Buried channel aquifers and present open drainage system of East Gelderland, the Netherlands

In the eastern part of the province of Gelderland, two buried valley systems have been traced. One system is filled with fluvioglacial deposits dating from the Saalian lce Age, the other with preglacial fluvial sediments which are remarkable rich in vulcanic minerals. Both systems have a course which is almost perpendicular to the present drainage system. This change in stream direction is explained by postglacial replacement of the main drainage channel in the area, tectonic movement perpendicular to the old channels, and postglacial filling of the old channels with wind blown sand.