The Hans Cloos Lecture (HCL) 2024 was delivered by the first author Niek Rengers, in an abridged version, during the opening session of the 4th EurEngeo conference of the International Association for Engineering Geology and the Environment (IAEG), in Dubrovnik, Croatia, October 10th, 2024. Niek Rengers looks back on his personal involvement in more than 60 years of study, teaching, and research in engineering geology, and, with the team of authors, they focus on the main activities of the Dutch engineering geological community during the five decades since 1973. A brief description is given of the challenges of civil engineering over the past 2,000 years in once marshy land, below high tide sea level, with soft soils, and subject to flooding by the sea and the main rivers Rhine and Meuse. Dutch engineers tackled these challenges by dike construction, land reclamation in polders, and the use of pile foundations for building on soft soils. They so gathered over the ages a wealth of practical experience with soft soils. Based on this practical expertise, Dutch engineers developed a sound basis for theoretical and experimental Soil Mechanics. However, in the early seventies, it became clear that a thorough knowledge of the geological structure of the underground was indispensable for adequate geotechnical analysis and modelling. This led to the founding of the Dutch National Group of the IAEG in 1974. Since 1972 the International Institute for Aerospace Surveys and Earth Sciences (ITC) offered full year university level courses in engineering geology. The Mining Engineering faculty of the Technical University Delft followed in 1975. In close cooperation and with extensive staff exchange, both institutions have further developed engineering geological education and research programs leading to MSc and PhD degrees. A summary description is given of these developments during the last 5 decades.

Large areas behind the historic quay walls and bridges in Amsterdam city center are prone to soil mobilization and cavity (sinkhole) formation due to intensified infrastructure developments and extreme groundwater level fluctuations caused by climate change. We carried out a geophysical survey to investigate a sinkhole formed under the Muntplein (Amsterdam, The Netherlands). The surface trace (hole) of the sinkhole was triggered by a heavy vehicle passing over the street which lies in the vicinity of a quay wall and behind the abutment of the Muntsluis bridge. The application of ground penetrating radar (GPR) and electric resistivity tomography (ERT) provided continuous data of the shallow subsurface which enabled the detection of the backfilled cavity, its southwest (SW) extension, the bridge abutment-to-soil transition, key utility lines and the presence of two potential targets for further investigation. A follow-up geotechnical assessment supported by hydrographic survey in the canal validated our findings and substantiated our first interpretation (i.e., sinkhole in development). The paper demonstrates the applicability of non-invasive electromagnetic (EM) methods to rapidly detect cavities in critical urban areas, and, thus, to de-risk climate-smart infrastructure developments.

Evidence of different compound resin-based adhesives is present in South Africa from at least 77000 years ago. Ancient glue production is considered one of the oldest known highly complex technologies, requiring advanced technological and mental abilities. However, our current knowledge of adhesive materials, recipes, and uses in South Africa is limited by the lack of in-depth analysis and molecular characterization of residues. To deepen our knowledge of past adhesive technology, we performed a detailed multi-analytical analysis (use-wear, XRD, μ-CT, IR spectroscopy, GC-MS) of 30 Later Stone Age tools with adhesive remains from Steenbokfontein Cave, South Africa. At the site, tools made of various rocks were hafted with compound adhesives, and we identified three recipes: 1) resin/tar of Widdringtonia or Podocarpus species combined with hematite; 2) resin/tar of Widdringtonia or Podocarpus species mixed with hematite and another plant exudate; 3) resin/tar without hematite. The studied scrapers were used in hide-working activities, and the studied cutting tools were used to work animal and soft plant matters. All scrapers display evidence of intense resharpening and were discarded when no longer useable. The combination of different methods for residue analysis reveals the flexibility of adhesive technology at Steenbokfontein. Despite the consistent use of conifer resin/tar throughout the sequence, we observed that other ingredients were added or excluded independently of the tools’ raw materials and functions. Our results highlight the long-lasting tradition of using adhesive material from conifer species but also the adaptability and flexibility of adhesive traditions. The systematic application of this multi-analytical approach to Pleistocene adhesives will be useful to better characterise adhesive traditions and enhance the debate on the technological, cognitive, and behavioural implications of this technology.

Understanding the geological and geotechnical characteristics of the shallow subsurface is crucial for engineering decisions in densely populated regions like the Netherlands. Urban areas are for a large part built on a complex stack of sand, clay, silt, gravel and organics that were deposited over the last hundreds of thousands of years under gradually subsiding tectonic conditions. One of these units, a fluvially deposited sand known as the Kreftenheye Formation, is widespread across the western part of the country and is vital for foundation design and groundwater dynamics. The Kreftenheye Formation is therefore well described by geotechnical and geological tests, yet integrating both types of data has rarely been done on a nationwide scale.

