Small tools from the Olorgesailie Acheulian sites: scraper, nosed and beaked forms, and a notched piece. Most artifacts, both large and small, are made of lavas from the vicinity of the lake basin. This selection is of obsidian, quartz and chert which were presumably brought in from more remote areas.
Excavations nearby disclosed the existence of a dense patch of artifacts that had not yet been cut into by erosion. This patch has a diameter of 12 - 15 m. and contains more than a tone of stone, which was apparently imported by early man. This is the site of DE/89 horizon B. The material has been concentrated by current action in part of the seasonal streambed in which the early humans camped.
However in one area, far inland from the lake, erosion has exposed a concentration of stone tools at a horizon between that dated to 1.3 and 1.6. This is the site RHS. Here Margaret Leakey and Glynn Isaac sort specimens from the eroded surface of this site.
An Olivine basalt flow in Humbu Formation tuffs. These tuffs are equivalent to the tuffs just above the mandible. The potassium-argon age of the lava thus helps to date the mandible (Isaac and Curtis, 1974).
Diagrams illustrating the stratigraphy and dating of the mandible. It was stratified below one lava dated at 1.3 million years and also below another one with normal polarity. This suggests Olduvai event age 1.8 - 1.6 million years (see Isaac and Curtis, 1974).
The fault scarps cut the Lower Pleistocene Peninj Group sediments so that some outcrops are down in the Natron trough as seen here, while others over large areas of the plateau above. The Peninj australopithecine jaw was found in the eroded area seen here.
A closer view of the fault scarp plus a Pleiocene volcano, Mozonik, that projects through a flood of lavas. Behind is the active volcano Lengai which has been built up entirely since the period in which the Peninj beds were deposited.
Air view of the escarpment that runs parallel to the western shore of the lake. The faults creating this scarp have moved mainly since the deposition of the Peninj fossiliferous beds. The plain above runs through a gap to join with the Serengeti at Olduvai Gorge, which is only about 30 miles away.
View from the north end of Lake Natron. The active volcano Lengai can be seen in the far distance. The modern delta of the Peninj River can be seen projecting into the lake from the right. The flower is a desert rose (Adensonia sp.)
Excavating a Gal-dies camp that had been buried by sand a short while after occupation had ended. The fishing group had chosen this spot because the ephemeral water course provided comfortable sand to sit on. The small stream then flooded, burying the discarded flood refuse and the hearth. The situation involves many parallels with the KBS site. Ms. Diane Gifford (left rear) conducted the study and will publish detailed reports.
The eastern shores of Lake Turkana (Rudolf) are inhabited by mobile groups of fishers, the Gal-dies, who are a segment of the mainly pastoral and agricultural Dassanetch. A fisherman in a dugout canoe.
Site KBS (Kay Behrensmeyer Site): A schematic reconstruction of the paleogeographic setting of the sites KBS and HAS in a delta floodplain just inland of a swampy lakeshore with lagoon (this reconstruction is subject to some revision as a result of more recent geological work).