July 2, 2011
It feels great to be out of the noisy, diesel-filled traffic of Nairobi, back to the serene quiet of Olorgesailie. The nice thing about the quiet is that it’s easy to hear the sounds of the wild. Hyenas called last night as they prowled close to camp, and we woke this morning to the barking of baboons in the distance.
It’s Saturday, but it’s still a work day at Olorgesailie. It was a big day at BOK-2 where we carried out our first ‘lift’ of the season. When an artifact is found in situ, ‘in its original place,’ it is left there untouched. The excavators continue chipping the sediment around the artifact, forming a pedestal with the artifact on top. When enough artifacts accumulate on the excavation floor, we carefully label and store each and every artifact and fossil, no matter how small. As we do, we bring in special equipment to record the exact place of each piece. This process is called a lift. Today the crew lifted 135 stone artifacts from BOK-2.
We do the lift using a device called a transit. It operates by using two pieces. One piece, the transit itself, is a telescope attached to a computer. It’s placed on a tripod at a well-known (and precisely measured) position away from the site. The other piece is a prism attached to a pole. When an artifact is recovered, our transit experts, who are also members of the Kenya crew, place the prism at the location where the artifact was found. The transit reads information from the prism and records its geographic coordinates. With this technology, we are able to map the location of every artifact, within millimeters, on a single coordinate system!
Why is knowing the location of an artifact so important? Well, it helps us reconstruct how and why early humans left behind objects on the ground at any given spot. And this information helps us figure out what kinds of activities they practiced at that site. For example, today the crew recovered a number of artifacts that were clumped together. One piece appeared to be a stone core, while others were slender flakes. Could the flakes have been struck from a single core? If so, we may have uncovered the exact place where a toolmaker, more than 300,000 years ago, sat or squatted and made tools. We’ll have to analyze the artifacts later to find out.