In a recent paper in this journal (Hancock et al. (2024) Stonehenge revisited: A geochemical approach to interpreting the geographical source of sarsen stone #58. Archaeometry https://www.doi.org/10.1111/arcm.12999 ), Hancock and colleagues present a reanalysis of the geochemical dataset used to identify the likely source for the majority of the sarsen megaliths at Stonehenge as West Woods, Wiltshire, UK. This comment discusses the analytical approach used by Hancock and colleagues, and evaluates its conclusions. In our view, there are three significant methodological issues with the study: (i) the use of absolute element concentration data (as opposed to normalised ratio data) as the basis for much of the analysis, which is inappropriate for a material like silcrete with variable proportions of introduced silica, both between and within outcrops; (ii) the choice of highly mobile elements (specifically Si and Fe) to discriminate between potential source areas, which is inappropriate for many geochemically altered sediments; and (iii) the comparison of data from single samples rather than multi‐sample ranges, which fails to capture the inherent geochemical variability that may be present within an outcrop area or set of samples. There are other sections of the paper that demonstrate a lack of understanding of sarsen formation and the geological and geomorphological history of the British and Irish Isles. We conclude by urging that future studies employing sarsen/silcrete as a material for source provenancing are grounded in the now extensive literature on sarsen/silcrete properties, mode of formation and geochemistry, and reflect this body of knowledge in their research design.

In April 2022, flooding and associated geohazards caused major loss of life and extensive damage in the greater Durban region and large areas of the KwaZulu-Natal (KZN) coastal zone. Heavy rainfall that triggered the flooding and mass movement events was reported in national and international media as having 'smashed weather records'. However, no systematic and up-to-date flood record exists for KZN to allow the April 2022 floods to be viewed within their full historical context. This study presents an historical geographic account of flooding in KZN, with a particular focus on the greater Durban region. The flood record expands upon available databases held by the South African Weather Service, drawing on missionary accounts, newspapers and personal diaries to identify all significant flood events in KZN since the mid-nineteenth century. We document 53 significant flood events from 1850-1899 (average similar to 1.1 per annum) and 210 from 1900-2022 (average similar to 1.7 per annum). Within the limits of our data, we suggest that the frequency of flooding in Durban has likely doubled over the last century. Our research confirms that the April 2022 floods were likely the most catastrophic natural disaster yet recorded in KZN, in collective terms of lives lost and overall economic impact.

Documentary climate data describe evidence of past climate arising from predominantly written historical documents such as diaries, chronicles, newspapers, or logbooks. Over the past decades, historians and climatologists have generated numerous document-based time series of local and regional climates. However, a global dataset of documentary climate time series has never been compiled, and documentary data are rarely used in large-scale climate reconstructions. Here, we present the first global multi-variable collection of documentary climate records. The dataset DOCU-CLIM comprises 621 time series (both published and hitherto unpublished) providing information on historical variations in temperature, precipitation, and wind regime. The series are evaluated by formulating proxy forward models (i.e., predicting the documentary observations from climate fields) in an overlapping period. Results show strong correlations, particularly for the temperature-sensitive series. Correlations are somewhat lower for precipitation-sensitive series. Overall, we ascribe considerable potential to documentary records as climate data, especially in regions and seasons not well represented by early instrumental data and palaeoclimate proxies.

The influence of natural factors such as bioturbation or sediment movement caused by wind and water is a perennial concern for Stone Age site selection and subsequent interpretation. This paper discusses the spatial artefact distribution of five recently excavated, open-air exposed Middle Stone Age (MSA) sites in Ntwetwe Pan, Botswana. The finds comprise lithic assemblages dominated by MSA points, manufactured in a variety of silcretes. The sites were examined following the assumption that archaeological sites are the product of a combination of natural and cultural factors, occurring both during and after artefacts are deposited. The results indicate that some of these exposed pan floor sites do preserve cultural artefact distribution patterns, and that the level of post-depositional disturbance varies locally. Refitting was an important tool of analysis, especially on the largest site, MAK33, where it was possible to identify working areas that focussed on different modes of lithic manufacture. In combination with a chaîne opératoire analysis of lithic production stages, it was then possible to map movement of artefacts across the site. We argue that the spatial organization of open-air sites may preserve behavioural records that are not present at caves and rock shelters, and provide a view into the short-term, single-use locations that likely formed the basis of MSA occupation patterns.

