We investigate the stratigraphy of Neogene and Quaternary intervals of the Schelphoek borehole (Schouwen, Zeeland, the Netherlands). The Breda Formation (Miocene-Zanclean) contains three sequences separated by hiatuses. The Oosterhout Formation (Zanclean-Piacenzian) contains at least two sequences. This formation is overlain by seven sequences of the Gelasian Maassluis Formation that almost certainly represent glacial cycles. The three lowermost sequences are provisionally assigned to the Praetiglian (MIS 96, MIS 98 and MIS 100). A large hiatus exists between the top of the Maassluis Formation and the base of the late Middle to Late Quaternary succession. Due to extensive in situ reworking of older strata (including fossils) at the base of several of the formations, their exact boundaries are difficult to establish. The Neogene succession in the Schelphoek borehole is compared to the stratigraphic successions in the Antwerp area to the south and the Dutch coastal area and continental platform to the north. Finally, the stratigraphic context of the Gelasian (‘Tiglian’) mammal fauna dredged from the bottom of a major tidal channel in the adjacent Oosterschelde is assessed by comparison with the Schelphoek borehole.

Taphonomic analysis of Eemian marine mollusks and barnacles at Ristinge Klint on the island of Langeland (Denmark) provides a distinct record of a temporal succession in preservation states. Four different states of preservation are recognized and related to a decreasing hydrodynamic regime in the depositional setting of the Eemian Baltic Sea. The states show a deepening-upward transition from shallow bay environment towards deeper offshore environment. The depositional setting changed significantly in hydrodynamics about 620 and 1550 years into the Eemian (130,000 to 115,000 years BP), according to biostratigraphic correlation with the varves of the Bispingen succession. The taxonomic composition of the paleofauna supports such a deepening-upward interpretation with a contemporaneous change from brackish water to nearly full marine conditions. The sea bottom was affected by at least one period of oxygen deficiency. The analysis also shows that the preservation of shells varies according to differences in shell structures and life habits. Here we show how these differences should be considered in paleoenvironmental reconstructions based on taphonomic analyses. Taphonomy may play an important role in understanding the hydrodynamic conditions within the Eemian Baltic Sea.

We present new local groundwater-level rise data from two Late Glacial aeolian dunes, located near Barendrecht and Oud-Alblas in the western Rhine-Meuse delta. These data are based on AMS radiocarbon dating of terrestrial macrofossils, collected from the base of peat formed on the slopes of these dunes. This method avoids contamination of bulk peat samples by old soil carbon or younger rootlets and rhizomes, as well as the hardwater effect. The new data are used to assess the reliability of previously published groundwater-level index data based on conventional radiocarbon dating of bulk basal peat samples from the slopes of the Late Glacial aeolian dunes at Barendrecht, Hillegersberg, Bolnes and Wijngaarden, all located in the western Rhine-Meuse delta.

Comparison of the new and published groundwater-level data shows no significant systematic difference between conventionally dated bulk peat samples and AMS-dated samples of terrestrial macrofossils. The new data from the dune at Barendrecht confirm the reliability of the younger than 6600 cal yr BP age-depth data from the dunes at Hillegersberg and near Bolnes. This result supports the validity of this part of the mean sea-level (MSL) curve for the western Netherlands. Consequently, the position of the groundwater-level curve for Flevoland (central Netherlands) below this MSL curve can most likely be attributed to differential land-level movement.

The available data show that the groundwater-gradient effect in the western Rhine-Meuse delta became less than 5 cm/km after 6600 cal yr BP. Finally, temporal correlation between temporary increases in local groundwater-level rise with known shifts of river courses in the delta plain suggests, that avulsions can explain sudden local deviations from the trend in groundwater-level rise. A general conclusion of this study is that a complex relationship exists between sea level and local delta-plain water levels.

