During the Cretaceous period (145 to 66 million years ago), the world was very different! It was hotter, with more rainfall, and dinosaurs would have roamed the lush wetlands and forests that existed in the UK. Understanding these past warm worlds can help us better understand how our planet has changed over time, and even give us clues about how our climate may change in the future. Using the chemistry of minerals preserved in rocks from this time (like rocks from Sussex and Dorset), we can work out past rainfall patterns.