Studies of early human occupation of Africa over recent decades have profoundly changed how we understand our early ancestors, their inventiveness and adaptability. The spread of Homo sapiens to new environmental settings, the expansion of diet breadth, the development of more complex technology and the use of personal ornaments have all been recognized at well-documented Middle Stone Age (MSA) cave and shelter sites, particularly along the South African coast. This paper addresses two under-represented aspects of MSA research: open-air sites and the African interior. We present here recent surveys and excavations in Ntwetwe Pan, Botswana, a remote, open landscape, that formerly contained a vast palaeolake. The five excavated sites yielded assemblages composed exclusively of silcrete, a locally available raw material. The lithic industry at these sites was deposited during dry periods following palaeolake high stands dating to c.128–81 ka and c. 72–57 ka. This industry, characterized by a limited toolkit dominated by highly retouched unifacial and bifacial points, is not previously documented but shows similarities to dated MSA sites of equivalent age in north-western Botswana and Zimbabwe. Combined, these exposed open-air sites document the successful MSA adaptation to a hydrologically dynamic, interior landscape and arguably display MSA behavioural patterns that complement and balance the more well-documented perspectives from coastal cave and shelter sites.

The pattern, style, and timing of glaciation of the last Fennoscandian Ice Sheet (FIS) on the Kola Peninsula and Russian Lapland (northwest Arctic Russia) is widely debated. This is due, in part, to the lower -resolution empirical data used in previous investigations. In this paper, we present an ice margin reconstruction, an updated database of previously published numerical ages, and a new time-slice reconstruction. The reconstruction, which is presented across a series of 10 maps, documents the spatial evolution of the ice sheet every 1000 years between 16 and 11 ka, and for four selected time periods back to 29 ka (19-17, 21-20, 25-22, and 29-26 ka). Our reconstruction indicates that the Kola Peninsula and Russian Lapland was probably ice-free prior to the advance of the FIS c. 29 ka. The FIS reached its maximum lateral extent in northwest Arctic Russia c. 19-17 ka, later than many other sectors of the ice sheet. This disparity probably arises as a result of both the topography of Fennoscandia and the position of the Kola Peninsula and Russian Lapland in a precipitation shadow of the Scandinavian Mountains. Thus, FIS glaciation in northwest Arctic Russia was strongly influenced by a fluctuating climate. Most of the FIS in northwest Arctic Russia was terrestrial -based, although marine-terminating margins existed in the fjords of northern Russian Lapland. The retreat of the White Sea lobe was probably not influenced by marine transgression until c. 12 ka because palaeo-sea levels during most of the Late Weichselian were considerably lower than present, and a shallow sill in the Mouth of the White Sea would have inhibited ocean waters entering the White Sea basin. Instances of ice margin readvance during deglaciation are also apparent, including a significant readvance of the White Sea lobe c. 14 ka. This study presents the first reconstruction grounded in high -resolution empirical data for the Kola Peninsula and Russian Lapland, and is presented in a time-slice format that is of critical importance for testing and validating numerical ice sheet and climate models.(c) 2022 Elsevier Ltd. All rights reserved.

