Day 19 (July 14, 2011): Excavation 101
Although I’m at Lake Victoria, I’ll be getting nearly daily updates by email from the research team at Olorgesailie. We’re just getting started with our studies on the Homa Peninsula, so for the next couple days, I’ll give you the updates from Olorgesailie.
The grid is labeled in a simple manner, much like an excel spreadsheet. At BOK-2, the columns are labeled as numbers (e.g. 1-13) and the rows as letters (e.g. F-J). This system makes it very easy for us to communicate about certain findings. For example, “F7 has been a prolific square this season, but we’ve found hardly anything in H11.”
The above system organizes the excavation across the site (horizontally). But how do we distinguish the artifacts at different vertical locations, that is, in terms of depth within the sediment? For this we use a system of layers, which we call spits. As the crew digs their assigned square, they dig each square one spit at a time. A spit is only 5cm thick, and the spits are numbered as they go down. So, the closest spit to the surface is 1, whereas a meter deep would be spit 20. Therefore when an artifact is lifted it could be called “Square I6, spit 25.” This system of thin layers allows us to follow the changes in the sediment as we dig deeper at the site. Keeping track of the spits is useful for determining different points in time when artifacts were left or deposited at the site, since deeper artifacts are usually older. And we might also be able to recognizes different environments as you dig into deeper spits and older periods of artifacts.