Clay is a common lithology in the Dutch shallow subsurface. It is used in earth constructions such as dikes, and as raw material for the fabrication of bricks, roof tiles etc. We present a new national assessment of Dutch clay resources, as part of a project that provides mineral-occurrence information for land-use planning purposes. The assessment is based on a 3D geological model, which consists of voxel cells with lithological composition as primary attribute, and has been obtained by interpolating data of more than 380,000 digital borehole descriptions. The occurrence of shell material and the extent to which clay is peaty were used as quality attributes, enabling us to tentatively distinguish between clay that is potentially suitable as ceramic material, and clay that is not.

As clay is extracted using dry (i.e. non-dredging) techniques, the model space has been dimensioned to fully encompass the unsaturated zone. A high-resolution model (with voxel cells of 250 · 250 · 0.2 m), based mainly on abundant, good-quality hand drillings, was constructed down to 3 m below the surface. This depth range suffices for clay-resource assessments in the lowlands, which have relatively high groundwater levels. Cells from a lower-resolution model (250 · 250 · 1 m, based on fewer data) were added to reach appropriate depths in upland areas.

We arrive at about 42.1 km3 of clay occurring in the model space (land areas only). Clay occurs mainly in the coastal domain and below the Rhine and Meuse river plains. Geological exploitability has been assessed within the unsaturated zone, taking overburden and intercalations with non-clay materials (especially peat) into account. The resulting exploitable stock is 12.3 to 18.0 (± 2.0) km3; an estimate in which the main source of uncertainty is presented by a lack of proper groundwater-table data. This amount equates to roughly 6000 annual consumption equivalents. Even when considering that the larger part of the clays is unsuitable for firing, and about one quarter is situated below built-up lands or nature preserves, clay is not a scarce resource in the Netherlands and supplies should present no problem in the near future.

A brief overview is given of the history of geological mapping of theHolocene Rhine-Meuse delta. The first accurate map of the delta, based onfield observations, was made by Vink (1926). The geological map of theNetherlands, scale 1 : 50,000, made by the ‘Geologische Stichting’ (1927 –1938) under the supervision of P. Tesch totally neglected Vink’s work, andwas a step backwards with regard to the mapping of the Holocene delta.Between 1940 and 1965, the Wageningen group of soil scientists produceddetailed regional soil maps, that had a strong ‘geogenetic’ component. Inthe 1960’s a revolutionary ‘profile type legend’ was introduced by theNetherlands’ Geological Survey. This allowed to map not only the outcroppingsediments, but the whole Holocene succession, which gave more insight intothe geological history. Over the past 30 years, the Rhine-Meuse delta hasbeen studied extensively by students of physical geography at UtrechtUniversity. More than 250,000 borehole descriptions, 1500 14Cdates and over 36,000 archeological artifacts with associated ages(collected by the National Service for Archaeological Heritage) haveaccumulated, resulting in the largest database of a delta in the world. Theproduction of detailed maps has been crucial to the solution of manyscientific problems. The use of GIS has greatly enhanced geological andgeomorphological mapping, and subsequently, understanding of the evolutionof the Holocene Rhine-Meuse delta. A new detailed digital elevation map ofthe Netherlands, based on very accurate laser-altimetry data, will enable usto map larger areas in greater detail, with greater accuracy, and in a muchshorter period of time.

A detailed reconstruction of the alluvial architecture of the Coevorden gas Field (Tubbergen Formation, Upper Carboniferous), which is located in the northeastern part of the Netherlands, is presented. This reconstruction is based on well logs, cross-sections and paleogeographic maps. Sedimentological analysis of a 93 m long core allowed to refine the interpretation of the depositional environment. Accurate width determinations are necessary to correctly correlate fluvial sandbodies and reconstruct alluvial architecture. Without using sedimentological information, sandbody width is likely to be overestimated. A method developed by Bridge and Tye (2000) was used to calculate the width of one sandstone body from cross-set thicknesses. On the basis of this calculation and the paleogeographic reconstructions, it may be stated that on average the width of the channel belts we studied in the Coevorden field does not exceed 4 km. Moreover, our paleogeographic reconstructions, which point to a northwestern direction of paleoflow, are in accordance with earlier observations from the study area. The Tubbergen Formation and time-equivalent sediments in Germany are reviewed briefly to put the Coevorden Field in a regional context. The thickness of the Tubbergen Formation is ∼450 m in our study area. In the adjacent German area, time-equivalent sedimentary sequences reach higher thicknesses. This may be attributed to tectonic movements along the Gronau Fault zone and the coming into existence of the Ems Low, of which the Coevorden Field is the westernmost part.

