ABSTRACT
Archaeology is a science that probes the depths of the human past. But archaeology is not time travel: Archaeologists and the objects they study remain firmly anchored in the present. The essential trick of archaeology is how to use static objects that exist in the present to infer the dynamics of past societies. Archaeological survey must take into consideration geological factors that affect the preservation and visibility of sites. Often, sites are so deeply buried that no artifacts are visible on the surface. Early prehistoric sites in East Africa, such as Olduvai Gorge, are examples of this kind of deeply buried context. At Olduvai Gorge, sites can be discovered only where natural erosion has cut through the accumulation of sediments, exposing fossil- and artifact-bearing levels. Most surveys involve little more than a team of archaeologists walking slowly, with heads bent, across the landscape. The problems faced in surface collection vary tremendously according to the context of the research.