Analyses of the distance over which lithic raw materials were transported for use in stone tool production provide important insights into early human mobility through prehistoric landscapes. This study combines the use of geochemical provenancing, chaine operatoire analysis and geochronology to examine patterns of lithic raw material procurement at five single-use open-air Middle Stone Age (MSA) archaeological sites in Ntwetwe Pan, part of the Makgadikgadi Pans complex in north-central Botswana. Maximum ages of the five sites ranged from 106 +/- 3 to 69 +/- 7 ka, with site formation thought to have occurred before and after a lake high stand dated to c. 72-57 ka. Tool manufacture at all sites was largely confined to the production of MSA points, with silcrete used exclusively as the raw material. Geochemical provenancing investigations aimed to identify the specific silcrete outcrops used as lithic raw material sources. Analysis of contemporary pan floor deposits show that sediment (and hence silcrete) geochemistry in Ntwetwe is determined by the proportional sediment input into the pan from fluvial systems with different catchment geologies. Immobile trace element signatures for 46 waste manufacturing flakes were compared against equivalent data for 321 silcrete samples collected at out-crops within and beyond Ntwetwe Pan. Waste flakes were chosen to be representative of the main silcrete raw material types present within the artefact assemblage at each site. Fifteen waste flakes were shown to match specific outcrops on the basis of their geochemical signatures and petrographic properties; all matching outcrops were within Ntwetwe Pan, at distances ranging from 7 to 55 km from individual sites. Multi-site analysis of procurement patterns identifies common silcrete source areas, revealing a preference for silcrete from particular locations within Ntwetwe Pan. Given that the five archaeological sites were likely occupied at different times, this resource preference may have been a longer-term behavioural feature of MSA populations in the Ntwetwe region. The distances over which silcrete was transported in Ntwetwe Pan are smaller than identified in investigations at similar-aged MSA sites in northwest Botswana. The reasons for the different silcrete procurement ranges in the two regions are likely related to silcrete availability and/or raw material preference, but this requires further investigation. (C) 2022 The Authors. Published by Elsevier Ltd.

Central southern Africa is often viewed as an archaeological void, especially when compared to the continent’s heavily researched coastal regions. This is in part due to its geomorphological context: the Kalahari basin is a flat depositional void with few archaeological sites due to limited traditionally-favoured preservation contexts. Yet recently, the Kalahari’s Makgadikgadi mega-palaeolake basin has been controversially proposed, through DNA research, as the ‘ancestral homeland’ of modern humans, prior to MSA dispersal c130k yr ago, with only small residual populations remaining thereafter (Chan et al., 2019), despite the absence of supporting archaeological data. Rather than being archaeologically-sterile, we provide new data from four field seasons that demonstrate the richness (hundreds) of MSA sites in the Makgadikgadi basin, their unique context on the palaeolake floor, and the significance of geomorphological processes in explaining their location, high preservation quality, and modern exposure at the surface. Six sites have been excavated, including extensive undisturbed silcrete MSA lithic spreads. One can be dated to within 81-68 ka, another occurred after 57ka, both resting on, and then buried by, OSL-dated palaeolake sediments derived from high lake stands. Human use of the basin floor occurring during low, or seasonally dry, phase of the basin’s complex hydrological history. Sites are being exposed at the surface of today’s dry basin through processes of aeolian deflation, removing ancient lake sediments from one of Africa’s major atmospheric dust sources. Our work shows that without a clear understanding of Makgadikgadi’s geomorphological history, and of the processes operating in the system, it is difficult to appropriately explain the preservation and quality of the MSA sites in the basin. Our work shows a more complex environmental dynamic, and likely a more complex early human history, that previous research has suggested. Reference: Chan EKF et al 2019 ‘Human origins in a southern African palaeo-wetland and first migrations’. Nature 575, 185-189

Conventional riversRiver are absent from much of BotswanaBotswana, with only the Okavango, ChobeChobe and ZambeziZambezi systems in the extreme north containing perennial flowing water. Ephemeral rivers occur in the eastern hardveldHardveld, but the most extensive components of the surface drainageDrainage are the networks of fossilFossil or dry valleysValley (termed mekgacha in Setswana and dum in various San languages) that cross the sandveldSandveld. This chapter presents the first holistic review of current knowledge about these enigmatic landforms. It does so using a range of evidence types, from radar remote-sensing to the analysis of historical documents written by missionaries and explorers. The chapter considers dry valley distribution, morphology and contemporary and historical hydrologyHydrology before discussing valley evolution over longer timescales. It concludes with a synthesis of the main arguments concerning how dry valley systems may have formed, including the balance between conventional fluvial incision and processes such as groundwaterGroundwater seepage erosionErosion.

