The Earth's Crust & Atmosphere Flashcards
What is the structure of the Earth?
Inner core, Outer core, Mantle and Crust
What is significant about the crust and mantle?
The crust and upper mantle are cracked into large pieces called tectonic plates. These plates move slowly, but can cause earthquakes and volcanoes where they meet.
What are the properties of the layers of the Earth?
- Crust (relatively thin and rocky)
- Mantle (has the properties of a solid, but can flow very slowly)
- Core (made from liquid nickel and iron)
How does the process ‘continental drift’ work?
Tectonic plates are constantly moving at a few centimetres each year. Although this doesn’t sound like very much, over millions of years the movement allows whole continents to shift thousands of kilometres apart. This process is called continental drift.
How do tectonic plates move?
The plates move because of convection currents in the Earth’s mantle. These are driven by the heat produced by the natural decay of radioactive elements in the Earth.
What happens when tectonic plates meet?
Where tectonic plates meet, the Earth’s crust becomes unstable as the plates push against each other, or ride under or over each other. Earthquakes and volcanic eruptions happen at the boundaries between plates, and the crust may ‘crumple’ to form mountain ranges.
What are the two types of tectonic plates?
Oceanic plates occur under the oceans.
Continental plates form the land.
Oceanic plates are denser than continental plates. They are pushed down underneath continental plates if they meet.
Describe earthquakes.
The movement of tectonic plates can be sudden and disastrous, causing an earthquake. It is difficult to predict exactly when and where an earthquake will happen, even when a lot of data is available.
Describe volcanic eruptions.
Magma (molten rock) is less dense than the crust. It can rise to the surface through weaknesses in the crust, forming a volcano.
Geologists study volcanoes to try to predict future eruptions. Volcanoes can be very destructive, but some people choose to live near them because volcanic soil is very fertile.
