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Full-Text Articles in Life Sciences
Equivalent Dose Distributions From Single Grains Of Quartz At Sibudu, South Africa: Context, Causes And Consequences For Optical Dating Of Archaeological Deposits, Richard Roberts, Zenobia Jacobs, Geoffrey Duller, Ann Wintle
Equivalent Dose Distributions From Single Grains Of Quartz At Sibudu, South Africa: Context, Causes And Consequences For Optical Dating Of Archaeological Deposits, Richard Roberts, Zenobia Jacobs, Geoffrey Duller, Ann Wintle
Richard G Roberts
No abstract provided.
Late-Surviving Megafauna In Tasmania Australia, Implicate Human Involvement In Their Extinction, Christian Turney, T Flannery, Richard Roberts, Craig Reid, Keith Fifield, T Higham, Zenobia Jacobs, Noel Kemp, Eric Colhoun, R.M. Kalin
Late-Surviving Megafauna In Tasmania Australia, Implicate Human Involvement In Their Extinction, Christian Turney, T Flannery, Richard Roberts, Craig Reid, Keith Fifield, T Higham, Zenobia Jacobs, Noel Kemp, Eric Colhoun, R.M. Kalin
Richard G Roberts
Establishing the cause of past extinctions is critical if we are to understand better what might trigger future occurrences and how to prevent them. The mechanisms of continental late Pleistocene megafaunal extinction, however, are still fiercely contested. Potential factors contributing to their demise include climatic change, human impact, or some combination. On the Australian mainland, 90% of the megafauna became extinct by ≈46 thousand years (ka) ago, soon after the first archaeological evidence for human colonization of the continent. Yet, on the neighboring island of Tasmania (which was connected to the mainland when sea levels were lower), megafaunal extinction appears …
The Cyrenaican Prehistory Project 2008: The Second Season Of Investigations Of The Haua Fteah Cave And Its Landscape, And Further Results From The Initial (2007) Fieldwork, Richard Roberts, Zenobia Jacobs, Johnny Morales, M. Morley, R. Grun, L Farr, C Hunt, G Barker, R Rabett, T Reynolds, Victoria Leitch, Robyn Inglis, Roisin Hamilton, John Davison, Hwedi El-Rishi, Alex Pryor, David Simpson, Marijke Van Der Veen, Chris Stimpson, Steven Pawley, Mohammed Touati, Caroline Cartwright, Franca Cole, Iain Morley, Lucilla Burn, Ian Brooks, Laura Basell
The Cyrenaican Prehistory Project 2008: The Second Season Of Investigations Of The Haua Fteah Cave And Its Landscape, And Further Results From The Initial (2007) Fieldwork, Richard Roberts, Zenobia Jacobs, Johnny Morales, M. Morley, R. Grun, L Farr, C Hunt, G Barker, R Rabett, T Reynolds, Victoria Leitch, Robyn Inglis, Roisin Hamilton, John Davison, Hwedi El-Rishi, Alex Pryor, David Simpson, Marijke Van Der Veen, Chris Stimpson, Steven Pawley, Mohammed Touati, Caroline Cartwright, Franca Cole, Iain Morley, Lucilla Burn, Ian Brooks, Laura Basell
Richard G Roberts
No abstract provided.
