If you travelled from the surface to the centre of the earth, describe the four major layers you would encounter in terms of their physical and chemical properties. Suggest how each layer influences (or may influence) our life on the earth"s surface. The earth, as we know it today, is thought to have formed approximately 4. 6 billion years ago. With the passing of hundreds of millions of years, the early earth was created by accretion. It continued to transform due to asteroidal barrage by a special kind of meteorite known as a. These chondrites in particular have much more of the element iron (fe) than typical mantle rocks and are very similar in composition to the sun (except for the absence of a few gaseous elements). They are known to have an age of roughly 4550 million years which is early in the evolution of the solar system.