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The 8.2 ka event is a well-known cooling event in the Northern Hemisphere, but is poorly understood in Madagascar. Here, we compare paleoclimate data and outputs from paleoclimate simulations to better understand it. Records from Madagascar suggest two distinct sub-events (8.3 ka and 8.2 ka), that seem to correlate with records from northern high latitude. This could indicate causal relationships via changes in the Atlantic Meridional Overturning Circulation (AMOC) with changes in moisture source's δ18O, and changes in the mean position of the Inter-Tropical Convergence Zone (ITCZ), as climate modelling suggests. These two sub-events are also apparent in other terrestrial records, but the climatic signals are different. The prominent 8.2 ka sub-event records a clear antiphase relationship between the northern and southern hemisphere monsoons, whereas such relationship is less evident during the first 8.3 ka sub-event. Data–model comparison have also shown a mismatch between the paleoclimate data and the model outputs, the causes of which are more or less understood and may lie in the proxies, in the model, or in both data and model. Knowing that paleoclimate proxies and climate models produce different sets of variables, further research is needed to improve the data–model comparison approach, so that both paleoclimate data and paleoclimate models will better predict the likely climate status of a region during a specified time in the past with minimal uncertainties.

Paleodischarge estimates based on the slope-area method and channel boundaries determined from stratigraphic cross-sections indicate that large, terminal Pleistocene meandering paleochannels (“mega-meanders”) in river valleys of the southeastern Atlantic Coastal Plain of the United States represent bankfull flows that were at least double the magnitude of those on modern rivers. Correlation of radiocarbon- and luminescence-dated paleomeanders with previously reported pollen and eolian sedimentary records suggests that greater discharge was driven by seasonally wetter conditions resulting from dynamic changes to regional precipitation and runoff that occurred in association with global warming at the end of the Pleistocene. While reflecting larger channel-forming flows, the exceptionally large widths and radii of curvature of mega-meanders were nonetheless maintained by a relatively modest discharge magnitude that was between two and four times larger than modern bankfull flow and within the size range of the present two- to five-year flood. Despite their large planform, the paleochannels conveyed relatively modest bankfull discharges because a wide, shallow shape limited their cross-sectional area and hydraulic radius. Within the late Quaternary evolution of fluvial systems in the region, scrolled mega-meanders constitute a transitional meandering planform that remained influenced by large volumes of sandy bedload following the sand-bed braided channels of the late Wisconsin interval, circa 30–17 ka. In addition to greater discharge, the large planimetric dimensions of paleochannels reflect a lack of cohesive vertical accretion facies on paleomeander floodplains, a sediment regime that transported large quantities of bedload sand, and the influence of these factors on channel boundary composition, bank stability, and channel shape. Findings underscore the importance of reconstructing channel cross-sectional dimensions and slope when estimating discharge for infilled paleomeanders. This approach reduces uncertainties surrounding channel cross-sectional area, gradient, and boundary composition inherent to studies lacking subsurface data that rely upon meander geometry to retrodict discharge.

Speleothem, tufa and sand dune age data for Namibia, Botswana and the Transvaal of South Africa have provided a detailed record of wet and dry periods in the southern African summer rainfall zone to 300 ka. Three sites record moister conditions between 202–186 ka. The period 50–14 ka was characterized by five wet periods at 50–43, 38–35, 31–29, 26–21, and 19–14 ka. There is also strong evidence for increased moisture during the mid and late Holocene from 6.9–2.6 and 1.8–0.5 ka. Ages from submerged speleothems in Namibia and for dune activity at Etosha Pan and in the Kalahari Desert indicate significant dry periods at 35–31, 29–28, and 11–8 ka. Speleothem, tufa and rock shelter sediment data for Somalia show wet conditions at 260–250, 176–172, 160, 116–113, 87–85, 13, 10, 7.5, 5, and 1.5 ka. The most obvious differences in the last 35 ka, between the two records, are that southern Africa experienced wet conditions in late glacial times, when East Africa was dry, and East Africa experienced wet conditions in the early Holocene, when southern Africa was dry.

El objetivo de este trabajo es presentar los nuevos resultados obtenidos en torno a las ocupaciones tempranas en el sitio La Gruta 1, área de La Gruta, extremo sur del Macizo del Deseado, Patagonia argentina. Éstos se refieren tanto a la transición Pleistoceno-Holoceno como al Holoceno temprano y abarcan aspectos paleoambientales, nuevos fechados radiocarbónicos, además de la disponibilidad y utilización de materias primas. Se presentan los resultados de los nuevos análisis polínicos, realizados en un mallín del área ubicado en la meseta central, cerca de la localidad arqueológica Viuda Quenzana, con una edad basal de ca. 12.500 años AP (14.500 cal AP). Por otra parte, a partir de los resultados obtenidos se infiere una vegetación similar a la reconstruida por otros registros polínicos del área que sugieren condiciones húmedas durante el segundo período de ocupación humana del sitio arqueológico La Gruta 1, comprendido entre ca. 11.000 y 8000 cal AP Las evidencias procedentes de la ampliación de las excavaciones en este sitio muestran la falta de continuidad entre los fechados correspondientes a la transición Pleistoceno-Holoceno y los del Holoceno temprano. En ambos períodos existe evidencia de transporte de materias primas desde otros espacios, que incluyen artefactos bifaciales, lo que es consistente con la información obtenida previamente., This work presents new results obtained regarding early occupations at La Gruta 1 site, in the area of La Gruta, at the southern extreme of the Deseado Massif, Argentine Patagonia. These results encompass both the Pleistocene-Holocene transition and the Early Holocene and include paleoenvironmental information and new radiocarbon dates, as well as additional data on the availability and utilization of lithic raw materials. We present the results of the analysis of the lowest part of a wet meadow located in the Deseado Massif, close to the Viuda Quenzana archaeological locality. Its base is dated at ca. 12,500 years BP (14,500 cal BP). The results obtained allow us to infer the existence of vegetation similar to the one reconstructed for other sites of the area, suggesting the occurrence of more humid conditions during the second period of human occupation in La Gruta 1, dated between ca. 11,000 and 8000 cal BP Evidences obtained through broadening of the excavation show a lack of continuity between the samples dating from the Pleistocene-Holocene transition and those that correspond to the Early Holocene. Both periods present evidences of the transport of raw material from other zones into the area, including bifacial artifacts, which is consistent with human behavior during this time period., O objetivo deste trabalho é apresentar os novos resultados obtidos em torno das ocupações iniciais no sítio de La Gruta 1, região de La Gruta, extremo sul do Maciço de Deseado, Patagônia argentina. Referem-se tanto à transição Pleistoceno-Holoceno quanto ao Holoceno inicial e abrangem aspectos paleoambientais, novas datação radiocarbônicas, além da disponibilidade e uso de matérias-primas. Apresentam-se os resultados das novas análises de pólen, realizadas em um banhado da área localizado no planalto central, próximo à localidade arqueológica Viuda Quenzana, com idade basal de ca. 12.500 anos AP (14.500 cal AP). Por outro lado, a partir dos resultados obtidos infere-se uma vegetação similar à reconstruída por outros registros polínicos da área que sugerem condições úmidas durante o segundo período de ocupação humana do sítio arqueológico La Gruta 1, compreendido entre ca. 11.000 e 8000 cal AP As evidências procedentes da expansão das escavações neste sítio mostram a falta de continuidade entre as datações correspondentes à transição Pleistoceno-Holoceno e as do Holoceno inicial. Nos dois períodos há evidência de transporte de matérias-primas de outros espaços, que incluem artefatos bifaciais, o que é consistente com a informação obtida previamente., Dossier: Ocupaciones tempranas en América: voces desde el Cono Sur, Facultad de Ciencias Naturales y Museo

