C2a - The structure of the earth
The earth has a layered structure. It is (from out to in):
- inner core
It's is difficult to get information about the centre of the earth because the deepest mines have only dug a few kilometres into the earth's crust
Scientists rely on studying SEISMIC WAVES to understand the structure of the earth.
Movement of the Lithosphere
the LITHOSPHERE is made of the crust and the top of the mantle
^it is 'cracked' into large interlocking pieces called TECTONIC PLATES:
- Oceanic plates (under oceans)
- Continental plates (form continents)
The plates sit on top of the mantle because they are LESS DENSE than the mantle
The plates move about 2.5cm a year
^cause earthquakes and volcanoes
What causes the plates to move?
Just below the crust, the mantle is quite cold and rigid, and gets hotter and less rigid the deeper you go, which means it can flow.
There are convection currents in the mantle, which causes magma to rise to the surface at plate boundaries
When the molten rock (magma) solidifies, it forms igneous rock.
This movement of the magma causes the plates to move…