Quaternary geological mapping of the lowlands of The Netherlands, a 21st century perspective

Abstract

Old borehole descriptions, modern lithostratigraphical classification and geostatistics have been combined in recent geological mapping in The Netherlands. Recent developments in geostatistics and the increased computing capacity of personal computers enable three-dimensional geological mapping, based on already available data. The data originate from a mapping programme at the scale of 1:50,000 that was started in the 1950s by the National Geological Survey (Rijks Geologische Dienst). Although started on a lithostratigraphical basis, the increased use of radiocarbon dates since the 1950s influenced the map legend. The map units were largely defined by age boundaries that were supposed to coincide with transgressions and regressions. More recent research revealed that not only sea level but also regional basin topography, sediment supply and regional neo-tectonics are important factors controlling coastal development. The Netherlands Institute of Applied Geoscience TNO–– National Geological Survey (the successor of the Rijks Geologische Dienst) recently redefined the classification of Holocene coastal and alluvial deposits in a purely lithostratigraphical way. The old borehole descriptions contain purely lithological descriptions as well as interpretations that were derived from those descriptions. The larger part of the originally defined map units represents boundaries that characterise a change in lithology. By returning to the original lithological descriptions, the borehole data and the geological maps are applicable in the new lithostratigraphical framework. They are now used in modern three-dimensional geological mapping/modelling of the subsurface. These models are very useful for applied geological research.