Earth's Mantle
The ground under our feet may feel solid but the truth is we stand on a thin solid layer of rocks that is the earth's crust and beneath that is the Mantle.The Mantle is the thickest layer inside the earth,it's about 2900 km thick, all though the Mantle is largly hidden from our view,we can see it in places where cracks open up allowing the melted rocks to escape. These are volcanos. When the molten rocks escape throught a volcano the lava will cool and turn solid, to form a family of rocks called igneous rocks.The mantle is divided into two parts the Upper Mantle and the Lower Mantle.