The 4.2 ka Event has generally been regarded as a period of decades to at most a few centuries in which comparatively dry conditions existed in the Middle East and more broadly across the mid-latitude Northern Hemisphere. This paper presents new stable-isotopic and petrographic observations from two previously-unreported U-Th-dated stalagmites from Dante Cave in northeastern Namibia. The results are most compatible with wetter conditions during the 4.2 ka Event, and wetness during the 4.2 ka Event is the only inference supported by evidence. These new results add to observations previously reported from a third Dante Cave stalagmite suggesting a comparatively wet 4.2 ka Event in which Africa's Tropical Rain Belt migrated southward and rainfall increased along the Congo Air Boundary and/or Kalahari Discontinuity. The new results support findings from three other locations in Namibia and Botswana, from at least seven other locations in the Southern Hemisphere, and at least one in southern China, that suggest a wetter rather than drier 4.2 ka Event in those regions. The pattern emerging from these sites generally agrees with recent modeling results indicating increased moisture over broad areas (but not all) of the Southern Hemisphere. This in turn suggests a 4.2 ka Event that was not a global drought but was instead a set of latitudinally-dependent responses to global-scale southward migration of the Inter-Tropical Convergence Zone (ITCZ), and thus Africa's loosely linked Tropical Rain Belt, as a result of cooling of the Northern Hemisphere, which brought drier conditions to some areas and wetter conditions to others.

A multi-proxy record of past climate from a stalagmite from Bone Cave in northwestern Botswana suggests relatively wet conditions late in the Little Ice Age and progressively drier conditions in the twentieth century. The proxies include surfaces of dissolution, variation in layer-specific width, changing mineralogy, varying abundance of detrital material, varying growth rate, and oxygen and carbon isotope data. They combine to suggest a period of exceptional wetness that can be assigned with greatest certainty to ~1810–1820 CE and may have been wettest in 1817. The same proxy data conversely suggest relatively dry conditions after about 1835, and increasing dryness after about 1930. Bone Cave lies in the summer rainfall zone, at the southern margin of the tropical rain belt associated with the Inter-Tropical Convergence Zone (ITCZ). Previously published data from other records combine with the Bone Cave record to support wetter conditions in the 1700s and until about 1830, and drier conditions thereafter. The period of exceptional wetness in ~1810–1820 recorded in BC97-14 coincides with a decade of exceptional cold in the Northern Hemisphere, and its acme may be coincident with the Tambora eruption and its resultant “year without a summer” in Europe and North America. These results are thus compatible with movement of the austral-summer ITCZ southward (rather than an increase in rain its customary position) when the Northern Hemisphere cooled relative to the Southern Hemisphere. Conversely, they suggest that the ITCZ has not come as far south as frequently during Earth's warming in the past century.

The first direct AMS radiocarbon dating of two rock art motifs in separate rock shelters (VQ1 and VQ2) at the Viuda Quenzana (VQ) archaeological locality in Patagonia, has provided median probability ages of 3190 cal BP for two reddish dots, and 520 cal BP (1430 CE) for a pink negative hand. These ages are consistent with evidence of occupation of sites in the locality and in the nearby region during the later part of the Middle Holocene (8200–4200 cal BP) and Late Holocene (4200 cal BP to present), as indicated by ages for bones and charcoal from sediments in the VQ8 and VQ7 rockshelters, and the nearby La Martita 4 and La Gruta 1 and 3 rockshelters ranging from ca. 5470 to 305 cal BP (Rubinos Perez 2003; Franco et al. 2013; Brook et al. 2015). The pink hand is relatively recent, which supports the notion that such artwork continued through the Late Holocene despite changes in other artistic motifs. Characterization by Raman spectroscopy, powder x-ray diffraction, and high-resolution scanning electron microscopy with energy dispersive spectroscopy shows that: 1) hematite is the main pigment in both the dot and hand motifs, 2) the reddish dot paint includes a specific type of hematite, microplaty hematite, and 3) animal fat appears to have been added as a binder to the reddish dot paint. Thus, rock art paint production at VQ involved two distinct processes. One, used to paint dots, entailed mixing a mineral coloring substance (hematite) with an organic binder (animal fat), which was then applied to the rock substrate with a painting tool and/or fingers. The second process, used to produce the hand motif, entailed using a mineral coloring substance (hematite) with no binder (or with a binder that left little chemical trace), which was then applied to the rock substrate by spraying, probably with the mouth. Fil: Brook, George. University of Georgia; Estados Unidos Fil: Franco, Nora Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas; Argentina Fil: Cherkinsky, Alexander. University of Georgia; Estados Unidos Fil: Acevedo, Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas; Argentina Fil: Fiore, Dánae. Asociación de Investigaciones Antropológicas; Argentina Fil: Pope, Timothy R.. University Of Georgia. Department Of Chemistry And Physics; Estados Unidos Fil: Weimar, Richard D.. University Of Georgia. Department Of Chemistry And Physics; Estados Unidos Fil: Neher, Gregory. University Of Georgia. Department Of Chemistry And Physics; Estados Unidos Fil: Evans, Hayden A.. University Of Georgia. Department Of Chemistry And Physics; Estados Unidos Fil: Salguero, Tina T.. University Of Georgia. Department Of Chemistry And Physics; Estados Unidos

El objetivo de este trabajo es informar sobre la recuperación de seis tiestos en el área ubicada entre el extremo sur del Macizo del Deseado y el río Santa Cruz. Si bien se trata de un registro arqueológico poco abundante, constituye un aporte significativo al conocimiento sobre el uso de esta tecnología entre grupos cazadores-recolectores en estas latitudes y en espacios intermedios entre la costa y la cordillera. Se presenta la información cronológica (AMS) e isotópica (δ13C y δ15N) generada a partir de la datación y análisis de las sustancias adheridas a las superficies planas de los fragmentos cerámicos. Asimismo, se exhiben los resultados de los análisis macroscópicos de los tiestos y microscópicos de las pastas. Sobre esta base se indaga acerca de las características de la cerámica, su posible función y el marco cronológico de uso de esta tecnología. Los resultados alcanzados son consistentes con aquéllos obtenidos en la región y apuntan a un uso tardío de la cerámica, a la utilización de recursos de estepa y a la posible obtención y transporte de recipientes por grupos indígenas con alta movilidad desde otros espacios. The purpose of this paper is to provide information about six sherds recovered from the area between the Southern Deseado Massif and the Santa Cruz River Basin. Very few sherds have been recovered from this region previously, and so these findings make a significant contribution to what is known about ceramic technologies used by hunter-gatherers at these latitudes, in an area located between the Andean range and the Atlantic coast. This paper provides macroscopic and microscopic data of the six sherds, which show considerable variability. It also reports isotopic values (δ13C and δ15N) and direct AMS radiocarbon ages for organic residues adhering to the flat faces of two sherds. The results are consistent with those from earlier studies indicating the use of ceramic technology by highly mobile indigenous groups in Southern Patagonia for steppe resources. Variations in sherd composition suggest that the original ceramic containers were probably acquired and transported into the region from other spaces. Fil: Cirigliano, Natalia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas; Argentina Fil: Montenegro, Teresita Francis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina Fil: Franco, Nora Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas; Argentina. Universidad de Buenos Aires. Facultad de Filosofía y Letras; Argentina Fil: Brook, George. University of Georgia; Estados Unidos Fil: Cherkinsky, Alexander. University of Georgia; Estados Unidos

