Deep time history is a way of looking at the Earth's history that looks at the very large time frames. Instead of looking at years or decades, we look at Millions and even Billions of years. We look at the changes that have taken place over long periods of time - like how continents have moved and the climate has changed - to help us understand how the Earth and all of the living things on it have changed over time. For example, studies of deep time history can show us how long ago animals and plants that are now extinct were living on the planet.