Ontwikkelingen in de Kwartair-geologische opvattingen over ons land na Staring's proefschrift van 1833 : Herkenning van de glaciale morfologie in de periode van Lorié, eind 19e eeuw, tot de 21e eeuw

After acceptance of the glacial theory in northwestern Europe (1875), gradually the morphological expression of a former landice cover is being recognized. Endmoraines, pushmoraines and related fenomena like eskers and ice marginal valleys are observed in the field. Increasing information from the subsoil reveals the presence of glacial valleys flanked by pushmoraines and refilled with meltwaterdeposits. At first, such valleys are thought to represent former rivervalleys deepened by the landice mass. When their outline becomes better known it is concluded that actually the valleys are glacial basins, of which five are found in the central Netherlands. In the subsoil of the adjacent North Sea the presence of pushmoraines and glacial basins is established as well. The landice is supposed to have spread out over the Netherlands from the northeast to the southwest. During phases of standstill two or more series of pushmoraines had been formed. In the middle of the 20th century on the contrary the general opinion holds that five series of pushmoraines have been formed during the retreat of the landice. In both views formation of the glacial basins received no special attention, because they were considered as glacially eroded rivervalleys. These would have been formed during the maximum extension of the landice. Erosion of the glacial valleys as well as the glacial basins was ascribed to the pushing power of the icemass. The idea found further support when the sudden spreading of glaciers (glacial surge) had been observed. Already in the middle of the 20th century the coarseness respectively fineness of the subsoil under the glacier has been put forward to explain the difference between the glacigenic landscapes of the northern and central Netherlands. Growing insight in the behaviour of glaciers confirms this idea: meltwaterproduction and the related drainage system as well as the ability of the subsoil to react thereupon are now considered as determining factors for the way of deformation of the subsoil during surging phases. In this way the difference in the geohydro- logical structure of the subsoil between the northern- and the Central- Netherlands explains the different glacial landscapes of the two areas. Recognition of the glacial morphology in the course of time is reflected in the subsequent maps depicting the glacial elements (Fig. 5). The most recent one, presented on Fig. 6, has been compiled especially at the occasion of the opening of the new builing of the National Geological Survey.