Bright and shiny, we were driven out to the Olorgesailie Site Museum, in a desert area about two hours away from Nairobi. It is an archaeological dig that has possibly uncovered the highest known density/quantity of stone tools anywhere in the world. Mostly hand-axes, which were used for skinning animals, for cutting meat, and for stripping flesh from bone (each activity required a different type of surface).
Excavation can only take place June-to-September. This year's primary digger from the Smithsonian just arrived this week. The soil here is very, very fine, which has allowed nature to remove dirt and partially-/fully-expose a number of artifacts, but it turns out that you can't sift mud. Research can only take place during the dry months of the year.
After a long period of volcanic activity, the area was intermittently a lake-bed, which left many layers of sediment. The area appears to have been a factory of sorts for making stone tools - effectively any volcanic stone embedded in the sediment above the lower igneous layer was brought in by hominids, and are pretty easily identifiable as having been modified or chipped. The lake is long gone, and there have been some fault-line shifts which have exposed some of the older layers. Erosion has done a good job at removing some of the surface layers.
In 1919, the site was discovered, with a large number of hand-axes and other stone tools plain view on the surface. It turns out that if nothing is exposed, no one knows where to dig. Here, there was a lot exposed. Not much happened afterward until the Leakys came in the 1940s. The excavation has uncovered thousands of tools. Since, a number of sites have been dug out, but for a place this abundant in artifacts, it is surprising how sporadic the activity at the site has been (picture below). Most of the artifacts that have been uncovered are at the Nairobi National Museum, but some was intentionally left at the original site for viewing. The density is incredible.
Because the layering from the historical lake-bed is so well-defined, dating the tools has been straight-forward. The tools range in time from 500,000 to 1M years ago.
We were able to walk the pits with a guide, who explained what was discovered at each site, and the process of excavating the area (arduous, slow, methodical, work in a hot/dusty area). With only the small fraction of tools left at each dig, it was mind-blowing at how productive each dig was. When I asked the guide if every igneous rock above the volcanic bed was a tool, he said "Pretty much," and then flicked a stone in the path a few yards from one of the digs, and said "That one is a chip from a hand-ax" and flipped another and said "and this one is a whole ax."
A very cool place. If you find yourself in Nairobi, and you have a few hours, I highly recommend the visit.
Afterward, we went to the Nairobi National Museum for a walking tour of the grounds. This was also interesting and engaging (sculpture gardens, gardens, a peace-path). The highlight, though, was the excavation site.
Pictures:
The museum is a working-site. This is the entry-sign.
History of the digs in the area. Considering the area's importance, the number of 20-year gaps in research is astonishing.
Description of the research at the site.
Almost all of the hand-axes found in the region are composed of trachyte or basanite. If these stones were found above the volcanic layers, they were brought in by hominids. They would either be full hand-axes, or flakes from the manufacture of hand-axes.
A panorama of the area.
The sign describing the first dig-site we viewed.
Most of what they dug up in this pit was taken to the National Museum. A small amount of the remainder was left for viewing. This photo is of the majority of the area. The dig was maybe 10 feet deep. Every stone here is either a chip from a hand-ax, a hand-ax, or a chipping stone. The quantity within this one excavation site is amazing.
Sign at the 3rd site.
The round rock is a 'chipping stone' for cutting flakes off a rock while turning it into a hand-ax.
The 'cat-walk' area, the original site where stone tools were found, mostly on the ground surface (no digging required).
Many of the stones here show obvious signs of manufacture/chipping. I am grateful, but cannot quite believe that they leave this open to the public and to the elements.
Our second-to-last of many viewed sites. In addition to stone tools, fossils were also found.
The fossil at bottom is a humerus of an extinct species of elephant (elephus recki). The comparison bone above is the same bone of a modern elephant. The fossil was found in the same bed as a number of stone tools, but there is no direct evidence (cutting marks on the bone) that the elephant was killed/carved by hominids.
After the archaeology tour, we returned to Nairobi.
An outdoor sculpture exhibited at the Nairobi National Museum.
No comments:
Post a Comment