Wikipedia Wrote:In early stages of Earth's formation about 4.5 billion (4.5 × 109) years ago, melting would have caused denser substances to sink toward the center in a process called planetary differentiation (see also the iron catastrophe), while less-dense materials would have migrated to the crust. The core is thus believed to largely be composed of iron (80%).Structure of the Earth
They must have 'sent down' that iron with a lot of force to send it all the way to the planet's core. Either that, or iron is a large part of what the planet earth is made up of to begin with. Which idea sounds more scientifical?
