- Email: [email protected]
The Laacher See-eruption (c. 13ky BP) and societal change amongst peripheral Late Glacial hunter-gatherers in southern Scandinavia
Abstracts / Quaternary International 279-280 (2012) 346–461
THE LAACHER SEE-ERUPTION (C. 13KY BP) AND SOCIETAL CHANGE AMONGST PERIPHERAL LATE GLACIAL HUNTER-GATHERERS IN SOUTHERN SCANDINAVIA Felix Riede. Aarhus University, Denmark E-mail address: [email protected]
This paper is concerned with the palaeolecological, societal and culturehistorical impact of the catastrophic Laacher See volcanic eruption (c. 13ky BP), especially at a great distance from the eruptive center. It has been suggested that various mechanistic links (e.g. increased dental abrasion, negative respiratory effects as well as F-poisoning) may have contributed to animals and humans deserting the areas affected by tephra fall-out from this eruption. Consequently, a case can be made that at least one particular archaeological phenomenon of this period - the so-called Bromme culture of southern Scandinavia - emerged as a result of the redistribution of human populations following the eruption. The potential full extent of the societal impact of this eruption cannot, however, be understood with reference to direct negative impacts alone. Many of these would have been of insufficient duration to cause a medium-to-long term fragmentation of otherwise highly mobile hunter-gatherers. In considering aspects of the perception of this dramatic events, it is possible to suggest that a) mobility would have been the response of choice for these foragers in avoiding the immediate effects of the eruption, and that b) other, less tangible factors may have played an important role in extending the temporality of this extreme event beyond these immediate effects. A coupled consideration of both the ecological, demographic as well as the psychological and cultural effects of this high magnitude/low frequency event throws new light on the origin of the Bromme culture. Some 200-300 years after this event the rapid cooling of GS-1 once again reshuffled populations on the Northern European Plain, leading to the disappearance or transformation of this culture. A LAACHER SEE-ERUPTION SUPPLEMENT TO TEPHRABASE. A REVISED TEPHRA FALLOUT MAP AND NEW GEOCHEMICAL DATA Felix Riede. Aarhus University, Denmark E-mail address: [email protected]
Tephrabase (www.tephrabase.org) is an online data repository and research tool for tephrochronological investigations in northern Europe. Here we present an update to Tephrabase that contains geographic and, as far as available, geochemical data on 444 data-points for the widespread isochronous Laacher See tephra. This tephra is dated to c. 12,920 calendar years BP and acts as an important chronostratigraphic marker for the Lateglacial GI-1a/late Allerød chronozone in terrestrial and lacustrine palaeoenvironmental archives as well as in archaeological stratigraphies. Based on these data, we present a revised map of the total tephra distribution, suggesting that it is even more widespread than previously stated and that the north-eastern fallout lobe might contain a secondary thickness maximum between 200-300 km distance from the eruptive centre. In addition, new geochemical data from a series of distal tephra deposits spanning most of the north-eastern fallout lobe are used to evaluate previous suggestions regarding the distribution of fallout from distinct eruption phases. The aim of our study is that future tephrochronological investigations can use this database and our revised distribution map for effectively targeting sites for analysis. CONSTRUCT THE MIDDLE PLEISTOCENE CLIMATE OF SOUTH EAST MEDITERRANEAN USING SPELEOTHEM ISOTOPIC AND ELEMENTAL COMPOSITIONS, EGYPT Rifai Rifai. Environmental Studies & Research Institute, Minufi, Egypt E-mail address: [email protected]
The Wadi Sannur speleothems record climate changes spanning 188 and 136 kyr before present. Petrographically, the studied speleothem laminae are made up entirely of fibrous calcite except for one lamina that displays microspar fabric. Time-series analysis of the data set reveals regular changes in Sr/Ca and Mg/Ca at a scale that matches the thickness of the
403
different laminae. d18O values of the stalactite laminae range from -7.2 to -10.1 VPDB&. The lower d18Ocalcite values, which are correspond to the second oldest lamina (WSS5), indicate that the drip-waters were likely affected by evaporative fractionation and that the speleothem activity has probably stopped due to the very arid conditions that followed the pluvial period. The variations of the d13C values between -5.0 and -2.3& VPDB argue that the drip water composition is influenced by the interaction with the overlying grass-covered ecosystem and the degree of aridity rather than the bedrock (d13C -0.9&VBDP). 87Sr/86Sr ratios of the interglacial lamina are low (0.70781-0.70808), whereas the glacial lamina display higher ratios (0.70826- 0.70859) in comparison with the nummulitic limestone bedrock (0.70823). Keywords: Egypt, Mediterranean, Wadi Sannur speleothems, fibrous textures, U-series dates, Middle Pleistocene, stalactite, pluvial period. DEPOSITIONAL PALAEO-ENVIRONMENTS OF THE BOTETI DELTA, MAKGADIKGADI PANS (BOTSWANA KALAHARI) Susan Ringrose. ORI-University of Botswana, Botswana E-mail address: [email protected]