Over the last decades luminescence dating techniques have been developedthat allow earth scientists to determine the time of deposition ofsediments. In this contribution we review: 1) the development of themethodology; 2) tests of the reliability of luminescence dating onNetherlands’ sediments; and 3) geological applications of the method in theNetherlands. Our review shows that optically stimulated luminescence datingof quartz grains using the single aliquot regenerative dose method yieldsresults in agreement with independent age control for deposits ranging inage from a few years up to 125 ka. Optical dating of quartz has successfullybeen applied to sediments from a wide range of depositional environmentssuch as coastal dunes, cover sands, fluvial channel deposits, colluvialdeposits and fimic soils. These results demonstrate that optical dating is apowerful tool to explore the natural archive of the Netherlands’subsurface.

In the Netherlands North Sea area, the Chalk Group has thus far been subdivided into the Cenomanian Texel Formation, the Turonian to Maastrichtian Ommelanden Formation and the Danian Ekofisk Formation. This paper describes the attempt to arrive at a more detailed lithostratigraphic subdivision for this area, particularly of the Ommelanden Formation. To this end, a seismic stratigraphic analysis was carried out on a regional 2D and 3D seismic dataset. The Chalk Group was subdivided into eleven seismic stratigraphic sequences, named CK1 through CK11, based on the mapping and correlation of unconformities. The identified seismic sequence boundaries were used as the main chronostratigraphic markers in the Chalk Group interval. The seismic dataset was subsequently expanded with well log data of 45 boreholes. These were tied to the seismic dataset by constructing a synthetic seismogram for each borehole, after which the seismic sequence boundaries were noted and correlated on the logs. Finally, micropaleonthological data available in 15 boreholes were used to date the seismic sequences. The sequences were interpreted to be of Cenomanian (CK1), Turonian (CK2), Coniacian (CK3), Santonian (CK4), Early Campanian (CK5; CK6), Middle to Late Campanian (CK7), Early Maastrichtian (CK8; CK9), Late Maastrichtian (CK10) and Danian (CK11) age. The seismic units recognised in this study were compared with formal lithostratigraphic units defined in the Chalk Group in the surrounding North Sea sectors. Based on this comparison, a revision of the formal lithostratigraphic scheme, recognising Tor Formation and Herring Formation equivalents, is suggested for the Netherlands North Sea area.

Over the past 80 years, the Rhine-Meuse delta has been mapped extensively by drilling boreholes. These maps are compared with a new detailed digital elevation map of the Netherlands (AHN) that became available in 2004 and is based on very accurate, (sub-decimeter) laser-altimetry data. Examples show, that existing maps can be significantly improved. However, field checks remain a necessity. Therefore, the AHN-data need to be confronted with existing borehole descriptions using a GIS. Geomorphological analysis and geological interpretation of surface elevation patterns now enable us to map larger areas, in greater detail, with greater accuracy, and much faster. It is argued that detailed (≥1 : 50,000) geological mapping of the Netherlands should be resumed, combining the databases of Utrecht University, the National Geological Survey and Alterra.

A dendrogeomorphological approach is presented, using wood characteristics of native oak (Quercus robur L.) to infer dynamics of aeolian sediment transport in drift-sand areas. Wood samples, taken from oaks in two drift-sand areas, were analysed to study changes in tree-ring pattern and wood anatomy as a consequence of burying or exposure from drift sand.

In all cases, the wood of the sampled oaks showed sudden changes in anatomy and tree-ring width due to burial by drift sand or subsequent exposure after erosion of the new soil surface. After aerial stems became covered by drift sand, the wood lost its characteristic ring-porous features, and tree rings became strongly reduced in width with less distinct ring boundaries. Buried stems that became exposed after erosion showed an abrupt increase in ring width and turned distinctly ring porous again. Roots that were exposed also adopted clear ring-porous features, increased in ring width and anatomically resembled aerial stem wood.

