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Quaternary environments on the Arabian Peninsula shifted between pronounced arid conditions and phases of increased rainfall, which had a profound impact on Earth surface processes. However, while aeolian sediment dynamics are reasonably well understood, there is a lack of knowledge with regard to variability in the fluvial systems. Presented here are the findings from several locations within wadi drainage systems to the west of the Hajar Mountains (United Arab Emirates). The performance of optically stimulated luminescence dating using a customized standardized growth curve approach is investigated, showing that this approach allows reliable determination of ages by reducing the machine time required. Three main periods of fluvial activity occurred at 160–135, 43–34, and ca. 20 ka. Additional ages fall into the latest Pleistocene and Late Holocene. None of the ages coincides with major wet periods in SE Arabia that have been identified in stalagmites and by the deposition of lake sediments. It is shown that fluvial activity was partly contemporaneous (within the given time resolution) with phases of aeolian deposition and was almost continuous, but likely sporadic, during the Middle to Late Pleistocene. This highlights the need for regionally defined paleoenvironmental records to fully understand the response of dryland systems to long-term climatic change.

Although phytolith research has come of age in archaeology and palaeoecology internationally, it has remained relatively marginalised from mainstream practice in Australasia. The region’s initial isolation from international scientific communities and uniqueness of its vegetation communities, has led to an exclusive set of challenges and interruptions in phytolith research. Examining a history of Australasian phytolith research presents the opportunity to recognise developments that have made phytoliths a powerful tool in reconstructing past environments and human uses of plants. Phytolith research arrived early in Australia (1903), after a convoluted journey from Germany (1835–1895) and Europe (1895–1943), but phytoliths were initially misidentified as sponge spicules (1931–1959). Formal understanding of phytoliths and their applications began in Australasia during the late 1950s, continuing throughout the 1960s and 1970s (1959–1980). After a brief hiatus, the modern period of phytolith analyses in Australasian archaeological and palaeoenvironmental research began in the 1980s (1984–1992), focusing on investigating the deep past. Advancements continued into the 1990s and early 2000s. Wallis and Hart declared in 2003 that Australian phytolith research had finally come of age, but more a fitting description would be that it had peaked. Since then phytolith research in Australasia slowed down considerably (2005-present). Local phytolith reference collections for Australasian flora, critical for identifying ancient phytoliths, are essentially no longer produced.

Quaternary palaeoenvironmental (QP) sites in Southeast Arabia are important not only to understand the history of global climate change but also to study how ancient humans adapted to a changing natural environment. These sites, however, are currently missing from conservation frameworks despite reports of destroyed sites and sites under imminent threat. This study presents the Geocultural Database of Southeast Arabia, the first open-access database on QP sites in this region, created as a comprehensive inventory of regional QP sites and a tool to analyse QP records and archaeological records. The endangerment assessment of QP sites in this database reveals that 13% of QP sites have already been destroyed and 15% of them are under imminent threat of destruction, primarily due to urban development and infrastructure development. Chronological and spatial analyses of QP and archaeological sites and records highlight the intricate relationship between palaeoenvironment and archaeology and emphasise the need for sub-regional-scale studies to understand the variation of climatic conditions within the region, especially to study changes in the ancient human demography. This database illustrates the potential of a geocultural approach that combines archaeological heritage with Quaternary geoheritage as a way forward for the conservation of QP sites at risk.

Enzel et al. (2015) reassess sedimentary records of Early to Mid-Holocene lake sites in Arabia based on a reinterpretation of published multiproxy data and a qualitative analysis of satellite imagery. The authors conclude that these sites represent palaeo-wetland environments rather than palaeolakes and that the majority of the Arabian Peninsula experienced no or, if at all, only a very minor increase of rainfall at that time mainly due to eastward expansion of the East African Summer Monsoon. We disagree with their reassessment and identify several cases where unequivocal evidence for early Late Pleistocene and Early to Mid-Holocene perennial lake environments in Arabia, lasting for centuries to millennia, was neglected by Enzel et al. (2015). Here we summarize findings which indicate the presence of lakes from the sites of Jubbah, Tayma, Mundafan (all Saudi Arabia), Wahalah, Awafi (both UAE), and the Wahiba Sands (Oman), supported by evidence including occurrence of barnacle colonies in living position, remnant bioclastic shoreline deposits, undisturbed varve formation, shallowing-up lacustrine sequences, various aquatic freshwater, brackish and saline micro- and macrofossils, such as ichnofaunal remains, which are the result of prolonged field-based research. While the precise depth, hydrology and ecology of these water bodies is still not entirely resolved, their perennial nature is indicative of a markedly increased precipitation regime, which, in combination with more abundant groundwater and increased spring outflow in terminal basins fed by charged aquifers, was sufficient to overcome evaporative losses. The palaeolakes' influence on sustaining prehistoric populations is corroborated by the presence of rich archaeological evidence.

This study investigates hydrological responses to climatic shifts using sediment flux data derived from two dated palaeolake records in south-east Arabia. Flux values are generally low during the early Holocene humid period (EHHP) (∼9.0–6.4k cal a BP) although several short-lived pulses of increased detrital input are recorded, the most prominent of which is dated between ∼8.3 and 7.9k cal a BP. The EHHP is separated from the mid-Holocene humid period (MHHP) (∼5.0–4.3k cal a BP) by a phase of increased sediment flux and aridity, which began between ∼6.4 and 5.9k cal a BP and peaked between ∼5.2 and 5.0k cal a BP. The termination of the MHHP is marked by a phase of high detrital sediment flux between ∼4.3 and 3.9k cal a BP. While long-term shifts in climate are most likely linked to changes in the summer position of the Intertropical Convergence Zone and associated Indian and African monsoon systems, it is noted that the abrupt, short-term phases of aridity observed in both records are coeval with intervals of rapid climate change globally, which triggered non-linear, widespread landscape reconfigurations throughout south-east Arabia.

