The Earth’s lithosphere is broken into large pieces called tectonic plates:
- oceanic plates occur under the oceans
- continental plates form the continents - land
Tectonic plates are less dense than the mantle, so they are found on top of it. The plates are moving constantly, at a rate of a few centimetres each year.
Volcanic activity
Where tectonic plates meet, the Earth’s crust becomes unstable as the plates push against each other, or ride under or over one another. Earthquakes and volcanic eruptions happen at the boundaries between plates.
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. It contains minerals needed by plants for healthy growth.
Comments
No comments have yet been made