THE JADE SEA AND A TREASURE-TROVE OF FOSSILS


Koobi Fora is located in east Africa on the east side of Lake Turkana (formerly Lake Rudolf). The Koobi Fora area has yielded a large number of fossils representing both Australopithecenes and early Homo. The sediments yielding these fossils were laid down mainly by streams flowing into Lake Turkana from uplands to the east. A series of tuff layers, or volcanic ash layers, are interspersed through the sequence providing materials for radiopotassium dating. These serve as basic markers used to correlate fossilized hominids.

Hominid evolution has been studied extensively in east Africa. Sites such as Olduvai Gorge and Koobi Fora have been important in helping reconstruct a picture of human natural history emerging around 2.0 million years ago.



[THE FOLLOWING IS THE DESCRIPTION RICHARD LEAKEY HAD FOR THE SETTING OF THE KOOBI FORA EXERCISE IN HIS BOOK, CO-AUTHORED WITH ROGER LEWIN, PEOPLE OF THE LAKE: MANKIND AND ITS BEGINNINGS IN 1978.]
The year was 1967 and Richard Leakey's life was to change as a result of Koobi Fora.

Urgent business had forced Richard to leave the camp temporarily and return to Nairobi. On the return journey in the small two-seater place, the pilot decided to fly along the eastern shore of Lake Turkana rather than goind over the more normal western route so that he would avoid the threat of local bad weather there. Glancing from the window of the passenger seat Richard saw what he thought might be eroded layers of lake deposits on the eastern shore -- this would be a promising site for finding fossils, he thought.

And so it was. A reconnaissance trip by helicopter hired especially for the occasion from the american party confirmed that the inhospitable-looking black rocks were, in face, fossil-bearing sandstone layers and not lava flows as everyone had always imagined. With a small grant from the National Geographic Society, and in the company of five colleagues, Richard, still lacking the conventional academic credentials, set off in 1968 for the first survey expedition of the lake deposits.

During the next few years the Koobi fora camp slowly became established. The five-hundreed mile journey from Nairobi was sometimes covered by a grueling, though spectacularly beautiful, drive direct to the camp, and on others by an easier twelve-hour road stint to the lodge on the lake's west shore, and the last leg of the journey being completed by boat. and on one occasion the team drove to Marsabit, some two-hundred miles south of Koobi Fora, where they picked up some camels which they used as pack and (not very efficient) riding animals.

In the most meager conditions, and against difficult odds which at one time included having all their equipment destroyed by the local people, the determined team built a permanent camp. Located on a spit jutting out into the lake, the camp, which consisted of a group of stone-built thatched bandas, can now accomodate fifty people confortably -- and seventy uncomfortably. Being surrounded on three sides by the lake helps cool the camp environs by as much as 10 degrees F.; in January and February the temperature out in the field can reach 115 degrees day after relentless day, and even in the cooler months of the year exploration is done routinely with the termometer hovering aorund 100 degrees. The relief of returning to a considerably cooler camp with the opportunity to bath in the lake need not be described.

As the Rift Valley sweeps northward out of Kenya and into Ethiopia in modern-day Africa, it forms the spectacular Lake Turkana basin. Spectacular, not only because of the stunning beauty of the lake iselft and its pwerfully stark surroundings, but also for its treasure-trove of prehuman fossils, buried in the layered deposits on the eastern shore of the lake. Here, beginning with a small tentative exploration in 1968, we have been searching for ancient human ancestors in Kenya.

The long shallow waters of the lake, which stretch 155 miles north to south and up to 35 miles east to west, sparkle green in the tropical sun; someone called it the Jade Sea, a very apt name. At the south a barrier of small volcanic hills prevents the lake spreading farther down into the arid lands of northern Kenya. From the west side rises the Rift Valley wall, a range of mountains with some peaks of more than five thousand feet. This is the land of the Turkana people, a tall, elegant pastoralist tribe. Beyond are the mountains and forests of Uganda.

Pouring its silt-laden waters into the north end of the lake is the Omo River, a huge river that drains the Ethiopian highlands to the north and meanders tortulously as it nears its end at the border with Kenya where it reaches the Jade Sea. Fly over Lake Turkana and you see the orange waters of the Omo carried miles by their massive momentum into the green lake until they finally disperse, orange into green - a spectacular sight. As the river reaches the lake, the sudden barrier to its progress forces it to dump its burden of silt, so creating an enormous delta. This process has been going on for at least four million years, and it is the ancient river and lake sediments that have helped preserve the fossils we find today.

One important source of fossils is the lower Omo valley itself, where over a period of about four million years more than three thousand feet of sediments built up, trapping the skeletons of ancient hominids and examples of their unusual stone technology. But the eastern shore of the lake is an even richer fossil treasure-trove.