WOS: 000443304600007, In the Avlam Valley, 10km north of Eskiehir (NW Anatolia), an undamaged triangular Levallois flake was encountered in a paleosol, 430cm beneath the ground surface. The artifact has a minimal dorsal retouch on the right margin, and there is a light beige partial patina on the ventral surface. Based on the technological investigations, this artifact was made using the centripetal recurrent Levallois technique. An observation of the trench walls revealed the triple nature of the stratigraphy: an upper gravelly sand (Unit-1), an underlying reddish-brown pebbly paleosol (Unit-2), and a lowermost dominantly pink, finer-grained deposit (Unit-3) where the artifact was retrieved. Optically stimulated luminescence ages indicate a strong influence of global marine isotopic stages (MIS) on the trench stratigraphy, with the deposit hosting the artifact dating to 148 +/- 20 ka (MIS 6 cold period). The available pollen data from the same stratigraphic level verified an open steppe landscape with some arboreal plant cover during deposition. This is the first stratigraphically dated Middle Palaeolithic artifact from NW Anatolia, and one of the few in the whole country, thus igniting further discussion about the ways Pleistocene hominins adapted to cold and arid environmental conditions., Commission for Scientific Research at Eskisehir Osmangazi University, Turkey [2013/15009], The authors are grateful to Engin Basaran and Celik Ocako. glu for their assistance with the trench studies and the OSL sampling. The comments from two anonymous reviewers significantly improved our manuscript, for which we are grateful. This study was financially supported by the Commission for Scientific Research at Eskisehir Osmangazi University, Turkey (project no. 2013/15009).

The climatic event between 4.2 and 3.9 ka BP known as the “4.2 ka event” is commonly considered to be a synchronous global drought that happened as one pulse. However, careful comparison of records from around the world shows that synchrony is possible only if the published chronologies of the various records are shifted to the extent allowed by the uncertainties of their age data, that several records suggest a two-pulsed event, and that some records suggest a wet rather than dry event. The radiometric ages constraining those records have uncertainties of several decades if not hundreds of years, and in some records the event is represented by only one or two analyses. This paper reports a new record from Stalagmite DP1 from northeastern Namibia in which high 230Th/232Th activity ratios allow small age uncertainties ranging between only 10–28 years, and the event is documented by more than 35 isotopic analyses and by petrographic observation of a surface of dissolution. The ages from Stalagmite DP1 combine with results from 11 other records from around the world to suggest an event centered at about 4.07 ka BP with bracketing ages of 4.15 to 3.93 ka BP. The isotopic and petrographic results suggest a two-pulsed wet event in northeastern Namibia, which is in the Southern Hemisphere's summer rainfall zone where more rain presumably fell with southward migration of the Inter-Tropical Convergence Zone as the result of cooling in the Northern Hemisphere. Comparison with other records from outside the region of dryness from the Mediterranean to eastern Asia suggests that multiple climatic zones similarly moved southward during the event, in some cases bringing wetter conditions that contradict the notion of global drought.

In view of a scarcity of terrestrial Quaternary pollen records relating to climate change in desert areas, we present new terrestrial sequences from hyrax middens in Namibia. While the few previously available pollen records are mainly Holocene, we present climate time series for Marine Isotope Stages 2 and 3 (MIS 2 and MIS 3). The data are from two sites in central Namibia that are surrounded by desert plains and close to the Namibian escarpment, viz., the Dâures Massif (Brandberg) and 200 km further south, the Mirabib Shelter located in a small inselberg. In the studied material, grass-rich pollen assemblages were more common at Mirabib where the vegetation is desert grassland, than at Brandberg with its mountain vegetation. Hyrax radiocarbon ages range from 21 ka to >50 ka, with inconsistencies in ages near the limit of effective radiocarbon dating. However, correlation of overlapping sequences supports the chronology we present. Despite chronological gaps in the available deposits, pollen assemblages from different middens indicate marked climate cycles, starting with moderately cool dry conditions with grassy karroid vegetation at Mirabib c. 50 ka. After a gap in the record, warmer conditions with savanna woodland are indicated at both Mirabib and Brandberg around 40 ka. Eventually, cool conditions supporting shrubby grassland with wild olives developed at Brandberg during MIS 2, c. 21 ka. Comparison with marine pollen data confirms earlier findings that terrestrial pollen assemblages differ markedly from South Atlantic Ocean marine pollen assemblages of the same age presumably due to mixing of pollen from wide source areas at the marine localities versus the more locally restricted terrestrial pollen sources trapped in hyrax dung. The results therefore add information for the interpretation of local vegetation shifts on land during the interval between 50 ka and 21 ka in Namibia.

Petrographic features, mineralogy, and stable isotopes from two stalagmites, ANJB-2 and MAJ-5, respectively from Anjohibe and Anjokipoty caves, allow distinction of three intervals of the Holocene in NW Madagascar. The Malagasy early Holocene (between ca. 9.8 and 7.8 ka) and late Holocene (after ca. 1.6 ka) intervals (MEHI and MLHI, respectively) record evidence of stalagmite deposition. The Malagasy middle Holocene interval (MMHI, between ca. 7.8 and 1.6 ka) is marked by a depositional hiatus of ca. 6500 years. Deposition of these stalagmites indicates that the two caves were sufficiently supplied with water to allow stalagmite formation. This suggests that the MEHI and MLHI intervals may have been comparatively wet in NW Madagascar. In contrast, the long-term depositional hiatus during the MMHI implies it was relatively drier than the MEHI and the MLHI. The alternating wet–dry–wet conditions during the Holocene may have been linked to the long-term migrations of the Intertropical Convergence Zone (ITCZ). When the ITCZ's mean position is farther south, NW Madagascar experiences wetter conditions, such as during the MEHI and MLHI, and when it moves north, NW Madagascar climate becomes drier, such as during the MMHI. A similar wet–dry–wet succession during the Holocene has been reported in neighboring locations, such as southeastern Africa. Beyond these three subdivisions, the records also suggest wet conditions around the cold 8.2 ka event, suggesting a causal relationship. However, additional Southern Hemisphere high-resolution data will be needed to confirm this.

The first systematic research on the funerary record at the Rió Bote 1 (RB1) rockshelter, located next to the Bote River, a tributary of the Santa Cruz River in southern Patagonia, has revealed at least three human burial events dating to the very early Late Holocene and one dating to the middle Late Holocene. The RB1 site appears to have been used for both subsistence and inhumation activities. All of the burials uncovered postdate the deposition of a prominent volcanic ash layer. Technological information indicates that RB1 was used by groups that were also using spaces to the west and south. Mortuary evidence indicates connections with groups living in areas extending from the Última Esperanza region to the Pali Aike volcanic field, at least at the beginning of the Late Holocene. The selection of the same place for multiple burials may explain why so few human burials are known in southern Patagonia from the beginning of the Late Holocene and earlier periods, as it is possible that sites like RB1 are yet to be discovered. Fil: Franco, Nora Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas; Argentina Fil: Brook, George. University of Georgia; Estados Unidos Fil: Garcia Guraieb, Solana. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; Argentina. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Mancini, Maria Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Guarido, Ana Lucía. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Mehl, Adriana Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Montenegro, Teresita Francis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina

Air temperature is correlated with precipitation oxygen isotope (δ18Oprcp) variability for much of the eastern and central United States, but the nature of this δ18Oprcp-temperature relationship is largely based on data coarsely aggregated at a monthly resolution. We constructed a database of 6177 weeks of isotope and precipitation-day air temperature data from 25 sites to determine how more precise data change our understanding of this classic relationship. Because the δ18Oprcp-temperature relationship is not perfectly linear, trends in the regression residuals suggest the influence of additional environmental factors such as moisture recycling and extratropical cyclone interactions. Additionally, the temporal relationships between δ18Oprcp and temperature observed in the weekly data at individual sites can explain broader spatial patterns observed across the study region. For 20 of 25 sites, the δ18Oprcp-temperature relationship slope is higher for colder precipitation than for warmer precipitation. Accordingly, northern and western sites with relatively more cold precipitation events have steeper overall relationships with higher slope values than southeastern sites that have more warm precipitation events. Although the magnitude of δ18Oprcp variability increases to the north and west, the fraction of δ18Oprcp variability explained by temperature increases due to wider annual temperature ranges, producing stronger relationships in these regions. When our δ18Oprcp-temperature data is grouped by month, we observe significant variations in the relationship from month to month. This argues against a principal causative role for temperature and suggests the existence of an alternative environmental control on δ18Oprcp values that simply co-varies seasonally with temperature.

