Paula Reimer | Queen's University Belfast (original) (raw)
Papers by Paula Reimer
Antiquity, 2018
Longhouses are a key feature of Neolithic Linearbandkeramik (LBK) settlements in Central Europe, ... more Longhouses are a key feature of Neolithic Linearbandkeramik (LBK) settlements in Central Europe, but debate persists concerning their usage, longevity and social significance. Excavations at Versend-Gilencsa in south-west Hungary (c. 5200 cal BC) revealed clear rows of longhouses. New radiocarbon dates suggest that these houses experienced short lifespans. This paper produces a model for the chronology of Versend, and it considers the implications of the new date estimates for a fuller understanding of the layout and duration of LBK longhouse settlements.
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Terrestrial gastropods are problematical for radiocarbon (14 C) measurement because they tend to ... more Terrestrial gastropods are problematical for radiocarbon (14 C) measurement because they tend to incorporate carbon from ancient sources as a result of their dietary behavior. The 14 C ecology of the pulmonate land snail, Helix melanostoma in Cyrenaica, northeastern Libya, was investigated as part of a wider study on the potential of using terrestrial mollusk shell for 14 C dating of archaeological deposits. H. melanostoma was selected out of the species available in the region as it has the most predictable 14 C ecology and also had a ubiquitous presence within the local archaeology. The ecological observations indicate that H. melanostoma has a very homogenous 14 C ecology with consistent variations in F 14 C across sample sites controlled by availability of dietary vegetation. The majority of dated specimens from non-urbanized sample locations have only a small old-carbon effect, weighted mean of 476 ± 48 14 C yr, with between ~1% and 9% of dietary F 14 C from non-organic carbonate sources. Observed instabilities in the 14 C ecology can all be attributed to the results of intense human activity not present before the Roman Period. Therefore, H. melanostoma and species with similar ecological behavior are suitable for 14 C dating of archaeological and geological deposits with the use of a suitable offset.
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Quaternary Science Reviews, 2010
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Quaternary Science Reviews, 2012
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We present a varve thickness chronology from glacier-dammed Iceberg Lake in the southern Alaska i... more We present a varve thickness chronology from glacier-dammed Iceberg Lake in the southern Alaska icefields. Radiogenic evidence confirms that laminations are annual and record continuous sediment deposition from A.D. 442 to A.D. 1998. Varve thickness is positively correlated with Northern Hemisphere temperature trends, and more strongly with a local, ∼600 yr long tree ring width chronology. Varve thickness increases in warm summers because of higher melt, runoff, and sediment transport (as expected), but also because shrinkage of the glacier dam allows shoreline regression that concentrates sediment in the smaller lake. Varve thickness provides a sensitive record of relative changes in warm season temperatures. Relative to the entire record, temperatures implied by this chronology were lowest around A.D. 600, warm between A.D. 1000 and A.D. 1300, cooler between A.D. 1500 and A.D. 1850, and have increased dramatically since then. Combined with stratigraphic evidence that contemporary jökulhlaups (which began in 1999) are unprecedented since at least A.D. 442, this record suggests that 20th century warming is more intense, and accompanied by more extensive glacier retreat, than the Medieval Warm Period or any other time in the last 1500 yr.
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The antiquity of the practice of grazing on and/or foddering with seaweed is of interest in terms... more The antiquity of the practice of grazing on and/or foddering with seaweed is of interest in terms of understanding animal management practices in northwest Europe, where provision had to be made for overwintering. Orkney holds a special place in this discussion, since the sheep of North Ronaldsay have been confined to the seashores since the early nineteenth century, and are entirely adapted to a diet consisting mainly of seaweeds. Here, we report the results of stable carbon and nitrogen isotope analysis of twenty-five faunal specimens from the Neolithic chambered tomb of Quanterness, Orkney. Three of the 12 sheep analysed show elevated δ 13 C values that can only be explained by the consumption of seaweed. Radiocarbon dates place two of the three animals in the Neolithic, coeval with the use of the monument for burial, while the third animal dates to the Chalcolithic/Early Bronze Age. The findings are placed into the wider context of previous isotopic analyses of domestic fauna from prehistoric Orkney. A possible disjoint is noted between the results for bone collagen – where seaweed consumption seems to relate to the pre-natal period, since all the animals with high δ 13 C values are less than ca. three months of age – and previous studies using high-resolution sequential enamel measurements, which suggest a repeated pattern of winter consumption of seaweed in older animals.