Using tree-ring analysis, it is possible to precisely date sand deposition and erosion events by detecting the concurrent changes in anatomy of woody structures. This study indicates the high potential of dendrogeomorphology as a tool to study drift-sand dynamics with a high temporal, i.e. annual, resolution for a period going back as long as the maximum age of the trees present (in this study at least 250 years). Since the signals of past deposition and erosion events are conserved in the wood, this is the only method that can be used to reconstruct drift-sand dynamics when the actual landforms are no longer present.

In boulder clays and glacial deposit sands, exposed in the northern part of the Netherlands, erratic blocks of (ultra)high pressure (UHP) metamorphic rocks may be found that originate from the Baltic Shield (Scandinavia). The occurrence of (U)HP metamorphic rocks in Scandinavia is limited to: (1) isolated occurrences within the Scandinavian Caledonides (Western part of Scandinavia); (2) Sveconorvegian rocks from the Halland area, Southwest Sweden; and (3) Kola Peninsula (Northern Scandinavia). For this reason (U)HP rocks form excellent indicator pebbles/rocks that may be used to trace back the source area from where the erratic blocks, found in the Netherlands, were derived. An example of this, an erratic (retro) eclogite block found in Haren, is investigated in the present study using naked eye, light-optical and electron microprobe (EMP) techniques. EMP mineral analyses were used to reconstruct the PT conditions under which the (retro) eclogite was formed (T = 756 °C/min. P = 16,2 kb). This result, in combination with the mineral chemistry of the major rock forming minerals, provides evidence that this erratic block originates from the upper HP tectonic lens exposed in the Caledonian Seve Nappe Complex of Northern Jämtland, Sweden.

The Holocene Rhine-Meuse delta is formed under the influence of sea-level rise, tectonics, and variations in discharge and sediment supply. This paper aims to determine the relative importance of these external controls to improve our understanding of the evolution of the Rhine-Meuse fluvio-deltaic system. To do this, the geological and lithological composition of the fluvio-deltaic wedge has to be known in detail, both in space and time. This study presents five cross-valley sections in the Holocene Rhine-Meuse delta, based on almost 2000 shallow borings. Over 130 14C dates provide detailed time control and are used to draw time lines in the sections. Distinct spatio-temporal trends in the composition of the Holocene fluvio-deltaic wedge were found. In the upstream delta, the Holocene succession is characterised by stacked channel belts encased in clastic flood basin deposits through which several palaeo-A-horizon levels are traceable. In a downstream direction, the fluvio-deltaic wedge thickens from 3 to 7 m. The Holocene succession in the downstream cross sections formed from <8000 cal yr BP onwards and is characterised by single channel belts encased in organic flood basin deposits. The main part of the organic beds accumulated between 6000 and 3000 cal yr BP. After 3000 cal yr BP, clastic deposition dominated throughout the delta, indicating an increase in the area of clastic sedimentation. The Holocene fluvio-deltaic wedge is subdivided into three segments based on the relative importance of eustatic sea-level rise, subsidence, and upstream controls (discharge and sediment supply). Before 5000 cal yr BP, eustatic sea-level rise controlled the build-up of the wedge. After eustatic sea-level rise ceased, subsidence was dominant from 5000 to 3000 cal yr BP. From 3000 cal yr BP onwards, increased sediment supply and discharge from the hinterland controlled the formation of the fluvio-deltaic wedge. A significant part of the present-day Rhine-Meuse fluvio-deltaic wedge aggraded after eustatic sea-level rise ceased. We therefore conclude that external controls other than eustatic sea-level rise were also of major importance for the formation of the fluvio-deltaic wedge. Because this is probably true for other aggrading fluvial systems at continental margins as well, all external controls should be addressed to when interpreting (ancient) fluvio-deltaic successions.

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.

