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.

Over the last ten to twenty years, geological surveys all over the world have been entangled in a process of digitisation. Their paper archives, built over many decades, have largely been replaced by electronic databases. The systematic production of geological map sheets is being replaced by 3D subsurface modelling, the results of which are distributed electronically. In the Netherlands, this transition is both being accelerated and concluded by a new law that will govern management and utilisation of subsurface information. Under this law, the Geological Survey of the Netherlands has been commissioned to build a key register for the subsurface: a single national database for subsurface data and information, which Dutch government bodies are obliged to use when making policies or decisions that pertain to, or can be affected by the subsurface. This requires the Survey to rethink and redesign a substantial part of its operation: from data acquisition and interpretation to delivery. It has also helped shape our view on geological surveying in the future.

The key register, which is expected to start becoming operational in 2015, will contain vast quantities of subsurface data, as well as their interpretation into 3D models. The obligatory consultation of the register will raise user expectations of the reliability of all information it contains, and requires a strong focus on confidence issues. Building the necessary systems and meeting quality requirements is our biggest challenge in the upcoming years. The next step change will be towards building 4D models, which represent not only geological conditions in space, but also processes in time such as subsidence, anthropogenic effects, and those associated with global change.

The histology of a femur of Plagiosuchus, a Middle Triassic temnospondyl amphibian, is described on the basis of two supplementary methods: classic thin sectioning and micro-CT scanning. In addition, the effectiveness of high-resolution micro-CT scanning for histological analysis is assessed. A classic, mid-shaft thin section of the femur was prepared, but prior to slicing two micro-CT scans were made. One of these has an image stack of a total of 1,024 images in the horizontal plane and a slice thickness of 87.8 μm, so that the entire bone could be captured, while the second was at mid-shaft region only, yet with a higher resolution of 28.3 μm and an image stack of 787 images in the horizontal plane. The classic thin section shows a very small medullary region which is surrounded by a layer of endosteal bone. The thick cortex is highly porous with numerous large, mainly longitudinal, vascular canals arranged in layers. In the deepest cortex woven bone occurs and primary osteons had locally started to form (incipient fibro-lamellar bone), which gradually passes into parallel-fibred bone and more lamellar bone close to the outer surface. Remains of a Kastschenko line were identified, enabling a reconstruction of the entire growth record. Five Lines of Arrested Growth (LAG) could be counted. The micro-CT scan enabled observations of the ontogenetic growth stages and calculation of growth rate on the basis of a single specimen. The micro-CT scan permitted a reconstruction of the ontogenetic development and the exact deposition rate per annum. Moreover, at higher resolution the micro-CT scan revealed data on micro-anatomical characters, such as porosity and skeletochronology (growth mark count). In conclusion, micro-CT scans do provide an alternative in cases where thin sectioning of the original bone is not possible.

A unique complex of multiphased Holocene drift sands and paleosols, with at least two lacustrine phases, was discovered during a major sanitation project in the Laarder Wasmeren area near Hilversum, the Netherlands. The complex could be studied in detail, highly facilitated by the excellent and large-scale exposure of the various deposits and soils. OSL dating was used to establish ages of the phases, where possible differentiating between time of deposition and time of burial by taking into account the potential effects of bioturbation. Pollen analysis served to reconstruct the vegetation during the various phases.

A first minor phase of aeolian activity already started before approx. 5,000 BC, followed around 4,000 BC by a second phase and a rather massive third phase around 3,000 BC. After a long phase of soil formation, the latest, massive drift sand phase started around the 14th to 15th century. It clearly represents the classic drift sand phase that started in the Late Middle Ages in the Netherlands. Sand drifting followed on soil forming phases during which the vegetation became increasingly dominated by ericaceous plants and culminated in heathlands. The first three aeolian phases and associated heathlands are much older than generally assumed for heathland and drift sand to occur in the Netherlands. Moreover, podzolisation was found to have started very early, true podzols already occurring before 4,000 BC.

Around 3,000 BC groundwater in the area reached a maximum altitude of about 230 cm +NAP, resulting in local open water in the area. This rise is probably linked to the development of the Dutch coastal area, where at that time peat accumulated and drainage was poor, inducing a rise of the groundwater level in ‘het Gooi’. This groundwater level fell later on, to never reach this altitude again. The Groot Wasmeer was formed by local stagnation on a slowly permeable podzol and already reached a level of 320-325 cm +NAP by 400 BC, which more or less equals its 20th century level.