New Excavations Of Middle Stone Age Deposits At Apollo 11 Rockshelter, Namibia: Stratigraphy, Archaeology, Chronology And Past Environments, Ralf Vogelsang, Jurgen Richter, Zenobia Jacobs, Barbara Eichhorn, Veerle Linseele, Richard Roberts
New Excavations Of Middle Stone Age Deposits At Apollo 11 Rockshelter, Namibia: Stratigraphy, Archaeology, Chronology And Past Environments, Ralf Vogelsang, Jurgen Richter, Zenobia Jacobs, Barbara Eichhorn, Veerle Linseele, Richard Roberts
Richard G Roberts
This paper presents new information obtained from a recent excavation and reassessment of the stratigraphy, chronology, archaeological assemblages and environmental context of the Apollo 11 rockshelter, which contains the longest late Pleistocene and Holocene archaeological sequence in Namibia. The Middle Stone Age (MSA) industries represented at the site include an early MSA, Still Bay, Howieson's Poort and late MSA. Optically stimulated luminescence (OSL) dating of individual quartz grains yielded numerical ages for the Still Bay and Howieson's Poort, and indicated the presence of a post-Howieson's Poort phase. OSL dating also verified conventional and accelerator mass spectrometry radiocarbon ages for a …
Ages For The Middle Stone Age Of Southern Africa: Implications For Human Behavior And Dispersal, Zenobia Jacobs, Richard Roberts, Rex Galbraith, Hilary Deacon, Rainer Grun, Alex Mackay, Peter Mitchell, Ralf Vogelsang, Lyn Wadley
Ages For The Middle Stone Age Of Southern Africa: Implications For Human Behavior And Dispersal, Zenobia Jacobs, Richard Roberts, Rex Galbraith, Hilary Deacon, Rainer Grun, Alex Mackay, Peter Mitchell, Ralf Vogelsang, Lyn Wadley
Richard G Roberts
The expansion of modern human populations in Africa 80,000 to 60,000 years ago and their initial exodus out of Africa have been tentatively linked to two phases of technological and behavioral innovation within the Middle Stone Age of southern Africa—the Still Bay and Howieson's Poort industries—that are associated with early evidence for symbols and personal ornaments. Establishing the correct sequence of events, however, has been hampered by inadequate chronologies. We report ages for nine sites from varied climatic and ecological zones across southern Africa that show that both industries were short-lived (5000 years or less), separated by about 7000 years, …
Dating In Landscape, Archaeology, Richard Roberts, Zenobia Jacobs
Dating In Landscape, Archaeology, Richard Roberts, Zenobia Jacobs
Richard G Roberts
A common need in archaeology is for objects and events of interest to be dated, so that they can be arranged in the correct temporal sequence. Here we briefly review several methods available to the archaeologist to assist in age determination of the "target" object or event-comprehensive treatments of the subject are given by Aitken 0990, 1999), Wagner (998), and Walker (2005).
An Improved Osl Chronology For The Still Bay Layers At Blombos Cave, South Africa: Further Tests Of Single-Grain Dating Procedures And A Re-Evaluation Of The Timing Of The Still Bay Industry Across Southern Africa, Zenobia Jacobs, Elspeth Hayes, Richard Roberts, Rex Galbraith, Christopher Henshilwood
An Improved Osl Chronology For The Still Bay Layers At Blombos Cave, South Africa: Further Tests Of Single-Grain Dating Procedures And A Re-Evaluation Of The Timing Of The Still Bay Industry Across Southern Africa, Zenobia Jacobs, Elspeth Hayes, Richard Roberts, Rex Galbraith, Christopher Henshilwood
Richard G Roberts
This paper presents a series of new single-grain optically stimulated luminescence (OSL) ages for the Still Bay at Blombos Cave, South Africa, and compares them to previously published OSL, thermoluminescence (TL) and electron-spin resonance (ESR) ages for this site. Details are provided about the measurement and analytical procedures, including a discussion of the characteristics of the OSL signals of individual quartz grains. This forms the basis for further investigations into the sensitivity of the equivalent dose (De) estimates to a range of different analytical approaches, including changes in the size of the test dose, the choice of signal integration interval, …