The widespread formation of organic rich sediments in south-east Australia during the Holocene (Marine Isotope Stage [MIS] 1) reflects the return of wetter and warmer climates following the Last Glacial Maximum (LGM). Yet, little is known about whether a similar event occurred in the region during the previous interglacial (MIS 5e). A 6.8 m sediment core (#LC2) from the now ephemeral Lake Couridjah, Greater Blue Mountains World Heritage Area, Australia, provides insight into this question. Organic rich sediments associated with both MIS 1 and 5e are identified using 14C and optically stimulated luminescence (OSL) dating techniques. Also apparent are less organic sedimentary units representing MIS 6, 5d and 2 and a large depositional hiatus. Sediment δ13C values (−34 to −26‰) suggests that C3 vegetation dominates the organic matter source through the entire sequence. The pollen record highlights the prevalence of sclerophyll trees and shrubs, with local hydrological changes driving variations in the abundance of aquatic and lake-margin species. The upper Holocene sediment (0–1.7 m) is rich in organic matter, including high concentrations of total organic carbon (TOC; 20–40%), fine charcoal and macrophyte remains. These sediments are also characterised by a large proportion of epiphytic diatoms and a substantial biogenic component (chironomids and midges). These attributes, combined with low δ13C and δ15N values, and C:N ratios of approximately 20, indicate a stable peat system in a swamp like setting, under the modern/Holocene climate. In comparison, the lower organic rich unit (MIS 5e-d) has less TOC (5–10%), is relatively higher in δ13C and δ15N, and is devoid of macrophyte remains and biogenic material. Characterisation of the organic matter pool using 13C-NMR spectroscopy identified a strong decomposition signal in the MIS 5e organic sediments relative to MIS 1. Thus the observed shifts in δ13C, δ15N and C:N data between the two periods reflects changes in the organic matter pool, driven by decompositional processes, rather than environmental conditions. Despite this, high proportions of aquatic pollen taxa and planktonic diatoms in the MIS 5e–d deposits, and their absence in the Holocene indicates that last interglacial Lake Couridjah was deeper and, or, had more permanent water, than the current one.

This paper presents the key findings of a multidisciplinary study investigating the nature and timing of coastal landscape evolution in eastern Saudi Arabia during the Holocene. To date, most sea level reconstructions for the Arabo-Persian Gulf are based on uncalibrated 14C ages without correction for marine reservoir effects, or lack precision with regard to the effects of neotectonic changes, indicators of sea level used, errors in elevation of sedimentary units used, and the relationship with actual tides. As a consequence, the nature and timing of relative sea level (RSL) changes during the Late Pleistocene and Holocene remain poorly understood. To help address this, we use sea level index points (SLIPs) based on calibrated 14C ages to present a RSL curve for the central-southern Gulf of Saudi Arabia from coastal sabkha deposits near the archaeological site of Dosariyah. The sediments record rapid transgression during the early Holocene with a mid-Holocene high-stand immediately prior to 6880–6560 cal. BP when the upper limit for the palaeo Mean Highest High tide water (MHHW) was 2.8–3.10 m above present day mean sea level. Transgression continued until shortly after 5575–5310 cal. BP with an upper limit to the palaeo-MHHW of 3.75 m above present sea levels. Thereafter a fall in RSL was recorded, with the regression leading to the progradation of the coastal system and the development of coastal sabkhas. Nonetheless later transgressions are recorded in the region between 4848–4536 and 4335–3949 cal BP. Radiometric dating results from archaeological excavations at Dosariyah, one of the most important Neolithic coastal sites in the Gulf, suggest that occupation of the site during the Neolithic coincides with the mid-Holocene marine transgression (ca. 7200–6500 cal. BP). Whilst the close proximity of the site to the sea may have facilitated maritime exchange activities, occupation of the site was short-lived and the phase of abandonment occurred during a period of rapid RSL rise, which would have transformed the area around Dosariyah into an island or certainly cut it off tidally from the mainland. acceptedVersion

The Fertile Crescent, its hilly flanks and surrounding drylands has been a critical region for studying how climate has influenced societal change, and this review focuses on the region over the last 20,000 years. The complex social, economic, and environmental landscapes in the region today are not new phenomena and understanding their interactions requires a nuanced, multidisciplinary understanding of the past. This review builds on a history of collaboration between the social and natural palaeoscience disciplines. We provide a multidisciplinary, multiscalar perspective on the relevance of past climate, environmental, and archaeological research in assessing present day vulnerabilities and risks for the populations of southwest Asia. We discuss the complexity of palaeoclimatic data interpretation, particularly in relation to hydrology, and provide an overview of key time periods of palaeoclimatic interest. We discuss the critical role that vegetation plays in the human–climate–environment nexus and discuss the implications of the available palaeoclimate and archaeological data, and their interpretation, for palaeonarratives of the region, both climatically and socially. We also provide an overview of how modelling can improve our understanding of past climate impacts and associated change in risk to societies. We conclude by looking to future work, and identify themes of “scale” and “seasonality” as still requiring further focus. We suggest that by appreciating a given locale's place in the regional hydroscape, be it an archaeological site or palaeoenvironmental archive, more robust links to climate can be made where appropriate and interpretations drawn will demand the resolution of factors acting across multiple scales. This article is categorized under:Human Water > Water as Imagined and RepresentedScience of Water > Water and Environmental ChangeWater and Life > Nature of Freshwater Ecosystems, We discuss the impact of a changing regional hydroscape (pictured) on the proxy archives and people of southwest Asia over the last 20,000 years.

The Arabian Peninsula is situated at an important crossroads for the movement of Pleistocene human populations out of, and into, Africa. Although the timings, routes and frequencies of such dispersals have not yet been confirmed by genetic, fossil or archaeological evidence, expansion into Arabia would have been facilitated by humid periods driven by incursions of monsoon rainfall, potentially from both Indian Ocean and African monsoon systems. Here we synthesise terrestrial and marine core palaeoclimatic data in order to establish the spatial and temporal variability of humid periods in Arabia between late Marine Isotope Stage (MIS) 7 and 3. Incursions of monsoon rainfall occurred during periods of insolation maxima at ca. 200e190, 170, 155, 130e120, 105e95, 85e75 and 60e55 ka, providing multiple ‘windows’ of favourable climatic conditions that could have facilitated demographic expansion through Arabia. Strong summer monsoons are generally associated with mid-high latitude interglacials, however, enhanced monsoon convection also brought rainfall into Arabia during global glacial phases, possibly due to a strengthened winter monsoon and a greater influence of southern hemispheric temperature changes. Key periods for dispersal into northern regions of Arabia correspond with the synchronous intensification of both eastern Mediterranean and monsoon rainfall systems at insolation maxima during MIS 7 and MIS 5, which may have facilitated demographic connectivity between the Levant and the Arabian interior. Environmental conditions throughout southern and southeast regions were also favourable to expansion during these times, although strong monsoons in these regions during MIS 6 and MIS 3 suggest further opportunities for demographic expansion and exchange. Terrestrial and marine evidence show that during early MIS 3 (ca. 60e50 ka), a strengthened monsoon led to the activation of interior drainage systems and increased productivity in coastal zones, indicating that favourable environmental conditions existed along both coastal and interior routes at that time.