This paper focuses on 76 pairs of Cone Penetration Tests and boreholes that include Kreftenheye, out of a full database of nearly 200 pairs from TNO - Geological Survey of the Netherlands, generally reaching depths up to 40 meters. The study reveals significant spatial variations and depositional patterns within the Kreftenheye Formation, illustrating how overlying or interlayered flood plain or soft channel lag sediments influences the response of the CPT. Furthermore, CPT response and borehole samples have helped with making geological distinctions between the upper, Weichselian part of the Kreftenheye Formation and the lower Saalian part, showing how integrating both datasets can give both geological and geotechnical insights.

We conducted ground penetrating radar (GPR) surveys to detect the presence of simulated clandestine burials at the Amsterdam Research Initiative for Subsurface Taphonomy and Anthropology (ARISTA) test facility. Our aim is to determine the characteristic responses of the simulated clandestine burials in this man-made sandy environment (reclaimed land) and use them to provide recommendations for forensic investigations. We performed GPR surveys over three simulated clandestine burials at ARISTA during four non-consecutive days. The acquired data represent common-offset data to investigate changes to burial detectability depending on central antenna frequency (250 MHz and 500 MHz), different GPR instruments (NOGGIN or pulseEKKO), changes to survey grid orientation relative to burials, and increased soil moisture content in the survey area. In common-offset radargrams the burial anomalies take on many forms, appearing as disruptions to existing features (direct-wave arrivals and soil horizons) and as isolated reflection events (hyperbolic events and burial-length horizontal anomalies). In time slices, the burials are characterized by high- or low-amplitude rectangular anomalies. When used in conjunction, the radargrams and time slices produce characteristic responses consistent with the locations of the burials, regardless of the survey grid orientation. Increased soil moisture at the site improves the detectability of the burials.

We studied the corrosion of Roman copper alloy coins that experienced alternations or progressive changes in their burial environment. We used coins that were still embedded in soil or in a concretion selectedfrom three professional excataved sites - Berlicum and Krommenie in the Netherlands and Kempraten in Switserland. mCT scanning and neutron scanning were used to record the 3-D properties of these coins prior to (destructive) analyses. It proved possible to tentatively identify the coins. Microscope observations and SEM-EDX analyses revealed complex corrosion processes, related to changing burial environments. In soil horizon with fluctuating groundwater levels in a region with upwelling reducing, iron-rich groundwater, the copper in a gunmetal coin is essentially replaced by iron oxides while tin remains and forms tin-oxide bands. Fluctuating redox conditions in marine-influenced environments was shown to transform a copper-alloy coin into strongly laminated copper sulphides with embedded gypsum crystals, with an outer surface of copper and copper-iron sulphides. Burial of bronze in a charcoal rich layer probably caused temporary highly alkaline soil conditions. This caused most of the copper to leach from this coin, leaving behind a laminated tin-dominated mass, with only a limited amount of (malachite) corrosion products remaining in the surrounding groundmass. In all three cases, corrosion processes tend to be anisotropic, probably because of cold-hammering of the coins during their manufacture. Such corrosion processes on massive copper alloy coins may produce features that may lead to their incorrect classification as subferrati, i.e. copper alloy coins with an iron core. Our results may help in future to distinguish strongly corroded massive coins from subferrati.

The National Museum of Raqqa in Syria has suffered immensely from the ongoing violence since 2011. Much of its valuable collection of movable archaeological heritage (ca. 6000 items) is considered lost. Starting from 500 of the most precious objects of the museum stored in the Raqqa Central Bank and stolen from there in 2013, the pilot project Focus Raqqa created a concrete, workable database to enable identification by Syrian and international police and heritage institutions. The project made a pivotal first step towards potential reconstruction of the Raqqa Museum in the future. The Raqqa museum collection included cuneiform tablets. Some of the tablets were cast before the war to allow detailed study in Europe. Today the tablets have vanished. The pilot project Scanning for Syria safeguarded information from the lost artefacts by making high-resolution three-dimensional scans of the silicone rubber moulds and subsequently physical replicas of the original objects by 3D printing. The short life expectancy (30 years) of the moulds necessitated measures for long-
3
term preservation. The Scanning for Syria team not only succeeded at the preservation and sharing of knowledge in the academic circle. It also told the story of Syrian culture and its people to everyone for raising more voices in the united effort to keep cultural heritage safe in a zone of conflict.