The timing and causes of paleoenvironmental changes in Madagascar have been debated, specifically in respect to human activity following the settlement in the late Holocene. Here we present δ18O, δ13C, layer-bounding surfaces, layer-specific width, mineralogy, and distribution of macroholes from Stalagmite MA3 from Anjohibe Cave to provide a detailed understanding of the paleoenvironmental changes in northwestern Madagascar between 370 CE and 1300 CE. The stable isotope records of Stalagmite MA3 are compared with stable isotope records of Stalagmites ANJ94-5 and MA2. Detailed examination of the proxies suggests three distinct intervals of changes. (1) Prior to 795 CE, changes in vegetation seem to have responded to changes in monsoonal rainfall linked to the relative position of the ITCZ. The period between ca. 755 CE and 795 was the driest, and the Stalagmite MA3 record is consistent with sediment records (pollen and lithology) from Lake Mitsinjo, northwestern Madagascar, and with sediment records (fossil pollen and charcoal) from Sainte Luce, southeastern Madagascar. (2) Between 795 CE and 870, the environmental conditions became more favorable, when vegetation recovered from the driest interval. The new conditions must have been suitable for community development in the region as suggested by archaeological evidence around Lake Mitsinjo and the Boeny region, and the establishment of the stone town of Mahilaka. (3) After 870 CE, a gradational change in plant communities from C3 to C4 marks the record until around 1130 CE, after which vegetation was dominated by C4 plants. This change cannot be explained by climate alone, as there is no clear relationship in the climate-sensitive proxies. Instead, it could have been caused by “Tavy”, a variety of “swidden” agriculture practiced in the region.

Geomorphological studies have been carried out in rapidly evolving salt caves related to small watersheds in the San Pedro de Atacama area, Chile. Radiocarbon ages of bones and wood from cave deposits, combined with the presence of large salt caves, geomorphological and sedimentological observations, and the results of micrometer measurements outside and in some of the caves, suggest a period of speleogenesis in the Cordillera de la Sal during the onset of the Holocene, during which the large halite cave systems developed, followed by an early Holocene hyperarid period. Most smaller caves (i.e. Lechuza del Campanario) most probably formed at the start of the wetter mid-Holocene period (5–4.4 ka), when precipitation was never intense enough to entrain large amounts of sediments, but enough to trigger cave development. A diamicton in Lechuza del Campanario Cave radiocarbon dated at ca. 4.4 ka shows that at least one high intensity rainfall event occurred in this recharge basin during the mid-Holocene wet interval. A wet period with lower intensity rainfall events followed between 4.0 and 2.5 ka, causing the 4.4 kyrs old diamicton in Lechuza del Campanario Cave to be entrenched, and the alluvial fan at the downstream end of Palacio del Sal Cave to be covered with windborne sediments dated by OSL at around 3.6 ka. At ca. 2 ka there was a high-intensity rainfall event documented by the age of a twig stuck in the ceiling of the Palacio del Sal Cave, followed by a period with lower intensity rain events until ca. 1.3 ka, when another intense flood produced a mudflow that deposited a second diamicton in Lechuza del Campanario Cave. From then on clustering of radiocarbon ages for wood and bone recovered from caves indicates increased rainfall intensity in the period ca. 0.9–0.5 ka, followed by no registered events until a minor flood at ca. 0.13 ka. The four-centuries long wetter time interval (0.9–0.5 ka), corresponding to the Medieval Climate Anomaly, has been an archeologically important period in the Atacama Desert (Tiwanaku culture). The observations and a detailed review of paleoclimate literature from this key area have allowed the development of a landscape evolution model related to changing climate conditions during the Late Holocene.

The stalagmite MC01 was recovered from Macal Chasm cave on the Vaca Plateau of Belize in 1995, and an initial paleoclimate interpretation was published in 2007. Additional uranium-thorium ages have extended the paleoenvironmental record back from 3250 to 5250 cal yr BP, and the stable isotope (δ18O and δ13C) record is dramatically improved by 660 new values. A series of major dry events (MDEs) evident in stable isotopes, ultraviolet-stimulated luminescence, and petrography began ~ 3100 cal yr BP, and the initiation of these events coincides with an increase in El Nino dominance and southern shift in the Intertropical Convergence Zone. Three MDEs, centered at 1750 cal yr BP (200 CE), 1100 cal yr BP (850 CE), and 850 cal yr BP (1100 CE) and found in other regional climate records, coincide with Maya sociopolitical changes. Residuals from regression of δ13C versus δ18O are interpreted as a proxy for maize cultivation and land clearing, with residual values gradually increasing at the start of Preclassic Period settlement (3950 cal yr BP/2000 BCE), peaking after 2250 cal yr BP (300 BCE) during major Maya development in the Late Preclassic and Classic Periods, and dropping to pre-Preclassic values after regional land abandonment (~ 850 cal yr BP/1100 CE). Regional Maya population growth and cultural expansion may have been aided by abnormally low precipitation variability, as stable isotope variability suggests the Late Preclassic through the Late Classic was the most stable precipitation regime of the past 4000 years. This additional research on MC01 complements other regional paleoenvironmental records that suggest that MDEs coincided with disruptions in Maya society from the Preclassic through the Postclassic Periods. Although it is clear that not all significant sociopolitical changes can be attributed to the MDEs, these events likely played an antagonistic role in social stability.

Multiple proxies using variation in δ18O, δ13C, mineralogy, and petrography in a newly generated high-resolution record of Stalagmite DP1 from Dante Cave indicate a linkage between changes in hydroclimate in northeastern Namibia and changes in solar activity and changes in global temperatures. The record suggests that during solar minima and globally cooler conditions (ca. 1660–1710 and ca. 1790–1830), wetter periods (reflecting longer summer seasons) in northeastern Namibia were linked to advances of the Inter-Tropical Convergence Zone (ITCZ) and the Inter-Ocean Convergence Zone (IOCZ) southwestward. A slight southward push of the Angola–Benguela Front (ABF) during such intervals could also be expected, bringing more rainfall inland. On the other hand, drier and warmer periods in northeastern Namibia, inferred from the increasing δ18O trend in Stalagmite DP1 after AD 1715, coincide with globally warmer conditions, and thus a northeastward migration of the ITCZ, specifically with more warming of the Northern Hemisphere (NH). This finding agrees with reducing precipitation observed in the summer rainfall zone of southern Africa since ca. 1900. Therefore, predictions of warming in high-latitude regions of the NH in the next century should suggest that the presently semi-arid climate of northern Namibia may become even drier.

Horizontal cores from a large stalagmite and two tufa deposits in the entrance to Wonderwerk Cave, South Africa, dated by radiocarbon methods, have provided climate proxy data on late Holocene environments near the cave. The δ18O and δ13C time series from stalagmite Core WW1–3 and tufa Core WW3 correlate well with isotope records for other sites in the summer rainfall zone of southern Africa and suggest that late Holocene warm periods in the Northern Hemisphere, including the Medieval Warm period, Roman Warm period, and Minoan Warm period, were times of increased moisture in this rainfall zone. In contrast, late Holocene cold intervals in the Northern Hemisphere, including the Dark Ages Cold period and Sub-Atlantic Cold period, were times of drier climate in the summer rainfall zone. Comparison of the Wonderwerk records with information on human settlement patterns, agricultural expansion or decline, and population growth or decline, shows that growth occurred preferentially during wetter climate periods and declines, including the abandonment of the important town of Mupungubwe in the Shashe-Limpopo area of northeast South Africa and the fall of Great Zimbabwe, which occurred during periods of low precipitation.

