The rocky crust averages 10-40km deep.
The mantle extends about halfway to its centre.
The core is made mostly from iron, solid at the centre and liquid above.
The rock cycle
The cycle of changes in rock material, caused by processes such as erosion, sedimentation, compression, and heating.
Estimating the age of an object such as a rock by measuring its radioactivity. Activity falls with time, in a way that is well understood.
All the continents used to be all joined together, forming a single giant continent called Pangaea.
There is a chain of mountains on the ocean floor, this is called the ocean ridge.
All seafloor moves away from the ocean ridge.
Therefore seafloor spreading could move continents.
The Earth's crust is made up from a dozen giant slabs of rock and many smaller ones. These are called techtonic plates.
Convection currents on the Earth's sold mantle carry the plates along.
Collisions between tectonic plates make mountains. This could happen in 3 ways?
- An ocean plate dives back down to Earth, volcanic peaks form at the surface.
- Pushing movement at destructive margins also cause rocks to buckle and fold, forming a mountain chain.
- Or an ocean closes completely, 2 continents collide slowely. The edges of the continents crumple together and pile up, making mountain chains.
These are caused by tectonic plates rubbing together.
These are simply a vent in the Earth's surface that erupts magma.
An explosion ofa single mass of material. This is an explanation about the start of the universe.