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 of stone flakes. There is a large concentration
of artifacts in the northeast corner of the site, and more pieces of fossil
bone have been uncovered. The fact that the artifacts are clustered like this
may be indicative of multiple visits to the site through time, where each
clustering of tools and bone would correspond to a visit by the early humans.
We
also lifted bones and tools again at Site 15 this afternoon. We are excavating
a paleosol layer that contains a scatter of equid (horse) and bovid (antelope)
skeletons, and stone tools as well. At one point during the lift, the lighting
was just right to see cut marks visible in the field. The fact that we could
see them in the field is amazing. It usually requires a cleaned, prepared
fossil in a lab setting with the correct lighting to see these marks. But
every once in a while, conditions allow you to see them in the trenches, like
today, where the sun was low in the sky, and went behind a cloud at just the
right time. We are sure that these marks are not excavation marks (accidentally
etched into the bones by one of our team members while digging the bone out
of the sediment) because the scratches were filled in with sediments. If they
had been caused in excavation, they would have been empty. Of course, we need
to confirm that they were indeed caused by stone tools, and not some other
factor (for example, the sharp teeth of a young hyena) by studying the marks
with a scanning electron microscope (SEM).
-RP