Our Changing planet Flashcards
What is the mantle?
The layer of the earth between its crust and its core. It is almost entirely solid
What is the core?
The centre of the earth. It has a liquid outer part and solid inner part
What is the atmosphere?
The relatively thin layer of gases that surround planet earth
Which layers of the earth are solid?
Inner core, mantle, crust
Where do the earths resources come from?
The crust, the oceans, and atmosphere
What causes techtonic plates to move?
Convection currents
What are techtonic plates?
The huge stabs of rock that make up the earths crust and top of its mantle
What are the convections currents in the mantle caused by?
Energy released by the decay of radioactive elements heating up the mantle
What causes earthquakes, volcanoes or mountains to form?
Where the plates meet huge force build up eventually the rocks give way changing shape or moving suddenly
Why can scientist not predict when and where earthquakes will happen?
We do not know up enough info or data or models to make accurate predictions
Why was wegener’s theory of continental drift not accepted for many years?
He could not explain why continents moved and at the time people accepted their own ideas
What is continental drift?
His idea was that the Earth’s continents were once joined together, but gradually moved apart over millions of years. It offered an explanation of the existence of similar fossils and rocks on continents that are far apart from each other.
What was wegener’s evidence?
the same types of fossilised animals and plants are found in South America and Africa
the shape of the east coast of South America fits the west coast of Africa, like pieces in a jigsaw puzzle
matching rock formations and mountain chains are found in South America and Africa
When do scientist think the earth was formed?
4.5 billion years ago
What was the earth like in the early stages?
Covered with volcanoes that released carbon dioxide, water vapour and nitrogen
What happened as the earth cooled?
The water vapour condensed to form oceans
What else do scientist believe may have been present on earth in the early stages?
Nitrogen, some methane and ammonia
What happens just after the early stages?
Bacteria, algae and plants evolved which used the co2 for photosynthesis and released oxygen
What did the plants that produced oxygen in the atmosphere probably evolve from?
Simple organisms such as plankton and algae
What did the Miller Urey experiment show?
They used a mixture of water, ammonia, methane and hydrogen and high voltage spark to simulate lightening, after a weak they found that amino acids the building blocks of proteins had been produced
What is the primordial soup theory?
Organic molecules formed a primordial soup and that the amino acids in this mixture combined to make proteins from which life began
What happened to most of the carbon dioxide in the early atmosphere?
It became locked up in sedimentary rocks
Where did sedimentary rocks probably come from?
Co2 dissolved I. The ocean forming compounds that deposited on the seabed
In what ways did co2 become locked up?
It’s in fossil fuels and sedimentary rocks
How much of the nitrogen is in the atmosphere?
80%
How much oxygen is in the atmosphere?
20%
How can the gases in air be separated?
Fractional distillation
Is the co2 in the atmosphere relatively the same as 200 million years ago?
Yes
What is the carbon cycle?
The natural processes that means co2 goes in and out of the atmosphere
Name 2 processes that release co2 into the atmosphere and 2 that remove it from the atmosphere
Release 2: burning, respiration, decay
Remove: photosynthesis, dissolved in oceans and water
Why has the amount of co2 risen recently?
The large amount of fossil fuel we burn
What is the crust?
A very thin layer at the surface , outer layer of the earth beneath the atmosphere. It is solid
