Born in Africa_ The Quest for the Origins of Human Life - Martin Meredith [5]
A specialist in volcanology, Reck had already proved his ability to handle African expeditions. In 1912, he had been appointed leader of a university expedition to Tendaguru in the southern region of German East Africa which had uncovered a complete skeleton of a Braciosaurus , one of the largest land animals ever to have lived. His team of porters from Tendaguru had joined him for this new expedition. But the journey across the Maasai Steppe proved arduous: In the searing heat Reck’s column struggled to keep pace and was strung out for miles. Water was scarce.
Climbing up the western escarpment of the Great Rift Valley onto the slopes leading to Ngorongoro, Reck caught sight in the distance of Ol doinyo Lengai, the Maasai’s ‘Mountain of God’, so named because it was still an active volcano. Reaching the rim of Ngorongoro, he marvelled at the spectacle around him: Below lay a collapsed crater, twelve miles across and 2,000 feet deep, forming a natural amphitheatre of 100 square miles that teemed with wildlife. Once rising to a height of 15,000 feet, the Ngorongoro volcano had exploded 2.5 million years ago, causing its dome to crumple inwards and leaving walls that were only half their original size.
But Reck was still unable to find out anything about Oldoway. A German official he met at Ngorongoro had never heard of it. Local Maasai also had no information, but they agreed to show him the way to a spring called Langavata on the western side of Ngorongoro which overlooked the great Serengeti Plains stretching away to the horizon.
For three days, Reck wandered along the fringes of the Serengeti. Then on 7 October 1913, he set up camp on the rim of a steep gorge. The surrounding terrain seemed familiar. Looking at photographs that Professor Kattwinkel had taken two years previously, Reck realised that he had found Oldoway.
In the months that followed, Reck collected more than 1,700 fossils and completed a geological survey of the area. He discovered that the gorge offered a remarkable geological record of past millennia. Its walls consisted of five distinct layers, or ‘beds’, of lava and ash, providing a sequence of time dating far back into antiquity. At the base was a layer of black lava; above stood a layer cake of colours—rich copper sandwiched between duller buffs and greys. No means of accurate dating were then available. But in time Oldoway was to yield crucial clues about the importance of the volcanic regions of the Great Rift Valley in revealing the origins of humankind.
The Great Rift Valley acts as a history book of the deep past. Over the last 10 million years, as two of Africa’s tectonic plates have slowly pulled apart, a giant fissure has developed in the earth’s crust, running for more than 3,000 miles from the lower reaches of the Zambezi Valley in Mozambique, through eastern Africa to the Red Sea where it divides Africa from Arabia. Tectonic upheavals and volcanic eruptions have transformed a relatively flat rain-forest region into a dramatic landscape of mountains, lakes and a complex array of fractures, faults and scarps. Ethiopia’s landmass rose 8,000 feet above the surrounding plains, like a huge blister on the continent’s skin, to form the largest volcanic massif in Africa. Eruptions in Kenya built a similar dome. Most of the uplift occurred after 7 million years ago. To the west, running parallel to the main Rift Valley, a new fissure began to develop, creating another chain of mountains and lakes, including Lake Tanganyika, the deepest lake in Africa, where the lake bottom lies 2,200 feet below sea level. Shoulders of land along the western rift were pushed up to form new mountain ranges