 HE
KOOBI FORA REGION has, over the last 35 years of
exploration, produced a wealth of palaeontological,
geological and archaeological data. Research in the
area has revealed a complex history of volcanism,
tectonics and sedimentary cycles preserving fluvial
and lake phases of the basin. Some 16,000 fossil
specimens have been collected from the Turkana
basin, almost 10,000 from the Koobi Fora Region.
This includes an impressive 350 hominid specimens
from the basin and this has contributed
significantly to our present understanding of human
origins and hominid diversity through time. Hominid
behaviour, including tool use, has been interpreted
from the archaeological remains. The huge collection
of fossil mammals provides an opportunity to trace
the evolution of numerous mammalian lineages back in
time.
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AREA OF DEPOSITS
The great potential of the Koobi Fora region, in
terms of new fossil discoveries, lies in the fact
that some 1200 km sq of fossil exposures remain to
be explored. Much of this includes unexplored areas,
and areas previously explored have undergone
significant erosion over the years, yielding a
freshly exposed fossils. All have huge potential to
turn out new finds which will contribute greatly to
furthering our understanding of palaeoenvironmets
and the context in which our own genus Homo
evolved. Olduvai Gorge by comparison is only about a
quarter of this size, with a much smaller exposure
area. Hadar, the fossil-rich Ethiopian site which
has yielded such magnificent finds as “Lucy,” is
even smaller still and represents about 40 km sq.
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WHY TURKANA?
A number of factors have made the Turkana Basin what
it is in terms of its fossil potential. The most
significant aspect is that the Turkana Basin is in
the Great East African Rift Valley. It is a
depression and therefore water flows into the basin
from the highlands. Rivers flowing into the basin
carry sediment which is deposited as the water moves
more slowly, burying remains of animals living and
dying along the banks of the rivers or the shores of
the lake. A buried bone becomes mineralized over
time and fossils are formed over millions of years.
A fossil must be brought to the surface again if it
is to be found. Tectonic activity in the Rift Valley
causes the sediments to fault and be tilted, thus
bringing older deposits once buried deep below up to
the surface. These faulted sediment are gently
eroded away through the action of wind and water and
due to the fact that the Lake Turkana region is so
arid, there is little vegetation cover to protect
the hillsides.
Through the process of erosion, any fossils in the
sediment slowly become visible on the surface. It is
these fossils or fragments of these fossils that the
fossil hunters working in the area search for and
collect.
Volcanic activity in the Rift Valley is very
important to our calculating the age of the fossils
that are collected. Volcanic ash layers can be dated
if pumice stones containing feldspar crystals can be
extracted from them, using Argon dating. If no
crystals can be extracted, the volcanic ash layer
can be identified from its chemical composition and
can be related to dated ash horizons. The fossils
are then aged relative to dated horizons so that if
they are above a layer logically they are younger
than it.
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A BRIGHT FUTURE
Over the next five to ten years, field work in the
Koobi Fora region is likely to produce significant
new finds and build upon three decades of previous
work. A great deal has been learned so far: the
long-term research at Koobi Fora has led to hundreds
of publications, including five monographs. Many
scientists who have spent much of their careers
investigating the strata and faunal records from
Koobi Fora are still involved in this research and
will impart their knowledge to the next generation
of scientists through fieldwork and training. The
Leakeys (www.leakey.com)
still lead palaeontological expeditions to the
region. New advances in technology are making
research in paleontology and archaeology more
efficient and exact. For example, a new technique of
analyzing oxygen and carbon isotopes in fossils can
provide information about the diet of extinct
herbivores and the environments in which they lived.
Computers can handle larger, more complex data sets
(including images), and satellite technology has
dramatically improved collection techniques. Earlier
records can now be collated using this technology;
this facilitates the work in the field and in the
analysis of the data.
New sites are being discovered all the time, and the
number of students and professionals in this field
has greatly increased. Fossils continue to erode from
the exposures and require collection to reveal more
clues about the past.
In summary, the previous thirty years work at Koobi
Fora has given us detailed understanding of
mammalian and hominid evolution of the last four
million years. The unique geological and fossil
resources and the exceptional size of the
fossiliferous exposures combine to provide potential
for future research unavailable at any other site.
Not to realize this potential by continuing the
research at Koobi Fora would be to miss an
opportunity that is unlikely, in the near future, to
become available again. [
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