In Locality G, where we've discovered Middle Stone Age sites, there's one site in particular called the Green Clay Site. A portion of the site was excavated two years ago. Amanda and one of our crew members, Vincent Kimeu, have renewed the digging at this site, and they've already unearthed several more MSA flakes. What's intriguing about this site is that all the flakes seem to have been left there at once, not over a period of many years. They're all from the same kind of stone, they're clustered in a small area, and there's no evidence that water or other forces disturbed the site. Even the tiniest flakes are present in the green soil, which is the best sign that nothing was disturbed after early humans knapped stone at the site.

There's not much other than flakes at the site, but we can still get a lot of information about the behavior of the individual or individuals who visited this spot on the ancient landscape. Alison is an expert in analyzing stone tools, and she explained to Amanda the basics of how to examine the flakes that were found a couple years ago.

The first goal is to get an idea of the size of the flakes. This is done by sorting the flakes into groups, placing all the flakes shorter than 1 centimeter in one group, the flakes between 1 and 2 centimeters in another group, and so on. We know from experiments that when stone tools are made, most of the flakes are less than 1 centimeter, with fewer and fewer in the larger groups. By comparing the distribution of the flakes from the Green Clay Site to the size distribution found in the experiments, we can test for certain whether the site has been disturbed or not, since flowing water usually removes the smallest flakes.

The second part of the study is to look at four important attributes of all the flakes larger than 2 centimeters. The first attribute is the type of stone raw material. In an earlier dispatch, I mentioned how this can help us understand some things about the behavior of the toolmakers. The second attribute is the size of the flake. From basic measurements, we can see how carefully the humans made the tools. Did they make large, thick, crude flakes, or small, thin ones? Or large, thin ones? This gives us an idea how much they valued the raw material, or how skilled they were in making tools. The third attribute involves looking for how much the humans prepared the rock by careful chipping before striking off larger flakes. It's possible, for instance, to see on one side of each flake how many previous flakes were chipped off. By counting the scars, we can measure the amount of preparation. The final attribute involves identifying the kind of technology used in making the flakes. Is there a pattern in the shape of the flakes or in the number of scars on the one side? Can we find a consistent pattern of blade making, which are flakes twice as long as they are wide?

With these attributes noted for each flake, Amanda hopes to get a clearer picture of the skill involved in making tools, and possibly even the degree of thought used by these Middle Stone Age toolmakers.