The 1717 Christmas flood is one of the most catastrophic storm surges the Frisian coast (Netherlands and Germany) has ever experienced. With more than 13,700 casualties it is the last severe storm surge with a death toll of this order. At the same time, little is known about the hydrodynamic conditions and the morphological effects associated with this storm surge.

In this study, 41 potential dyke failures in the Province of Groningen (Netherlands) associated with the 1717 Christmas flood were systematically reconstructed and mapped by using historical maps and literature and by analysing the recent topography in search of typical pothole structures and sediment fans. The dimensions of the sediment fans as derived from the topography show a good accordance with the dimensions documented by vibracore profiles, direct push tests and electrical resistivity tomography data taken at three fieldwork sites. Moreover, the fan dimensions closely agree with the dimensions as simulated using a process-based morphodynamic numerical model for one of the three sites, the village of Wierhuizen. Consequently, the recent topography is still indicative for the locations and dimensions of dyke failures and sediment fans associated with the 1717 Christmas flood. Considering the large number of detected dyke failures (41) and the large dimensions of the potholes and particularly of the sediment fans up to a few hundred metres wide and up to 0.7 m thick, this study proves significant morphological effects of the 1717 Christmas flood on the mainland of the Province of Groningen.

Based on the numerical simulation approach and the comparison with field data and field observations, a maximum seaward water level of 5 m NAP for the dyke failure at Wierhuizen during the Christmas flood can be derived. A similar maximum water level is indicated for the two other fieldwork sites Vierhuizen and Kohol, which is in good agreement with the maximum storm surge level of 4.62 m NAP historically documented for the city of Emden located almost 50 km to the east of Wierhuizen.

The results of the current study demonstrate that the reconstruction of historical dyke failures based on (i) historical sources, (ii) recent lidar/high-resolution topographical data, (iii) multi-proxy sedimentary field data and (iv) hydro- and morphodynamic numerical simulations is a highly promising approach to derive hydrodynamic conditions and the morphological onshore response of the 1717 Christmas flood in the Province of Groningen. This knowledge is essential to improve our understanding of extreme storm surge dynamics, their influence on the coastal landscape and the associated hazards for the coastal population.

The Late Cretaceous was a time of blossoming teleost diversification that came to a sudden restriction and partial termination during the extinction event at the Cretaceous–Paleogene (K/Pg) boundary. Among the dominant and diverse Late Cretaceous teleost groups prior to the K/Pg boundary event were certain pelagic Aulopiformes (e.g., Ichthyotringoidei and Enchodontoidei) and a large variety of basal Acanthomorpha whose relationships are difficult to determine. The skeletal record diminishes during the late Campanian and is low in the Maastrichtian and Paleocene, constituting the so-called ‘Patterson’s Gap’. Recent studies of fossil otoliths, however, have significantly increased the number of taxa recognised for this time inerval, but most of the putative extinct forms lack adequate calibration with otoliths found in situ in articulated skeletons. However, the otolith assemblages do confirm the presence of great morphological diversity among Aulopiformes and Acanthomorpha incertae sedis that became extinct at the K/Pg boundary. In the present review, we elucidate the effect of the K/Pg boundary from an otolith perspective and categorise extinct lineages and survivors. It is interesting to recognise that several of the surviving lineages are represented by groups that probably originated during the Late Cretaceous but were not particularly common up to the K/Pg boundary and began to expand rapidly and diversify during the early Paleogene. Such lineages probably took advantage to populate void ecospace that may have opened following the extirpation of previously dominant lineages. During the early Paleogene, the otolith record shows that the Ophidiiformes and perciforms s. lat. were the ones that diversified the most rapidly and became the most abundant, and in certain areas associated with the Gadiformes.

