Important sciences conceptualise their practice as an exploration into a hidden past, removing surfaces downwardly, in response to their prior vertical accumulation. Common initially to the geosciences, this view has been adopted through the twentieth century by the humanities and social sciences. Drawing on ethnographic work with scientists who excavate the past with an analysis of the visual language of disciplines that adopt a stratigraphic view of time – including anthropology, history, psychology, philosophy and neurology – this chapter traces key debates in the history of science, showing how knowledge came to be enclosed by surfaces, providing a frame for discussion amongst rival approaches.