Climate models are potentially useful tools for addressing human dispersals and demographic change. The Arabian Peninsula is becoming increasingly significant in the story of human dispersals out of Africa during the Late Pleistocene. Although characterised largely by arid environments today, emerging climate records indicate that the peninsula was wetter many times in the past, suggesting that the region may have been inhabited considerably more than hitherto thought. Explaining the origins and spatial distribution of increased rainfall is challenging because palaeoenvironmental research in the region is in an early developmental stage. We address environmental oscillations by assembling and analysing an ensemble of five global climate models (CCSM3, COSMOS, HadCM3, KCM, and NorESM). We focus on precipitation, as the variable is key for the development of lakes, rivers and savannas. The climate models generated here were compared with published palaeoenvironmental data such as palaeolakes, speleothems and alluvial fan records as a means of validation. All five models showed, to varying degrees, that the Arabia Peninsula was significantly wetter than today during the Last Interglacial (130 ka and 126/125 ka timeslices), and that the main source of increased rainfall was from the North African summer monsoon rather than the Indian Ocean monsoon or from Mediterranean climate patterns. Where available, 104 ka (MIS 5c), 56 ka (early MIS 3) and 21 ka (LGM) timeslices showed rainfall was present but not as extensive as during the Last Interglacial. The results favour the hypothesis that humans potentially moved out of Africa and into Arabia on multiple occasions during pluvial phases of the Late Pleistocene.

International audience; The Empty Quarter (or Rub' al Khali) of the Arabian Peninsula is the largest continuous sandy desert in the world. It has been known for several decades that Late Pleistocene and Holocene deposits, representing phases of wetter climate, are preserved there. These sequences have yielded palaeontological evidence in the form of a variety of vertebrate and invertebrate fossils and have been dated using various radiometric techniques. However, evidence for human presence during these wetter phases has until now been ephemeral. Here, we report on the first stratified and dated archaeology from the Empty Quarter, recovered from the site of Mundafan Al-Buhayrah (MDF-61). Human occupation at the site, represented by stone tools, has been dated to the later part of Marine Isotope Stage (MIS) 5 using multiple luminescence dating techniques (multigrain and single grain OSL, TT-OSL). The sequence consists primarily of lacustrine and palustrine sediments, from which evidence for changing local environmental conditions has been obtained through analysis of fossil assemblages (phytoliths and non-marine molluscs and ostracods). The discovery of securely-dated archaeological material at ∼100 to 80 ka in the Empty Quarter has important implications for hypotheses concerning the timing and routes of dispersal of Homo sapiens out of Africa, which have been much debated. Consequently, the data presented here fill a crucial gap in palaeoenvironmental and archaeological understanding of the southern Arabian interior. Fossils of H. sapiens in the Levant, also dated to MIS 5, together with Middle Palaeolithic archaeological sites in Arabia and India are thought to represent the earliest dispersal of our species out of Africa. We suggest that the widespread occurrence of similar lithic technologies across southern Asia, coupled with a growing body of evidence for environmental amelioration across the Saharo-Arabian belt, indicates that occupation of the Levant by H. sapiens during MIS 5 may not have been a brief, localized ‘failed dispersal’, but part of a wider demographic expansion.

Records of former lake and wetland development in present day arid/hyper-arid environments provide an important source of information for palaeoclimatic and palaeoenvironmental studies. In Arabia, such records are typically confined to eccentricity-modulated insolation maxima, and are often spatially and temporally discontinuous. Here we present records from a single locality in Northern Arabia of wetter interludes during both global interglacial and glacial conditions, providing a unique opportunity to examine the nature of these events in a common setting. At Jubbah, in the southern Nefud Desert, lake and wetland deposits reveal the repeated formation of a water body within a large endorheic basin over the past ca. 360 kyr. Lake/wetland formation occurred during MIS 11/9, 7, 5, 3 and the early Holocene, assisted by local topographic controls, and spring recharge. Palaeoenvironmental and palaeoecological data reveal the existence of a large still water body formed during either MIS 11 or 9 (ca. 363 ka), and basin wide alluviation followed by lake formation during MIS 7 (ca. 212 ka). During MIS 5e (ca. 130 ka) a large freshwater lake occupied the basin, while during MIS 5a (ca. 80 ka) the basin contained a shallow wetland and freshwater lake complex. Lake/wetland formation also occurred during early MIS 3 (ca. 60 ka), at the Terminal Pleistocene-Holocene transition (ca. 12.5 ka), and the early-middle Holocene (ca. 9–6.5 ka). Phases of lake and wetland development coincided with human occupation of the basin during the Middle Palaeolithic, Epipalaeolithic and Neolithic periods, highlighting the significance of the region for early demographic change.

To disperse out of sub-Saharan Africa, it was necessary for hominins to cross the deserts of either the Sahara and/or Arabia. Thus, understanding the palaeoclimate of the Saharo-Arabian region is central to determining the role these deserts played in the peopling of the planet; when did they act as barriers and when were they more humid, opening dispersal routes across them? To address these questions we have conducted a temporal and spatial evaluation of dated sites from 20 to 350 ka using combined probability density function (PDF) and geographical Information System (GIS) analyses of all sites dated using uranium/thorium (U/TH) or optically stimulated luminescence (OSL) methods. Radiocarbon dates were not considered because of contamination problems in this time range. The results show that during MIS 2 there is little evidence for humidity in Arabia as would be expected during the height of the last glacial maximum, however, the Sahara shows a sharp rise in probability at the beginning of MIS 2, peaking near the boundary with MIS 3 at ∼29 ka. There appear to be brief periods of humidity in MIS 3 and 6, though at different times in the Sahara (ca. 37, 44, 138, 154 and 180 ka) and Arabia (ca. 40, 54 and 163 ka). During MIS 5, both regions show much evidence for humidity, with PDF peaks corresponding to insolation maxima, though not all maxima are represented in either the Saharan or Arabian record. This situation can be explained by eccentricity-modulated precession: when eccentricity is strong, insolation is enhanced (but also more variable) and the desert climate is generally more humid, particularly at times of high insolation. The opposite happens when eccentricity is low, and deserts tend to be more arid, but local factors exert more of an influence on climate, affecting the timing and strength of the brief humid periods experienced, so that they no longer coincide with insolation maxima. The spatial distribution of humid sites is compatible with a number of different modern human dispersal theories. Southern Arabia experienced humid periods centred on 54 ka and 125 ka, and this could have facilitated dispersal from east Africa to southern Arabia and beyond via the Bab el Mandab. The Sahara shows considerable evidence for humidity during MIS 5 and may have had dispersal across its expanse at this time.