The Boteti delta (Delta 1) forms an important link between the OkavangoBoteti drainage system and the Makgadikgadi salt pans and comprises an extensive plain which is incised (3m) by the present Boteti river channel. This channel flows across the distal margin of Delta 1 before cutting through a mainland peninsula (as the inter-delta channel) before disgorging into a second pan delta (Delta 2). The aims of this work are to ascertain the relative ages of Delta 1 and Delta 2 and to determine the nature of deposition in Delta 1 and the inter-delta channel. Using height data from SRTM 2 imagery, we determined that Delta 1 increases in height distally throughout its downstream length (12 km) from 907 to 913 m above sea level while elevations along the inter-delta channel are higher. Sediment analysis using SEM and XRD techniques showed that the interdelta channel was underlain by 40 m of ‘silcrete’, comprising halite, amorphous silica and clay with upper diatomaceous units. Sediments from Delta 1 comprised at least two metres of massive sediment made up of fragmented calcite-rich plates (< 2 mm), silica (diatoms mainly with amorphous silica), halite and minor clay, being mostly smectite with illitite and halloysite. The sediments appear to represent a weathering suite interspersed with and surmounted by evaporates and diatoms indicative of shallow, rapidly drying aquatic environments. The results shed light on the anomaly of co-deposited calcium and silca rich sediments in saline environments and imply that the inter-delta channel and Delta 2 pre-date the formation of Delta 1. Although radiocarbon dates are pending it is expected that the results have wider applications for palaeo-climatic interpretations in the southern African region. 400-YEAR MAY-AUGUST PRECIPITATION RECONSTRUCTION FOR ENGLAND USING STABLE OXYGEN ISOTOPE RATIOS (d 18O) OF TREE RINGS Katja Rinne. Paul Scherrer Institute, Switzerland E-mail address: [email protected]
We present annually resolved data of precipitation covering the most recent 400 years for England. The May-August precipitation series, which was formed by combining reconstructed values (1613-1893) and instrumental data (1894-2003), indicates significant decadal and centennial precipitation variability culminating in dry conditions in the early-middle 17th century and the late 20th century. The period 1613-1893 is based on d18O in tree ring cellulose of pedunculate oak (Quercus robur). The analysis demonstrated statistically robust May-August precipitation signal in the d18O values of Woburn oak cellulose back to 1697, the first year of the oldest instrumental precipitation series in England. Independent proxy NAO reconstructions have reported a prevailing low winter NAO index prior to the end of the 17th century possibly induced by the decreased solar irradiance. The observed late spring-summer precipitation pattern observed in the present study may indicate the extension of these atmospheric conditions to summer months at this time. A potential problem in using tree ring parameters for climate reconstruction is the effect of non-
THE LAACHER SEE-ERUPTION (C. 13KY BP) AND SOCIETAL CHANGE AMONGST PERIPHERAL LATE GLACIAL HUNTER-GATHERERS IN SOUTHERN SCANDINAVIA Felix Riede. Aarhus University, Denmark E-mail address: [email protected]
This paper is concerned with the palaeolecological, societal and culturehistorical impact of the catastrophic Laacher See volcanic eruption (c. 13ky BP), especially at a great distance from the eruptive center. It has been suggested that various mechanistic links (e.g. increased dental abrasion, negative respiratory effects as well as F-poisoning) may have contributed to animals and humans deserting the areas affected by tephra fall-out from this eruption. Consequently, a case can be made that at least one particular archaeological phenomenon of this period - the so-called Bromme culture of southern Scandinavia - emerged as a result of the redistribution of human populations following the eruption. The potential full extent of the societal impact of this eruption cannot, however, be understood with reference to direct negative impacts alone. Many of these would have been of insufficient duration to cause a medium-to-long term fragmentation of otherwise highly mobile hunter-gatherers. In considering aspects of the perception of this dramatic events, it is possible to suggest that a) mobility would have been the response of choice for these foragers in avoiding the immediate effects of the eruption, and that b) other, less tangible factors may have played an important role in extending the temporality of this extreme event beyond these immediate effects. A coupled consideration of both the ecological, demographic as well as the psychological and cultural effects of this high magnitude/low frequency event throws new light on the origin of the Bromme culture. Some 200-300 years after this event the rapid cooling of GS-1 once again reshuffled populations on the Northern European Plain, leading to the disappearance or transformation of this culture. A LAACHER SEE-ERUPTION SUPPLEMENT TO TEPHRABASE. A REVISED TEPHRA FALLOUT MAP AND NEW GEOCHEMICAL DATA Felix Riede. Aarhus University, Denmark E-mail address: [email protected]