The risk of five pesticides (atrazine, simazine, bentazone, mecoprop and MCPA) contaminating a Quaternary phreatic aquifer (the water supply area of Sint-Jansteen, the Netherlands) is assessed based on laboratory experiments and solute transport modelling (MODFLOW-MT3D). Batch experiments either show long half-lives (at least 1500 days) or no degradation at all for bentazone, atrazine and simazine while mecoprop and especially MCPA degrade much faster (half-lives down to 4.1 days). Column experiments show significant sorption to the aquifer sediment only for atrazine and simazine under certain circumstances. A series of experiments were conducted during which the type of the sediment, the grain size, the content of the organic matter and the acidity of the groundwater were varied. These experimental results were subsequently incorporated in a solute transport model for the aquifer resulting in the following ranking of the contamination risk for the selected pesticides (from low to high): MCPA, mecoprop, simazine, atrazine, bentazone. This ranking was confirmed by observed pesticide concentrations in samples taken from piezometers and extraction wells from the aquifer.

Although not exhaustive, the contributions to the present liber amicorum illustrate the wide range of geological, palaeontological and archaeological subjects that Bert Boekschoten has been interested in during his long, productive career. Not only has he carried out research by himself – often in far-flung and occasionally inhospitable places – he also has that special ability to fuel enthusiasm and zeal in others. ‘Have another look’, ‘What about …’, or ‘But maybe it is just the opposite …’ – typical phrases uttered to one of his former PhD students in distress. Always an eye opener, and always at the right time! The present tome covers the fields of (actuo)palaeontology and prehistoric archaeology, papers having been written by some of Bert's former PhD students at Groningen and Amsterdam and by a number of close friends, both at home and abroad. Here we present summaries of the various chapters, add pertinent items of literature and note Bert's involvement in these projects.

Discrimination between quarry blasts and earthquakes has gained importance due to signature of the Comprehensive Test Ban Treaty. In this context, large chemical explosions are significant. In the routine analysis of data from local seismograph networks, discrimination between smaller blasts and micro-earthquakes is not always clear. Many quarries are in operation and blasts far outnumber natural earthquakes in the highly industrialized northern Rhine area.

We compiled a list of active quarries in the Northern Rhine Area and mapped their locations. We then created a database from a questionnaire sent out to all quarries on the list. From the 33% of questionnaires that were returned, we discerned some representative values for the main blasting parameters and explosive consumption. In the study area of 72,000 km2, approx. 21,000 blasts are fired per year (80 per working day). Most of the blasts (72%) have total explosive charges between 400 and 4500 kg. Shots with charges above 10 tons are rare (20-30 per year). Some 80% of the blasts are ripple-fired with a nominal firing time interval of 20 ms.

Based on empirical amplitude vs. distance curves from vibration control measurements, a relation between maximum charge weight per delay time, L (kg), and a ‘quarry blast’ magnitude, MQB, is derived: MQB = 0.6·log10(L) + 0.131. Using this relation and extrapolating the database from the questionnaire shows that for magnitudes between 1 and 2, blasts occur 200–250 times more frequently than micro-earthquakes in the Northern Rhine area.

Various trace fossils are known from the Upper Triassic (Rhaetian) shale deposits of western Europe, especially from Great Britain. Here we present a unique specimen, unknown from Rhaetian shales in western Europe thus far to our knowledge. The specimen consists of a string of small knobs collected from the dark-coloured Rhaetian shales from the eastern Netherlands, deposited in a marine, near-coastal environment. The specimen represents the first described trace fossil from these shales. The identity of this specimen appears enigmatic. However, SEM-EDS analysis showed that the string of knobs is pyritised and does not contain phosphorus nor did the sediment directly around the specimen, suggesting a non-coprolitic origin of the specimen. Eggs and larvae are also excluded as possibilities. The specimen closely resembles several trace fossils identified as burrows, which is why we favour this interpretation. The rare presence of trace fossils reinforces the hypothesis that the Dutch Rhaetian shales were deposited under a stresses regime with low oxygen conditions.

This special issue focuses on the interactions between Quaternary Geology and Archaeology and results from the INQUA-NL Symposium: ‘Late Quaternary Climate Change: a Human Perspective’ held on April 14th 2009, KNAW Trippenhuis, Amsterdam. The symposium was attended by over 125 scientists and students with interest in the fields of Quaternary Geology and Archaeology. The symposium was organized for the INQUA Netherlands commission (INQUA-NL) by Wim Hoek, Faculty of Geosciences, Utrecht University (UU), Henry Hooghiemstra, Faculty of Science, University of Amsterdam (UvA), and Jos Deeben, National Service for Cultural Heritage (RCE). The INQUA Netherlands commission (INQUA-NL) is the Netherlands' national representation in INQUA, the International Union for Quaternary Research (see further www.geo.uu.nl/inqua-nl).