The major driver of palaeoclimatic dynamics over the southeast Arabian region is the varying latitudinal interface between the Westerly driven shamaal winds and a northward branch of the southwesterly Indian Ocean Summer Monsoon (IOM). At present, this latter system is restricted in extent to the southern coastal regions of Yemen and Oman. Monsoonal winds are widely believed to have increased in strength and penetrated much further north across southeast Arabia at various intervals during the Quaternary, resulting in a series of humid phases, which early studies suggested focussed within MIS 3 and MIS 1. Recent speleothem studies from Oman and UAE have indicated humidity within MIS 5 which, with current debates surrounding early human dispersal and occupation, could be significant for affirming the regional potential for early occupation. We investigate two new geoproxy suites, from Al Ain and Tawi Asmar, northern UAE, in the presently hyper-arid. Rub’ al-Khali Sand Sea, that preserve evidence of multiple episodes of aeolian deposition and humidity in the form of fluvial gravels, sands and silts, and dune sands. 35 OSL ages demonstrate humid episodes occurred in MIS 5e, 5a and the early Holocene, with a major dry dune building phase in late MIS 3, and the onset of dry conditions again from 6 ka. The fluvial sedimentary evidence from MIS 5e and 5a suggest that the present hyper-arid desert landscape of the northeastern Rub’ al-Khali was at those times represented by an environment experiencing significant seasonal wadi flow. This provides an environmental context that supports recent studies indicating archaeological visibility in Arabia dating from MIS 5, and the presence of anatomically modern humans in Arabia at this time.

Key to the understanding of Pleistocene human dispersals and settlement dynamics is knowledge about the distribution of human habitats in space and time. To add information about the characteristics of inhabited environments along the South Arabian dispersal route, this paper presents paleo-environmental data from deposits excavated at Jebel Faya (FAY-NE1) in the Emirate of Sharjah, UAE. The sedimentary sequence at FAY-NE1 spans a period of about 125,000 years, including the last interglacial and the Holocene. Particle size and phytolith content of samples from two sediment columns were analyzed, including both archaeology bearing layers and archaeologically sterile layers. The results demonstrate that human occupation of the site is related to pluvial periods. Assemblage C, dated to about 127–123 ka, was deposited during a wet phase with an environment characterized by an increased proportion of C 3 grasses. Grassland with sedges but lacking tree cover characterize ecological conditions during the youngest of the Paleolithic occupation periods, Assemblage A, dated to about 45–40 ka. Environmental conditions during periods lacking archaeological remains are characterized by the absence of vegetation cover during phases of desiccation. There is no evidence for human presence at the site between 38 and 11 ka.

The early to mid-Holocene has long been recognised as a period of wetter climate with widespread lacustrine development and vegetation expansion throughout south-east Arabia. Recent palaeoclimate data has, however, transformed our understanding of the Holocene Pluvial Phase (HPP) and evidence presented in this paper demonstrates that climate was neither homogeneous during the period, nor were shifts between pluvial and arid episodes synchronous across the region. This dynamic setting provided the backdrop for human expansion during the Neolithic, and in turn raises important questions about the interactions between these populations and the natural environment in south-east Arabia.

An early-to mid-Holocene humid phase has been identified in various Arabian geo-archives, although significant regional heterogeneity has been reported in the onset, duration and stability of this period. A multi-proxy lake and dune record from Wahalah in the United Arab Emirates (UAE) documents significant variations in hydrology, biological productivity and landscape stability during the first half of the Holocene. These data reveal that post-Last Glacial Maximum dune emplacement continued into the earliest part of the Holocene, with the onset of permanent lacustrine sedimentation at the site commencing ~8.5. ka. cal.BP. A long-term shift towards more arid conditions is inferred between ~7.8 and 5.9. ka. cal.BP, with intermittent flooding of the basin and distinct phases of instability throughout the catchment area. This transition is linked to the southwards migration of the Intertropical Convergence Zone (ITCZ) and associated weakening of monsoon rains. A peak in landscape instability is recorded between ~5.9 and 5.3. ka. cal.BP and is marked by a pronounced increase in regional dune emplacement. These variations are considered alongside the record of human settlement raising important questions about the interactions between population demographics, climate and environment in southeast Arabia during the Neolithic.

Despite the present hyper-aridity, archaeological investigations in South-east Arabia have demonstrated that the region supported extensive human communities throughout the Neolithic and Bronze Age. These early populations utilised the region’s natural environment in a variety of ways, ranging from the exploitation of coastal resources to practicing pastoral and agrarian lifestyles in the interior. Palaeoclimate data suggests the corresponding period was characterised by considerable climatic variability yet, to date, few studies have attempted to investigate the relationship between climate, the environment and early human populations in the region. This paper combines new high-resolution palaeoclimate data from Awafi palaeolake, United Arab Emirates (UAE), with the region’s archaeological record from the Neolithic through to the onset of the Bronze Age. The evidence presented in this paper suggests that the environment of South-east Arabia offered different constraints and opportunities for early human occupation and subsistence. In particular, abrupt phases of aridity are demonstrated to have had a profound impact. Most notable is the change which occurred following the onset of climatic aridity at 5900 cal yr BP, when the region’s semi-nomadic, herder-gatherer populations abandoned much of the landscape and concentrated in selected environmental refugia, such as along the northern Omani coast. Human repopulation during the Bronze Age coincided with a return to more pluvial conditions under which a network of oasis agricultural settlements appeared along the piedmont zone of the northern Hajar Mountains.

The Youngest Toba Tuff (YTT) eruption ∼74 ka is the largest volcanic event to occur during the last two million years. This paper presents a high resolution landscape reconstruction for the Jurreru Valley, south India, immediately prior to this eruption. Primary ash fall deposits have sealed the pre-Toba surface of the Jurreru Valley, and subsequent deposition of remobilised ash has helped preserve this horizon. These primary YTT deposits provide an isochron that allows for the study of palaeoenvironmental conditions across a 25,000 m2 area in the Jurreru Valley, permitting the reconstruction of the pre-Toba landscape. Sixty sites with exposed primary ash deposits have been recorded as part of a Total Station survey, twelve of which have been subject to detailed stratigraphical study. This has enabled a reconstruction of the topography of the buried surface in the Jurreru Valley. Stable isotope and phytolith analyses are used to explore diversity across this buried landscape, indicating that the ratio of C3 to C4 plants varies with regard to changes in topographic height in the landscape of up to ∼5 m. High levels of spatial heterogeneity within these proxy data are indicated by this study, highlighting the risks of extrapolating regional palaeoenvironmental sequences from vertically sampled sedimentary sections, which may well reflect highly localised influences of topography and geomorphology.

Extreme Late Quaternary climatic events, sometimes of considerable continental extent, are being proposed as major contributors to ancestral human behaviour, particularly migration, in Africa. Most recently, a catastrophic drought in the Afro-Asian monsoon region has been proposed for 16000-17000 years ago, driven by global impacts of the Heinrich event 1 (H1), with potentially significant consequences for Palaeolithic cultures. We provide a new analysis of the assertion and find, on examination of a wide set of palaeoenvironmental records, that the scale and extent of the proposed drought is not supported. While some parts of the African tropics, close to the equator, do appear dry at this time, data for the tropics as a whole suggest markedly variable terrestrial conditions, with some environmental systems experiencing very positive hydrological excursions during H1. We contend that in the quest for evidence of climate drivers of ancestral human behaviour, the variability associated with spatially and temporally complex climatic conditions is a significant factor in itself. Copyright # 2011 John Wiley & Sons, Ltd.

