Olorgesailie 1999 Field Season

Posted on 1999-07-05 by Rick Potts

July 5, 1999

Back to work today, after yesterday's R'n'R.We hit our target at Site 15 today; the paleosol layers that contained the elephant fossils we originally excavated. Just within this layer we began uncovering fossils very different from those above. While the microfauna are present in this layer as well, we are uncovering bones of large grazing animals, which is consistent with the switch from diatom-rich sediments to soils. We are going to excavate the layers following the contours of sediments from here on out, instead of sticking to arbitrary 5 cm thick spits. This is done to ensure that artifacts and fossils are properly assigned to the correct sedimentary environment, as well as to aid our attempts to reconstruct the landscape of the basin at this period.…

Posted on 1999-07-04 by Rick Potts

July 4, 1999

Today is a well deserved day off for the crew, as we have put in a long week of hard work. We thought that a report of the state of our excavations would be appropriate.At Site A11-10, overburden removal continues. We are expecting to hit the target layer soon. Although we expected the work to take a long time, due to the quantity dirt, progress was complicated this week by an unexpectedly hard layer in the sediments above our target sand. The diatomite layer was particularly well cemented; usually it will break readily. In fact, it bent one of our picks.

The Locality B excavation is nearing completion already, as the Member 8 layer has nearly been completely removed, and all of the fossils have been…

Posted on 1999-07-03 by Rick Potts

July 3, 1999

Today, the morning was spent attempting to resolve a particularly puzzling question of stratigraphy.In its simplest form, stratigraphy is a simple thing to resolve. A few commonsense rules govern the entire discipline, such as layers deposited on top are younger than those deposited on the bottom. If you think about it this makes sense; if it is on the bottom, it had to be there first, and, hence, is older. Stratigraphy in the field is usually straightforward; however, faults, erosion, subtle changes in the appearance of the rock layers, all contribute to complicated patterns that can be downright baffling.Take our Member 11 sand layer that we are attempting to reach at Site A11-10. It is full of fossils and artifacts. Both above it and below it, though,…

Posted on 1999-07-02 by Rick Potts

July 2, 1999

After breakfast, the team broke into two groups. One of them continued excavations at site A11-10, and the other carried out the first of four surveys of the basin planned for the early portion of the season --today' s survey is of Locality A.These surveys give us an idea of what the rate of erosion is from year to year, and how many artifacts and bones are being uncovered by erosion. While we come to camp each season with specific questions we want to answer and an idea of which sites to excavate in order to answer them, the discovery of new sites is very important. Often answers to your questions can be better found in places that you never expected. Or, as is more often the…

Posted on 1999-07-01 by Rick Potts

July 1, 1999

Today we had a visitor in camp, Denne Reed, who is a graduate student at the University of New York at Stony Brook. He is studying East African microfauna (the small animals in an ecosystem) through their remains in owl pellets. The fossil remains of microfauna found in the basin are important indicators of ancient environments. Small animals tend to breed and evolve faster than larger ones, and they also tend to be more sensitive to changes in the environment. Thus collection of the microfauna bones from our sites, such as Site 15, is of equal importance as the butchered elephant we found there.

The study of the modern microfauna in the Olorgesailie Basin is another important facet of our research here. Jennifer Clark recognized the…

Posted on 1999-06-30 by Rick Potts

June 30, 1999

Excavations continued today in the same four sites as yesterday. With all equipment and vehicles back in camp and functioning correctly (for the time being), we were full staffed and expect to make decent progress if we can continue in this manner. We thought that a brief primer of the geology of the Olorgesailie Basin would be helpful, especially as we are always referring to "Member 11' " or "the redbeds of Member 8."First off, the Olorgesailie Formation is a group of sediments that were deposited in the Olorgesailie Basin between one million and two hundred thousand years ago. The Formation is dominated by lake deposits with river channel and soils also preserved. Within the Olorgesailie Formation (hereon we will refer to it as "OF") there are…

Posted on 1999-06-29 by Rick Potts

June 29, 1999

Despite needing to send three team members back to Nairobi today, excavation continued at the three sites from yesterday, and we were able to open up the site B8-1.Work at the Member 11 site, A11-10, is still pick'n'shovel, and will remain so probably into tomorrow. Because we are interested in following the sand layer into the hill, the deeper we follow it the more dirt there is on top to remove. As such, the volume of overburden involved will keep eight people busy for several days.

"Hand excavation" began at the Elephant Site. Hand excavation is the point where the overburden is removed, and a small layer of dirt, usually only 20 cm thick, remains above the main layer containing fossils and artifacts. As the name…

Posted on 1999-06-28 by Rick Potts

June 28, 1999

Excavation began in earnest today, although not exactly according to plan...One of the important things in the field is to be flexible. Today, two guys on the team got sick, and some of our equipment broke and needed to be repaired in Nairobi, cutting the number of people available for work by four. So, we had to change our initial excavation plan.We decided to have three teams start work at three promising sites found last year, including one where digging had already begun in 1998. They are close to Kampi Safi, and the excavation boundaries had already been marked, so being shorthanded wasn't be too bad.This early stage of excavation mainly involves pick 'n' shovel work - moving large amounts of dirt and overburden. For instance, at…

Posted on 1999-06-27 by Rick Potts

June 27, 1999

Sunday is a day of rest in the camp, and although it really isn't necessary for us to rest after only being in the field for a day, it is good to get traditions started early. So the entire crew was given the day off. Many of the members decide to head into Magadi, the nearest town about 45 km to the south, for a day of fun. However, several of the research team members chose to use the day to prepare for tomorrow's dig.Those of us that remained decided to retrace our steps from yesterday's geology hike. Upon reaching a particualrly deep and dangerous gully we refer to as "Hell Hole," we tracked along the floor of the gully until we found a trench from last…

Posted on 1999-06-26 by Rick Potts

June 26, 1999

Today began bright and early with breakfast at 6:45 in the morning.Several things were in order for the day including a traverse of the basin to orient ourselves with the local stratigraphy. We spent the morning hiking across the basin from east to west passing through all of the major rock formations noting their properties, and commenting on which we would particularly focus upon in the upcoming field season. Starting with the oldest and moving up to the youngest, we walked through the thirteen distinct units of sediments present at Olorgesailie. Although the aim of the hike was to familiarize ourselves with the geological units, we couldn't help but find a few fossils which had eroded out of the surface. Unfortunately, we couldn't stay and look in…

Posted on 1999-06-25 by Rick Potts

June 25, 1999

Today was Day One of the expedition, and the majority of the day was spent getting us and our supplies from Nairobi to the site. The most important thing in any expedition like this is always the vehicles. Outfitting a group of twenty-seven for excavation work, and living in the bush for several weeks takes a lot of equipment, and without vehicles in good enough condition to make the trip, you don't go anywhere. When we awoke this morning, the lorry that we had arranged to take our supplies out to Olorgesailie was not in Nairobi, and our other vehicles were late in returning from the mechanics. On to plan B...

Eventually, things worked out. We were able to secure a lorry for transport,…