Olorgesailie 1999 Field Season

Posted on 1999-07-19 by Rick Potts

A Final Word From Our Team

We have really enjoyed the opportunity to bring a bit of our research at Olorgesailie to you through this web site. While the dispatches for this field season stop today, excavations are going to continue through the last week of August. By the end of the season, we will have completed the excavations at the sites you have become familiar with (extending Site B7/8-1, hoping to solve the interesting puzzles it presents, tracing the interesting stone cobbles at the Elephant Site, and mapping out the relationship of early human behavior in the A11 sites). We will also continue our stratigraphic study of the basin, and we plan to put in several more excavations, particularly around sites A11-10 and 20, to further our…

Posted on 1999-07-19 by Rick Potts

July 19, 1999

Several teams of three were assigned to dig geologic trenches today as part of our continuing effort to understand in detail the structural and sedimentary history of the Olorgesailie Basin. While our excavation trenches tend not to be very deep (we try to dig through the least amount of overburden as possible), geologic trenches often climb the entire hillside, and we try to pick the tallest slopes that will crosscut the most amount of sediment. Also, while excavation trench sizes (length and width) are determined by the distribution of fossils and artifacts within the site (the Elephant Site, with its nine extensions, is now about a hundred square meters), geologic trenches are usually only a meter to a meter and a half wide. Thus they resemble knife…

Posted on 1999-07-18 by Rick Potts

July 18, 1999

Today we decided that a trip to Magadi was in order; every so often it is nice to get out of camp and take an afternoon trip. Magadi is a town roughly 45 km to the south and west of our site. It is located on the shores of Lake Magadi, a "soda lake," or lake that is highly alkaline (the opposite of acidic). People have long taken advantage of this natural resource, and there is a factory in Magadi that produces soda ash (Na2CO3). Soda, as it is generally called, is used as an ingredient in many things, such as the manufacture of glass, soap and other cleansers, and also is used by chemical industries including pharmaceuticals. Other products of the factory include sodium bicarbonate (baking…

Posted on 1999-07-17 by Rick Potts

July 17, 1999

We have temporarily closed down site B7/8-1, pending investigation by our stratigraphy team.Continued excavation at Site A11-10 is showing that the site is as productive as we had hoped. The crew is digging through the "C" sand layer, carefully removing this layer to the surface of the layer underneath. As each layer was formed by an event in the past, it is important at this site to excavate stratigraphically, that is, following the sediments. This way, we can associate each artifact and fossil with a particular fine layer within our target sand layer. After we are through excavating layer C, we will continue with layer B underneath.

The artifacts recovered so far are occurring in clustered areas of high density, separated by a less dense scatter…

Posted on 1999-07-16 by Rick Potts

July 16, 1999

Site B7/8-1 certainly looks like a place where early humans butchered a large animal, probably a rhinoceros. We have about 25 bones from the animal, including some of the ribs and vertebrae arranged in roughly the correct anatomical order. This means that the excavations are right where the animal died (as a rhinoceros is too large to carry as one big mass, and transporting it in pieces would disturb the anatomical order). And we have sharp stone tools indicating the presence of humans at the site. All of the bones and tools are buried in a soil that is about 780,000 years old. Soils are indicative of stable land surfaces, so it wasn't a river, and the bones and tools were not simply washed together…

Posted on 1999-07-15 by Rick Potts

July 15, 1999

This morning, we decided to take advantage of the continuing lack of dust from the rain of two days ago. The fossils on the surface of the ground were much more easily visible than the last time we did a survey on July 2. Today's survey concentrated on the gully that emanates from Hell Hole. This is an area of the basin that hasn't been surveyed in several years (due to the very rough terrain). A visitor to our site, Jillani Galla, from the Paleontology Department of the National Museums of Kenya, helped us out, giving us an extra set of eyes to scan the ground. We were able to find some interesting stone tools, including a beautiful Achulean handaxe, and a small partial cranium (part…

Posted on 1999-07-14 by Rick Potts

July 14, 1999

At Site B7/8-1, our improvised plastic coverings held up, and we were able to extract the last of the bones from the second lift without any problems. We decided to take the excavation down one more spit (the ninth at this site) in order to ensure that we had indeed unearthed all artifacts and fossils. Pretty quickly after beginning work on this spit, we uncovered another bone; what appears to be another of the ribs. However, the rib appears isolated, and we haven't hit many stone tools as yet in this layer, so we think that this spit may be the last one for this site. We will need to bring the transit team back out for a final lift of the last few stone tools and…

Posted on 1999-07-13 by Rick Potts

July 13, 1999

We lifted artifacts and fossils today at Site 15 (the Elephant Site). Roughly thirty stone tools and bones were taken from the site. The fragmented skeleton of an antelope was identified, although an exact identification of the species will have to wait until we get back to the lab in Nairobi. Pieces of the skull and several of the long bones (legs, ribs, etc.,) and teeth were found. This was from the paleosol layer directly above that in which the fossil elephant was found.

