Processual archaeology came about in the 1960s and is an approach to archaeology; this means it is a way of doing archaeology that people choose to follow. Before the processual approach, another approach was ‘culture history’ which tried to only create histories for particular places. Culture history archaeologists started with a modern culture and traced its roots back as far as they would go. Culture history archaeologists dug units (square holes that are dug very carefully) that went very deep to find the oldest objects. Anywhere you dig, the youngest materials are close to the surface at the top and the oldest materials are at the bottom. Archaeologists learn about the history of a place by knowing what objects came in what order. This helps archaeologists understand the history of a place.