July 3, 2011
Today is Sunday, usually a day of relaxation and catching up with writing or other tasks. Alison and Katie, though, decided to seize an opportunity to go on an excursion with Dr. Stanley Ambrose. Stan is an archeologist and geochemist at the University of Illinois, where he works on the Urbana-Champaign campus. He’s also a well-known figure in East African research.
One of Stan’s projects focuses on southern, central, and western Kenya, where he is seeking to find out the sources of obsidian, a dark, glass-like, and very sharp rock used by ancient toolmakers. He was accompanied by an archaeology graduate student from Washington University in St. Louis, Missouri.
A large percentage of artifacts from our project’s BOK sites are made from obsidian. Obsidian, which originally is erupted from volcanoes, is called an ‘exotic material’ because it’s not found in the immediate vicinity of Olorgesailie. Instead, it had to be carried in by early humans from many kilometers away. So, we have something of an ‘obsidian hunt’ going on! Where exactly did early toolmakers get the obsidian?
Stan’s work in understanding the sources of obsidian is important in tracing the routes where prehistoric groups moved or even traded with other groups. So far it seems the closest obsidian source to the BOK sites was almost 20 km away. But it’s possible that the obsidian in our digs comes from several different places. That’s exactly what Stan and our team intends to find out.
Of course, finding obsidian sources requires local knowledge. So Stan and the group first drove to a nearby town where they picked up the local sub-chief, Samuel, and his friend Mathias. Samuel and Mathias are both Maasai, the dominant ethnic group in the area. To make navigation easier, Stan spent the entire day communicating with Samuel and Mathias in Swahili. After several decades of research in Kenya, Stan’s Swahili is very good. Katie is also proficient, and we encourage anyone who joins our research team to learn at least the basics.
Based on the later retelling by Katie and Alison, the group then set off for Lake Kwenia, to the southeast of Mt. Olorgesailie. Well, everyone calls it Lake Kwenia, but most of the year it’s a plain of tall grass, which then turns swampy during the rainy seasons. (There are two rainy seasons each year in the Kenya Rift Valley). The moisture in the ground expands into a lake only during very rainy periods, when it rains several years in a row. Right now, Lake Kwenia is dry ground. They drove through the bush for another hour before pulling over under the shade of a large acacia tree for a lunch of sandwiches and fruit, greeting Maasai as they passed by.
In the afternoon they drove across the plains to Oldonyo Nyoki, the name of an isolated mountain – what’s left of a volcano that was active more than 600,000 years ago. It’s the place nearest Olorgesailie that’s also best known for obsidian. At Nyoki the intrepid group trekked along the foot of the mountain and examined rocks. Stan thought the obsidian looked interesting and collected some samples in bags for later analysis. It’s the fact that obsidian rocks from different places have different combinations of chemical elements in them that we can eventually tell where the obsidian tools at Olorgesailie come from. There’s a lot of chemical analysis ahead using scientific instruments, but Stan is determined to get there!
Soon after their trek, they had to hop back in the Stan’s vehicle to head back to camp. On the way home they raced the fading sun, and spotted several wildlife: ostriches, Grant’s gazelle, African hare, and even a king cobra slithering across the road!
Altogether, it was great excursion!