Changes in the Earth and its atmosphere Flashcards
What are the four main layers of the Earth?
Give details about each layer.
1) Crust - very thin layer that varies in thickness, between 5km and 70km
2) Mantle - under the crust, around 3000km thick, it is almost entirely solid but parts of it can flow very slowly.
3) Core - about half the diameter of the earth, it has a high proportion of the magnetic metals iron and nickel, it has liquid outer part and a solid inner part.
4) Atmosphere - surrounds the earth, most of the air is within 10km of the surface and most of the atmosphere is within 100km of the surface.
What are tectonic plates?
Tectonic plates are large pieces that cover the surface of the earth, which the crust and upper part of the mantle are cracked into.
What causes the tectonic plates to move?
How fast do tectonic plates move?
Convection currents within the mantle, caused by energy released through the decay of radioactive elements in the core.
They move few centimetres each year.
What two things happen when tectonic plates meet?
What does this cause?
1) Huge forces build up
2) Eventually the rocks give way changing shape or moving suddenly.
causing earthquakes, volcanic eruptions and mountains to form.
What does the primordial soup theory suggest about how three gases lead to the formation of life on earth?
The primordial soup theory suggests methane, water vapour and ammonia in the earth’s early atmosphere may have interacted with the presence of lightning, forming amino acids, that combined to make proteins from which life began.
What was the Miller-Urey experiment and what four gases were involved?
What was formed after a week?
An experiment that combined water vapour, ammonia, methane and hydrogen with electrical currents simulating lightning. After a week amino acids, the building blocks for proteins had formed.
Why is there now (lots of) oxygen in the atmosphere?
Plants and algae photosynthesised, which took CO2 from the atmosphere and released oxygen.
What is air?
How can it be split into different raw materials to be used in various industrial processes?
A mixture of gases with different boiling points.
Fractional distillation.
Approximately what is the diameter of the earth?
12,800km.
From which three sources do all of the raw materials and other resources that we depend on come from?
What does this mean about the resources?
The crust, the oceans and the atmosphere, this means the resources are limited.
Why can’t scientists predict when volcanic eruptions or earthquakes will occur?
As the don’t know enough about what is happening inside the earth.
Who put forward the idea of continental drift in 1915?
Why did other scientists not believe him at first?
Alfred Wegener
As he couldn’t explain how why the continents moved.
How long ago do scientists think the earth was formed?
What happened in the first billion years, and how did this affect the earth’s atmosphere?
4.5 billion years ago.
The earth’s surface was covered in volcanoes that released carbon dioxide, water vapour and nitrogen into the atmosphere.
What happened to the earth’s early atmosphere as the earth cooled?
What do some scientists believe was also in the atmosphere?
What happened to some of the carbon dioxide after the formation of the oceans?
Most of the water vapour condensed to form the oceans, so the earth’s early atmosphere was mainly carbon dioxide with some water vapour.
Some scientists believe that there was also nitrogen and possibly some methane and ammonia.
Some of the CO2 dissolved in the oceans.
What happened in the next two billion years of the earth’s history after the formation of the oceans?
What happened to the earth’s atmosphere as the number of plants increased?
Algae and plants evolved, they used carbon dioxide for photosynthesis and this released oxygen.
As the number of plants increased the amount of carbon dioxide in the atmosphere decreased and the amount of oxygen increased.
