposited on the sea bed and became sedimentary rocks
How can the main gases in the air be separated
By fractional distillation
Describe the carbon cycle
Plants photosynthesise and respire (take in CO2, give out CO2) plants die and there are organic compounds in dead organisms.
Animals feed on the plant and respite. Animals die and there are organic compounds in dead organisms. Burial and sedimentation of organic compounds means there ends up being organic compounds in fossil fuels. Burning fossil fuels releases CO2. Decay and respiration by decomposers of organic compounds give out CO2.
Describe the structure of the earth
On the surface is the crust which is a thin layer. The mantle is under the crust. The core is about half the diameter of the earth. It had a liquid outer part and solid inner part