In the Abu El-Egl playa basin between Kharga and Dakhla, below the Abu Tartur plateau, over 10 m thick thinly stratified sediments remain as long dissected ridges. On the basis of luminescence ages they were deposited during the humid period in the Sahara corresponding to MIS 5, up to a level of a lake at about 180 m a.s.l. The floor, at about 170 m a.s.l., consisting of homogenous loamy material and sands with an early Holocene luminescence age, surrounds the ridges. The playa floor was later occupied at about 7000 yr BP according to radiocarbon ages of charcoal from fireplaces and a sample of ostrich eggshell. The main erosion of the old lake sediments was assumed to have taken place during the humid period of MIS 3, before the subsequent arid period of MIS 2. This is supported by the finds of Middle Palaeolithic artefacts on the playa floor between the ridges of the eroded lake sediments.

There is very little dated evidence on wet periods in the Eastern Desert and Sinai Peninsula of Egypt during the Late Pleistocene and Holocene. To obtain such information, we have studied the petrography, isotope geochemistry and AMS radiocarbon ages of mostly relict tufas deposited by springs draining perched ground water bodies in metamorphic and volcanic rocks. The tufas unconformably overly Precambrian basic igneous rocks (basalt, diabase and gabbro). As the ages of tufa carbonate are frequently older than the true ages of the deposits because of the incorporation of old, 14C-dead carbon, we have dated both the carbonate matrix and insoluble organic material of the tufas. These ages show that the tufas were largely formed during two broad time periods, the most recent from 12,058 to 6678 cal yr BP (African Humid Period), and the other from ∼31,200–22,500 cal yr BP, with preferential growth during the coldest times of this period namely during Heinrich Events 2 and 3 (H2 and H3) and the Last Glacial Maximum (LGM). The time span between 19,000–9000 cal yr BP, including the YD and H1, appears to have been relatively more arid than the earlier LGM or H2 periods or the later Holocene. The Late Pleistocene tufas are depleted in 18O relative to the Holocene tufas and were deposited at a lower temperature (∼14.0°–20.8 °C vs. 18.4°–23.4 °C). We believe that the Holocene tufas in the Sinai were formed by rainfall from the Mediterranean and those in the southern part of the Eastern Desert by African monsoon rainfall derived from the Red Sea-Gulf of Aden and Indian Ocean. In contrast, the moisture that fed the Late Pleistocene tufas, which are depleted in 18O relative to Holocene deposits, and progressively depleted from north to south, was probably brought by the Westerlies from the Atlantic-Mediterranean Sea when the Westerly circulation was pushed southwards during the coldest periods of the Late Pleistocene. Periods of tufa deposition correlate with major documented paleoclimatic events in North Africa during the late Pleistocene and Holocene; such as the Nile floods, high sea level and the formation of sapropels in the Mediterranean.

Stalagmite ANJ94-2 from Anjohibe Cave in northwestern Madagascar provides an exceptionally detailed and precisely dated record of changing environmental conditions that, combined with previously published data from stalagmites, wetland deposits, and archaeological sites, allows insights into past climate change, human environmental impact, and megafaunal extinction. Proxies of past conditions recovered from Stalagmite ANJ94-2 include ratios of carbon and oxygen stable isotopes (δ13C and δ18O), mineralogy (calcite and aragonite), layer-bounding surfaces, layer-specific width, and detrital material. Those proxies suggest that the natural environment changed in response to changes in rainfall at time scales of a few decades to multiple centuries; comparison with distant proxies suggests that wetter conditions in northwestern Madagascar may have been linked to cooling in the Northern Hemisphere. Carbon isotope data nonetheless suggest that the greatest environmental change in the area coincided with human introduction of swidden (tavy) agriculture about 1200 years ago, during a time not of drought but perhaps of slightly increasing wetness. The timing and extent of environmental change 1200 to 600 years ago seen in stalagmite and wetland data suggest that human modification of the landscape had a causal role in the extinction of Madagascar’s megafauna. On the other hand, the results combine with other recent research to indicate that drought was not the cause of the megafaunal extinction.

Dating by the 230Th method indicates that Stalagmite DANf from Dante Cave in northern Namibia, in the Summer Rainfall Zone (SRZ) of southern Africa, formed about 92 ka, at the boundary of Marine Isotope Stages (MIS) 5b and 5c. In this dominantly semiarid zone, stalagmite growth may be evidence of a relatively wetter period, and trends in DANf's mineralogy and its C, O, and U isotope ratios further support formation in a period wetter than those before or after its formation. DANf's time of formation at 92 ka, like other wet periods in the SRZ of southern Africa over the most recent 100 kyr, coincides with a maximum in January insolation at 30°S that brought the SRZ, and more generally the tropical rain belt, farther south than before or after.

A horizontal core through a large, standing, stalagmite in Carlsbad Caverns National Park, New Mexico, USA, provides a radiometrically dated record of wetter glacial stages and drier interglacial stages over the last 560 kyr. The stalagmite, the Texas Toothpick, is about 7 m tall and about 3 m wide at its base. Two cores through the stalagmite reveal five distinct matching layers, and the best estimates from twenty U–Th ages indicate that those layers were deposited during MIS 6, 8, 10, 12, and 14, the five glacial periods ending with the Penultimate Glacial Maximum (PGM). Stable isotope data, measurements of remanent magnetism, and petrographic observations combine to suggest that conditions during glacials, the periods in which deposition took place, were significantly wetter than today. On the other hand, the stalagmite's hiatuses seemingly represent conditions during interglacials similar to or drier than today. These results combine with modern climatological observations to suggest 100-kyr-scale alternation between wetter conditions with an increased proportion of winter rainfall from a Pacific source during glacials to drier conditions with largely summer rainfall derived from the Gulf of Mexico during interglacials. The length and continuity of the results confirm that the pattern of wetter glacials and drier interglacials, known previously from studies isolated in time, existed across all of at least the last six glacial cycles. Simple monotonic extrapolation of these findings from cooler wetter glacials of the past and warmer drier interglacials like the present to a warmer climate expected in the coming century suggests that groundwater in the already dry southwestern United States may become even more scarce.

Variations in petrography, stable isotopes, reflectance, and luminescence along the central growth axis of a 14.5 cm stalagmite from Panigarh cave indicate cooler and slightly wetter conditions in the Himalayan foothills of northern India during the Little Ice Age (LIA), which lasted from ∼AD 1489–1889 based on deposition of calcite, and AD 1450–1820 based on rapid changes in δ18O values. Conditions were warmer and drier during the preceding Medieval Climate Anomaly (MCA) and also in the post-LIA periods, as evidenced by deposition of aragonite. A review of currently existing stalagmite and other proxy data from south and east Asia reveals a broad spatial pattern in precipitation over south and east Asia during the LIA, with northern areas showing generally increased precipitation and southern areas reduced precipitation. During the MCA and after the LIA, the records suggest this pattern was reversed. Weaker ISM during the LIA brought drought conditions to the core ISM area but triggered more monsoon ‘breaks’ that brought higher precipitation to the Himalayas. At the same time, the weaker ISM may also have pushed more depressions along the path of the southern winter jet which brought more winter precipitation to the Himalayas and therefore a LIA wetter in our study area.

