Helen M. Rendell

Asynchronous glaciation at Nanga Parbat, northwestern Himalaya Mountains, Pakistan

We present a new glacial chronology demonstrating asynchroneity between advances of Himalayan glaciers and Northern Hemisphere ice-sheet volumes. Glaciers at Nanga Parbat expanded during the early to middle Holocene ca. 9.0–5.5 ka. No major advances at Nanga Parbat during the last global glacial stage of marine oxygen isotope stage 2 (MIS-2) between 24 and 11 ka were identified. Preliminary evidence also indicates advances between ca. 60 and 30 ka. These periods of high ice volume coincide with warm, wet regional climates dominated by a strong southwest Asian summer monsoon. The general lack of deposits dating from MIS-2 suggests that Nanga Parbat was too arid to support expanded ice during this period of low monsoon intensity. Advances during warm, wet periods are possible for the high-altitude summer accumulation glaciers typical of the Himalayas, and explain asynchronous behavior. However, the Holocene advances at Nanga Parbat appear to have been forced by an abrupt drop in temperature ca. 8.4–8.0 ka and an increase in winter precipitation ca. 7–5.5 ka. These results highlight the overall sensitivity of Himalayan glaciation to orbital forcing of monsoon intensity, and on millennial or shorter time scales, to changes in North Atlantic circulation.

Effects of storminess, sand supply and the North Atlantic Oscillation on sand invasion and coastal dune accretion in western Portugal

Holocene forested coastal dunes fringe the Atlantic coast of western Portugal. Mapping of dunes in the field and using air photographs shows a range of forms reflecting dominant northwest and westerly onshore wind regimes. Planting of maritime pine forests in the thirteenth and twentieth centuries was initiated because of sand invasion causing problems for human settlement and agriculture. Early Holocene dunes have a well-developed podsol and date to 9.7 and 8.2 ka, suggesting at least some of these sands may have been emplaced during a global cooling event. Significant transgressive dune accretion at 2.2 and 1.5 ka, implies abundant sand supply and strong onshore winds The most recent dune-building period dates to AD 1770-1905 and coincides with a predominantly negative winter North Atlantic Oscillation index (NAOi). Accretion of dunes along the Portuguese coast appears out of phase with dune development in southwest France, which may reflect different Atlantic storm tracks driven by changes in the dominance and state of the NAOi.

The timing of climbing dune formation in southwestern Niger: fluvio-aeolian interactions and the rôle of sand supply

Contemporary gully erosion has exposed sections in a climbing dune which is banked up against ferricrete terraces along the southern bank of the Niger River in southwestern Niger. The main sand transport direction in this area is from northeast to southwest, and the immediate source of the dune sand is the Niger River. Dune stratigraphy contains evidence of episodic, fluvially controlled accretion, separated by two palaeosols. Channel fills and stone stringers suggest occasional alluvial and colluvial reworking. Infra-red stimulated luminescence dating of the aeolian sands shows that dune development occurred episodically during the African Humid Period (15–5 ka), probably in response to an increase in sediment supply from the Niger River. Soil development occurred during the relatively short-lived period of enhanced aridity associated with the Younger Dryas, driven by weakening of the southwesterly monsoon circulation. Climate-driven dune accretion and further soil development occurred during the Holocene period.

Climate, Extreme Events and Land Degradation

The frequency of occurrence of climate extremes in temperature and precipitation is expected to increase during the next century (Easterling et al. 2000). Here we examine the impact of the climate extremes of heavy rainfall, drought, and high winds, on processes of land degradation, including floods, mass movements, soil erosion by both water and wind, and salinisation. Case studies are used to explore the impacts of individual events on land degradation, as well as the role of decadal-scale temporal and spatial variability in climate systems in driving extreme events. Predictions of future trends in the frequency and magnitude of extreme events, based on an ensemble of general circulation models and on regional climate models, are examined

The Projet SAHEL 2004: an archaeological sequence in the Parc W, Niger

Projet SAHEL, a multidisciplinary project, was initiated to investigate long-term patterns of human occupation in the environmentally sensitive and archaeologically under- researched Sahel. This paper outlines an initial field survey carried out in this context in December 2004, in the Mekrou Valley, Parc W, Niger. This pilot study incorporated specialists in Palaeolithic and historic archaeology, and aimed to refine our understanding of the chronology and nature of the occupation of this area, an occupation already known from earlier work by other researchers to have been extensive. On the Palaeolithic front, Projet SAHEL carried out sampling aimed at assessing the potential for OSL dating of the Pleistocene sediments lining the Mekrou Valley — dating remains the major unknown in this sequence — and explored questions linked with raw materials procurement and the pattern of Pleistocene landscape use. On the historical front, Projet SAHEL carried out the first systematic collection of ceramic material, and obtained dates on an iron-working episode which allowed the cross-checking of radiocarbon and optically stimulated luminescence dating and extends the known time-depth of iron-working in the area.