It has been hypothesised that in sand seas where multiple dune generations occur, each generation represents a distinct terrestrial response to contrasting palaeoatmospheric circulation conditions (Lancaster N, Kocurek G, Singhvi A, Pandey V, Deynoux M, Ghienne J-F et al. (2002) Late Pleistocene and Holocene dune activity and wind regimes in the western Sahara Desert of Mauritania. Geology 30: 991–994). However, reconstructing dunefield accumulation and preservation chronologies has often utilised a limited suite of samples because of the difficulties realised in accessing unconsolidated aeolian sands, which has limited the capacity to test this hypothesis. In the eastern United Arab Emirates, artificial excavation for quarrying and construction have generated a unique opportunity to examine and sample the internal structures of dune systems, and to generate data to test the hypothesis of dune generational development. This paper presents new data and chronologies from a multigenerational analysis of dune accumulation in the northeast dunefield of the Rub’ al-Khali. A complex developmental history during the Holocene is revealed, which does not fully conform to the notion of each dune generation forming in distinct palaeoclimatic phases, since the age ranges represented in the accumulation of secondary dunes is also found within a longer suite of accumulation ages from the underlying megaridges.

International audience; Major hydrological variations associated with glacial and interglacial climates in North Africa and the Levant have been related to Middle Paleolithic occupations and dispersals, but suitable archaeological sites to explore such relationships are rare on the Arabian Peninsula. Here we report the discovery of Middle Paleolithic assemblages in the Nefud Desert of northern Arabia associated with stratified deposits dated to 75,000 years ago. The site is located in close proximity to a substantial relict lake and indicates that Middle Paleolithic hominins penetrated deeply into the Arabian Peninsula to inhabit landscapes vegetated by grasses and some trees. Our discovery supports the hypothesis of range expansion by Middle Paleolithic populations into Arabia during the final humid phase of Marine Isotope Stage 5, when environmental conditions were still favorable.

The late Holocene environmental history of the Lesotho highlands, southern Africa, is poorly understood with few detailed studies to date. At Likoaeng, Senqu Valley, Lesotho, a 3 m stratified sedimentary sequence from an open-air archaeological site records vegetation development for the period 3400–1070 cal. BP. Phytolith analyses and bulk sediment organic matter δ 13 C indicate that C 4 grassland dominated the lower part of the sequence until approximately 2960 cal. BP when there was a switch to C 3 Pooid grassland (2960–2160 cal. BP). Also noted was a change from hunting mainly bovids to a dominance of fishing at the site. The change in grassland type and archaeological subsistence strategies corresponds with an episode of neoglacial cooling and the expansion of Alpine sourgrasses into lower altitudes. From 2160 to 1600 cal. BP grassland became a mix of C 3 and C 4 types and by 1600–1070 cal. BP there was a return to C 4 dominated grassland. During this latter phase there was a reversal from fishing to hunting again (and eventually some keeping of domestic livestock) at the site. These data outline the vegetation response to latitudinal shifts of frontal systems, and relatively strong atmospheric circulation variability, perhaps underpinned by variations of polar water into the Benguela Current during the late Holocene.

A research programme has been set up at Higueral de Valleja Cave in southern Spain to investigate the late survival and eventual extinction of the southern Iberian Neanderthals and the arrival of modern humans. Of key interest in the first phase of research was to understand the depositional environment in the entrance chamber of the cave and to establish whether palaeoenvironmental and dating samples could be retrieved from the Middle and Upper Palaeolithic sequences. The outcome is a series of OSL, TL and radiocarbon dates showing that the cave was occupied by Neanderthal populations in Marine Isotope Stage (MIS) 3, if not earlier, and by modern human Solutrean populations during the last glacial maximum. Cave sediments provisionally indicate that the lower Middle Palaeolithic sequence (X-VIII) formed in warm and humid environments and the upper sequence (VIII-V) formed when the climate was cooler and drier. The presence of long grass phytoliths and of the small mammals Microtus duo-decimcostatus, Microtus brecciensis, and Apodemus sylvaticus in the upper sequence indicates that a range of habitat types persisted near the cave including grassland, scrubby vegetation, patchy tree cover and ponds. This raises the possibility that environmental factors were key factors in the late survival of Neanderthal populations at the cave.

Evidence of small glaciers is often used to infer past atmospheric climate through calculation of steady-state ELAs. However, if topographic niches such as shading or windblown-snow augmented mass-balance then ELAs cannot reflect regional climate and determining the significance of these topoclimates is therefore important. The Brecon Beacons, South Wales, contains upland glacial landforms dating to the Younger Dryas (11,000-10,000 yr BP) when local climate was at the threshold for glaciation. This case study categorises topoclimate using three-dimensional modelling of topography and reconstructed palaeoglaciers from two sites containing mapped moraines whose orientation suggest complex patterns of deglaciation. Ablation season solar radiation is modelled over multiple ice-surfaces as shade from surrounding topography and intensity from ice-surface incidence angle. Snowblow and avalanching potential models are also used and the significance of all topoclimate variables assessed against a mass-balance deficit calculated for each glacier given palaeoclimate models for the region. Results demonstrate that both glaciers were likely to be heavily reliant on topoclimate and that previous studies underestimate the significance of solar radiation. Modelled over multiple ice-surfaces reflecting patterns of recession, results indicate that the distribution of topoclimate variables predicts the style of deglaciation at both sites, possibly explaining the complexity of glacial evidence in this environment. © 2008 Elsevier Ltd. All rights reserved.

The January 2009 fieldwork season conducted geomorphological and palaeoenviromental surveys in as yet unexplored parts of the Lake Megafazzan Basin, as well as continuing research in the Wadi al-Hayat and Ubari Sand Sea. Lake Megafazzan sediments were investigated at two sites on the eastern margin of the basin. At the first site, east of Tamessah, 24 m of stratigraphy was investigated and found to consist of a lacustrine carbonate unit at the base progressing into a fluvial unit and then an upper carbonate unit. The sediments were sampled for magnetostratigraphy and cosmogenic nucleide dating in order to determine their age. Similar studies were undertaken in the vicinity of the Arial Agricultural Project, where 31 m of section were logged and sampled. Here the sediments were quite different, being composed of a deltaic sequence consisting of stacked channels and palaeosols, thought to represent the outflow delta of the palaeolake. Many new Holocene lake sediment deposits were discovered and sampled in the Wadi al-Hayat and the Ubari Sand Sea, including a 5 m section through Jarma Playa that appears to record the last arid-humid cycle. Lake Gabr 'Awn and the moat round Old Jarma were cored in order to gather a detailed picture of recent palaeoenvironmental change. Finally, we implemented a pilot geophysical survey to test the ability of state-of-the-art Ground Penetrating Radar (UltraGPR) technology for detecting and mapping buried palaeolake sediments under the dunes of the Ubari Sand Sea. The UltraGPR was found to be very effective, detecting palaeolake sediments as much as 60 m beneath the surface. Preliminary results suggest such sediments underlie much of the region.

