Our changing planet Flashcards
How thick is the crust?
5-70km.
How thick is the mantle?
3000km.
What is the core made mostly of?
Iron and nickel.
Name the layers of the Earth.
Atmosphere Crust Mantle Outer core Inner core
Why do tectonic plates move and by how much?
Convection currents in the mantle.
A few centimetres per year.
What causes convection currents in the mantle?
Decay of radioactive elements heating up the mantle?
What did Alfred Wegener put forward?
The idea of continental drift.
What did other scientists believe in contrast to continental drift?
The earth was shrinking as it cools.
What was the early atmosphere made of?
Carbon dioxide, water vapour and nitrogen.
Possibly also methane and ammonia.
How were the oceans formed?
As the earth cooled, the water vapour condensed to create the oceans.
How was oxygen introduced into the atmosphere?
Algae and plants photosynthesised, replacing the carbon dioxide with oxygen.
What gases were used in the Miller-Urey experiment?
Water vapour
Methane
Ammonia
Hydrogen
What was the result of the Miller-Urey experiment?
Production of amino acids.
What are the proportions of gases in the atmosphere?
Nitrogen: 78% Oxygen: 21% Argon: 0.9% Carbon dioxide: 0.04% Trace of other gases
Why is fractional distillation of liquid air done industrially?
To produce pure oxygen and liquid nitrogen, which have important uses.