The Netherlands is a country made by humans, but before the large-scale impact of humans that formed the typical Dutch landscape, people inhabited our area and needed to be able to deal with natural disasters like climate change, river floods or sea-level change. In the field of archaeology, there is increasingly more space to include the environmental changes that partly determined the behaviour of prehistoric communities. The interactions between quaternary geology and archaeology are not only restricted to provide stratigraphical information during archaeological prospection or on exposures during excavations. Quaternary geology is increasingly applied to gain insight in the landscape development and environmental setting where people have lived in the past. Above this, predictive models can be improved by the interaction of archaeological and geological/palaeogeographical research (see also Deeben et al., 2010).

A lower molar of Castor fiber from the sandpit of Langenboom (the Netherlands) represents, so far, the oldest occurrence of a beaver in the North Sea Basin. Its presence in the marine sand deposit of the Langenboom Formation indicates that Castor fiber inhabited areas in or near the river systems of Rhine and Meuse in the Early Pliocene.

The vegetation history of the area around the confluence of the rivers Meuse and Swalm (the Netherlands) during the Middle Ages is covered by two pollen diagrams. The diagram Swalmen reveals a large-scale deforestation as a result of the foundation of a nobleman's homestead around 950. The diagram Syperhof shows a period during which the forest partly returns after a long history of unremitting anthropogenic stress. This temporary phenomenon is ascribed to the onslaught of the Black Death in 1349. Both diagrams provide evidence of the start of buckwheat growing.

Spectral observations show that volcanic glass is the dominant ingredient of the aeolian landforms which cover the northern lowlands on Mars. Surface winds subject these sands to physical alteration processes in the present-day surface environment. This work highlights the role of glaciovolcanism throughout Mars’ geologic history and the parallels with landforms and materials found in Iceland. As the physical properties of Martian volcanic glass particles are difficult to constrain from orbit, Icelandic materials can provide valuable insights in their transport and modification characteristics. The processing of glass grains by environmental processes by means of the dune transport cycle is discussed. Experiments targeted the grain-size alteration effects experienced during the dune transport cycle, including the effect of ‘low-energy’ avalanching and ‘high-energy’ aeolian regimes (i.e. particle rolling and saltation). Saltation transport was found to rapidly alter grains and particle size distributions, which contributes to a positive feedback loop where the new smaller grains are mobilised more easily after fracturing and surficial abrasion. Post-depositional physical alteration therefore needs to be reconciled with the present-day silicic spectral signatures of these glasses in order to infer the relevant landform genetic. This effort is especially relevant in respect to the loss of possible signatures of biochemical alteration from microbial interactions, as glaciovolcanic environments are favourable habitats for life. As chemical and physical weathering is limited to the grain exterior, the grain interior may still retain a geochemical record of the subglacial eruption environment in which these grains were formed. Quantification of the volatiles sequestered in the glass can therefore be used to identify the formative conditions of the amorphous component in aeolian sediments.

High-resolution Early Holocene palynological records from the middle Meuse River valley were missing until recently. In order to investigate environmental and inferred climate changes during the Preboreal, sediments from a former residual channel of the Meuse River near Haelen were studied. Detailed multi-proxy analyses, including microfossils, macroremains and loss-on-ignition measurements, were carried out at a high temporal resolution. An accurate chronology of the >1000-year-long record was provided by accelerator mass spectrometry (AMS) 14C wiggle-match dating.

The channel was abandoned during the late Younger Dryas, when accumulation started with gyttja. This period was characterised by an open landscape with herbaceous vegetation and dwarf shrubs. Patches of birch were present on the floodplains around depressions and (oxbow) lakes. Some pines survived the cold in sheltered locations. In the residual channel the water was flowing temporarily and aquatic plant communities developed with predominantly submerged taxa and algae. The shores were fringed by willows and sedges and were probably used as a watering place by large herbivores.