The Middle Stone Age (MSA) was a time of great human adaptation and innovation. In southern Africa, coastal locations have been viewed as key places for the development of human resource use and behaviour, with the dryness of the continental interior after c.130 ka regarded as both an obstacle to occupation and a limit on behaviour. Newly excavated MSA sites on the floor of the now-dry palaeolake Makgadikgadi basin, central Botswana, along with accompanying environmental data, have provided a significant opportunity to reassess the nature of MSA adaptation to, and behaviour under, dry conditions. Excavated sites dated to 80-72 ka and post 57 ka reveal purposeful early human use of an extensive 60,000 km2 lacustrine basin during dry, as opposed to lake-high, phases, as well as highlighting movement strategies for tool-making resource procurement. Findings have significant implications for theories of early human mobility and innovation, as well as for understanding the drivers, constraints and opportunities for the use of drylands. The deliberate selective movement of lithic raw materials within the basin for artefact manufacture evidences thoughtful adaptation to dry conditions within the lake basin. This research shows that open-air sites in the Kalahari drylands of central southern Africa can make important contributions to debates surrounding the development of human-environment re-lationships during the MSA, as well as challenging narratives of a hostile and largely empty landscape.(c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

This paper documents the abundance of Stone Age finds in the Middle Kalahari, both through earlier publications and newly documented sites. Results of several decades of Stone Age research are presented through a variety of projects and placed within the context of previous archaeological investigations in the region. We argue for the importance of open-air sites in constructing a more representative picture of prehistoric behaviour in the interior of southern Africa.

Little is known of the properties of the sarsen stones (or silcretes) that comprise the main architecture of Stonehenge. The only studies of rock struck from the monument date from the 19 th century, while 20 th century investigations have focussed on excavated debris without demonstrating a link to specific megaliths. Here, we present the first comprehensive analysis of sarsen samples taken directly from a Stonehenge megalith (Stone 58, in the centrally placed trilithon horseshoe). We apply state-of-the-art petrographic, mineralogical and geochemical techniques to two cores drilled from the stone during conservation work in 1958. Petrographic analyses demonstrate that Stone 58 is a highly indurated, grain-supported, structureless and texturally mature groundwater silcrete, comprising fine-to-medium grained quartz sand cemented by optically-continuous syntaxial quartz overgrowths. In addition to detrital quartz, trace quantities of silica-rich rock fragments, Fe-oxides/hydroxides and other minerals are present. Cathodoluminescence analyses show that the quartz cement developed as an initial <10 μm thick zone of non-luminescing quartz followed by ~16 separate quartz cement growth zones. Late-stage Fe-oxides/hydroxides and Ti-oxides line and/or infill some pores. Automated mineralogical analyses indicate that the sarsen preserves 7.2 to 9.2 area % porosity as a moderately-connected intergranular network. Geochemical data show that the sarsen is chemically pure, comprising 99.7 wt. % SiO 2 . The major and trace element chemistry is highly consistent within the stone, with the only magnitude variations being observed in Fe content. Non-quartz accessory minerals within the silcrete host sediments impart a trace element signature distinct from standard sedimentary and other crustal materials. 143 Nd/ 144 Nd isotope analyses suggest that these host sediments were likely derived from eroded Mesozoic rocks, and that these Mesozoic rocks incorporated much older Mesoproterozoic material. The chemistry of Stone 58 has been identified recently as representative of 50 of the 52 remaining sarsens at Stonehenge. These results are therefore representative of the main stone type used to build what is arguably the most important Late Neolithic monument in Europe.