The results demonstrate that earlier concepts on the occurrence and age of aeolian phases, podzols and heathland vegetations in the Netherlands are far too schematic, and that early, pre-agricultural cultures may already have had an impact on the stability of fragile cover sand landscapes, e.g. through burning. Results are in line with those from several contemporary studies on early prehistoric cultures and their impact in river dune areas in the Central and Eastern Netherlands.

We report here the addition of two rare mosasaur taxa to the Maastrichtian marine amniote fauna of Angola, both of which are also found in northern Europe. The new specimens include a dentary fragment referable to the large carnivore Prognathodon cf. saturator and an isolated tooth of the small durophage Carinodens belgicus. Both were recovered from Maastrichtian outcrops in southern Angola in 2011. Additionally, a complete posterior mandibular unit of a large mosasaur from the type Maastrichtian of the Netherlands, collected some time prior to 1879 and previously identified as ‘Mosasaurus giganteus’, is described and reassigned here to Prognathodon saturator; historical issues surrounding the taxonomic attribution of this specimen are clarified. The new material extends the known geographic distribution of Prognathodon saturator and Carinodens belgicus.

From the 40s A.D. onwards a dense military system was established in the Lower Rhine delta in the Netherlands. Long since, it is questioned why this system was established in a wetland area and even turned into the northwest frontier of the Roman Empire, the Limes. A new detailed palaeogeographical map, based on a digital elevation model (LIDAR), soil maps and excavation results, was constructed. This reconstruction provides insight and understanding of the interactions between the natural environment in this part of the delta on the one hand and the establishment of this part of the Limes along the Old Rhine between Utrecht and Katwijk on the other. This study shows that the distinctive landscape of the western Rhine-Meuse delta, with an exceptionally large number of tributaries, determined the spatial pattern of the military structures. All forts (castella) were erected on the southern natural levees of the river Rhine, directly alongside the river, regardless of height and composition of the subsoil and alongside or opposite routes that provided natural access to the river. We conclude that their aim was to guard all waterways that gave access to the river Rhine from the Germanic residential areas further north and from/to the Meuse tributary further south in the delta. In addition, a system of small military structures, mostly watchtowers, was erected between the forts to watch over the river Rhine and its river traffic. Furthermore, at least two canals were established to create shorter and safely navigable transport routes to the river Meuse. At first, this integrated system of castella and watchtowers probably aimed to protect against Germanic invasions and to create a safe corridor for transport and built up of army supplies for the British invasion in 43 A.D. Only later on, probably by the end of the first century, this corridor turned into a frontier zone.

In recent years, a range of operculate sixth abdominal tergite types of pylochelid and parapylochelid hermit crabs (Anomura, Paguroidea) have been recorded from Upper Jurassic (Oxfordian and Kimmeridgian) strata in southern Poland and southern Germany. Here we add two new genera (Parapylochelitergites, Paguritergites) and four new late Early Cretaceous species (Parapylochelitergites pustulosus, Pylochelitergites alatus, Pylochelitergites rugosus and Paguritergites yvonnecooleae) from Navarra, northern Spain. In the reefal limestones at Koskobilo quarry near Alsasua, of late Albian age, the number of sixth abdominal paguroid tergite taxa approximates that of paguroid carapace types. Thus, linking fossil paguroid carapaces to tergites can now be attempted. Assemblages of symmetrical hermit crabs (parapylochelids and pylochelids) in reefal settings appear to have changed drastically from the late Albian onwards, with asymmetrical forms (Diogenidae, Paguridae) becoming predominant.