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Seventeen samples of burnt olive pits discovered inside a jar in the destruction layer of the Iro... more Seventeen samples of burnt olive pits discovered inside a jar in the destruction layer of the Iron Age city of Khirbet Qeiyafa were analyzed by accelerator mass spectrometry (AMS) radiocarbon dating. Of these, four were halved and sent to two different laboratories to minimize laboratory bias. The dating of these samples is ~1000 BC. Khirbet Qeiyafa is currently the earliest known example of a fortified city in the Kingdom of Judah and contributes direct evidence to the heated debate on the biblical narrative relating to King David. Was he the real historical ruler of an urbanized state-level society in the early 10th century BC or was this level of social development reached only at the end of the 8th century BC? We can conclude that there were indeed fortified centers in the Davidic kingdom from the studies presented. In addition, the dating of Khirbet Qeiyafa has far-reaching implications for the entire Levant. The discovery of Cypriot pottery at the site connects the 14 C datings to Cyprus and the renewal of maritime trade between the island and the mainland in the Iron Age. A stone temple model from Khirbet Qeiyafa, decorated with triglyphs and a recessed doorframe, points to an early date for the development of this typical royal architecture of the Iron Age Levant.
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Sedimentological and accelerator mass spectrometry (AMS) 14C data provide estimates of the struct... more Sedimentological and accelerator mass spectrometry (AMS) 14C data provide estimates of the structure and age of five submarine landslides (»0.4–3 km3) present on eastern Australia’s continental slope between Noosa Heads and Yamba. Dating of the post-slide conformably deposited sediment indicates sediment accumulation rates between 0.017 m ka–1 and 0.2 m ka–1, which is consistent with previous estimates reported for this area. Boundary surfaces were identified in five continental slope cores at depths of 0.8 to 2.2 m below the present-day seafloor. Boundary surfaces present as a sharp colour-change across the surface, discernible but small increases in sediment stiffness, a slight increase in sediment bulk density of 0.1 g cm–3, and distinct gaps in AMS 14C ages of at least 25 ka. Boundary surfaces are interpreted to represent a slide plane detachment surface but are not necessarily the only ones or even the major ones. Sub-bottom profiler records indicate that: (1) the youngest identifiable sediment reflectors upslope from three submarine landslides terminate on and are truncated by slide rupture surfaces; (2) there is no obvious evidence for a post-slide sediment layer draped over, or burying, slide ruptures or exposed slide detachment surfaces; and (3) the boundary surfaces identified within the cores are unlikely to be near-surface slide surfaces within an overall larger en masse dislocation. These findings suggest that these submarine landslides are
geologically recent (<25 ka), and that the boundary surfaces are either: (a) an erosional features that developed after the landslide, in which case the boundary surface age provides a minimum age for the landslide; or (b) detachment surfaces from which slabs of near-surface sediment were removed during landsliding, in which case the age of the sediment above the boundary surface indicates the approximate age of landsliding. While an earthquake-triggering mechanism is favoured for the initiation of submarine landslides on the eastern Australian margin, further evidence is required to confirm this interpretation.
