Each day, our group of six scientists and 15 Afar split into two big groups after breakfast for the day’s work. The group working with Bill usually drives to a locality of the project where fossil hominids have been found in the past to survey for new finds. Survey requires all group members to fan out over the landscape and keep their eyes peeled for anything that just looks “different.”
It’s hard to describe what a good surveyor is thinking, but fossil bone is usually a different color from non-fossil rocks, and there are obviously some shapes that we look for (teeth, in particular). Some objects, especially root casts, are frustratingly disguised as bone and can really fool the hopeful hunter.
We find all kinds of fossils at Hadar—fish and bovid are most common, but we’ve found parts of a fossilized pig, hyena, and monkey this trip, too. Once something interesting (like a hominid mandible!) is found, the team all gathers and switches to excavation mode. We collect the sediment around the original find and sift it to make sure we find even the smallest fragments. Sifting is extremely dusty work, but it’s satisfying to see the pile of searched sediment grow.
Erella’s team drives out to AL 666, a site in the most recent sediments at Hadar, to excavate each day. This excavation is very regulated, unlike the random walking required for survey. Each excavator is assigned a square, one meter on a side, and levels it approximately 10 cm at a time. All the removed dirt is sifted and searched for stone tools and small pebbles that might indicate the presence of hominins on the ancient landscape. The position and orientation of each artifact can be recorded using a Total Station, a very useful machine that determines 3D coordinates of the objects using lasers. The coordinates of the lithics are then mapped in programs like ArcGIS to examine density and depositional patterns. Erella is also collecting soil samples from the site to take back to Israel, which will be analyzed to determine their chemical makeup. Such information is useful for reconstructing environmental and depositional change over time at the site.
Despite being a short field season with only a small group of workers, it has been a productive and successful trip! We will pack up to head back to Addis in a few days, drop off the new specimens at the museum in Addis Ababa, and head home. Plans are already well underway for the next trip back to Hadar, scheduled for the spring of 2012.
Editor’s note: Thank you to Benjamin Reed for these images from the Hadar field season 2009.