Teeth of the small durophagous mosasaur Carinodens belgicus are known from Maastrichtian Atlantic-Tethyan deposits worldwide. The peculiar dentition of Carinodens inspired debate and speculation on its dietary niche ever since its first description. In this contribution, we describe the macro- and microwear pattern in five well-preserved isolated teeth, allowing further and independent evaluation of aspects of feeding behaviour and diet. Macroscopically, wear is concentrated on the apex and mesiodistal sides. Microwear was mapped using Scanning Electron Microscopy at several magnifications and can be characterised as scratches and pits. Coarse scratches were found to be the most common and pits were found to be the least common feature. Scratch orientation is primarily along the mesiodistal plane or in the labiolingual plane with an angle of ~130°. These microwear features can be explained either by oral processing or passive abrasion by sediments or food. As scratch width only indicates the minimum width of the abrading particle, the material causing the wear here could have ranged from silica-based silts to larger abrasives. However, in this case, abrasion by sediments might not explain this wear because of the biocalcarenitic nature of the type Maastrichtian sediments; siliciclastics are virtually absent. Therefore it is more likely that hard food particles, such as benthic organisms with hard exoskeletons, caused the wear on the enamel of Carinodens, or Carinodens ventured out to more sandy areas to forage as well. The mesiodistal and labiolingual direction of the microwear scratches might suggest that Carinodens showed more complexity in the use of its teeth than simple grasping, and that a gripping and pulling motion during feeding similar to that employed by modern varanids may have been the cause.

A 3D geological raster model has been constructed of the onshore of the Netherlands. The model displays geological units for the upper 500 m in 3D in an internally consistent way. The units are based on the lithostratigraphical classification of the Netherlands. This classification is used to interpret a selection of boreholes from the national subsurface database. Additional geological information regarding faults, the areal extent of each unit and conceptual genetic models have been combined in an automated workflow to interpolate the basal surfaces of each unit on 100 × 100 metre (x,y dimensions) raster cells. The combination of all interpolated basal surfaces results in a 3D Digital Geological Model (DGM) of the subsurface. A measure of uncertainty of each of these surfaces is also given. The automated workflow ensures an easily updatable subsurface model. The outputs are available for end users through www.dinoloket.nl.

A specimen of the Early Cretaceous amiiform fish Calamopleurus cylindricus with stomach content is described from the Santana Formation, Brazil. The prey concerns a smaller conspecific individual. Until now, prey items documented for Calamopleurus almost exclusively involved the aspidorhynchid Vinctifer. On the basis of the present record it is suggested that the prey preference of Calamopleurus was less pronounced than previously assumed.

Boom Clay is considered as one of the potential host rocks for the disposal of high level and/or long lived radioactive waste in a geological formation in Belgium (Mol study site, Mol-1 borehole) and the Netherlands. The direct characterisation of the pore space is essential to help understand the transport properties of radionuclides in argillaceous materials.

This contribution aims to characterise and compare the morphology of the pore space in different Boom Clay samples, representing end-members with regard to mineralogy (i.e. clay content) and grain-size distribution of this formation. Broad ion beam (BIB) cross-sectioning is combined with SEM imaging of porosity and Mercury injection Porosimetry (MIP) to characterise the variability of the pore space in Boom Clay at the nm- to μm-scale within representative 2D areas and to relate microstructural observations to fluid flow properties of the bulk sample material. Segmented pores in 2D BIB surfaces are classified according to the mineralogy, generating representative datasets of up to 100,000 pores per cross-section.

Results show total SEM-resolved porosities of 10-20% and different characteristic mineral phase internal pore morphologies and intra-phase porosities.

Most of the nano-porosity resides in the clay matrix. In addition, in the silt-rich samples, larger inter-aggregate pores contribute to a major part of the resolved porosity. Pore-size distributions within the clay matrix suggest power-law behaviour of pore areas with exponents between 1.56-1.74. Mercury injection Porosimetry, with access to pore-throat diameters down to 3.6 nm, shows total interconnected porosities between 27-35 Vol.-%, and the observed hysteresis in the MIP intrusion vs. extrusion curves suggests relatively high pore-body to pore-throat ratios in Boom Clay. The difference between BIB-SEM visible and MIP measured porosities is explained by the resolution limit of the BIB-SEM method, as well as the limited size of the BIB-polished cross-section areas analysed. Compilation of the results provides a conceptual model of the pore network in fine- and coarse-grained samples of Boom Clay, where different mineral phases show characteristic internal porosities and pore morphologies and the overall pore space can be modelled based on the distribution of these mineral phases, as well as the grain-size distribution of the samples investigated.