Large-scale floodplain excavations at Dorney in the Middle Thames valley have revealed organic-rich Holocene palaeochannels as well as a rich archaeological record. High-resolution (decadal) palaeobotanical and sedimentological analyses from a Late Holocene palaeochannel have enabled detailed reconstruction of the landscape spanning from ca. 2850 C14 yr BP (Late Bronze Age), through the Iron Age, Roman and Saxon periods and into the Medieval period (ca. 450 C14 yr BP). The application of sedimentological, palaeovegetation and mineral magnetic analyses coupled with the use of simultaneous R- and Q-mode factor analysis helps to underpin phases of active channel flow, phases of channel ‘ponding’, and alluviation. These phases developed in response to human activity and land use within the region that resulted from deforestation, changes from pastoral to arable practice, burning and the associated destabilisation and inwash of soils into the channel. A series of wooden bridges and timber structures were constructed across this channel between the Middle Bronze Age and Late Iron Age which influenced local sedimentation patterns, fluvial energy and competency within the channel. A number of erosive events coupled with inwashing from the clearance of the last vestiges of woodland for agriculture into an active channel were identified. During the Roman period, flow along the Thames channel ceased, resulting in a pond-like feature in which peaty silts rapidly accumulated. This phase of ponding was punctuated by renewed channel activity in which inorganic carbonate sediments rich in ferrimagnetic minerals were deposited. This coincides with a major peak in cereal cultivation and related catchment disturbance of soils because of ploughing with associated runoff and inwash of soils associated with flooding.

During the Late Quaternary, the climate of Arabia has fluctuated between periods of higher rainfall and fluvial activity, dominated by the influence of the Indian Ocean Monsoon (IOM) and drier/arid conditions under the influence of the westerlies. This has left a rich legacy of landforms from which temporal and spatial patterns of environmental change are reconstructed. The coastal desert region of the southeastern Arabian Gulf has been a focal point for human settlement since ~ 8000 cal yr BP. The region is strategically located on an important trade route between two ‘cradles of civilization’, namely, Mesopotamia and the Indus. Changes in the evolution and modification of this landscape under varying climatic conditions have influenced humans living in and exploiting this landscape for food and water, raw materials and trade routes. In this study, geomorphological and palaeoenvironmental investigations are integrated to provide a framework of environmental change for the Late Glacial and early–mid Holocene periods against which the archaeology of the area can be set. The Late Glacial and earliest Holocene was characterised by intense aridity and accumulation of mega linear dunes driven by the Shamal winds. In the Arabian Gulf region, this continued into the earliest part of the Holocene, whilst southern Arabia was under the influence of the IOM. The monsoon rains migrated into the Gulf region between 8500–6000 cal BP. During this time, semi-nomadic herders occupied this region and grazing their animals in a landscape covered with C3 savanna grassland. The Neolithic peoples also practised hunting and fishing and the collection of shellfish was an important activity. Pottery shows links with Mesopotamia at this time. From 6000 cal BP the IOM retreated south and rainfall was derived from winterly westerly sources. Under drier conditions a switch occurred to a sparser cover of C4 grasses. From 4500 cal BP the climate became much drier with the development of stronger westerly summer Shamal winds and the reactivation of dunes across the region. An intense arid period occurred at 4100 BP which corresponds with major drought conditions in Mesopotamia and the Indus region, which led to major changes in society. This event occurs at a major transition in the Arabian Gulf Bronze Age archaeological record with a decline in population and trade. The last 4000 yr has largely been characterised by arid conditions similar to those found in the region today.

Archaeological excavations in 2002–3 at Hattab II Cave in northwestern Morocco revealed an undisturbed Late Palaeolithic Iberomaurusian human burial. This is the first Iberomaurusian inhumation discovered in the region. The skeleton is probably that of a male aged between 25 and 30 years. The individual shows a characteristic absence of the central upper incisors reported in other Iberomaurusian burials. Accompanying the burial are a stone core and a number of grave goods including bone points, a marine gastropod and a gazelle horn core. Thermoluminescence dating of a burnt stone artefact in association with the burial has provided an age of 8900?1100 bp. This is one of the youngest ages reported for the Iberomaurusian and raises questions about persistence of hunter-gatherer societies in the Maghreb and the potential for continuity in burial practices with the earliest Neolithic.

This paper presents the first study of phytoliths from the Saharan region. Phytolith analysis shows the potential of reconstructing grassland dynamics during the Holocene, refining our knowledge of palaeoecosystems in the Ubari sand sea, Libya. The lake sediments studied range in age between 3,273–9,440 cal. BP. Tree cover was very low around 3,273–3,436 cal. BP and 6,678–6,796 cal. BP, and the landscape was dominated by C4 grasslands around 6,678–6,796 cal. BP, shifting to a more mixed C3-C4 grassland community around 3,273–3,436 cal. BP. These differences may be caused by the older sample being deposited during the onset of a brief arid period, but a similar phytolith assemblage could arise due to a more pronounced seasonality in the climate, with C3 grasses dominating late and early in the growing season when the climate is cooler and less arid, and C4 grasses becoming dominant in the hot, dry summer season.

Six mature wheat (Triticum aestivum L.) plants from one crop were collected one week before harvest, and organs were separated as follows: culm, rachis, leaf sheaths, leaf blades and inflorescence bracts. Percentage silica (% SiO2), % C, % N and δ13C were determined in these samples. Phytoliths isolated from the individual organs were subsequently analysed for δ29Si, δ30Si, and δ18O, as well as % C, % N and δ13C from occluded organic material within the phytoliths. Percentage silica was highest in the leaf sheaths and leaf blades and lower in the inflorescence bracts, culm and rachis. δ30Si and δ29Si were highly correlated, and both increased in the upper parts of the plant. It appears there are two routes for Si transport within the plant, and that heavier isotopes increase towards the end of both routes. The δ18O results indicate that the culm and the leaf blades were the sites of highest δ18O, with lower values in the rachis, leaf sheath and inflorescence. There was no correlation between the accumulation of either heavy silicon isotope (29Si and 30Si) and heavy oxygen accumulation (18O). δ13C values were typical of C3 species, and whole plant and isolated phytolith values were similar. Low % N concentrations were detected in phytoliths. © Natural Environment Research Council (NERC) copyright 2008. Reproduced with the permission of NERC. Published by John Wiley & Sons, Ltd.

