After the preliminary investigations, the
main field trip will proceed during summer 2001. It will
bring together a team of multi-disciplined scientists and
a team of speleologists. The schedule of these
explorations is quite challenging:
Archaeology
In the winter 2000, during the first phase of the
archaeological study, we will select the shelter to
excavated in priority from the group of objects on the
western edge of the Marang mountains located by
helicopter flights in May 1999. These first excavations
of a rock-shelter will be directed by Jean-Michel
Chazine, in collaboration with the Indonesian
authorities at the local and national level. At the time
of the reconnaissance mission of winter 2000, surveys
will make it possible to define the shelter to be
excavated in priority. These excavations could finally
give stratigraphic elements and a first grid of datations
concerning the many archaeological objects that we could
observe on the surface of the caves or on the logging
tracks! It should be noted that to date no cave
excavation seems to have been undertaken on Kalimantan;
thus, in 1992, Jean-Michel Chazine was the first
prehistorian to prospect this part of Borneo, a region as
large as France.
Another purpose of this mission will be to undertake a
complete recording of all the paintings. So far,
we have only been able to work for a few hours in four of
the six most beautiful caves. The surveys were made
hurriedly, because of the logistic restrictions, and the
photographs, even if they show almost all the prehistoric
paintings, have to be taken again with the best (and
heaviest) photographic equipment.
Lastly, a return for the second time to one or more of
theses caves, in particular to Gua Payau (where we
remained only 4 hours), Liang Sara (6 hours) or
Ilas Kenceng (7 hours), should enable us to
discover new paintings, or to interpret them differently
based on the new discoveries.
The study and the observation of paintings require
time, as we have seen in 1995. During the two weeks we
spent in Gua Mardua, the number of the known
handprints increased from 23 to 54. We were also able to
build 4 m high platforms, allowing us to record all
paintings on transparent film.
The transport of the team from one site to another is
only possible by helicopter, since the archaeological
caves can be as far as 100 km apart, which would require
several weeks on foot through the jungle.
3D recordings
During these later visits to the memorable ornate
sites, discovered 4 or 5 years ago, we will take
advantage of the method developed by Martin Heller
to record the volumes of the caves.
In France, 3D reconstruction will allow us, to
virtually "come back" to the cave when desired.
Karstology
Study of the limestone formations of Mangkalihat -
Borneo's vastest - which so far has never been
properly investigated by a karstologist. These
sharp-edged peaks and these pitons contain an incredible
quantity of caves, mainly dry ones, free of water since a
long time. In those the speleothems were formed as well
as the clay deposits which trap useful information for
archaeology: paleoclimatic or paleo-environmental data,
etc.
That would make it possible to learn if there were
more humid phases at the end of the last
glaciation, (end of Pleistocene). This could explain for
example why people left their rock-shelters, or why more
marked erosion of the walls and therefore of paintings
began.
Protection of the
paintings
The thorough study of prehistoric paintings shows
that, everywhere, the oldest ones were created on a
fine layer of calcite which covers the limestone
walls of the caves. This calcite probably had to settle
several million years ago, when the water, that
originally formed the tunnel, started to flow through
lower levels. However, for some reasons not yet known, a
specific bacterium attacks the layer of calcite
and thus causes the destruction of paintings.
Without this erosion, one would probably find that
caves like Gua Mardua or Gua Tewet were painted on their
entire surface, since we found some remnants of ochre
painting on every intact layer of calcite.
In Gua Tewet, we could observe paintings that cover
some others. They are sometimes painted on a wall
where the bed rock and bits of calcite layers alternate.
This could prove the use of the caves during very
distinct periods. The examination of the corrosion
phenomena can give hints for dating the paintings.
Lastly, such an analysis could form the basis for a
protection policy of Borneo's caves paintings, by
studying the various degrading agents: wind, rain, water
circulation, bacteria, sunlight, forest fires.
Speleology
During our preceding explorations we had the chance to
observe speleological phenomena of highest
importance. But lack of time, equipment and manpower,
prevented an adequate exploration. The potential for new
discovery is immense. Gua Kambing offers a
through-trip several kilometers long, which the swallows
nests hunters use as shortcut, as it is less inconvenient
than to cross the surface of the karst. According to our
guides, there exists up to 7 fossil levels in this
giant cavity. 600 meters lower, at the bottom of the
karst, the resurgence of the underground water was found,
indicating the unique depth potential for Borneo's
karst.
The cave of Sedepan, with its gigantic entry
that we reached in 1998 (and where the bird nests hunters
told us they could collect up to 140 kg of nests every 40
days) is also the entrance of a surface river that
according to the official map runs in the opposite
direction. Using only aerial photographs and without
access to local ground truth, the cartographers did not
realize that the river flows underground through this
giant sinkhole. In May 1999, we could see the resurgence
of this river, some 5-km to the west. This river thus
crosses an unexplored calcareous range by an underground
course probably exceeding 30 kilometers.
All the speleological explorations will be
documented by topography. The software TOPOROBOT
will then be used to generate perspective views and
virtual reality
walk-throughs.