X-ray fluorescence spectroscopy (XRF) and X-ray micro computed tomography (μ-CT) were applied to the study of four archaeological glass objects from the collection of the Allard Pierson in Amsterdam, The Netherlands. Often, little is known about the provenience and provenance of archaeological glass objects, as documentation is regularly insufficient to assign a specific place and date of excavation or place of production. This paper demonstrates the value of μ-CT for visualising the internal structures of archaeological glass objects, providing insight into production techniques and condition. The XRF results presented are consistent with published glass compositions but are, as yet, insufficient to assign the glass objects to a specific place of production. Part of a broader research project to apply non-destructive techniques to the study of archaeological glass objects, the results presented here will be the basis for the future evaluation of less commonly applied methods, such as neutron tomography and gamma spectroscopy.

The aim of this final chapter is to integrate the results obtained from the multi-disciplinary study applied to a series of coprolites from the Late Mesolithic and Early Neolithic Swifterbant Culture sites, to determine their role as a source of information about the prehistoric dietary tradition and health. The study of coprolites provides a unique opportunity to reconstruct the most complete spectrum of the foods that were consumed in the past, both as cooked meals as well as foods that were eaten raw. In addition to the food remains, coprolites also contain intestinal parasites which affected the health of prehistoric populations. Coprolite studies can also provide information about palaeoenvironmental conditions through the types of microfossils and macrofossils they contain.

The structure of five rare filigree spheres from a seventeenth century shipwreck was examined in order to unravel their condition, manufacturing process and function. This study focuses on the application of non-invasive imaging techniques: optical microscopy, X-radiography, X-ray micro-computed tomography and neutron computed tomography. A valuation of different aspects of the applied techniques was made, aiding stakeholders in decision-making on research and conservation. The combination of theory and scientific information was used to obtain an improved understanding of the manufacturing process and function of the filigree spheres.

In recent years, several researchers have illustrated the potential of X-ray micro-computed tomography (micro-CT) in the study of archaeological soils and artefacts. Hunt et al., Huisman et al., Wang et al., Qvarnström et al., and Shillito et al. have already foreseen and even demonstrated the added value of the technique for the investigation of ancient coprolites.114 Coprolites contain partially digested macro-food remains which can be distinguished on a micro-CT scan when they are large enough and contrast sufficiently in terms of X-ray attenuation values and/or patterns with the faecal mass. The scans of coprolites provide a direct and non-destructive way to assess diets from the past.

The geometric variability of soil layers is a large source of uncertainty in the reliability assessment of dikes. Because direct samples of the subsurface soils are often insufficient to capture the complexity of the subsurface, geophysical methods provide a powerful source of complementary information. A combined approach to estimate the geometry of soil layers is presented. The approach combines local point data, i.e. data obtained from a CPT or a borehole log, and geophysical tomography in a universal cokriging framework. The approach uses the contact points between soil layers obtained from local point data and the orientations of the layers derived from geophysical tomography. To reduce subjectivity in the interpretation of tomographic images, an automated edge detection technique was used. The combined approach was applied to characterise two test sites where the presence of paleochannels locally change the geometry of soil layers. The results show that a combined approach enables the reduction of sampling efforts with an improved estimation of geometric variability.

We investigated the characteristics of a group of 13 Middle Iron Age egg-shaped crucibles and crucible fragments from Tilburg (The Netherlands). We used a combination of optical and chemical analyses, including hand-held XRF, microCT scanning and 3-D printing polarizing light microscopy and SEM-EDX. The chemical analyses confirmed that the crucibles were used for copper alloy metallurgy. Impressions in the lids of the crucibles turned out to be imprints of copper alloy scrap, including fragments of twisted wire and fibulae. Most remarkable, however, is the large proportion of sheet metal among the scrap.

In order to make crucibles from the local, non-refractory clays, a hitherto unknown ceramic-faience hybrid was used: A combination of clay and halophytic plant ash was mixed with silt into a paste, and this was used to construct the crucible. During firing, the flux would promote melting of the clays and probably prevent catastrophic failure of the crucibles. The resulting glassy groundmass – in which silt grains are embedded and partially dissolved – is rich in Al2O3 as well as in Na2O, K2O, CaO, MgO and Fe2O3.

It is likely that this technique of crucible manufacture was widespread in Late Prehistory in areas where no refractory clays were available.

