why do we have so many layers in in the earth

Question: why do we have so many layers in in the earth
- Keywords:
  core,
  earth,
  geology,
  layer,
  planet
Asked by ibak to Jon on 16 Mar 2012.
- Jon Benton answered on 16 Mar 2012:
  
  When the Earth was formed millions of years ago the heavier elements all gathered at the centre – the big iron core. This is because the heavier the element the greater gravity. As there are loads of different elements all of different masses they came to form the earth at different speeds. This results in a layering effect on the earth starting with the heavy centre moving to lighter elements on the surface.

Question: why do we have so many layers in in the earth