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Science, Jan 1, 2005
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A formally modeled radiocarbon chronology for a new profile through the great Neolithic tell of V... more A formally modeled radiocarbon chronology for a new profile through the great Neolithic tell of Vinča-Belo Brdo, Serbia, is the third interwoven strand in refining the chronology of the tell. This now joins models for the whole sequence based on the archive of early excavations, and for the last two known horizons at the top of the settlement mound, investigated in recent decades. In the new deep sounding, Vinča culture occupation from the 52nd century cal BC is slightly later than in the main sequence, probably reflecting the horizontal extension of the tell as it began to grow. The last dated occupation falls in the late 47th–early 46th century cal BC, slightly earlier than in the main sequence, but the top of the profile is affected by the slippage that caused the new excavations. Formal estimates are given for the succession and varying durations of burnt and unburnt houses, and indicate a period in the first part of the 5th millennium without house burning. Overall, the combined results from the three interwoven strands serve to produce a radically enhanced understanding of the temporality of the tell, which builds on, rather than supplants, previous research. We knew previously that Vinča-Belo Brdo was very long-lived, but now we can time that history with much greater precision. We can assert with much greater confidence that its vertical buildup was steady and largely uninterrupted. We have begun, from the work on the top of the tell and in the new deep sounding, to grasp better the fluctuations in house durations from generation to generation, and can now contrast the relative fortunes of unburnt and burnt houses. We can say much more about the timing and tempo of the ending of the tell, and about the possible circumstances in which that took place.
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Journal of Quaternary Science, 2014
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Geology, 2009
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Radiocarbon, 2012
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A new stomatal proxy-based record of CO2 concentrations ([CO2]), based on Betula nana (dwarf birc... more A new stomatal proxy-based record of CO2 concentrations ([CO2]), based on Betula nana (dwarf birch) leaves from the Hässeldala Port sedimentary sequence in south-eastern Sweden, is presented. The record is of high chronological resolution and spans most of Greenland Interstadial 1 (GI-1a to 1c, Allerød pollen zone), Greenland Stadial 1 (GS-1, Younger Dryas pollen zone) and the very beginning of the Holocene (Preboreal pollen zone). The record clearly demonstrates that i) [CO2] were significantly higher than usually reported for the Last Termination and ii) the overall pattern of CO2 evolution through the studied time period is fairly dynamic, with significant abrupt fluctuations in [CO2] when the climate moved from interstadial to stadial state and vice versa. A new loss-on-ignition chemical record (used here as a proxy for temperature) lends independent support to the Hässeldala Port [CO2] record. The large-amplitude fluctuations around the climate change transitions may indicate unstable climates and that “tipping-point” situations were involved in Last Termination climate evolution. The scenario presented here is in contrast to [CO2] records reconstructed from air bubbles trapped in ice, which indicate lower concentrations and a gradual, linear increase of [CO2] through time. The prevalent explanation for the main climate forcer during the Last Termination being ocean circulation patterns needs to re-examined, and a larger role for atmospheric [CO2] considered.► A stomatal proxy-based CO2 record from the Last Termination is presented. ► The stomata based CO2 record is much more dynamic than ice core-based CO2 records. ► CO2 first increases abruptly before decreasing at cooling transitions and vice versa.
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South Africa's southwestern Cape occupies a critical transition zone between Southern Hemisphere ... more South Africa's southwestern Cape occupies a critical transition zone between Southern Hemisphere temperate (winter) and tropical (summer) moisture-bearing systems. In the recent geological past, it has been proposed that the relative influence of these systems may have changed substantially, but little reliable evidence regarding regional hydroclimates and rainfall seasonality exists to refine or substantiate the understanding of long-term dynamics. In this paper we present a mid-to late Holocene multi-proxy record of environmental change from a rock hyrax midden from Katbakkies Pass, located along the modern boundary between the winter and summer rainfall zones. Derived from stable carbon and nitrogen isotopes, fossil pollen and microcharcoal, these data provide a high resolution record of changes in
humidity, and insight into changes in rainfall seasonality. Whereas previous work concluded that the site had generally experienced only subtle environmental change during the Holocene, our records indicate that significant, abrupt changes have occurred in the region over the last 7000 years. Contrary to expectations based on the site's location, these data indicate that the primary determinant of changes in humidity is summer rather than winter rainfall variability, and its influence on drought season intensity and/or length. These findings are consistent with independent records of upwelling along the southern and western coasts, which indicate that periods of increased humidity are related to increased tropical easterly flow. This substantially refines our understanding of the nature of temperate and tropical circulation system dynamics in SW Africa, and how changes in their relative dominance have impacted regional environments during the Holocene.