This paper documents technological and behavioral changes in the southern part of the Upper Santa Cruz River Basin during the Late Holocene and examines possible relationships with environmental changes. The findings suggest an important relationship between human use of space and long-term trends in precipitation. This relationship is emphasized by the inverse correlation between precipitation near the Andes and that in the steppe further east.

Petrographic features, mineralogy, and stable isotopes from two stalagmites collected from Anjohibe and Anjokipoty Cave allow distinction of three intervals of the Holocene in northwestern Madagascar. The Malagasy early Holocene interval (between ca. 9.8 and 7.8 ka) was wet, and vegetation changes seem to have been controlled by changes in climate. The Malagasy late Holocene interval (after ca. 1.6 ka) also records evidence of wet conditions, but changes in vegetation were influenced by anthropogenic effects, as suggested by the stalagmite δ13C shift. The Malagasy middle Holocene interval seems to be characterized by drier conditions, relative to the early and late Holocene. The alternating wet/dry/wet conditions in northwestern Madagascar during each of these Holocene intervals could be linked to the long-term migration of the Inter-Tropical Convergence Zone (ITCZ). Higher southern hemisphere (SH) insolation and globally colder conditions drove the ITCZ's mean position further south, bringing more rainfall to northwestern Madagascar. This condition was favorable for stalagmite deposition. In contrast, higher northern hemisphere (NH) insolation and globally warmer conditions displaced the ITCZ further north, bringing less rainfall to northwestern Madagascar. This condition was not favorable for stalagmite deposition. The linkage between global cooling and wet conditions in regions of the SH, in response to the southward migration of the ITCZ, is further exemplified at centennial scale by the negative δ18O and δ13C values in northwestern Madagascar during the 8.2 ka cold event when the Atlantic Meridional Overturning Circulation (AMOC) weakened. Weakening of the AMOC led to an enhanced temperature gradient between the two hemispheres, i.e. cold NH and warm SH, shifting the mean position of the ITCZ further south. This brought wet conditions in the SH monsoon regions, such as northwestern Madagascar, and dry conditions in the NH monsoon regions, including the Asian Monsoon and the East Asian Summer Monsoon. This climatic relationship is useful to test for climate models that are used to predict changes in future climate.

An elephant molar recovered from the Windhoek Zoo Park Gardens in 1961/1962, dating to 6991–7241 cal BP, is a rare specimen of Loxodonta africana zulu. Although pollen and diatom assemblages in the sediment suggest wetter conditions and more C4 grass during the elephant's life, a bioapatite δ13C estimate of its diet indicates that it fed predominantly on C3 vegetation.

The geochemistry and petrography of a stalagmite from Wanxiang Cave in central China provide a paleoclimate record of the Penultimate Glacial Maximum (PGM) suggesting unexpectedly abundant non-monsoonal atmospheric precipitation at the nadir of the PGM. Eleven U–Th ( 230 Th) ages from 149 to 140 ka BP place the stalagmite in Marine Isotope Stage 6b, coincident with the greatest benthic marine δ 18 O calcite values of MIS 6. Carbon and oxygen stable isotope data, measurements of layer-specific width, positions of surfaces of non-deposition or dissolution, changes in the character and thickness of seemingly annual layers, changes in concentration of organic acids within the stalagmite's calcite, and patterns in the Mg concentration of that calcite all combine to give a coherent paleoclimate record. These data suggest that the stalagmite represents a wetter period than before or after its growth, with the wettest and coldest phase at 145 to 144 ka BP. This extreme in climate yields a striking correlation with the LR04 stack of oxygen isotope records from marine benthic forams, if the latter is subjected to a 4500-year chronological adjustment previously suggested by U–Th data from corals. The timing of the Wudu stalagmite's deposition combines with findings elsewhere to suggest that the PGM was the most extreme of later Pleistocene glacial maxima. Petrography and U–Th age determinations suggest dramatic changes in climate during the PGM. At the beginning (149–146 ka BP) and end (143–140 ka BP) of the stalagmite's growth, abrupt (century-scale) drying caused lengthy hiatuses as dripwater to the stalagmite diminished. On the other hand, delivery of water to the stalagmite during the wettest phase (145–144 ka BP) caused dissolution of previous layers of the stalagmite. Enhanced atmospheric precipitation during the cold of a glacial maximum is unexpected because, within the spectrum of Holocene climate, cooler conditions lessen the impact of the East Asian monsoon. Changes in the character of stalagmite layers indeed suggest weakened to negligible influence of the East Asian monsoon during the nadir of the PGM. However, data from the stalagmite are compatible with atmospheric precipitation from westerly winds that today reach only northwestern China but that may have been deflected southward in the PGM by southward migration of the Siberian High. This unexpected significance of the Westerlies during the PGM may be a result of the hypothesized extreme nature of the PGM relative to other glacial maxima of the later Pleistocene.

Objectives The study aimed to assess the feasibility and acceptability of third-trimester antenatal HIV testing within our service after two cases of HIV seroconversion in pregnancy were noted in 2008. North American Guidelines recommend universal third-trimester HIV testing in areas with an HIV prevalence of more than 1 per 1000. The HIV prevalence rate in our area is 3.01 per 1000. Methods Pregnant women prior to 28 weeks of gestation were recruited at booking between 1 September 2008 and 31 August 2009 and offered an additional third-trimester HIV test. Consent was obtained and testing was performed by hospital and community midwives. Information was entered into a modified existing electronic maternity database. A qualitative e-mail survey of midwives investigated barriers to participation in the study. Results A total of 4134 women delivered; three (

We document frequent, rapid, strong, millennial-scale paleovegetation shifts throughout the late Pleistocene, within a 100,000+ yr interval (~ 115–15 ka) of terrestrial sediments from the mid-Atlantic Region (MAR) of North America. High-resolution analyses of fossil pollen from one core locality revealed a continuously shifting sequence of thermally dependent forest assemblages, ranging between two endmembers: subtropical oak-tupelo-bald cypress-gum forest and high boreal spruce-pine forest. Sedimentary textural evidence indicates fluvial, paludal, and loess deposition, and paleosol formation, representing sequential freshwater to subaerial environments in which this record was deposited. Its total age"depth model, based on radiocarbon and optically stimulated luminescence ages, ranges from terrestrial oxygen isotope stages (OIS) 6 to 1. The particular core sub-interval presented here is correlative in trend and timing to that portion of the oxygen isotope sequence common among several Greenland ice cores: interstades GI2 to GI24 (≈ OIS2–5 d). This site thus provides the first evidence for an essentially complete series of "Dansgaard"Oeschger" climate events in the MAR. These data reveal that the ~ 100,000 yr preceding the Late Glacial and Holocene in the MAR of North America were characterized by frequently and dynamically changing climate states, and by vegetation shifts that closely tracked the Greenland paleoclimate sequence.