The Maloti-Drakensberg Mountains are southern Africa’s highest and give rise to South Africa’s largest river, the Orange-Senqu. At Melikane Rockshelter in highland Lesotho (~1800 m a.s.l.), project AMEMSA (Adaptations to Marginal Environments in the Middle Stone Age) has documented a pulsed human presence since at least MIS 5. Melikane can be interrogated to understand when and why early modern humans chose to increase their altitudinal range. This paper presents the results of a multi-proxy paleoenvironmental analysis of this sequence. Vegetation shifts are registered against a background signal of C3-dominated grasslands, suggesting fluctuations in temperature, humidity and atmospheric CO2 within a generally cool highland environment with high moisture availability. Discussing Melikane in relation to other paleoenvironmental and archeological archives in the region, a model is developed linking highland population flux to prevailing climate. It is proposed that short-lived but acute episodes of rapid onset aridity saw interior groups disperse into the highlands to be nearer to the Orange-Senqu headwaters, perhaps via the river corridor itself.

Recent sand quarrying operations for building and construction work in the eastern extremity of the Rub’ al-Khali sand sea has revealed sediment exposures through a number of coastal and inland dunes. In the al-Daith district of Ras al-Khaimah (U.A.E.) a Holocene shell midden was exposed 2.8 m below the present dune surface interstratified between phases of Late Pleistocene and late Holocene dune sands. C14 and OSL ages constrain the site giving an insight into phases of landscape instability, dune formation, rates of sediment accretion, and a period of stability and human occupation. To date, Hafit period sites (5200–4500 cal BP) have been recorded in large numbers in the mountains and gravel plains of the Oman mountains. Coastal shell middens have not, as yet, been ascribed to the Hafit period from this part of the region and the study presents the first radiocarbon age from such a site. This study indicates the potential that many other sites exist elsewhere buried under late Holocene dune sediments and these provide an important insight into the development of the coastal landscape of this region.

Lacustrine sediments from southeastern Arabia reveal variations in lake level corresponding to changes in the strength and duration of Indian Ocean Monsoon (IOM) summer rainfall and winter cyclonic rainfall. The late glacial/Holocene transition of the region was characterised by the development of mega-linear dunes. These dunes became stabilised and vegetated during the early Holocene and interdunal lakes formed in response to the incursion of the IOM at approximately 8500 cal yr BP with the development of C3 dominated savanna grasslands. The IOM weakened ca. 6000 cal yr BP with the onset of regional aridity, aeolian sedimentation and dune reactivation and accretion. Despite this reduction in precipitation, the lake was maintained by winter dominated rainfall. There was a shift to drier adapted C4 grasslands across the dune field. Lake sediment geochemical analyses record precipitation minima at 8200, 5000 and 4200 cal yr BP that coincide with Bond events in the North Atlantic. A number of these events correspond with changes in cultural periods, suggesting that climate was a key mechanism affecting human occupation and exploitation of this region.

Geomorphological and geoarchaeological studies from the lower Gulf region of southeastern Arabia are increasing our knowledge of hydrological, ecological, and aeolian changes during the Holocene. Preliminary analyses of sediment records from two palaeolakes in the United Arab Emirates are presented, highlighting the potential of these sediment sources for providing high-resolution decadal studies of climate change and landscape evolution over the past 10,000 years. In order to study the society-environment relationship in this marginal region, a framework of environmental change is being developed against which the archaeology of the region can be set.

The increase in both automation and precision in the analysis of geological materials has had significant impact upon forensic investigations in the last 10 years. There is however, a fundamental philosophical difference between forensic and geological enquiry. This paper presents the results of forensic geoscientific investigations of three cases of wildlife crime. Two cases involve the analysis of soils recovered after incidents of illegal badger baiting in the United Kingdom. The third case involves the illegal importation of Eleonora's Falcon (Falco eleonorae) into the United Kingdom from the Mediterranean. All three cases utilise the analysis of soils by a variety of physical, chemical and biological techniques. These involve mineral and grain size analyses, cation and anion compositions, pH, organic content and pollen analysis.The independent analysis undertaken by specialists in each of these three main fields conclude firstly, that there is a significant similarity between sediments taken at the crime site at both badger setts and with sediments recovered from various spades, shovels and clothing belonging to suspects and secondly, that the soils analysed associated with the removal of the falcon eggs in the Mediterranean contained characteristics similar in many respects to the soils of the breeding areas of E eleonorae on the cliffs of Mallorca. The use of these independent techniques in wildlife crime detection has great potential given the ubiquitous nature of soils and sediments found in association with wildlife sites. (c) 2006 Elsevier Ireland Ltd. All rights reserved.

The Holocene vegetation history of the Arabian Peninsula is poorly understood, with few palaeobotanical studies to date. At Awafi, Ras al-Khaimah, UAE, a 3.3 m lake sediment sequence records the vegetation development for the period 8500 cal. yr BP to � 3000 cal. yr BP. 13 C isotope, pollen and phytolith analyses indicate that C3 Pooid grassland with a strong woody element existed during the early Holocene (between 8500 and 6000 cal. yr BP) and became replaced by mixed C3 and C4 grasses with a strong C4 Panicoid tall grass element between 5900 and 5400 cal. yr BP. An intense, arid event occurred at 4100 cal. yr BP when the lake desiccated and was infilled by Aeolian sand. From 4100 cal. yr BP the vegetation was dominated by C4 Chloridoid types and Cyperaceae, suggesting an incomplete vegetation cover and Aeolian dune reactivation owing to increased regio- nal aridity. These data outline the ecosystem dynamics and carbon cycling in response to palaeomon- soon and north-westerly variability during the Holocene. Copyright 2004 John Wiley & Sons, Ltd.

Despite the wealth of archaeological sites and excellent conditions for preservation, few phytolith investigations have been undertaken from the Arabian Gulf region. The results from the Sasanian and Islamic archaeological tell of Kush, Ras al-Khaimah, United Arab Emirates, are presented. Kush is situated just inside the Gulf on an important trade route. The occupation sequence dates from the 4th century A.D. until the 13th century A.D., recording the development of the site in the Sasanian period, followed by the arrival of Islam in the 7th century A.D. and the final abandonment of the site in the late 13th century when the nearby site of al-Mataf (Julfar) began to develop closer to the present day coastline. All the samples analyzed contained abundant phytoliths (short cells, elongated cells, and groups of elongated cells) of various types. They included date palm (Phoenix dactylifera), papillae (possibly from barley (Hordeum)), and hair cells possibly from species of canary grass (Phalaris spp.). Some researchers have suggested that groups of elongated cells may indicate the presence of irrigation in semiarid environments. The present results for this class of phytoliths appeared to imply that intensive irrigation was unlikely to have taken place around Kush.