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This paper presents the first continuous pollen record from the southern Namib Desert spanning th... more This paper presents the first continuous pollen record from the southern Namib Desert spanning the last 50,000 years. Obtained from rock hyrax middens found near the town of Pella, South Africa, these data are used to reconstruct vegetation change and quantitative estimates of temperature and aridity. Results indicate that the last glacial period was characterised by increased water availability at the site relative to the Holocene. Changes in temperature and potential evapotranspiration appear to have played a significant role in determining the hydrologic balance. The record can be considered in two sections: 1) the last glacial period, when low temperatures favoured the development of more mesic Nama-Karoo vegetation at the site, with periods of increased humidity concurrent with increased coastal upwelling, both responding to lower global/regional temperatures; and 2) the Holocene, during which time high temperatures and potential evapotranspiration resulted in increased aridity and an expansion of the Desert Biome. During this latter period, increases in upwelling intensity created drier conditions at the site. Considered in the context of discussions of forcing mechanisms of regional climate change and environmental dynamics, the results from Pella stand in clear contrast with many inferences of terrestrial environmental change derived from regional marine records. Observations of a strong precessional signal and interpretations of increased humidity during phases of high local summer insolation in the marine records are not consistent with the data from Pella. Similarly, while high percentages of Restionaceae pollen has been observed in marine sediments during the last glacial period, they do not exceed 1% of the assemblage from Pella, indicating that no significant expansion of the Fynbos Biome has occurred during the last 50,000 years. These findings pose interesting questions regarding the nature of environmental change in southwestern Africa, and the significance of the diverse records that have been obtained from the region.
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Antiquity, 2018
Longhouses are a key feature of Neolithic Linearbandkeramik (LBK) settlements in Central Europe, ... more Longhouses are a key feature of Neolithic Linearbandkeramik (LBK) settlements in Central Europe, but debate persists concerning their usage, longevity and social significance. Excavations at Versend-Gilencsa in south-west Hungary (c. 5200 cal BC) revealed clear rows of longhouses. New radiocarbon dates suggest that these houses experienced short lifespans. This paper produces a model for the chronology of Versend, and it considers the implications of the new date estimates for a fuller understanding of the layout and duration of LBK longhouse settlements.
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Terrestrial gastropods are problematical for radiocarbon (14 C) measurement because they tend to ... more Terrestrial gastropods are problematical for radiocarbon (14 C) measurement because they tend to incorporate carbon from ancient sources as a result of their dietary behavior. The 14 C ecology of the pulmonate land snail, Helix melanostoma in Cyrenaica, northeastern Libya, was investigated as part of a wider study on the potential of using terrestrial mollusk shell for 14 C dating of archaeological deposits. H. melanostoma was selected out of the species available in the region as it has the most predictable 14 C ecology and also had a ubiquitous presence within the local archaeology. The ecological observations indicate that H. melanostoma has a very homogenous 14 C ecology with consistent variations in F 14 C across sample sites controlled by availability of dietary vegetation. The majority of dated specimens from non-urbanized sample locations have only a small old-carbon effect, weighted mean of 476 ± 48 14 C yr, with between ~1% and 9% of dietary F 14 C from non-organic carbonate sources. Observed instabilities in the 14 C ecology can all be attributed to the results of intense human activity not present before the Roman Period. Therefore, H. melanostoma and species with similar ecological behavior are suitable for 14 C dating of archaeological and geological deposits with the use of a suitable offset.
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Quaternary Science Reviews, 2010
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Quaternary Science Reviews, 2012
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We present a varve thickness chronology from glacier-dammed Iceberg Lake in the southern Alaska i... more We present a varve thickness chronology from glacier-dammed Iceberg Lake in the southern Alaska icefields. Radiogenic evidence confirms that laminations are annual and record continuous sediment deposition from A.D. 442 to A.D. 1998. Varve thickness is positively correlated with Northern Hemisphere temperature trends, and more strongly with a local, ∼600 yr long tree ring width chronology. Varve thickness increases in warm summers because of higher melt, runoff, and sediment transport (as expected), but also because shrinkage of the glacier dam allows shoreline regression that concentrates sediment in the smaller lake. Varve thickness provides a sensitive record of relative changes in warm season temperatures. Relative to the entire record, temperatures implied by this chronology were lowest around A.D. 600, warm between A.D. 1000 and A.D. 1300, cooler between A.D. 1500 and A.D. 1850, and have increased dramatically since then. Combined with stratigraphic evidence that contemporary jökulhlaups (which began in 1999) are unprecedented since at least A.D. 442, this record suggests that 20th century warming is more intense, and accompanied by more extensive glacier retreat, than the Medieval Warm Period or any other time in the last 1500 yr.