Following the Late-glacial/Holocene climate warming, dated in the Haelen record around 11,520 cal BP, birch woodlands expanded on the river floodplains and slopes of terraces during the Friesland Phase. Open vegetation with herbs and juniper remained present on the nearby terraces. An increase in the water level of the oxbow lake and seepage of groundwater occurred. Along the shores herbaceous vegetation was present. Around 11,420 cal BP, birch expansion was interrupted by the dry continental Rammelbeek Phase. On the river floodplain and terrace slopes, open grassland vegetation developed and on the terraces, grasslands and open grounds were abundant. In the residual channel the water became stagnant and floating-leaved vegetation developed. At the start of the Late Preboreal, around 11,270 cal BP, a sudden shift to a more humid climate took place and birch forests expanded again on the river floodplains and terrace slopes. Poplar became more abundant in these forests, and birch and poplar swamp forests were present near the site. Pine expanded at c. 11,160 cal BP on the higher sandy and gravelly terraces. During the Late Preboreal a reed swamp developed on the shores of the residual channel.

At the onset of the Boreal, around 10,710 cal BP, woodlands, initially with hazel, but later also with oak, elm and lime, started to develop, while pine forest remained present on the higher terraces. Hazel shrubs were growing on the terrace slopes. Birch and poplar forests occurred on moist parts of the floodplains. Around the residual channel they formed a zone behind the reed swamps surrounding the oxbow lake. Vegetation with water lilies was present in open water.

The Haelen record shows, despite a lack of archaeological evidence, indications for the presence of Mesolithic people in the area during the Preboreal. These include the occurrence of (natural or man-made) fires, in combination with the presence of trampled areas and disturbed grounds and possibly consumption of Nymphaeaceae seeds and tubers.

The issue of detecting changes beyond the range of natural variability (detection) and of attributing causes to such changes (attribution) are central to any rational debate about anthropogenic climate change. This concept, introduced by Klaus Hasselmann in the late 1970s, is usually not understood by either so-called sceptics or by activist scientists.

Often rigorous detection and attribution analysis is replaced by mere declarations and by naïve applications of methods to determine if certain trends are ‘significant’ or not.

In this talk, the concepts are introduced; the invoked assumptions and the roles of dynamical models and of time-scales are explained. The concept is illustrated with a few examples related to global and regional air temperature and to NE Atlantic storminess.

For global and regional air temperature, the recent variations are found to be beyond the range of natural variability (detection) and the changes are best explained by a dominant contribution by elevated greenhouse gas concentrations. For NE Atlantic storminess recent trends are found to be intermittent and within the historical range of variations. The finding of significant GHG contributions to temperature change and the lack of such for changes in storminess are not contradictions.

From the middle of the 1st century AD, the Lower Rhine was part of the frontier of the Roman Empire (Limes). However, this Limes was not an impermeable line, but rather an open corridor that served as march area and as a trade and supply route for the adjacent military and civilian settlements as well as the hinterland. This required access to the river and permanent harbours. When planning military camps and towns along the Rhine, the existing topography and the challenge of a dynamic riverine landscape had to be taken into account. The prefered location for forts and towns were the raised edges of the Lower Terraces close to the undercut bank of a meander. For many years, research assumed that the river bend adjacent to a Roman site had to be an oxbow lake. The main argument being that only an oxbow situation would have protected the Roman sites against strong currents and the risk of demolition of land and settlements by the main stream (abandoned channel hypothesis). A re-evaluation of the extensive archaeological, sedimentological and palynological archive and published data from the Rhine plain, as well as of supplementary data from new boreholes, lead to a considerable increase in the previously incomplete knowledge of the fluvial history, especially regarding the timing of palaeomeander infilling. It showed that most of the meanders and river bends of the Rhine with Roman settlements on their banks not silted up before Late Antiquity (from the end of the 3rd century AD on). Before that those meanders were part of the main stream. The advantage of steep undercut banks was that a quay could be built on a location that ensured mooring all year round, even at low water level. However, it was necessary that stabilising bank protections were present in order to avoid shifting the course of the river with subsequent destruction of the infrastructure. Such an antique bank protection construction (a so called “Packwerk”) could be recognised in front of the Colonia Ulpia Traiana (CUT, Xanten). With this knowledge in mind, other excavated structures on the banks of palaeomeanders, previously mostly interpreted as Roman harbour remains, could be interpreted as bank protections.

