Olorgesailie

Landscape near Olorgesailie

Olorgesailie is a geological formation in East Africa containing a group of Lower Paleolithic archaeological sites.^{[ 1]} It is on the floor of the Eastern Rift Valley in southern Kenya, 40 miles (64 km) southwest of Nairobi along the road to Lake Magadi. Olorgesailie is noted for the large number of Acheulean hand axes, associated with animal butchering, discovered there.^{[ 1]} According to the National Museums of Kenya, the finds are internationally significant for archaeology, paleontology, and geology.^{[ 1]}

History

Hand axes

The artifacts were first discovered by the British geologist John Walter Gregory in 1919,^{[ 1][ 1]} but it was not until 1943 that excavation began in earnest under the direction of Mary and Louis Leakey, with the assistance of paroled Italian prisoners of war.^{[ 1]} Work continued there until 1947. Glynn Isaac took up the excavation in the 1960s^{[ 1]} for his dissertation. In the 1980s, research was continued by Richard Potts of the Smithsonian Institution in conjunction with the National Museums of Kenya.

Finds

Animal fossils from Olorgesailie

Human tools are the most prominent of all historic items in the area. The abundant hand axes are characteristic of the Acheulean period, made by hominids between about 600,000 and 900,000 years ago^{[ 1]}along what was then the shore of a now dried-up lake. Fossils of various animals have also been found, including those of extinct species of hippo, elephant, zebra, giraffe, and baboon, likely to have been butchered with the aid of the hand axes.^{[ 1][ 1]}

In June 2003, a team led by Potts discovered a frontal bone in situ.^{[ 1]} Other parts of the small skull (designated KNM-OL 45500) were found in following months. The frontal bone is 900,000 to 970,000 years old and probably belonged to Homo erectus, thereby making it the first human fossil found on the site.^{[ 1]} The fossil remains were in the same stratigraphic level as two hand axes and several flakes, near dense deposits of hand axes.^{[ 1]}

Geology

Preservation of the Aechulean hand axe culture was made possible by heavy falls of alkaline ash from volcanoes near the site; volcanoes that were active at the time. Mounts Suswa and Longonot are volcanoes and their vents are likely to have contributed to the ash that accumulated in the Olorgesailie basin. Subsequent sedimentation covering the site has preserved the fossils and created a stratigraphy allowing for age determination.^{[ 1]} Existing temporary lakes and swamps give evidence of a humid climate during the middle Pleistocene. Sediments left by the lake cover an area of 50 square miles (about 130 square km).^{[ 1]} Of the artifacts, 99 % were made from locally derived lavas, particularly trachyte, although small amounts of quartzite and obsidian have been found, indicating a transport over 16 to 40 km.^{[ 1]}

References

Bibliography

• Isaac, Glynn Llywelyn; Isaac, Barbara (1977). Olorgesailie: Archeological Studies of a Middle Pleistocene Lake Basin in Kenya. Chicago: University of Chicago Press. ISBN 0-226-38483-7. 

Coordinates: 1°35′S 36°27′E / 1.58°S 36.45°E / -1.58; 36.45

v t e Archaeological sites in Kenya Sites Enkapune Ya Muto Enkorika Hyrax Hill Ileret Jumba la Mtwana Kapthurin Kiongwe Koobi Fora Lamu Mambrui Manda Island Namoratunga Ngenyn Olorgesailie Pate Island Ruins of Gedi Takwa