New Ages For Middle And Later Stone Age Deposits At Mumba Rockshelter, Tanzania: Optically Stimulated Luminescence Dating Of Quartz And Feldspar Grains, Luke Gliganic, Zenobia Jacobs, Richard Roberts, M Dominguez-Rodrigo, A Mabulla
New Ages For Middle And Later Stone Age Deposits At Mumba Rockshelter, Tanzania: Optically Stimulated Luminescence Dating Of Quartz And Feldspar Grains, Luke Gliganic, Zenobia Jacobs, Richard Roberts, M Dominguez-Rodrigo, A Mabulla
Richard G Roberts
The archaeological deposits at Mumba rockshelter, northern Tanzania, have been excavated for more than 70 years, starting with Margit and Ludwig Köhl-Larsen in the 1930s. The assemblages of Middle Stone Age (MSA) and Later Stone Age (LSA) artefacts collected from this site constitute the type sequences for these cultural phases in East Africa. Despite its archaeological importance, however, the chronology of the site is poorly constrained, despite the application since the 1980s of several dating methods (radiocarbon, uranium-series and amino acid racemisation) to a variety of materials recovered from the deposits. Here, we review these previous chronologies for Mumba and …
Would The Australian Megafauna Have Become Extinct If Humans Had Never Colonised The Continent? Comments On 'A Review Of The Evidence For A Human Role In The Extinction Of Australian Megafauna And An Alternative Explanation' By S.Wroe And J.Field, Barry Brook, David Burney, Timothy Flannery, Michael Gagan, Richard Gillespie, Christopher Johnson, Peter Kershaw, John Magee, Paul Martin, Gifford Miller, Benny Peiser, Richard Roberts
Would The Australian Megafauna Have Become Extinct If Humans Had Never Colonised The Continent? Comments On 'A Review Of The Evidence For A Human Role In The Extinction Of Australian Megafauna And An Alternative Explanation' By S.Wroe And J.Field, Barry Brook, David Burney, Timothy Flannery, Michael Gagan, Richard Gillespie, Christopher Johnson, Peter Kershaw, John Magee, Paul Martin, Gifford Miller, Benny Peiser, Richard Roberts
Richard G Roberts
The problem of the worldwide extinction of a diverse assemblage of Late Pleistocene and Holocene large-bodied animals continues to cause debate (Brook and Bowman, 2002; Barnosky et al., 2004; Burney and Flannery, 2005; Koch and Barnosky, 2006). The most recent contribution on the Australian megafaunal extinction (Wroe and Field, 2006), argues for a staggered series of extinctions over multiple glacial cycles, with most megafaunal extinctions predating the arrival of humans and driven primarily by climate change eventually causing a ‘hydrological threshold’ to be breached. At this point, accessible water became too scarce for megafauna to forage successfully. Although Wroe and …
Catalysts For Stone Age Innovations: What Might Have Triggered Two Short-Lived Bursts Of Technological And Behavioral Innovation In Southern Africa During The Middle Stone Age?, Richard Roberts, Zenobia Jacobs
Catalysts For Stone Age Innovations: What Might Have Triggered Two Short-Lived Bursts Of Technological And Behavioral Innovation In Southern Africa During The Middle Stone Age?, Richard Roberts, Zenobia Jacobs
Richard G Roberts
No abstract provided.
Still Bay And Serrated Points From Umhlatuzana Rock Shelter, Kwazulu-Natal, South Africa, Marlize Lombard, Lyn Wadley, Zenobia Jacobs, Moleboheng Mohapi, Richard Roberts
Still Bay And Serrated Points From Umhlatuzana Rock Shelter, Kwazulu-Natal, South Africa, Marlize Lombard, Lyn Wadley, Zenobia Jacobs, Moleboheng Mohapi, Richard Roberts
Richard G Roberts
No abstract provided.
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, Zenobia Jacobs, Richard Roberts, Roland Nespoulet, M El Hajraoui, Andre Debenath
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, Zenobia Jacobs, Richard Roberts, Roland Nespoulet, M El Hajraoui, Andre Debenath
Richard G Roberts
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 …
Testing Times: Old And New Chronologies For The Howieson's Poort And Still Bay Industries In Environmental Context, Richard Roberts, Zenobia Jacobs
Testing Times: Old And New Chronologies For The Howieson's Poort And Still Bay Industries In Environmental Context, Richard Roberts, Zenobia Jacobs
Richard G Roberts
No abstract provided.