The southern boundary of Region IV of ancient Ostia coincides with the southern limit of the excavated area of the ancient city. The perceived expanse of the city is influenced by the extent of the excavation. It is not known if the unexcavated part lying south of Region IV also contains structures of antiquity which might have important historical significance. We have carried out high-resolution, shallow seismic reflection surveys along two profiles, using shear (transverse) waves. The goal of these pilot surveys was to see if any indication of ultra-shallow scatterers, indicating potential location of shallow-buried structures, can be found in the shear wave data. The results show very distinct back-scattered shear-wave arrivals from a mysterious tumulus, whose location along Line A was known. It has been possible to interpret with reasonable confidence the location of several conspicuous, shallow scatterers in the two seismic profiles. Use of shear waves and a high-frequency, electromagnetic shear-wave vibrator was crucial to achieve seismic a resolution of nearly 25 cm. The amplitude of the scattered energy is helpful to locate the relatively strong scatterers. Our results suggest that the unexcavated areas located south of Region IV most likely contain buried underground structures. 3-D shear-wave seismic reflections together with new seismic-imaging approaches will be promising to illuminate the unknown shallow subsurface of this important archeological site in a noninvasive manner.

In this study, we generate novel insights regarding bodily ornaments from indigenous societies of late precolonial Greater Antilles. Previous research has highlighted the sociopolitical role of valuable, exotic, and figurative ornaments, yet there are many gaps in our current understanding of these artifacts. Here, we focus on ornaments from five recently excavated sites in the Dominican Republic (AD 800–1600). We used microwear analysis to investigate each ornament and assess its production sequence and use life. These data permitted the definition of morpho-technical groups, which we then compared to depositional contexts and the regional availability of raw materials. We demonstrate that (1) there was small-scale production of ornaments at the sites, (2) the most recurrent morpho-technical groups were likely imported from production centers, and (3) ornaments of the same group could lead different use lives and be deposited through varied processes. We conclude that bodily ornaments had highly diverse biographies involving local and regional interaction networks.

El presente estudio se centra en los adornos corporales indígenas de finales del período precolombino en las Antillas Mayores. El rol sociopolítico de los ornamentos figurativos realizados en materiales de valor o exóticos ha tenido un papel destacado en investigaciones anteriores. A pesar de la abundancia de estudios, poco se conoce acerca de estas piezas. En este trabajo presentamos el análisis de los adornos corporales de cinco yacimientos arqueológicos recientemente excavados en la República Dominicana (800–1600 dC). Para el análisis de cada artefacto se empleó la traceología, con el objetivo de comprender la secuencia de producción y utilización. Se definieron grupos morfo-tecnológicos los cuales fueron relacionados con los contextos de deposición y con la disponibilidad regional de materias primas. Los resultados muestran que (1) existió una producción local a pequeña escala de adornos en los sitios, (2) los grupos morfo-tecnológicos más frecuentes probablemente fueron importados desde los centros de producción y (3) los adornos pertenecientes a un mismo grupo pudieron ser utilizados de modos variados y ser depositados mediante diferentes procesos. Se concluye que los adornos corporales tenían biografías diversas que involucraban redes de interacción locales y regionales.

Een dwarsfluit uit het begin van de zestiende eeuw. Die doken archeologen op uit een scheepswrak in het Markermeer. Alleen dat al is een extreem zeldzame gebeurtenis. Maar van wie kan die fluit geweest zijn? Een stuk papier bij het mondgat zet een gevarieerd team van deskundigen op een spoor dat warmer en warmer wordt

We report the discovery of a 50,000-y-old birch tar-hafted flint tool found off the present-day coastline of The Netherlands. The production of adhesives and multicomponent tools is considered complex technology and has a prominent place in discussions about the evolution of human behavior. This find provides evidence on the technological capabilities of Neandertals and illuminates the currently debated conditions under which these technologies could be maintained. 14C-accelerator mass spectrometry dating and the geological provenance of the artifact firmly associates it with a host of Middle Paleolithic stone tools and a Neandertal fossil. The find was analyzed using pyrolysis-gas chromatography-mass spectrometry, X-ray micro-computed tomography, and optical light microscopy. The object is a piece of birch tar, encompassing one-third of a flint flake. This find is from northwestern Europe and complements a small set of well-dated and chemically identified adhesives from Middle Paleolithic/Middle Stone Age contexts. Together with data from experiments and other Middle Paleolithic adhesives, it demonstrates that Neandertals mastered complex adhesive production strategies and composite tool use at the northern edge of their range. Thus, a large population size is not a necessary condition for complex behavior and technology. The mitigation of ecological risk, as demonstrated by the challenging conditions during Marine Isotope Stage 4 and 3, provides a better explanation for the transmission and maintenance of technological complexity.