At Site B7/8-1 we began plastering the bones that were too fragile to lift last Saturday. We were able to get most of the bones in casts and extracted. However, just as we finished putting the plaster on the cluster of vertebrae…

Posted on 1999-07-12 by Rick Potts

July 12, 1999

Today, we closed down the A11-20 site, after finishing the last spit. In its place two new sites were opened, A11-15 and A11-30. A11-15 is a new site that is roughly halfway between the A11-20 site that we just completed and A11-10 (the site that is requiring the immense amount of digging). A11-30 is an old excavation that was covered over last season when it was not completed.

     You may notice that we are excavating a lot of sites beginning with "A11" (you will recall that A11 stands for: Locality A, Member 11)This is a function of our landscape approach to the archaeology of the Olorgesailie Basin.When Louis Leakey began excavations at Olorgesailie in 1947, the objective was to uncover dense concentrations of…

Posted on 1999-07-11 by Rick Potts

July 11, 1999

Sundays are liberty for the crew, giving people the opportunity to go into town, write letters to loved ones back home or to simply sleep in a bit later than normal. For me, it was a day of preparing notes for two talks to be given at a meeting of the International Union of Quaternary Research (INQUA), in South Africa during the first week of August.The talks center around the research that has been going on at Olorgesailie since 1985, dealing with early humans and the interaction of early humans with the environment. One talk in particular centers on a new model for early human evolution called "Variability Selection" (VS). During the course of human evolution, the environment became increasingly variable, that is, it changed more and…

Posted on 1999-07-10 by Rick Potts

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…

Posted on 1999-07-09 by Rick Potts

July 9, 1999

There was a lot of activity by our various crews today around the basin. To begin with, the excavations at site B8-1 continued. As we dig deeper into the paleosol we are realizing that there is a lot more to this fossil site than we had thought, even yesterday. We have now uncovered more than twenty new stone tools. Most of them are flakes; that is, they are small pieces of stone that have been broken off of a larger stone, or core. One core has also been uncovered. What is exciting about this site is that the stone tools that we thought may have been associated with the bones before, are now being found in amongst the bones. We are now pretty sure that this is…

Posted on 1999-07-08 by Rick Potts

July 8, 1999

B8-1 became a much more interesting site today.Today we discovered that what we had thought was a series of jumbled bones sitting on the top of a soil of Member 7 (and covered by the river sediments of Member 8), was actually something quite different. At first, the bones appeared to be out of their natural position, and a few stone tools were found around them. Maybe a river could have deposited the assemblage there. We knew that the site would be interesting to document, but if the bones and stone tools were not originally together, the site wouldn't yield much behavioral information.We were preparing to lift the large pieces of fossil and decided to start with the large scapula. While getting ready to put plaster around…

Posted on 1999-07-07 by Rick Potts

July 7, 1999

Today, we began the lift at site B8-1, in which we removed the fossils and stone tools found.The lift begins by setting the transit up on a datum point and shooting back to another datum to make sure that the instrument is reading correctly. Down in the trench, while the transit is being oriented, the site leaders go through all of the artifacts and fossils, deciding in what order to gently lift them from the sediment. Also, they must appraise the condition of the fossils and determine whether or not they can be lifted as is, or if they need to be encased in a protective sleeve of plaster. This preparative portion of the lift is much like establishing a game plan.

Each person in the…

Posted on 1999-07-06 by Rick Potts

July 6, 1999

In Locality B today, we set up the datum points that will allow us to locate our latest fossil discoveries on our mapping system for the entire Olorgesailie area. We would have liked to create a single datum point to service the entire locality, but the rugged terrain and the weird geometry of our site B8-1 required three datums (B1,2 and 3) in order to see the site. The first datum links us to our coordinate grid, and is on top of a hill. The second one sees down the hill, and from the third point we can see the site around the bend in the river bed. Our datum points are concrete markers with a nail sunk into the center. When we set up our transits…