An excerpt from an OUPblog article published on 17th March 2017, created with information from The Earth: A Very Short Introduction.
"We now know that the Earth is many billions of years old, and that it has changed an unimaginably number of times over millennia. But before the mid-eighteenth century we believed that the Earth was only a few thousand years old.
Then scientists (who we now call geologists) began to explore the Earth’s layers and found fossils, suggesting it was much, much older than they first thought. In the nineteenth century scientists started to study seismology, and so our knowledge of the deep Earth took shape. We also began to look up, exploring the skies, the atmosphere, and eventually we made it in to space itself.
But what are these layers made up of? How many are there and what is their impact on the whole...?"
Discover more: Read the rest of the article on the OUPblog.