Notes on the Harpoons from GaJi12
Four harpoon types from GaJi12 that correspond roughly to four periods in the use of Koobi Fora Spit. The early period is characterized by uniserial harpoons most of which have a small mini-barb just behind the tip, though a few lack this characteristic. In the late period, harpoons with mini-barbed tips continue and biserial harpoons appear or become common enough to be reflected in the small assemblage that has been recovered. Still later, possibly from the early Iron Age occupation, there is a crude, flat, biserial specimen. Then, probably later, an iron harpoon of the sort still used on Turkana.
None of the harpoons from GaJi12 were found in situ, so interpreting them in the context of their associated assemblages is fraught with the usual difficulties. However, one thing is certain. These assemblages and their harpoons were deposited when Koobi Fora Spit was emergent - during periods when the level of Lake Turkana was similar to its 1980 to 1995 stands. This is our first look at the low water prehistory of harpoon technology in the Turkana Basin. This shows that there is low water archaeology in the basin - that our record of Holocene prehistory will not be complete until its low water components have been explicated.
The white scale bars seen in the images below are all 1 cm. long.
Close to the cut bank, where erosion is most extensive, there is a poorly sorted, thin lag of coarser materials collapsed from sediments spanning a period from the modern well into the LSA horizons. Only grindstones, hammer stones and flaked tools survive from the Iron Age horizon. These have been conflated with stone tools and occasional harpoon fragments from earlier horizons. Only larger, highly mineralized specimens have survived, often quite fragmented, like the one photographed here as it was found.
In addition, specimens from this lag typically exhibit dendritic weathering, with a white deposit filling what appears to be a shallowly etched surface. This pattern of weathering is absent from specimens collected further out on the beach - specimens which are also typically less mineralized and have been exposed for a shorter period of time.
Also note that this specimen lacks the small mini-barb just in back of the harpoon tip, a feature that is ubiquitous in more recent assemblages from the beach.
Fifty meters and more out from the cut bank, where the lag caps somewhat more recent sediments, harpoons were better preserved and somewhat less mineralized. There was no dendritic etching and the black mineralization did not penetrate much beyond the surface, leaving the bone a dark, discolored brown beneath.
From 1994 to 1996, the deflation surface was working its way through the later harpoon horizons containing both uniserial and biserial varieties. Here we have fairly well-mineralized specimen peeking out from under a small slab of sandstone. You can see a 3 cm. high erosion scarp on its left side and wind erosion along this mini escarpment has undermined the slab back beyond it's center of gravity, causing it to pitch forward. When we lifted the slab, we found that the harpoon was no longer in situ. We found it about 3 mm. too late in the erosion process - the closest we came to finding a harpoon in place.
This is a typical uniserial harpoon in the early stages of mineralization. It shows the mini barb present on all but the smallest specimens during the later series. Of particular interest are the compression fractures that occur at the base and tip, suggesting that it was driven hard into a very solid object.
This is the same specimen shown displayed on sand in the header image. This specimen was fund out about 100 meters from the base of the cut bank. One side displays heavy surface mineralization, but the other side is only moderately altered.
Both faces of a typical uniserial harpoon.
Another longer, fragmentary uniserial harpoon.
A very small uniserial harpoon - with no mini-barb at the tip.
The base of a large, uniserial harpoon showing little mineralization.
A small biserial harpoon found on the extreme eastern edge of the site. Note the unusual ling guard and the small spalls of bone that have popped out of the base.
Fragment of a biserial harpoon that is made from a split long bone. Note the remnant of the medullary canal. This face of the harpoon is ground flat on this face. Notice also that the barbs are defined by a single, broad finishing groove instead of the two narrow grooves and intervening ridge typical of uniserial specimens.
Another biserial specimen with the flat ventral face and broad, well-defined grooves used to form barbs.
It is uncertain of specimens of this type are contemporary with the most recent uniserial specimens or if they are more recent and associated with a different subsistence mix.
This specimen is associated with a spread of polished bone tools and fiber tempered pottery thought to date from the Iron Age. It has a shallow, diamond-shaped cross section, blunt base, broad, convex tip. Note also the the multiple narrow cut marks that define the barbs. It would be worthwhile studying these in greater detail to see if they were made with an iron knife.
There is also an adhering residue near the base that might reward analysis.
Here is the other face of the specimen pictured above, in place as it was found.
And finally the iron harpoon, which was not found within an obvious scatter of material.
Here it is in place where it was found.
All Koobi Fora Spit web pages on this site