A synthesis of the geochemistry of silcretes and their host sediments in the Kalahari Desert and Cape coastal zone, using isocon comparisons, shows that silcretes in the two regions are very different. Kalahari Desert silcretes outcrop along drainage-lines and within pans, and formed by groundwater silicification of near-surface Kalahari Group sands. Silicification was approximately isovolumetric. Few elements were lost; silicon (Si) and potassium (K) were gained as microquartz precipitated in the sediment porosity and glauconite formed in the sub-oxic groundwater conditions. The low titanium (Ti) content reflects the composition of the host sands. Additional elements in the Kalahari Desert silcretes were supplied in river water and derived from weathering of silicates in basement rocks. Evaporation under an arid climate produced high-pH groundwater that mobilized and precipitated Si; this process is still occurring. In the Cape coastal zone, pedogenic silcretes cap hills and plateaus, overlying deeply weathered argillaceous bedrock. Silicification resulted from intensive weathering that destroyed the bedrock silicates, almost completely removing most elements and causing a substantial volume decrease. Some of the silica released formed a microcrystalline quartz matrix, and most Ti precipitated as anatase, so the Cape silcretes contain relatively high Ti levels. The intense weathering that formed the Cape silcretes could have occurred in the Eocene, during and after the Palaeocene-Eocene Thermal Maximum, when more acidic rainfall and high temperatures resulted in intensified silicate weathering worldwide. This could have been responsible for widespread formation of pedogenic silcretes elsewhere in Africa and around the globe. Trace element sourcing of silcrete artefacts to particular outcrops has most potential in the Cape, where differences between separate bedrock areas are reflected in the silcrete composition. In the Kalahari Desert, gains of some elements can override compositional differences of the parent material, and sourcing should be based on elements that show the least change during silicification. (C) 2020 John Wiley & Sons, Ltd.

In the absence of empirical and conceptual considerations of the negotiation of leadership in teams doing community-based research, this article adds to the leadership literature by offering a critical reflection on positioning and collaborative teams in the context of one interdisciplinary, co-productive, cross-generational and international research project. The project focused on youth and community resilience to drought in South Africa. Fourteen co-researchers reflected on their experiences of leadership within the project, using a collectively developed questionnaire. Findings uniquely highlight wider ethical considerations when youth and novice researchers are included in research teams. A strong emphasis on cultural responsiveness was found; with local and culturally led leadership seen to positively influence both processes and outcomes. Reflections suggest collaboration may be approached as an “ethos” and aided by transformational leadership theories and methodologies. Findings may be especially relevant to research teams, funders, and ethical bodies.

Groundwater dolocretes may exert an important geomorphic control on landscape evolution within sub-humid to arid regions. However, the geomorphic and hydrogeological settings of dolocrete remain poorly described. The hydrochemical conditions of dolomite precipitation in groundwater environments are also not well known. Classic models of dolocrete formation explain dolomite precipitation from highly evolved groundwaters at the terminus of major drainage but do not explain dolocrete distributed in regionally elevated landscapes, upgradient of major drainage. This study investigated the mineralogy, micromorphology and stable carbon and oxygen isotope compositions of three dolocrete profiles within a regionally elevated sub-basin of the Hamersley Ranges in the Pilbara region of northwest Australia. We sought to establish the environmental and hydrochemical conditions and present a model for dolocrete formation. We found that dolocrete formed within zones of emerging groundwater under saline-evaporitic conditions within internally draining sub-basins, most likely during the Late Miocene and Pliocene. Saline-evaporitic conditions were indicated by: (i) the mineralogy, dominated by dolomite, palygorskite and smectite; (ii) desiccation features and the presence of phreatic and vadose cements, indicative of a shallow fluctuating water table, and; (iii) dolomite delta O-18 values (median = -5.88 parts per thousand). Dolomite precipitation was promoted by evaporation and carbon dioxide degassing from shallow magnesium (Mg)-rich groundwater. These factors appear to have been the major drivers of dolocrete development without a requirement for significant down-dip hydrochemical modification. Primary dolomite precipitation was possible due to the presence of microbial extracellular polymeric substances (EPS). EPS provided negatively charged nucleation sites, which bound Mg2+, overcoming kinetic effects. High microbial activity within groundwater systems suggest these processes may be important for dolocrete formation worldwide and that groundwater dolocretes may be more pervasive in landscapes than currently recognized. (c) 2019 John Wiley & Sons, Ltd.