The dispersal of human populations out of Africa into Arabia was most likely linked to episodes of climatic amelioration, when increased monsoon rainfall led to the activation of drainage systems, improved freshwater availability, and the development of regional vegetation. Here we present the first dated terrestrial record from southeast Arabia that provides evidence for increased rainfall and the expansion of vegetation during both glacial and interglacial periods. Findings from extensive alluvial fan deposits indicate that drainage system activation occurred during Marine Isotope Stage (MIS) 6 (ca. 160–150 ka), MIS 5 (ca. 130–75 ka), and during early MIS 3 (ca. 55 ka). The development of active freshwater systems during these periods corresponds with monsoon intensity increases during insolation maxima, suggesting that humid periods in Arabia were not confined to eccentricity-paced deglaciations, and providing paleoenvironmental support for multiple windows of opportunity for dispersal out of Africa during the late Pleistocene.

Over the past 50 years the most enigmatic feature of pollen diagrams from northwest Europe has been the mid-Holocene ‘elm decline’, and there has been much speculation as to the origin(s) and cause(s) of this event. A total of 150 radiocarbon dates from 139 sites spanning the elm decline in Britain and Ireland have been collated and scrutinized. Statistical analyses on 138 dates show that the event has a mean date of 503614C yr BP with a standard deviation of ± 247. Calibration of the dates and combining the sum probabilities yielded a range spanning 6347-5281 cal yr BP (1s), covering 1066 years. The start of the elm decline event lies between 6343 and 6307 cal yr BP (1s), a period of 36 years, indicating that the onset was rapid. The end of the event lies between 5290 and 5420 cal yr BP (1s), a period of 130 years. The probability distribution indicates that the elm decline was a uniform phased event across the British Isles. It appears that the elm decline can be explained to a large extent by the outbreak of disease. However, recent research on palaeoclimatic change and the nature of the transition from the Mesolithic to Neolithic in the British Isles suggests that both climatic change and human activities were implicated. It was probably the interplay between these factors, rather than any in isolation, that catalyzed the widespread, catastrophic decline of elm populations during the mid-Holocene.

International audience; The transition from the Terminal Pleistocene to the Early Holocene is poorly represented in the geological and archaeological records of northern Arabia, and the climatic conditions that prevailed in the region during that period are unclear. Here, we present a new record from the site of Al-Rabyah, in the Jubbah basin (southern Nefud desert, Saudi Arabia), where a sequence of fossiliferous lacustrine and palustrine deposits containing an archaeological assemblage is preserved. Sedimentological and palae-oenvironmental investigations, both at Al-Rabyah and elsewhere in the Jubbah area, indicate phases of humid conditions, during which shallow lakes developed in the basin, separated by drier periods. At Al-Rabyah, the end of a Terminal Pleistocene phase of lake expansion has been dated to ~12.2 ka using optically stimulated luminescence (OSL), with a mid-Holocene humid phase dated to after ~6.6 ka. Palaeoecological reconstructions based primarily on non-marine molluscs and ostracods from the younger lacustrine deposits indicate a relatively shallow body of freshwater surrounded by moist, well-vegetated environments. A lithic assemblage characterized by bladelets and geometric microliths was excavated from sediments attributed to a drier climatic phase dated to ~10.1 ka. The lithic artefact types exhibit similarities to Epipalaeolithic industries of the Levant, and their occurrence well beyond the 'core region' of such assemblages (and at a significantly later date) has important implications for understanding interactions between Levantine and Arabian populations during the Terminal PleistoceneeEarly Holocene. We suggest that the presence of foraging populations in the southern Nefud during periods of drier climate is due to the prolonged presence of a freshwater oasis in the Jubbah Basin during the Terminal PleistoceneeEarly Holocene, which enabled them to subsist in the region when neighbouring areas of northern Arabia and the Levant were increasingly hostile.

Spatial variations in sand sea geochemistry relate to mixing of different sediment sources and to variations in weathering. Due to problems of accessibility, adequate spatial coverage cannot be achieved using field surveys alone. However, maps of geochemical composition produced from remotely sensed data can be calibrated against limited field data and the results extrapolated over large, inaccessible areas. This technique is applied to part of the Rub' Al Khali in the northern United Arab Emirates. Trend surface analysis of the results suggests that the sand sea at this location can be modelled as an east–west mixing zone of two spectral components: terrestrial reddened quartz sands and marine carbonate sands. Optical dating of these sediments suggests that dune emplacement occurred rapidly around 10 ka BP, when sea level was rising rapidly. The spatial distribution of mineralogical components suggests that this phase of dune emplacement resulted from coastal dune sands being driven inland during marine transgression, thereby becoming mixed with rubified terrestrial sands. Copyright © 2001 John Wiley & Sons, Ltd.

Optical dating of two dune profiles developed in linear dunes in Ras AlKhaimah, United Arab Emirates, has been used to establish the timing and rateof dune accretion. One section at Awafi was over 17 m high, while that at Idhnwas over 40 m high. The Awafi dune appears to have accumulated very rapidly»10 000 years ago, with a vertical accumulation rate of about 3AE3mka )1 . TheIdhn dune appears to have accumulated over the past 1000 years, with 20 m ofsediment accumulating in a time period of about 270 years. The Awafi dunemay have accumulated in response to the transgression of the Persian Gulf byrising sea levels in late Pleistocene and Holocene times. The Idhn dune mayhave accumulated rapidly because of intensified human activity, a short-livedclimatic event, or because it may periodically be reactivated after erosion byfluvial action at its base.Keywords Linear dune, optical dating, Rub Al-Khali, sand accumulation.INTRODUCTIONThere remains some uncertainty surrounding thestyle and timing of deposition of large aeoliandunes, with authors supporting both gradual andpunctuated models of dune development (for adiscussion, see Thomas, 1997). This divergence ofopinion results from both the general absence ofdating control within dunes in most studies, anddifficulties in gaining exposures within some ofthe larger dune bedforms. The purpose of thispaper is to establish a chronology of dunedevelopment for two thick (>10 m) dune sectionsexcavated within large, complex, linear dunesfrom within the Rub Al Khali, near Ras AlKhaimah, in the north of the United ArabEmirates (Fig. 1). The sites were selected becauseof the availability of thick, fresh sections inrecently excavated moist sand.With an area of around 600 000 km

Wind-blown silt deposits, generally termed loess, have been described from a range of desert areas. This paper describes the location, character and origin of a newly discovered coarse loess deposit in Ras Al Khaimah, United Arab Emirates.

The coastline of Ras Al Khaimah, United Arab Emirates, has three main constructional complexes: Jazirat al Hamra, Julfah, and Jazirat Hulaylah. Archival information, air photographs and maps dating back to 1819, enable the history of coastal change to be reconstructed. Jazirat al Hamra has been much affected by recent reclamation and harbour works, but appears to have been relatively stable. Jazirat Hulaylah also appears to have changed relatively little. However, the Julfah complex, which includes the harbour mouth for Ras Al Khaimah city, has shown very considerable change as a result of coastal breaching and spit growth and decay.