Holocene book review: Origin of the Dutch Coastal Landscape – Long-Term Landscape Evolution of the Netherlands during the Holocene, Described and Visualized in National, Regional and Local Map SeriesVosPeter C, Origin of the Dutch Coastal Landscape – Long-Term Landscape Evolution of the Netherlands during the Holocene, Described and Visualized in National, Regional and Local Map Series. Barkhuis: Groningen, 2015; 359 pp.: ISBN 9789491431821, €74.95 (hbk)

It could be argued that nowhere is an understanding of the changing nature of the land–sea interface more important than in the Netherlands. The devastating impact of the North Sea flood in 1953, which killed more than 1800 people, not only resulted in the development and implementation of the Netherlands’ Delta Plan but also provided the impetus for detailed surface and subsurface investigations of the Dutch coastal landscape. An understanding of the Holocene evolution of the Dutch coastal landscape informs both contemporary coastal management and modelling of future changes. Peter Vos has produced an impressive synthesis of geological, palaeoenvironmental, archaeological and historical data and then visualized this information in a series of palaeogeographic maps. This beautifully illustrated book starts with an explanation of the basic principles of landscape reconstruction and lithostratigraphic analysis. Chapter 2 focuses on Vos’ palaeogeographical maps constructed at the national scale which provide snapshots of the Netherlands’ (palaeo) geography at 9000 BC, 5500 BC, 3850 BC, 2750 BC, 1500 BC, 500 BC, AD 100, AD 800, AD 1500, AD 1850 and AD 2000. The maps draw on data from geological maps, borehole records, soil maps, morphological maps constructed using laser altimetry and historical maps. These reconstructions are underpinned by a chronological framework constructed using 14C dates from organic remains and inorganic carbonates and optically stimulated luminescence (OSL) depositional ages of sediments. The volume also captures the changing nature of human interaction with the coastal environment, both in terms of the exploitation of coastal resources and in dealing with the impacts of storm surges, as it shifts its focus to documenting and visualizing change at the regional and local scales. The interaction between natural and human-induced change is summarized in the first section of Chapter 3, where Vos focuses on the southwest Netherlands – the Province of Zeeland (literally sea-land) – and its flooding history. Vos argues that peat digging, construction of dikes creating polders from salt marshes, and changing and damming of channels not only created a cultural landscape but also increased the vulnerability of the area to storm surges. The construction of the dikes and the drainage of the marshes resulted in a lowering of surface elevations in the areas underlain by peat. In addition, the widespread practice of extraction of salt from peat during the Mediaeval Period also resulted in the lowering of ground levels – making the consequences of dike breaches by storm surges much more damaging. Vos presents a storm surge calendar for the period AD 1000–2000 in which there has been an attempt to distinguish between major inundations, minor ones and ‘military’ ones, in which dikes were deliberately cut by Dutch troops during military conflicts. Vos cautions against interpreting the changing frequencies of flood events in the calendar in terms of climate change, arguing that ‘... negligence of the dikes, insufficient coordination, incompetence, political circumstances, wars and economic crises all played important roles’ (Vos, 2015: 88). Clearly an uncritical interpretation of this type of record as simply indicating changes in storminess in the North Atlantic and North Sea should be avoided! Instead, we have a classic case of a system transformed by human action that then requires constant vigilance and maintenance. Given the substantial increase in populated areas of the Dutch coast since 1953, the maintenance of flood defences remains a political and economic imperative. The other two sections of Chapter 3 deal with the landscape history of the Oer-IJ tidal system of North Holland and the Holocene landscape reconstruction of part of the Wadden Sea area from 500 BC to present. All the reconstructions are again visualized in series of palaeogeographic maps. A substantial appendix is provided giving details of all of the dates used to develop chronologies within the regional study areas and provides a critical commentary on these dates and their interpretation. Details of particular excavations, borehole logs and sediment profiles also provide invaluable information. A series of geoarchaeological case studies is presented in Chapter 4. These touch on the reconstruction of the Mesolithic lowland landscape in the Port of Rotterdam and landscape reconstruction of a Bronze Age settlement near Alkmaar in North Holland. In the first of these case studies, a novel methodology is employed for what was essentially a rescue excavation of an area of the Yangtze Harbour within the Port of Rotterdam. The multistage methodology employed, including geophysical surveys and boreholes, enabled the construction of a palaeo-landscape model that in turn enabled investigations to focus on the selection of archaeological sites for sampling and excavation. As was the case with the regional-level studies, the case study material is supplemented by the dating and stratigraphic evidence used in the palaeoenvironmental reconstructions. The book concludes with Chapter 5 which provides a synthesis of Holocene landscape evolution in terms of the influence of changes in sea level, climate and human interactions. The Dutch coastal zone is an important example of the way(s) in which anthropogenic interventions transition from mitigation to management. Captured in the snapshots provided by Vos’ palaeogeographic maps, we see the Holocene becoming the Anthropocene. The immediate future for the Netherlands coast will not be straightforward as tensions are apparent between soft and hard coastal engineering, in an environment in which the ecological as well as the geomorphological status of beach and dune systems are of increasing concern (Oost et al., 2012), and where there are Holocene book review 629882 HOL0010.1177/0959683616629882The HoloceneHolocene book review research-article2016