June 29, 1999
Despite needing to send three team members back to Nairobi today, excavation continued at the three sites from yesterday, and we were able to open up the site B8-1.
Work at the Member 11 site, A11-10, is still pick'n'shovel, and will remain so probably into tomorrow. Because we are interested in following the sand layer into the hill, the deeper we follow it the more dirt there is on top to remove. As such, the volume of overburden involved will keep eight people busy for several days.
"Hand excavation" began at the Elephant Site. Hand excavation is the point where the overburden is removed, and a small layer of dirt, usually only 20 cm thick, remains above the main layer containing fossils and artifacts. As the name implies, all further excavation is now done with hand tools, with the excavators in the trench, where they can see fossils or artifacts if they are uncovered. This is also the point where shoes come off. We always work barefoot in the trenches, as many of the fossil and stone tool artifacts that we recover are exceedingly small and fragile.
The fossil and artifact hunting takes place by breaking though the hard dirt in layers only 5 cm thick, referred to by researchers here in East Africa as "spits." We watch for fossils that become visible on the excavation surface at all times, but sometimes, the fossils are not seen before they are piled up in the dirt. This is why we carefully sort through the debris looking for even the most minuscule fragments of bone or stone tool. And that's not the end of it. All of the debris that is cleared from the trench, after it has been looked over once by the crew, will be passed through a wire mesh screen (a process called sieving) to be absolutely sure nothing was missed.
At the end of the day, the trench is swept clean, our progress noted, and the fossils and artifacts placed in numbered bags with provenience information (exact position and elevation relative to a known point at the site) recorded. The "haul" from today isn't much in terms of amount, two people excavated for three hours in the afternoon and only found enough fossil bone to fill the very corner of a plastic bag. But these "microfaunal" remains can tell us a great deal about the environment of the Olorgesailie Basin in the time period just after the Elephant Site.