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1999 Field Season: Day 16
July 10, 1999
Today we started with a quick tour around some of the new sites that we surveyed yesterday. We needed to get to the antelope horn core site, in Member 9 just to the south of camp, to put "Butvar" on the fossil. Butvar Plus B98 is a preservative that forms a clear, strong layer over the surface of the fossil, preventing cracking and fragmentation. Another important aspect of Butvar is that with a little thinning agent, it is possible to completely remove it in the lab -- allowing us to restore the fossil to its original shape, and to study its original surface for things such as cut marks. For something as rare in the Olorgesailie Formation as a horn core, we wanted to get the Butvar on it as soon as possible, because when fossils are exposed, they can be weathered and destroyed very quickly. We hope that this site will contain more fossils within the outcrop, but we will have to wait and see.
After we visited this site we walked to another site in the same member that showed many fossils coming out of the outcrop. We decided to take the circuitous route; longer, more difficult terrain, but more chance at seeing things on the way. As is often the case here at Olorgesailie, we came across an area where a large number of stone tools and fossils were eroding out of a sandy portion of Member 9. We found a hippopotamus tooth, fish fossils, and a several stone tools in the erosional surface, including an Acheulean handaxe. The handaxe was about 20 cm in length and was quite impressive.
A hippopotamus tooth in diatomite sediments. A fish fossil was found a few feet away. The area appears to have been a river margin or possibly a channel with very still water. One can imagine this as an ideal spot for the early humans of Olorgesailie to gather food and drink water 700,000 years ago.
A hippopotamus tooth in diatomite sediments. A fish fossil was found a few feet away.
The area appears to have been a river margin or possibly a channel with very still water. One can imagine this as an ideal spot for the early humans of Olorgesailie to gather food and drink water 700,000 years ago.
Later on, we performed a second lift at Site B8-1 (which we are now going to have to rename "Site B7/8-1" because of the fossil finds in the Member 7 part of the site). During the lift we documented over forty new artifacts and fossils, and we were able to get all of the stone tools out. The bones, however, will have to wait until Monday or Tuesday. It is an extremely complicated site, with many of the bones overlapping, and all of the bones extremely fragile. Several of the bones have started to break into a fine dust when we attempt to clear the sediments away from the surface. We have sealed the surfaces with preservatives, so that we can restore them in the lab. We will need to proceed cautiously. After the lift was finished, we excavated the pedestals that the fossils and stones were on, and found three new stone tools.
In addition, we collected nodules of calcium carbonate from the paleosol layer, in the levels associated with the fossils and tools. These nodules will be sent to the Smithsonian for stable isotope analysis, which will tell us what the original vegetation was like when the soil was formed. If it is true that the large fossil animal we have found is a browsing rhinoceros, we would expect that the environment was comprised of thickets, bushes and trees, rather than grasses. This isotope study should help us test this idea.