June 26, 2004
Late yesterday afternoon, Dr. Bernie Owen arrived, a British-born geologist who lives and teaches in Hong Kong. His special area is the study of lake diatoms, which are microscopic plants that live in freshwater lakes. He mainly studies ancient diatoms, which can tell us a lot about the characteristics of the lake that existed at Olorgesailie between about 1.2 million and 500,000 years ago. Fresh water was one thing that certainly attracted early humans to this area so long ago. Even though the landscape today is dry and dusty, the thick layers of white sediment are filled with diatoms and tell us that there was once a big source of water here. In fact, these layers are known as diatomites. We've been arranging for a couple years for Bernie to join us to take samples of the white sediment, identify the diatoms, and then determine when and how much the lake changed in its characteristics. This will tell us a lot, potentially, about climate change in the past - certainly one of the challenges early humans and other forms of life had to face.
While the crew began work at the hominin discovery site and Site 15, and also another new excavation site, Bernie and I walked around to the many promising patches of diatomite sediment. About 25 years ago, he visited Olorgesailie and published an initial paper about the diatoms of Olorgesailie and how they changed over time. A couple years ago, we sent Bernie some other samples. Since different species of diatoms live under different lake conditions, he can identify the species in our samples and then build a picture of how Lake Olorgesailie spread, contracted, became deeper, shallower, more alkaline or fresher at various points in time. It's been great talking with him, and with some more work, we'll be able to tell a lot about the lake that attracted early humans to the Olorgesailie region. He'll be with us about a week. So I'll get him to tell us more about what he's finding another day.