The geology and chronology of the Acheulean deposits in the Mieso area (East-Central Ethiopia)

Benito-Calvo, A., Barfod, D. N. , McHenry, L. J. and de la Torre, I. (2014) The geology and chronology of the Acheulean deposits in the Mieso area (East-Central Ethiopia). Journal of Human Evolution, 76, pp. 26-38. (doi: 10.1016/j.jhevol.2014.08.013) (PMID:25440135)

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Abstract

This paper presents the Quaternary sequence of the Mieso area of Central-East Ethiopia, located in the piedmont between the SE Ethiopian Escarpment and the Main Ethiopian Rift-Afar Rift transition sector. In this region, a piedmont alluvial plain is terraced at +25 m above the two main fluvial courses, the Mieso and Yabdo Rivers. The piedmont sedimentary sequence is divided into three stratigraphic units separated by unconformities. Mieso Units I and II contain late Acheulean assemblages and a weakly consolidated alluvial sequence, consisting mainly of fine sediments with buried soils and, to a lesser degree, conglomerates. Palaeo-wetland areas were common in the alluvial plain, represented by patches of tufas, stromatolites and clays. At present, the piedmont alluvial surface is preserved mainly on a dark brown soil formed at the top of Unit II. Unit III corresponds to a fluvial deposit overlying Unit II, and is defined by sands, silty clays and gravels, including several Later Stone Age (LSA) occurrences. Three fine-grained tephra levels are interbedded in Unit I (tuffs TBI and TA) and II (tuff CB), and are usually spatially-constrained and reworked. Argon/argon (40Ar/39Ar) dating from tuff TA, an ash deposit preserved in a palustrine environment, yielded an age of 0.212 ± 0.016 Ma (millions of years ago). This date places the top of Unit I in the late Middle Pleistocene, with Acheulean sites below and above tuff TA. Regional correlations tentatively place the base of Unit I around the Early-Middle Pleistocene boundary, Unit II in the late Middle Pleistocene and within the Late Pleistocene, and the LSA occurrences of Unit III in the Late Pleistocene–Holocene.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Barfod, Dr Dan
Authors: Benito-Calvo, A., Barfod, D. N., McHenry, L. J., and de la Torre, I.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Journal of Human Evolution
Publisher:Elsevier
ISSN:0047-2484
ISSN (Online):1095-8606

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