Melting Ice Sheets 400,000 Yr Ago Raised Sea Level By 13 M: Past Analogue For Future Trends, David Roberts, Panagiotis Karkanas, Zenobia Jacobs, Curtis Marean, Richard Roberts
Melting Ice Sheets 400,000 Yr Ago Raised Sea Level By 13 M: Past Analogue For Future Trends, David Roberts, Panagiotis Karkanas, Zenobia Jacobs, Curtis Marean, Richard Roberts
Richard G Roberts
Marine Isotope Stage (MIS) 11 was possibly the longest (∼423,000–362,000 yr ago) and warmest interglacial of the entire Quaternary Period. This resulted from a special arrangement of Earth's orbital parameters-similar to the present interglacial (MIS 1)-suggesting that MIS 11 provides an analogue for future natural climate forcing and sea levels. Although precise documentation of MIS 11 sea level history is, therefore, crucial – especially considering additional impetus from anthropogenic warming – the maximum MIS 11 sea level remains highly contentious. Estimates from onshore indicators have ranged from below present sea level to about +20 m, resulting from uncertainties in reliability …
Advances In Optically Stimulated Luminescence Dating Of Individual Grains Of Quartz From Archaeological Deposits, Richard Roberts, Zenobia Jacobs
Advances In Optically Stimulated Luminescence Dating Of Individual Grains Of Quartz From Archaeological Deposits, Richard Roberts, Zenobia Jacobs
Richard G Roberts
No abstract provided.
Afromontane Foragers Of The Late Pleistocene: Site Formation, Chronology And Occupational Pulsing At Melikane Rockshelter, Lesotho, Brian Stewart, Genevieve Dewar, Mike Morley, Robyn Inglis, Mark Wheeler, Zenobia Jacobs, Richard Roberts
Afromontane Foragers Of The Late Pleistocene: Site Formation, Chronology And Occupational Pulsing At Melikane Rockshelter, Lesotho, Brian Stewart, Genevieve Dewar, Mike Morley, Robyn Inglis, Mark Wheeler, Zenobia Jacobs, Richard Roberts
Richard G Roberts
This paper provides a preliminary chronostratigraphic and palaeoenvironmental framework for the Late Pleistocene archaeological sequence at Melikane Rockshelter in mountainous eastern Lesotho. Renewed excavations at Melikane form part of a larger project investigating marginal landscape use by Late Pleistocene foragers in southern Africa. Geoarchaeological work undertaken at the site supports in-field observations that Melikane experienced regular, often intensive, input of groundwater via fissures in the shelter’s rear wall. This strong hydrogeological connection resulted in episodic disturbances of the sedimentary sequence, exacerbated by other processes such as bioturbation. Despite this taphonomic complexity, a robust chronology for Melikane has been developed, based …
Luminescence Characteristics And Dose Distributions For Quartz And Feldspar Grains From Mumba Rockshelter, Tanzania, Luke Gliganic, Zenobia Jacobs, Richard Roberts
Luminescence Characteristics And Dose Distributions For Quartz And Feldspar Grains From Mumba Rockshelter, Tanzania, Luke Gliganic, Zenobia Jacobs, Richard Roberts
Richard G Roberts
Mumba rockshelter is a key archaeological site for the Middle and Later Stone Age occupation of East Africa, but its chronology has remained unresolved. We report the results of a dating study, focussing on the characterisation of the optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) properties of quartz- and potassium-rich feldspar grains. Quartz has previously proven troublesome for dating in East Africa. We identified five general types of quartz grain behaviour, based on the shapes of their OSL decay and dose–response curves. Dose recovery experiments and measurement of the natural samples revealed particular problems with quartz grains that …
Single-Grain Osl Dating At La Grotte Des Contrebandiers ('Smugglers' Cave'), Morocco: Improved Age Constraints For The Middle Paleolithic Levels, Richard Roberts, Zenobia Jacobs, Michael Meyer, V Aldeias, M El Hajraoui, H Dibbie
Single-Grain Osl Dating At La Grotte Des Contrebandiers ('Smugglers' Cave'), Morocco: Improved Age Constraints For The Middle Paleolithic Levels, Richard Roberts, Zenobia Jacobs, Michael Meyer, V Aldeias, M El Hajraoui, H Dibbie
Richard G Roberts
Optically stimulated luminescence (OSL) measurements of individual quartz grains are reported for Middle Paleolithic (MP) or Middle Stone Age (MSA) deposits in La Grotte des Contrebandiers, Morocco. Single-grain measurements enable rejection of grains that may lead to under- or over-estimation of age due to malign luminescence properties or remobilisation of grains after burial. We identified the former using a range of experimental procedures and objective rejection criteria. Three post-depositional factors influenced the distribution pattern of equivalent dose (De) values for the remaining single grains: the disintegration of roof spall liberating unbleached, older grains into otherwise well-bleached sediments; the intrusion of …