"Earth’s main layers are the thin crust 4 – 50 miles (6.4 – 80.5 km)
deep, a mantle extending 1,800 miles (2,900 km) deep and the iron core.
But there are subdivisions."
Source: http://www.sci-news.com/geology/science-new-layer-earths-mantle-02631.html
Fascinating stuff!
Maddy