Application of the traditional lithostratigraphic framework to subdivide theMiddle- and Upper-Quaternary locally-derived fine-grained deposits in theNetherlands is problematic. Deposits of many formations cannot bedistinguished from each other based on lithological characteristics andstratigraphie position alone. To overcome this problem, we present a new,well-defined lithostratigraphy for these deposits, based on detailedresearch in the central part of the Roer Valley Graben. This area containsan up to 35 m-thick sedimentary record of Middle- and Upper-Quaternary sand,loam and peat deposits. These have mainly been formed by aeolian andsmall-scale fluvial processes and have been preserved as a result oftectonic subsidence. The traditional lithostratigraphic subdivision of thesedeposits into three formations (Eindhoven Formation, Asten Formation andTwente Formation) was based on a combination of litho-, bio- andchronostratigraphic evidence and the presumed widespread presence of ahorizon of organic-rich interglacial sediments of Eemian age. To avoidintermingling of criteria regarding lithological characteristics, genesisand age, we now incorporate all fine-grained sediments into the new BoxtelFormation. The implications for the lithostratigraphic framework in otherparts of the country are explored and discussed. Eight lithostratigraphicmembers are introduced that describe the most characteristic parts of theformation. To fully illustrate the sedimentary sequence in the Roer ValleyGraben, two new members are defined here. The Best Member incorporatesalternating floodloam deposits and sandy aeolian deposits in the lower partof the Boxtel Formation. The Liempde Member includes reworked aeolian loessand sandy loess deposits (‘Brabant loam’) that occur in the upper part ofthe sedimentary sequence.

Management of the Dutch embanked floodplains is of crucial interest in the light of a likely increase of extreme floods. One of the issues is a gradual decrease of floodwater accommodation space as a result of overbank deposition of mud and sand during floods. To address this issue, sediment deposits of an undisturbed embanked floodplain near Winssen along the river Waal were studied using ground-penetrating radar (GPR). A number of radar facies units were recognized. Boreholes were used to relate radar facies units to sedimentary facies and to determine radar velocity. The GPR groundwave is affected by differences in moisture and texture of the top layer and probably interferes with the first subsurface reflector. The architectural elements recognized in the GPR transects confirm earlier reported insights on human-influenced river behaviour. This is testified in the development of sand bars during flood regimes that are probably more widespread than previously established.

A small faunule of fragmentary Hettangian (earliest Jurassic) psiloceratoid ammonites collected from dark-coloured, clay-rich sediments in a subrosion pipe at Quarry III of the Winterswijk quarry complex is described. The genera Alsatites, Saxoceras and Schlotheimia are determined by comparison to extensive literature on coeval, north German faunas. Taphonomic features are apparent indicating condensation and reworking. Despite this, the portion of the subrosion pipe sediment fill which yielded this material can be dated as middle to late Hettangian.

Alluvial architecture has been subject of many studies because of theoccurrence of natural resources in ancient fluvial successions. This paperprovides an overview of the current state of research on alluvialarchitecture with special reference to Holocene fluvio-deltaic settings.Several examples from modern fluvio-deltaic areas, especially the HoloceneRhine-Meuse delta (the Netherlands) and the Lower Mississippi Valley(U.S.A.), are used to illustrate the architectural elements that can bedistinguished in fluvial successions and to show the influence of thevarious controls on alluvial architecture (base level, climate, tectonism,aggradation, avulsion, and compaction). Avulsion is regarded as a principalprocess in the formation of fluvio-deltaic sequences, because it determinesthe location and number of active channels on the floodplain. The avulsionmechanism is still subject of debate, though. A brief description of theevolution of process-based alluvial-architecture models is given. Thesemodels simulate the proportion and distribution of coarse-grained channelbelts in fine-grained overbank deposits. The major drawback of thepresent-day alluvial-architecture models is the lack of (three-dimensional)quantitative field data to test and validate them. The paper concludes withthe suggestion to collect more architectural data from natural fluvialsettings, to improve simulation of channel-belt geometry inalluvial-architecture models, and to implement new data and knowledge offluvial processes into models.