At Wesel near the strategically important mouth of the Lippe, the archaeological, sedimentological and palynological data showed that a meander that had silted up in Prehistoric times (Bronze Age) had been reactivated in Roman times and silted up again in Late Antiquity. A man-made diversion (perhaps by building a groyne) of the main stream could have been responsible for this.

With the beginning of the Late Antiquity crisis of the Roman Empire at the end of the 3rd century, it presumably became increasingly difficult to maintain these water works. This enabled the river to regain its morphodynamics, by cutting of the meanders that were active during Roman times. We hypothesise that this increase in fluvial activities of the Lower Rhine from the end of the 3rd century onwards is due to an anthropogenic trigger: the collapse of the Roman Empire.

Compound orchocladine sponges are unusual in the Early Palaeozoic. In Europe, silicified material of Late Ordovician age has hitherto been referred to as Aulocopium aurantium Oswald, 1847 and the invalid Aulocopium compositium Conwentz, 1905. An examination of new material has resulted in the recognition of a new genus, Hydraspongia, with two new species, H. polycephala and H. erecta, and a third new species, Perissocoelia megahabra, to which most specimens can now be assigned. These taxa form part of rich erratic sponge assemblages, which originate from unknown source areas in the Baltic, and have been collected in northern and western Europe from fluvial sandy deposits of the Eridanos River system, which drained the Baltic area from the Middle Miocene to Early Pleistocene.

The Earth’ climate is a complex system consisting of the atmosphere, the ocean and the land surface. This system receives energy from the sun. Latitudinal variations in insolation and the rotation of the Earth lead to a complex turbulent geophysical flow which induces important transports of heat and mass. Part of the solar radiation is reflected, the rest is radiated as long wave radiation. The radiative balance is complicated by atmospheric water vapour and other trace gases, clouds, heat transport and other factors.

Is it possible to step twice into the same river? That is the question I would like to put to you. At first glance, there is no reason to assume that a river will not look exactly the same tomorrow as it does today. And we tend to forget whether it was different yesterday or the day before. ‘Will the weather ever get any better?’ we tend to say to each other after a couple of rainy days. Will we ever see a cold winter again with an Elfstedentocht? Fortunately, some people keep records of the weather, or keep track of rivers flooding or falling dry. That makes it possible to know for sure what stays the same and what changes.

Geomorphology as a scientific discipline has underwent major developments since the mid 20th century. From its original descriptive nature aiming to understand landscape evolution, it developed towards a more process-based oriented discipline. To a large extent this evolution followed a quantitative approach whereby modelling becomes more and more important. A schism between applied or engineering geomorphology and system-based geomorphology aiming at understanding landscape change emerges in the 1950-1960's. Only at the end of the 20th century – early 21st century, integration of quantitative field-based approaches on longer term issues of landscape evolution with numerical modelling emerges. This is particularly true for the Holocene for which the importance of human impact on geomorphic processes and landforms became acknowledged. With respect to landscape evolution on much longer timescales, the development of tectonic geomorphology becomes apparent. In this paper, some evolution of ideas and trends within geomorphology with respect to understanding landscape dynamics are summarised and put into the career perspective of Jef Vandenberghe.

The collection of extended and updated abstracts presented here resulted from a two-day workshop of the Collaborative Research Centre ‘Interactions between and Modelling of Continental Geo-Systems’ (SFB 350) held on 19th and 20th November, 1999 at the Rheinische Friedrich-Wilhelms-Universität Bonn. This workshop was entitled ‘Rift Tectonics and Syngenetic Sedimentation - the Cenozoic Lower Rhine Graben and Related Structures’. Its central topic was devoted to various approaches of understanding the evolution of a young graben structure, with the aim to trace the interaction of tectonics, sedimentation, facies development, burial history, and coherent structural behaviour by integration of geodetic, seismological, gravimetric, sedimentological, paleontological, and climatological data.