Tephrabase (www.tephrabase.org) is an online data repository and research tool for tephrochronological investigations in northern Europe. Here we present an update to Tephrabase that contains geographic and, as far as available, geochemical data on 444 data-points for the widespread isochronous Laacher See tephra. This tephra is dated to c. 12,920 calendar years BP and acts as an important chronostratigraphic marker for the Lateglacial GI-1a/late Allerød chronozone in terrestrial and lacustrine palaeoenvironmental archives as well as in archaeological stratigraphies. Based on these data, we present a revised map of the total tephra distribution, suggesting that it is even more widespread than previously stated and that the north-eastern fallout lobe might contain a secondary thickness maximum between 200-300 km distance from the eruptive centre. In addition, new geochemical data from a series of distal tephra deposits spanning most of the north-eastern fallout lobe are used to evaluate previous suggestions regarding the distribution of fallout from distinct eruption phases. The aim of our study is that future tephrochronological investigations can use this database and our revised distribution map for effectively targeting sites for analysis. CONSTRUCT THE MIDDLE PLEISTOCENE CLIMATE OF SOUTH EAST MEDITERRANEAN USING SPELEOTHEM ISOTOPIC AND ELEMENTAL COMPOSITIONS, EGYPT Rifai Rifai. Environmental Studies & Research Institute, Minufi, Egypt E-mail address: [email protected]
The Wadi Sannur speleothems record climate changes spanning 188 and 136 kyr before present. Petrographically, the studied speleothem laminae are made up entirely of fibrous calcite except for one lamina that displays microspar fabric. Time-series analysis of the data set reveals regular changes in Sr/Ca and Mg/Ca at a scale that matches the thickness of the
403
different laminae. d18O values of the stalactite laminae range from -7.2 to -10.1 VPDB&. The lower d18Ocalcite values, which are correspond to the second oldest lamina (WSS5), indicate that the drip-waters were likely affected by evaporative fractionation and that the speleothem activity has probably stopped due to the very arid conditions that followed the pluvial period. The variations of the d13C values between -5.0 and -2.3& VPDB argue that the drip water composition is influenced by the interaction with the overlying grass-covered ecosystem and the degree of aridity rather than the bedrock (d13C -0.9&VBDP). 87Sr/86Sr ratios of the interglacial lamina are low (0.70781-0.70808), whereas the glacial lamina display higher ratios (0.70826- 0.70859) in comparison with the nummulitic limestone bedrock (0.70823). Keywords: Egypt, Mediterranean, Wadi Sannur speleothems, fibrous textures, U-series dates, Middle Pleistocene, stalactite, pluvial period. DEPOSITIONAL PALAEO-ENVIRONMENTS OF THE BOTETI DELTA, MAKGADIKGADI PANS (BOTSWANA KALAHARI) Susan Ringrose. ORI-University of Botswana, Botswana E-mail address: [email protected]
The Boteti delta (Delta 1) forms an important link between the OkavangoBoteti drainage system and the Makgadikgadi salt pans and comprises an extensive plain which is incised (3m) by the present Boteti river channel. This channel flows across the distal margin of Delta 1 before cutting through a mainland peninsula (as the inter-delta channel) before disgorging into a second pan delta (Delta 2). The aims of this work are to ascertain the relative ages of Delta 1 and Delta 2 and to determine the nature of deposition in Delta 1 and the inter-delta channel. Using height data from SRTM 2 imagery, we determined that Delta 1 increases in height distally throughout its downstream length (12 km) from 907 to 913 m above sea level while elevations along the inter-delta channel are higher. Sediment analysis using SEM and XRD techniques showed that the interdelta channel was underlain by 40 m of ‘silcrete’, comprising halite, amorphous silica and clay with upper diatomaceous units. Sediments from Delta 1 comprised at least two metres of massive sediment made up of fragmented calcite-rich plates (< 2 mm), silica (diatoms mainly with amorphous silica), halite and minor clay, being mostly smectite with illitite and halloysite. The sediments appear to represent a weathering suite interspersed with and surmounted by evaporates and diatoms indicative of shallow, rapidly drying aquatic environments. The results shed light on the anomaly of co-deposited calcium and silca rich sediments in saline environments and imply that the inter-delta channel and Delta 2 pre-date the formation of Delta 1. Although radiocarbon dates are pending it is expected that the results have wider applications for palaeo-climatic interpretations in the southern African region. 400-YEAR MAY-AUGUST PRECIPITATION RECONSTRUCTION FOR ENGLAND USING STABLE OXYGEN ISOTOPE RATIOS (d 18O) OF TREE RINGS Katja Rinne. Paul Scherrer Institute, Switzerland E-mail address: [email protected]
We present annually resolved data of precipitation covering the most recent 400 years for England. The May-August precipitation series, which was formed by combining reconstructed values (1613-1893) and instrumental data (1894-2003), indicates significant decadal and centennial precipitation variability culminating in dry conditions in the early-middle 17th century and the late 20th century. The period 1613-1893 is based on d18O in tree ring cellulose of pedunculate oak (Quercus robur). The analysis demonstrated statistically robust May-August precipitation signal in the d18O values of Woburn oak cellulose back to 1697, the first year of the oldest instrumental precipitation series in England. Independent proxy NAO reconstructions have reported a prevailing low winter NAO index prior to the end of the 17th century possibly induced by the decreased solar irradiance. The observed late spring-summer precipitation pattern observed in the present study may indicate the extension of these atmospheric conditions to summer months at this time. A potential problem in using tree ring parameters for climate reconstruction is the effect of non-