Overview Area of Deposits Why Turkana? A Bright Future

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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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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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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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. [ return to top ]

  Petrified remains of a primeval forest [enlarge]

Research team excavating a fossil [enlarge]

Fossilized remains of an ancient elephant  [enlarge]

Fossil crocodile [enlarge]

Exposed fossil crocodile mandible [enlarge]