Sedimentstructurele en glaciotektonische verschijnselen in het Midden-Saalien in een stuwwalafgraving bij Mook (N-Limburg)

In the central, northern and eastern parts of the Netherlands icepushed ridges were formed during the Saalian glaciation. This article gives a description of an E-W section in a sand pit in the most southern ridge (near the German border), in the neighbourhood of the village Mook (10 km south of Nijmegen). In this section three tectonic units are distinguished, the most western as an anticline, the middle as an steep dipping thrustsheet and the most eastern as a weak dipping thrustsheet. In the tectonic units three stratigraphic units are distinguished, from top to bottom these are: U-unit: (Formatie van Urk, Elsterian) consisting of brown coarse sands with abundant gravel and brownish clay. The sands contain augite and pinkish Triassic red sandstone grains, thickness 16-20 m. W-unit: very white sands, with relatively much well rounded quartz grains, thickness 8-12 m. Fz-unit: fine grained, dark brown sands, thickness 2-3 m. All these unconsolidated units were formed by the Pleistocene Rhine and Meuse rivers. Three tectonic phases are distinguished, which are all due to the formation of the pushed ridge, from old to young these are: phase A : thrusting; formation of thrustsheets and anticline. phase B: formation of kinkbands, small reverse faults and shearzones, all occuring in conjugate sets. phase C: normal faulting and the formation of recumbent folds. Phase A corresponds to the advance of a glacier, phase B probably to a second advance and phase C to the final retreat of the glacier. A description of the paleo-geography of the region of Mook is given as well.