Our Solar System: A Creation of Chaos - Rob Irion

Near the birth of our solar system, the planets still had a few things to work out. And approximately 3.8 billion years ago, Neptune and Uranus were forced into the path of a comet belt, which sent space shrapnel everywhere, including at Earth. Rob Irion, author of "It All Began in Chaos," in the July, 2013 issue of National Geographic magazine, describes how the Earth absorbed many large chunks of asteroids and other planets that had been knocked loose and over time, included these rocks into its crust.