Olduvai Gorge

The Olduvai Gorge or Oldupai Gorge in Tanzania is one of the most important paleoanthropological sites in the world; it has proven invaluable in furthering understanding of early human evolution. A steep-sided ravine in the Great Rift Valley that stretches across East Africa, it is about 48 km (30 mi) long, and is located in the eastern Serengeti Plains in the Arusha Region about 45 kilometres (28 miles) from Laetoli, another important archaeological site of early human occupation. The British/Kenyan paleoanthropologist-archeologist team Mary and Louis Leakey established and developed the excavation and research programs at Olduvai Gorge which achieved great advances of human knowledge and world-renowned status.The oldest human-made object in the British MuseumThe spot where the first P. boisei was discovered in TanzaniaOldowan stone chopperAbout 1.8 million years old The Olduvai Gorge or Oldupai Gorge in Tanzania is one of the most important paleoanthropological sites in the world; it has proven invaluable in furthering understanding of early human evolution. A steep-sided ravine in the Great Rift Valley that stretches across East Africa, it is about 48 km (30 mi) long, and is located in the eastern Serengeti Plains in the Arusha Region about 45 kilometres (28 miles) from Laetoli, another important archaeological site of early human occupation. The British/Kenyan paleoanthropologist-archeologist team Mary and Louis Leakey established and developed the excavation and research programs at Olduvai Gorge which achieved great advances of human knowledge and world-renowned status. Homo habilis, probably the first early human species, occupied Olduvai Gorge approximately 1.9 million years ago (mya); then came a contemporary australopithecine, Paranthropus boisei, 1.8 mya, followed by Homo erectus, 1.2 mya. Our species Homo sapiens, which is estimated to have emerged roughly 300,000 years ago, is dated to have occupied the site 17,000 years ago. The site is significant in showing the increasing developmental and social complexities in the earliest humans, or hominins, largely revealed in the production and use of stone tools. Prior to tools, evidence of scavenging and hunting can be noted—highlighted by the presence of gnaw marks that predate cut marks—and of the ratio of meat versus plant material in the early hominin diet. The collecting of tools and animal remains in a centralized area is evidence of developing social interaction and communal activity. All these factors indicate an increase in cognitive capacities at the beginning of the period of hominids transitioning to hominin—that is, to human—form and behavior. Oldupai means 'the place of the wild sisal' (Sansevieria), in Maasai. Twenty-five kilometers downstream of Lake Ndutu and Lake Masek, the gorge cuts into Pleistocene lake bed sediments up to a depth of 90 m. A side gorge, originating from Lemagrut Mountain, joins the main gorge 8 km from the mouth. This side gorge follows the shoreline of a prehistoric lake, rich in fossils and early man sites. Volcanic ash from Olmoti and Kerimasi ensured preservation of the fossils. While travelling in German East Africa in 1911 to investigate sleeping sickness,, German physician and archaeologist Wilhelm Kattwinkel visited Olduvai Gorge, where he observed many fossil bones of an extinct three-toed horse. Inspired by Kattwinkel's discovery, German geologist Hans Reck led a team to Olduvai in 1913. There, he found hominin remains radiocarbon dated to 17,000 BP. Four more expeditions were planned, but World War I prevented their start. After the war, as Tanzania came under British control, Louis Leakey visited Reck in Berlin and viewed the Olduvai fossils. Louis Leakey became convinced that Olduvai Gorge held stone tools, thinking the deposits were of similar age to the Kariandusi prehistoric site in Kenya. Reck and the paleontologist Donald McInnes accompanied Louis Leakey in his 1931 expedition, where Louis found a number of hand axes close to camp soon after their arrival. Mary Leakey first visited the site in 1935, joining Louis and Percy Edward Kent. Subsequent visits were made by the Leakeys in 1941, 1953, 1955 and 1957. Louis and Mary Leakey are responsible for most of the excavations and discoveries of the hominin fossils in Olduvai Gorge. In July 1959, at the FLK site (the initials of Louis' first wife Frida Leakey, and K for korongo, the Swahili language word for gully), Mary Leakey found the skull of Zinjanthropus or Australopithecus boisei. In addition to an abundance of faunal remains the Leakeys found stone tools Mary classified as Oldowan. In May 1960, at the FLK North-North site, the Leakeys' son Jonathan found the mandible that proved to be the type specimen for Homo habilis.:17-18,54,56-57,73-77,87 The stratigraphic sequence in the gorge is up to 90 m thick, with a welded tuff, the Naabi ignimbrite, forming the base. This is overlain by a series of lava flows from Otmoi and from another source to the south. The oldest fossils are found on this surface, dated at 1.89 mya, while stone tools have been dated at 1.7 mya through the first use of K-Ar dating by Garniss Curtis. In addition, fission track dating and paleomagnetism were used to date the deposits, while amino acid dating and Carbon-14 dating were used to date the bones. Hominid fossils and stone tools are found continuously throughout the entire exposed sequence in the gorge. Faulting between 100 to 30 kya, formed the Olbalbal Depression northwest of Ngorongoro.:41-43 Reck identified five main layers of deposition, which he labelled Beds I through V, with Bed I being the oldest and lowest in the sequence. The Bed IV interval was later distinguished as consisting of Bed IV and the Masek Beds, while Bed V was totally reclassified as the Ndutu Bed and the Naisiuiu Bed. The 20-46 m thick Lower Pleistocene Bed I sediments above the basalt consist of layers of Olmoti tuff and lake sediment claystone. Four well-preserved living sites of note are located within Bed I, the FLK and FLK North-North sites mentioned above, plus DK and FLK North. The DK site (Donald McInnes' first initial plus k for korongo) has a stone circle, many tools and fossil bones, and ranges in age from 1.75 mya to 1.9 mya.:45,50-58 Bed II consists of 21-35 m of clay and sandstone Olduvai Lake and stream deposits. Manuports are abundant at the MNK (Mark Nicol Korongo) site in addition to a chert nodule quarry containing over 14,000 pieces, including gneiss and lava anvils and hammerstones. Hand axes were found at the EF-HR (Evelyn Fuchs-Hans Reck) and TK (Thiongo Korongo) sites. The BK (Bell's Korongo) site contained an Australopithecus boisei deciduous molar and canine.:58-63