" Sedimentary rocks are formed by the deposition and then cementation together of material which either eroded from older rocks or was produced biologically – sandstone, limestone and chalk are all examples. Igneous rocks such as granite, on the other hand, solidify from volcanic lava or magma still deep underground. And when sedimentary or igneous rocks are subjected to high temperatures and pressures – caught in the crunch of continental collisions or when magma intrudes up into them – they are transformed physically and chemically, becoming a metamorphic rock like marble or slate. "

― Lewis Dartnell , Origins: How Earth's History Shaped Human History