Developing a methodology is everything in a science. Once you have it, you can go on to extract information, facts—a narrative—from the natural world. To human scientists and non-scientists alike, the use of fossils as evidence of past events on Earth is now taken for granted, is indeed ingrained into popular culture. Dinosaurs, for instance, stalk through our TV screens and cinemas and shopping malls, as virtual animations and plastic models and soft fluffy toys and comic book covers. An Age of Dinosaurs is widely accepted as a long-vanished era, a world lost within deep time. Our extraterrestrial investigators will, at some stage in their studies, be ready to try to recreate for themselves the eras of long-vanished animal and plant dynasties on this planet, to construct a coherent history out of the scattered relics preserved in the Earth’s abundant strata. By coming to understand the Earth’s marvellously regulated heat-release engine, that drives the tectonic plates, they will appreciate the continuous creation and preservation of strata. By getting to grips with the more subtle puzzle of how sea level has risen and fallen, they will have some idea of the finer controls on the preservation of the stratal record. And, as they grapple with these problems, they would undoubtedly try to put the strata themselves into some sort of order, just as did our Victorian and pre-Victorian predecessors. These pioneering geologists, after all, could recognize a prehistory when they saw one, even as they were still far from divining the workings of the Earth machine that lay at the heart of the story they were pursuing. What kind of strata will be available for study, one hundred million years from now? Many, if not all, of the classic fossil localities that we treasure today will have gone forever, eroded into scattered grains of sedimentary detritus that will ultimately accumulate on sea floors of the future. The Solnhofen Limestone of Germany, that yielded the archaeopteryx, will likely be gone. The Burgess Shale of British Columbia, with its wonderful array of early soft-bodied organisms from the Cambrian Period, half a billion years back, is almost certain to disappear, perched as it is high up a fast-eroding mountainside.