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The antiquity of the practice of grazing on and/or foddering with seaweed is of interest in terms... more The antiquity of the practice of grazing on and/or foddering with seaweed is of interest in terms of understanding animal management practices in northwest Europe, where provision had to be made for overwintering. Orkney holds a special place in this discussion, since the sheep of North Ronaldsay have been confined to the seashores since the early nineteenth century, and are entirely adapted to a diet consisting mainly of seaweeds. Here, we report the results of stable carbon and nitrogen isotope analysis of twenty-five faunal specimens from the Neolithic chambered tomb of Quanterness, Orkney. Three of the 12 sheep analysed show elevated δ 13 C values that can only be explained by the consumption of seaweed. Radiocarbon dates place two of the three animals in the Neolithic, coeval with the use of the monument for burial, while the third animal dates to the Chalcolithic/Early Bronze Age. The findings are placed into the wider context of previous isotopic analyses of domestic fauna from prehistoric Orkney. A possible disjoint is noted between the results for bone collagen – where seaweed consumption seems to relate to the pre-natal period, since all the animals with high δ 13 C values are less than ca. three months of age – and previous studies using high-resolution sequential enamel measurements, which suggest a repeated pattern of winter consumption of seaweed in older animals.
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Seventeen samples of burnt olive pits discovered inside a jar in the destruction layer of the Iro... more Seventeen samples of burnt olive pits discovered inside a jar in the destruction layer of the Iron Age city of Khirbet Qeiyafa were analyzed by accelerator mass spectrometry (AMS) radiocarbon dating. Of these, four were halved and sent to two different laboratories to minimize laboratory bias. The dating of these samples is ~1000 BC. Khirbet Qeiyafa is currently the earliest known example of a fortified city in the Kingdom of Judah and contributes direct evidence to the heated debate on the biblical narrative relating to King David. Was he the real historical ruler of an urbanized state-level society in the early 10th century BC or was this level of social development reached only at the end of the 8th century BC? We can conclude that there were indeed fortified centers in the Davidic kingdom from the studies presented. In addition, the dating of Khirbet Qeiyafa has far-reaching implications for the entire Levant. The discovery of Cypriot pottery at the site connects the 14 C datings to Cyprus and the renewal of maritime trade between the island and the mainland in the Iron Age. A stone temple model from Khirbet Qeiyafa, decorated with triglyphs and a recessed doorframe, points to an early date for the development of this typical royal architecture of the Iron Age Levant.
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Sedimentological and accelerator mass spectrometry (AMS) 14C data provide estimates of the struct... more Sedimentological and accelerator mass spectrometry (AMS) 14C data provide estimates of the structure and age of five submarine landslides (»0.4–3 km3) present on eastern Australia’s continental slope between Noosa Heads and Yamba. Dating of the post-slide conformably deposited sediment indicates sediment accumulation rates between 0.017 m ka–1 and 0.2 m ka–1, which is consistent with previous estimates reported for this area. Boundary surfaces were identified in five continental slope cores at depths of 0.8 to 2.2 m below the present-day seafloor. Boundary surfaces present as a sharp colour-change across the surface, discernible but small increases in sediment stiffness, a slight increase in sediment bulk density of 0.1 g cm–3, and distinct gaps in AMS 14C ages of at least 25 ka. Boundary surfaces are interpreted to represent a slide plane detachment surface but are not necessarily the only ones or even the major ones. Sub-bottom profiler records indicate that: (1) the youngest identifiable sediment reflectors upslope from three submarine landslides terminate on and are truncated by slide rupture surfaces; (2) there is no obvious evidence for a post-slide sediment layer draped over, or burying, slide ruptures or exposed slide detachment surfaces; and (3) the boundary surfaces identified within the cores are unlikely to be near-surface slide surfaces within an overall larger en masse dislocation. These findings suggest that these submarine landslides are
geologically recent (<25 ka), and that the boundary surfaces are either: (a) an erosional features that developed after the landslide, in which case the boundary surface age provides a minimum age for the landslide; or (b) detachment surfaces from which slabs of near-surface sediment were removed during landsliding, in which case the age of the sediment above the boundary surface indicates the approximate age of landsliding. While an earthquake-triggering mechanism is favoured for the initiation of submarine landslides on the eastern Australian margin, further evidence is required to confirm this interpretation.
