Think of it as Layers of Sediment

This was taken today at a special ‘In the Shadow of the Dinosaurs’ exhibit at the Musee Nationale de Histoire Naturelle. The accompanying text: Layers of sediment pile up as they are formed, much like newspapers are stacked, with the oldest on bottom and the most recent on top. By reading them from the bottom up, we can cover millions of years of geologic time.
And indeed, we can. All this talk about mass extinction is making me thirsty.