From Albian, Santonian and Campanian strata in south-central Sakhalin, four echinoid taxa are described, illustrated and discussed. In Far East Russia, echinoids are rare constituents amongst mid- and Late Cretaceous macrofaunal assemblages in which inoceramid and non-inoceramid bivalves, plus heteromorph and non-heteromorph ammonites predominate. The sole regular species in the present lot is represented by an incomplete external mould of a primary spine of a rhabdocidarid, Polycidaris(?) sp., from the lower Campanian. Irregular taxa include a fragmentary, specifically indeterminate ‘pygurid’, Echinopygus(?) sp., of late Albian age, as well as two spatangoids. One of these, a toxasterid of late Campanian age, is assigned to Niponaster cf. hokkaidensis (Lambert in Lambert & Thiéry, 1924). The other is a new hemiasterid with a semi-ethmophract apical disc, a peripetalous fasciole with diffuse boundaries (parafasciole) and posterior petals that are near-equal in length to anterior ones, from lowermost Campanian strata. For this, the name Palhemiaster natalyae n. sp. is introduced. Comparisons with coeval echinoid faunas from nearby Hokkaido (northern Japan) are hampered by the generally poor preservation of the latter. However, with the exception of Niponaster cf. hokkaidensis, none of the forms recorded in the present paper appears to be represented in those Japanese assemblages.

The geology of the Wicken Vision Area in the lower Cam valley is described with reference to a stacked series of ten cross-sections through Holocene and Pleistocene deposits, and Cretaceous/Jurassic bedrock across the region. A detailed cross-section through a Holocene palaeochannel, with radiocarbon dating and pollen analyses is also presented. The structural geology of the bedrock and the stratigraphic arrangement of the Pleistocene and Holocene deposits are used to describe landscape development for the area. This study offers a new understanding of the stratigraphy and context of the Holocene, Weichselian and earlier Pleistocene deposits of the lower Cam valley, and provides a unique view of sediment architecture in valley-fill sediments at the fen edge.

A possible other explanation is given for one of the probably jellyfish remains published by Oosterink & Winkelhorst in this Journal. Comparison with Recent traces suggests one (fig. 12) might be a ‘scribe mark’.

We describe a collection of borings in carbonate and xylic substrates (Gastrochaenolites ispp., Teredolites longissimus Kelly & Bromley), some of them containing their producers, from the Maastricht and Houthem formations (late Maastrichtian and early Danian) in the type area of the Maastrichtian Stage, but mainly from the ENCI-HeidelbergCement Group quarry, St. Pietersberg (southern Limburg, the Netherlands). Included are specimens of Gastrochaenolites dijugus Kelly & Bromley, showing different modes of formation of the figure-of-eight aperture, either as part of the lining, incorporating the substrate or both. Gastrochaenolites lapidicus Kelly & Bromley was produced by the gastrochaenid bivalve Gastrochaena, whereas G. orbicularis Kelly & Bromley is the trace of Jouannetia supracretacea (De Ryckholt). Bioglyph-like infills of G. orbicularis and G. torpedo Kelly & Bromley rather represent external moulds of the producing bivalves; they are termed pseudobioglyphs herein. Teredolites longissimus is preserved as clusters of in situ, parallel to sub-parallel tubes, although the woody substrate has decayed, and disarticulated fragments of calcareous tubes have been released from rotten wood. The latter include some specimens filled by flint and show good three-dimensional preservation. Some notes on the taxonomy of the producing bivalve taxa are added.

During recent years, regular round structures have been collected from the top of Bed 12 of the Vossenveld Formation (Lower Muschelkalk, lower Middle Triassic, Anisian) in the Winterswijk area, eastern Netherlands. These are here illustrated and described as probable remains of jellyfish.

Four recently collected tooth crowns of the rare latest Cretaceous (late Maastrichtian) durophagous mosasaur Carinodens belgicus are discussed; the first record from the Atlantic coast of North America (Maryland), and three additional in situ examples from the Maastrichtian type area in the southeast Netherlands and northeast Belgium. Also presented are an updated overview of the material recorded to date, and a discussion of the palaeobiogeographical and palaeoenvironmental distribution of the genus. Towards the end of the Cretaceous, Carinodens appears to have been successful in exploiting the margins of both the proto-Atlantic Ocean and the Tethyan Realm.