Pollen and archaeological records from two areas of southern Patagonia, one in the southern part of the Deseado Massif, the other south of Lago Argentino, suggest an important influence of climate on human movements into new areas. Pollen spectra record a significant dry climate throughout the region prior to ca. 12,900 cal BP that may correlate with the Antarctic Cold Reversal (ACR) from ca. 14,500 to 12,700 cal BP. The earliest archaeological sites date the initial exploration (sensu Borrero, 1994e95) of the Deseado Massif between 13,081 and 12,141 cal BP at the time of the Northern Hemisphere Younger Dryas (YD) cold interval (ca. 12,700e11,500 cal BP), which in the Southern Hemisphere was a time of gradually increasing temperatures. When humans set foot into the Deseado Massif, vegetation was grass steppe,indicating that conditions were wetter than during the ACR. The area south of Lago Argentino was occupied somewhat later around 11,000 cal BP, also when the vegetation changed to grass steppe. As temperatures increased during the early Holocene, forest replaced grass steppe in southwest Santa Cruz. A mix of forest and grass steppe persisted until ca. 9400 cal BP, when there was a return to drierconditions as those of today in the Deseado Massif. Fil: Mancini, Maria Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Franco, Nora Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas; Argentina Fil: Brook, George. University of Georgia; Estados Unidos

Stalagmite DP1, a speleothem 1.6 m in length from Dante Cave in northeastern Namibia, provides a paleoclimate record of a gradual transition from wetter to drier conditions from 4.6 to 3.3 ka BP, a variable but pronounced dry period from 3.3 to 1.8 ka, and a wetter but variable period from 1.8 ka to the present. This record is based on 30 U/Th radiometric dates and their resulting calculated growth rates, and on C and O stable isotope data, relative proportions of aragonite and calcite in layers, measurements of stalagmite width along layers, and observation of petrographic surfaces suggestive of changes from drier to wetter conditions and vice versa. The stalagmite's first deposition, which seemingly followed conditions too wet for deposition, coincided with desiccation in the Sahara and the end of the African Humid Period there. Gradual drying continued and led to a sustained very dry period from 3322 ± 11 to 1786 ± 10 BP, a “2–3 ka BP Dry Period”. That dry period began and ended abruptly. The abrupt transition from drier to wetter conditions at 1.8 ka coincides with the beginning of the Iron Age in southern Africa, suggesting that wetter conditions facilitated migrations and/or changes in food production that may have contributed to a transition in human technologies and lifestyles. This transition is coeval with transitions to colder conditions in ice core records from Greenland and Antarctica. The DP1 record suggests considerable change over the past 1800 years, with at least three wet/dry cycles. The wettest conditions may have occurred relatively recently, between 230 and 100 BP (A.D. 1720 and 1850), so that early European explorers may have seen and/or heard reports of conditions among the wettest during the later Holocene in southern Africa.

Lacustrine stromatolites are layered accretionary structures formed in shallow water by cyanobacteria. They are a precise indicator of high lake limits and their morphology and structure provide an insight into paleoenvironments of the time. Previous research on lacustrine stromatolites from Etosha Pan in Namibia based on radiocarbon ages of carbonates were close to the limit of the method and did not account for any possible 14C reservoir effect. The ages were used to suggest that the basin was not extensively flooded during the last 40,000 yr. To assess the reservoir effect, the age characteristics of a stromatolite from Poacher's Point were investigated by 14C dating both carbonate and organic residue from samples at different depths in the deposit. The ∼15-cm-diameter stromatolite was separated into 12 zones from the center to the edge and block samples were cut from each zone; the carbonate and residual organic residue were dated separately. The carbonate ages ranged from 34,700 to 24,700 14C yr BP and the organic ages from 15,700 to 2500 14C yr BP. Ages generally increased with increasing distance from the surface of the deposit. We believe that the organic ages are an accurate estimate of the stromatolite's age, while the much older carbonate ages reflect incorporation of old carbon from limestone bedrock and ancient calcrete introduced by stream and spring flow. Excluding the 2 oldest organic ages (15,700 and 13,600 14C yr BP), which may reflect contamination by older organic material washed into the lake during flooding, a linear regression relationship between carbonate and organic ages indicates that the reservoir effect on carbonate ranges up to ∼24,000 14C yr BP but decreases slightly as the true age of the deposit increases. This regression relationship was used to correct 2 finite carbonate ages for stromatolites from Pelican Island obtained in the early 1980s, which together with our new organic age for a stromatolite from Andoni Bay, document a >8-m-deep lake in Etosha Pan during the Late Pleistocene, at and prior to ∼34,000–26,000 cal yr BP. The organic carbon ages from the Poacher's Point stromatolite suggest prolonged lacustrine conditions during the early to middle Holocene (8000–6600 cal yr BP) but not to the extent seen during the Late Pleistocene.

Changes in artifact technology and environment during the Holocene are documented, within an organization of technology framework, for three different regions of Patagonia. Possible relationships between environmental changes and changes in artifact technology are explored. We examine past vegetation and geomorphic evidence of Holocene climate conditions in the three regions studied and what technologies were used during particular wetter and drier intervals. Our results suggest that many of the observed changes in technology use occurred at times of rapid climate change, particularly towards much drier conditions. Fil: Franco, Nora Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas; Argentina. Universidad de Buenos Aires; Argentina Fil: Brook, George A.. University of Georgia; Estados Unidos Fil: Mancini, Maria Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Vetrisano, Lucas Javier. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Departamento de Ciencias Antropológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

We present a synthesis of archaeological and paleoenvironmental information for the period MIS 6-2 in the Kalahari. Discussion centers on the implications of nine new, internally consistent OSL ages obtained from White Paintings Rock Shelter. These dates provide a better understanding of the Middle Stone Age (MSA) and Late Stone Age (LSA) sequence. In addition, the revised chronology dates 11 buried soil A-horizons that were formed during wetter periods. The buried A-horizons, along with dated speleothems and high lake levels in the Kalahari correlate with Antarctic warming events (A) and North Atlantic Heinrich events (H). We also discuss the implications of the Kalahari megalake, paleolake Makgadikgadi, for human populations and compare dated changes in the archaeological sequence at WPS with dates established in Khoisan genetic evolutionary studies.

This paper presents new information on the antiquity of the bow and arrow in the Kalahari. Excavations at White Paintings Shelter (WPS) uncovered bone point fragments that appear to have been parts of reversible arrowheads that could have been used with poison. We present a sequence of nine new, internally consistent OSL ages that date specific soil horizons at WPS. These dates/soil horizons are related to the bone point finds. The oldest bone points are estimated to date between 35–37 ka, while worked bone technology extends to at least 45 ka. Several engraved points are also discussed in relation to ethnographic evidence regarding decorated bone link-shafts collected in the 1970s. Additional information includes the first description of a reversible bone arrow point, made by a person who used such points with poison in his youth.

In order to define criteria for long-term climate change models in Southern Africa, an overview of the available pollen data during the Late Quaternary is needed. Here we reassess the paleo-climatic conditions in southern Africa by synthesising available fossil pollen data that can provide new insights in environmental change processes. The data considered here include the latest as well as previously published information that has been difficult to assess. Available calibrated pollen sequences spanning the Late Pleistocene and Holocene were subjected to Principal Components Analysis (PCA) to monitor taxa sensitive to moisture and temperature fluctuations. The PCA values are presented graphically as indicators of climate variability for the region. The results cover different biomes that include the summer-rain region in the north and east, the winter-rain area in the south and the dry zone in the west. The PCA plots directly reflect major changes of terrestrial environments due to variations in temperature and moisture. Mostly sub-humid but fluctuating conditions are indicated during the cold Marine Isotope Stage (MIS) 2, which were followed by a dry phase soon after the beginning of the Holocene but before the middle Holocene in the northern, central and eastern parts of the sub-continent. Marked but non-parallel moisture changes occurred in different subregions during the Holocene suggesting that climatic forcing was not uniform over the entire region. Some events seemed to have had a more uniform effect over the sub-continent, e.g., a relatively dry summer rain event at c. two thousand years ago, which can possibly be related to the ENSO phenomenon. The role of anthropogenic activities in some of the most recent vegetation shifts is likely.