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Science, Jan 1, 2005
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A formally modeled radiocarbon chronology for a new profile through the great Neolithic tell of V... more A formally modeled radiocarbon chronology for a new profile through the great Neolithic tell of Vinča-Belo Brdo, Serbia, is the third interwoven strand in refining the chronology of the tell. This now joins models for the whole sequence based on the archive of early excavations, and for the last two known horizons at the top of the settlement mound, investigated in recent decades. In the new deep sounding, Vinča culture occupation from the 52nd century cal BC is slightly later than in the main sequence, probably reflecting the horizontal extension of the tell as it began to grow. The last dated occupation falls in the late 47th–early 46th century cal BC, slightly earlier than in the main sequence, but the top of the profile is affected by the slippage that caused the new excavations. Formal estimates are given for the succession and varying durations of burnt and unburnt houses, and indicate a period in the first part of the 5th millennium without house burning. Overall, the combined results from the three interwoven strands serve to produce a radically enhanced understanding of the temporality of the tell, which builds on, rather than supplants, previous research. We knew previously that Vinča-Belo Brdo was very long-lived, but now we can time that history with much greater precision. We can assert with much greater confidence that its vertical buildup was steady and largely uninterrupted. We have begun, from the work on the top of the tell and in the new deep sounding, to grasp better the fluctuations in house durations from generation to generation, and can now contrast the relative fortunes of unburnt and burnt houses. We can say much more about the timing and tempo of the ending of the tell, and about the possible circumstances in which that took place.
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Journal of Quaternary Science, 2014
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Geology, 2009
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Radiocarbon, 2012
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A new stomatal proxy-based record of CO2 concentrations ([CO2]), based on Betula nana (dwarf birc... more A new stomatal proxy-based record of CO2 concentrations ([CO2]), based on Betula nana (dwarf birch) leaves from the Hässeldala Port sedimentary sequence in south-eastern Sweden, is presented. The record is of high chronological resolution and spans most of Greenland Interstadial 1 (GI-1a to 1c, Allerød pollen zone), Greenland Stadial 1 (GS-1, Younger Dryas pollen zone) and the very beginning of the Holocene (Preboreal pollen zone). The record clearly demonstrates that i) [CO2] were significantly higher than usually reported for the Last Termination and ii) the overall pattern of CO2 evolution through the studied time period is fairly dynamic, with significant abrupt fluctuations in [CO2] when the climate moved from interstadial to stadial state and vice versa. A new loss-on-ignition chemical record (used here as a proxy for temperature) lends independent support to the Hässeldala Port [CO2] record. The large-amplitude fluctuations around the climate change transitions may indicate unstable climates and that “tipping-point” situations were involved in Last Termination climate evolution. The scenario presented here is in contrast to [CO2] records reconstructed from air bubbles trapped in ice, which indicate lower concentrations and a gradual, linear increase of [CO2] through time. The prevalent explanation for the main climate forcer during the Last Termination being ocean circulation patterns needs to re-examined, and a larger role for atmospheric [CO2] considered.► A stomatal proxy-based CO2 record from the Last Termination is presented. ► The stomata based CO2 record is much more dynamic than ice core-based CO2 records. ► CO2 first increases abruptly before decreasing at cooling transitions and vice versa.
