title: Single-grain OSL chronologies for Middle Palaeolithic deposits at El Mnasra and El Harhoura 2, Morocco: implications for Late Pleistocene human-environment interactions along the Atlantic coast of northwest Africa.
abstract: Optically stimulated luminescence (OSL) measurements were made on individual, sand-sized grains of quartz from Middle Palaeolithic deposits at two cave sites (El Harhoura 2 and El Mnasra) on the Atlantic coast of Morocco. We were able to calculate OSL ages for 32 of the 33 samples collected from the Middle Palaeolithic deposits, including the earliest and latest Aterian levels at both sites. These ages reveal periods of occupation between about 110 and 95 ka (thousands of years ago), and at ~75 ka. A late Middle Palaeolithic occupation of El Harhoura 2 is also recorded at ~55 ka. Our single-grain OSL chronologies largely support previous age estimates from El Mnasra and other sites along the Atlantic coast of Morocco, but are generally more precise, reproducible and stratigraphically more coherent (i.e., fewer age reversals). We compare the single-grain ages for El Harhoura 2 and El Mnasra with those obtained from single- and multi-grain OSL dating of Middle Palaeolithic deposits in the nearby sites of Contrebandiers and Dar es-Soltan 1 and 2, and with records of past regional environments preserved in sediment cores collected from off the coast of northwest Africa. A conspicuous feature of the new chronologies is the close correspondence between the three identified episodes of human occupation and periods of wetter climate and expanded grassland habitat. Owing to the precision of the single-grain OSL ages, we are able to discern gaps in occupation during Marine Isotope Stages 5 and 4, which may represent drier periods with reduced vegetation cover. We propose that these climatic conditions can be correlated with events in the North Atlantic Ocean that exert a major control on abrupt, millennial-scale fluctuations between wet and dry periods in northwest and central North Africa.
authors.affiliation: Centre for Archaeological Science, School of Earth and Environmental Sciences, University of Wollongong, Wollongong, NSW 2522, Australia. zenobia@uow.edu.au
authors.forename: Zenobia
authors.initials: Z
authors.lastname: Jacobs
authors.forename: Richard G
authors.initials: RG
authors.lastname: Roberts
authors.forename: Roland
authors.initials: R
authors.lastname: Nespoulet
authors.forename: Mohammed Abdeljalil
authors.initials: MA
authors.lastname: El Hajraoui
authors.forename: André
authors.initials: A
authors.lastname: Debénath
mesh_terms: D001106:Archaeology; D002910:Chronology as Topic; D002980:Climate; D019015:Geologic Sediments / Q000032:analysis; D006801:Humans; D008163:Luminescent Measurements / Q000295:instrumentation / Q000379:methods*; D009018:Morocco; D011791:Quartz / Q000032:analysis
chemical_list: D011791:Quartz