One of the most ubiquitous artifact on the planet is debitage, tiny and not-so-tiny pieces of broken stone that are the results of a stone tool-making episode by one of our ancestors at some point during the past 2.6 million years or so. Broken stone can occur naturally, of course, and some of our primate cousins such as chimpanzees also do some stone breaking in the course of cracking nuts open, but only humans and our ancestors have produced recognizably patterned rock breaking, called somewhat more elegantly, systematic flaking routines.
The presence of sophisticated stone tools--projectile points, awls, adzes, and the like--is accepted as proof of human habitation to even the most skeptical of archaeologists. But not every site has formal tools. Luckily, in the broken rocks and fragments of tool working--the debitage--lie a wealth of information about past human behaviors. Different flaking patterns and tools are used as hallmarks of different cultural groups and periods, but in general, signs of systematic flaking are the first step in lithic analysis. Is this pile of rocks the result of cultural or natural forces?
By the way: natural broken rock which on the surface appears to have been man-made but does not have evidence of systematic flaking is known as geofacts.
Accepted Evidence of Systematic Flaking
Cores exhibiting logical reduction strategies. In lithic analysis, a 'core' is a piece of rock that can be thought of as the starting place from which stone working began. In plain language, rock breaking intended to create stone tools works like this: a person picks up a chunk of rock (called a 'core') and begins to bang on it with another rock (called a 'hammerstone'). The ostensible reason for this activity is to "reduce the core", break it into usable pieces of stone. If you're careful, and you have the right kind of stone, you can get thin, sharp flakes of stone that you can then use to cut things or scrape things. Doing this in a logical manner means directing the rock banging so that you optimize the number of flakes you get off the core. And that, my friends, is human behavior at its finest.Cores with more than five flake scars. A flake scar is the dent left behind in the core after a flake has been removed. More than five is considered more than can be accounted for by natural accident.
Intentional platform creation. For truly efficient flake removal, you need to prepare what lithic specialists call a platform--essentially you create a flat place on the core, and then bang on the top edge to pop off the flakes. Again, a human trait.
Bifacial reduction. Lithic analysts have developed a precise set of descriptive characteristics for the stepwise creation of bladed tools, called 'bifacial reduction'. Evidence for the various stages of this process includes purposeful, directed flaking on several sides of an artifact.
Retouch. Retouch is the term used for the evidence of refined flaking on the edges of an artifact, assisted with a billet of bone or antler pressed against the stone rather than hammering it, in a method called 'pressure flaking'.
For More Information
See the Stone Tools in Archaeology page for more information about stone tools. Also, several excellent articles are listed in the Lithic Analysis section, and see Tony Baker's site for some detailed descriptions of debitage and stone tool working analysis.This glossary entry is part of the Dictionary of Archaeology.