The Andean piedmont of Mendoza is a semiarid region covered by extensive and partially vegetated dune fields consisting of mostly inactive aeolian landforms of diverse size and morphology. This paper is focused on the San Rafael plain (SRP) environment, situated in the distal Andean piedmont of Mendoza (34° 30′S), and reports the sedimentology and OSL chronology of two representative exposures of late Quaternary deposits, including their paleoenvironmental and paleoclimatic significance. Eleven facies, including channel, floodplain, fluvio–aeolian interaction, and reworked pyroclastic and aeolian deposits, were described and grouped into two facies associations (FA1 and FA2). FA1 was formed by unconfined sheet flows, minor channelized streams and fluvial–aeolian interaction processes. FA2 was interpreted as aeolian dune and sand-sheet deposits. OSL chronology from the SRP sedimentary record indicates that between ca. 58–39 ka and ca. 36–24 ka (MIS 3), aggradation was governed by ephemeral fluvial processes (FA1) under generally semiarid conditions. During MIS 2, the last glacial maximum (ca. 24–12 ka), a major climatic shift to more arid conditions is documented by significant aeolian activity (FA2) that became the dominant sedimentation process north of the Diamante–Atuel fluvial system. The inferred paleoenvironmental conditions from the SRP sections are in broad agreement with regional evidence.

Previous research on lacustrine stromatolites from Etosha Pan in Namibia obtained ages on carbonate close to or beyond the limits of radiocarbon dating. These ages suggested that the basin was likely not subject to extensive flooding during the last ca. 40 ka. This study shows that AMS radiocarbon ages for the carbonate of a stromatolite from Poacher’s Point are 15–21 ka older than ages for organic material in the stromatolite structure. Calibrated ages range from 30 to 40 ka for carbonate and 3–19 ka for the organic residue. The new ages, together with petrographic and isotopic data for the stromatolite, have provided important new information on past flooding of Etosha Pan including evidence of prolonged lacustrine conditions during the Holocene Climatic Optimum.

Geophysical techniques have been widely employed for the noninvasive location of burial sites in archaeological and forensic investigations. This approach has met with varying degrees of success, depending on factors such as equipment choice, survey methodology, burial type, and geological setting. This paper reports the results of a multitechnique geophysical survey carried out immediately prior to the salvage excavation of two Indigenous burials from an eolian dune in coastal South Australia. Ground-penetrating radar was not successful in defining the location of the burials owing to the disturbed nature of the local stratigraphy. Magnetic field intensity and apparent magnetic susceptibility surveys identified discrete anomalies that coincided with the location of skeletal material revealed during excavation, which we hypothesize to be due to burning or ochre use during funerary practices. Despite the spatial association of these features, subsequent laboratory analyses of the mineralogy and magnetic properties of sediments collected from the site failed to find a definite cause of the anomalies. Nevertheless, the association between them and the primary interment locations has implications for archaeological surveys carried out in the Australian coastal zone, as it highlights the potential of magnetic field intensity and apparent magnetic susceptibility geophysical techniques undertaken with a more refined survey methodology to afford a noninvasive, culturally appropriate means through which to detect Indigenous burials. This approach may prove particularly useful in areas with disturbed stratigraphy where ground-penetrating radar is less effective. © 2010 Wiley Periodicals, Inc.

A 0.6-m-long horizontal core from a stalagmite in the entrance area of Wonderwerk Cave in South Africa, a National Heritage Site, has provided a 35 ka record of environmental change. A pollen sequence from the stalagmite, and two animal dung deposits, is longer and more detailed for the end of the Pleistocene than previous palynological reports from the southern Kalahari region. This pollen record closely matches information from spring peats at Wonderkrater in Northern Province indicating that speleothem pollen can provide reliable paleovegetation data. The δ18O and δ13C records resemble those from Cold Air Cave in Northern Province and parallel variations in Greenland Ice Sheet GISP2 paleotemperature. This indicates that past climate changes in southern Africa were linked to changes in global atmospheric and oceanic circulation patterns possibly triggered by conditions in the North Atlantic region. The Wonderwerk data suggest wetter conditions at ca. 33 ka, from 23 to 17 ka, and from 4 ka to present. Conditions were drier 17–13 ka, when microstromatolitic carbonate was deposited on the flank of the stalagmite, and possibly also during depositional hiatuses from 33 to 23 ka and 13 to 4 ka.

The late Pleistocene of Virginia's outer coastal plain consists of sediments dated to marine isotope stages (MIS) 5 and 3. Two members from the Tabb Formation south of the Chesapeake Bay in southeastern Virginia and two formations east of the bay on the southern Delmarva Peninsula were dated using optically stimulated luminescence (OSL). The stratigraphically older Butlers Bluff Member yielded OSL ages of 70 ka (62–78 ka) (MIS-5a), and the younger Poquoson Member and Wachapreague Formation, MIS-3 ages of approximately 43 ka (33–50 ka) and 42 ka (33–54 ka), respectively. These shoreface and near-shore geologic units reached maximum altitudes ranging from 3 to 12 m above present sea level, and were deposited when established glacial-eustatic sea-level curves suggest that sea levels were significantly lower than present by approximately 40 m. If these new ages and the sea-level curves are correct, there must have been regional uplift of more than 40 m, probably due to isostatic adjustments of forebulges peripheral to North American ice sheets when they were at their maxima during MIS-6 and MIS-2. If the late MIS-6 forebulge collapse continued throughout MIS-5 and MIS-4, we propose that regional land elevations may have been low enough for deposition to occur during the lower eustatic sea levels of MIS-3. During late MIS-3, the units experienced renewed uplift followed by subsidence to present-day elevations. If this paraglacial region is not yet in isostatic equilibrium and still requires further forebulge subsidence, this could explain the present-day altitude and age discrepancies associated with these relict marine deposits.

A 5.4 m peat core from the Sandy Run Creek (SRC) valley in the upper Coastal Plain of Georgia shows that before 30 ka the valley had an aggradational sandy floor with shallow swales and low ridges of 1–2 m amplitude suggesting a braided stream pattern and a low water table. The climate from 30–25 ka was cool and dry and the vegetation open grassland with stands of pine and spruce that produced few fires. At ca. 16 ka a warmer, wetter climate caused SRC to meander and incise the valley fill removing some previously deposited sediment at the site of our peat core so that sediments of 13 ka rest directly on sediments deposited at 25 ka. After ca. 13 ka higher groundwater levels initiated vertical accretion of floodplains allowing peat accumulation in shallow depressions across the valley. Pollen from the Younger Dryas period (ca. 13–11 ka) indicates a cool, moist environment of open oak woodland, mesic trees, riparian populations of alder, and reduced levels of pine. By the early to mid Holocene, tupelo and oak dominated over pine indicating wetter conditions, while sand stringers in peat record periodic heavy rains, an elevated water table, and intervals of substantial runoff. Cooling after ca. 4.5 ka brought drier and more variable conditions. Fires increased and southern pine replaced tupelo and oak. The absence of sand stringers in peat younger than 4.5 ka indicates fewer intense rainfall events.

The episodic nature of coastal dune development has been widely identified in many dune areas over the world. What causes such episodicity is still hotly debated. Sea-level change, climatic change and human impact have widely been reported as the main forcings, though there is no agreement yet upon which factors are critical. This research provides some evidence that sea-level fluctuation and climatic factors controlled the episodic dune building together, based upon optically stimulated luminescence (OSL) dune ages on the west coast of Korea. The newly obtained and published OSL dune ages on the west coast of the Taean Peninsula and Anmyeon Island, Korea, indicate the six main periods of dune building: 5.5, 4.3, 1.5, 1.3, 1.1 and 0.7 ka. They correlate with evidence of colder climate in East Asia that imply stronger dune-forming winds during the winter under the influence of a more intense Siberian High. They also correlate with periods of higher sea level over the present one with fluctuations. Thus, episodic dune activity along the west coast of the Korean Peninsula during the mid to late Holocene appears to be linked to stronger winter winds capable of moving sand from the beach to the foredune ridges with short-term fluctuations during the high stands. Copyright # 2009 John Wiley & Sons, Ltd.