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South Africa's southwestern Cape occupies a critical transition zone between Southern Hemisphere ... more South Africa's southwestern Cape occupies a critical transition zone between Southern Hemisphere temperate (winter) and tropical (summer) moisture-bearing systems. In the recent geological past, it has been proposed that the relative influence of these systems may have changed substantially, but little reliable evidence regarding regional hydroclimates and rainfall seasonality exists to refine or substantiate the understanding of long-term dynamics. In this paper we present a mid-to late Holocene multi-proxy record of environmental change from a rock hyrax midden from Katbakkies Pass, located along the modern boundary between the winter and summer rainfall zones. Derived from stable carbon and nitrogen isotopes, fossil pollen and microcharcoal, these data provide a high resolution record of changes in
humidity, and insight into changes in rainfall seasonality. Whereas previous work concluded that the site had generally experienced only subtle environmental change during the Holocene, our records indicate that significant, abrupt changes have occurred in the region over the last 7000 years. Contrary to expectations based on the site's location, these data indicate that the primary determinant of changes in humidity is summer rather than winter rainfall variability, and its influence on drought season intensity and/or length. These findings are consistent with independent records of upwelling along the southern and western coasts, which indicate that periods of increased humidity are related to increased tropical easterly flow. This substantially refines our understanding of the nature of temperate and tropical circulation system dynamics in SW Africa, and how changes in their relative dominance have impacted regional environments during the Holocene.
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This paper presents the first continuous pollen record from the southern Namib Desert spanning th... more This paper presents the first continuous pollen record from the southern Namib Desert spanning the last 50,000 years. Obtained from rock hyrax middens found near the town of Pella, South Africa, these data are used to reconstruct vegetation change and quantitative estimates of temperature and aridity. Results indicate that the last glacial period was characterised by increased water availability at the site relative to the Holocene. Changes in temperature and potential evapotranspiration appear to have played a significant role in determining the hydrologic balance. The record can be considered in two sections: 1) the last glacial period, when low temperatures favoured the development of more mesic Nama-Karoo vegetation at the site, with periods of increased humidity concurrent with increased coastal upwelling, both responding to lower global/regional temperatures; and 2) the Holocene, during which time high temperatures and potential evapotranspiration resulted in increased aridity and an expansion of the Desert Biome. During this latter period, increases in upwelling intensity created drier conditions at the site. Considered in the context of discussions of forcing mechanisms of regional climate change and environmental dynamics, the results from Pella stand in clear contrast with many inferences of terrestrial environmental change derived from regional marine records. Observations of a strong precessional signal and interpretations of increased humidity during phases of high local summer insolation in the marine records are not consistent with the data from Pella. Similarly, while high percentages of Restionaceae pollen has been observed in marine sediments during the last glacial period, they do not exceed 1% of the assemblage from Pella, indicating that no significant expansion of the Fynbos Biome has occurred during the last 50,000 years. These findings pose interesting questions regarding the nature of environmental change in southwestern Africa, and the significance of the diverse records that have been obtained from the region.
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Excavations at Knowth 6: The Passage Tomb Archaeology of the Great Mound at Knowth. Royal Irish Academy, Dublin, 2017
The 60 AMS 14C determinations on cremated and non-burnt human bone presented here have provided a... more The 60 AMS 14C determinations on cremated and non-burnt human bone presented here have provided a robust chronological framework for the interpretation of the main use phase at Knowth. This large series was seen as necessary to overcome the problem presented by the late fourth-millennium BC calibration plateau. To a large extent this strategy has been successful, but as is usually the case with modelling, there is not necessarily a single, clear-cut answer to questions of chronology, and much still depends on archaeological interpretation. Although the use of individual tombs is more variable, largely because of smaller sample sizes, overall modelling of funerary activity at Knowth consistently places the main phase of use as lasting between 100 and 300 years, maximum, in the period 3200–2900 BC (in a statement that now appears prescient, George Eogan (1991, 112) more than two decades ago suggested a date range of 3200–3000 cal. BC for the main phase of passage tomb construction and use at Knowth).
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