Optically Stimulated Luminescence (OSL) Dating
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OLDUVAI Gail M. Ashley Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, USA
Synonyms Oldupai (wild sisal plant); Olduvai (Maasai language); Olduvai Gorge Olduvai Gorge is a valley incised into the Serengeti Plain in northern Tanzania. The main tributary of the Olduvai River flows 46 km eastward from lakes Masek and Ndutu to a depression, Olbalbal, at the foot of the Ngorongoro Volcanic Highland (Hay, 1976). The gorge is 100 m deep and cuts across the Olduvai basin, exposing a two million-year-long sequence of volcaniclastic sediments interbedded with numerous tuffs that have been dated with 40 Ar/39Ar radiometric dating. Olduvai sediments contain a rich faunal and cultural record of early hominins – Paranthropus boisei, Homo habilis, and Homo erectus (Leakey, 1971). There are over 50 archaeological sites; the two sites with the densest concentration of stone tools, bones, and human modified bones are FLK Zinj, dating to 1.84 Ma (DomínguezRodrigo et al., 2007; Ashley et al., 2010a) and BK, dating to >1.2 Ma (Domínguez-Rodrigo et al., 2009). Paleoenvironmental studies have indicated that most of the archaeological sites are located near the margin of ancient Lake Olduvai. It was originally assumed that the lake was used by hominins as a water source (Leakey, 1971; Hay, 1976), but it is now known that the lake was saline-alkaline (toxic) and that it was a playa that fluctuated frequently in level and dried up periodically (Hay, 1976; Ashley, 2007). Recent studies show that freshwater springs were associated with many of the archaeological
sites and that these springs likely attracted hominins and other vertebrates to the area of Olduvai (Ashley et al., 2010b).
Bibliography Ashley, G. M., 2007. Orbital rhythms, monsoons and playa lake response, Olduvai Basin, equatorial East Africa (ca. 1.85–1.74 Ma). Geology, 35(12), 1091–1094. Ashley, G. M., Barboni, D., Domínguez-Rodrigo, M., Bunn, H. T., Mabulla, A. Z. P., Diez-Martín, F., Barba, R., and Baquedano, E., 2010a. A spring and wooded habitat at FLK Zinj and their relevance to origins of human behavior. Quaternary Research, 74(3), 304–314. Ashley, G. M., Domínguez-Rodrigo, M., Bunn, H. T., Mabulla, A. Z. P., and Baquedano, E., 2010b. Sedimentary geology and human origins: a fresh look at Olduvai Gorge, Tanzania. Journal of Sedimentary Research, 80(3), 703–709. Domínguez-Rodrigo, M., Barba, R., and Egelund, C. P., 2007. Deconstructing Olduvai: A Taphonomic Study of the Bed I Sites. Dordrecht: Springer. Vertebrate Paleobiology and Paleoanthropology Series. Domínguez-Rodrigo, M., Mabulla, A., Bunn, H. T., Barba, R., Diez-Martín, F., Egeland, C. P., Espílez, E., Egeland, A., Yravedra, J., and Sánchez, P., 2009. Unraveling hominin behavior at another anthropogenic site from Olduvai Gorge (Tanzania): new archaeological and taphonomic research at BK, Upper Bed II. Journal of Human Evolution, 57(3), 260–283. Hay, R. L., 1976. Geology of the Olduvai Gorge. Berkeley: University of California Press. Leakey, M. D., 1971. Olduvai Gorge: Excavations
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