ABSTRACTEstablishing long‐term records of rainfall variability is essential for understanding changes in the magnitude and frequency of extreme events. The need is particularly pressing for much of Africa, where the instrumental meteorological record rarely stretches back beyond the early 20th century. This study extends the rainfall record for present‐day Malawi back to the mid‐19th century through the analysis of historical documentary materials from British and African archives. Textual evidence within documents is used to construct a semi‐quantitative chronology of rainfall variability spanning the period 1858–1900. Widespread and severe droughts are identified during the austral summer rainy seasons of 1861–1863, 1877–1879, 1885–1888, and 1892–1894, and two unusually wet periods in 1889–1892 and 1894–1898. Instrumental rainfall data from Cape Maclear, Bandawe, and Kaningina spanning the period 1876–1880 – the earliest so far discovered for Malawi – are compared with nearby long‐term records from the Global Historical Climatology Network database. These analyses confirm the classifications for the equivalent years in the semi‐quantitative chronology. The results of this study are considered alongside other annually resolved rainfall reconstructions for the southern African summer rainfall zone to assess the spatial extent of late 19th century drought and wetter episodes and to explore the distribution of teleconnections arising from historical El Niño events. The very strong 1877 El Niño event was associated with drought from northern Malawi to the Eastern Cape. In contrast, drier conditions during the strong 1885 El Niño extended from Malawi as far south as the southern Kalahari, with Lesotho and KwaZulu‐Natal experiencing relatively wet conditions. The very strong 1891 El Niño was associated with very wet conditions from Malawi to KwaZulu‐Natal. In contrast, wetter conditions only extended as far south as Zimbabwe following the moderate 1896 El Niño. The study concludes with suggestions on how to extend historical climate information for the region.

Changing climates affect human societies differently depending on societal structures, cultural perceptions and their relative vulnerability and resilience. In this study, we explore the complex relationship between climate, conflict and society in nineteenth century Zululand. The paper first reviews current debates surrounding the links between climatic change, societal transformation and the rise of the Zulu Kingdom from the late-eighteenth to early-nineteenth centuries. It then considers new empirical evidence relating to conflict and socio-economic changes at a local scale in Zululand from the early-mid-nineteenth century onwards, using a combination of unpublished archival materials written by missionaries and other observers, together with oral histories and traditions. Our analysis highlights how changing precipitation patterns, especially towards drier conditions, may have contributed to changes in societal responses, including dominant narratives about rain-control, the migration and dissolution of society, and conflicts and unrest. We suggest that temporal differences in these responses were contingent upon the role of leaders, power structures, and the willingness and ability of leaders to yield this power. The case of nineteenth century Zululand exemplifies the complexity of environment-society interactions, and strengthens the call for a thorough scrutiny of the narratives of social unrest in specific socio-cultural contexts.

The use of documentary evidence to investigate past climatic trends and events has become a recognised approach in recent decades. This contribution presents the state of the art in its application to droughts. The range of documentary evidence is very wide, including general annals, chronicles, memoirs and diaries kept by missionaries, travellers and those specifically interested in the weather; records kept by administrators tasked with keeping accounts and other financial and economic records; legal-administrative evidence; religious sources; letters; songs; newspapers and journals; pictographic evidence; chronograms; epigraphic evidence; early instrumental observations; society commentaries; and compilations and books. These are available from many parts of the world. This variety of documentary information is evaluated with respect to the reconstruction of hydroclimatic conditions (precipitation, drought frequency and drought indices). Documentary-based drought reconstructions are then addressed in terms of long-term spatio-temporal fluctuations, major drought events, relationships with external forcing and large-scale climate drivers, socioeconomic impacts and human responses. Documentary-based drought series are also considered from the viewpoint of spatio-temporal variability for certain continents, and their employment together with hydroclimate reconstructions from other proxies (in particular tree rings) is discussed. Finally, conclusions are drawn, and challenges for the future use of documentary evidence in the study of droughts are presented.