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A geophysical profile at the foot of the Dutch coastal dunes near the former outlet of the 'Old Rhine'

Author: Seijmonsbergen, A.C. · Biewinga, D.T. · Pruissers, A.P.
Type:article
Date:2004
Source:Geologie en Mijnbouw/Netherlands Journal of Geosciences, 4, 83, 287-291
Identifier: 238151
Keywords: Geosciences · 'Old Rhine' · Dutch coast · Electrical conductivity · Geonics EM-34 · coastal sediment · dune field · electrical resistivity · electromagnetic survey · geophysical survey · Holocene · spatial distribution · Benelux · Eastern Hemisphere · Eurasia · Europe · Netherlands · Western Europe · World · Geological Survey Netherlands · Energy / Geological Survey Netherlands

Abstract

The apparent electrical conductivity of the subsurface along the Dutch coast between 'Wassenaarse Slag' (beach post 92.250) and north of Noordwijk aan Zee (beach post 77.750) reflects the spatial distribution of Holocene coastal deposits. Using a Geonics EM-34 a threefold division based on the mean electrical conductivity could be made in the outlet area of the River Old Rhine. 1) A section showing a sequence of sandy deposits that resembles the Schoorl Member of the Naaldwijk Formation on top of the Zandvoort Member of the Naaldwijk Formation. 2) A section underlain by a shallow clay/peat layer of varying thickness belonging to the Naaldwijk Formation (Walcheren Member) / Nieuwkoop Formation (Hollandveen Member), intercalated within the Schoorl Member and Zandvoort Member of the Naaldwijk Formation. South of the Old Rhine locally Wormer Member deposits of the Naaldwijk Formation underlie these clay/peat layers. 3) A section characterized by channel fill deposits of the former Rhine reaching to -20 m below Normaal Amsterdam Peil (N.A.P.), and belonging to deposits of the Wormer Member of the Naaldwijk Formation, and to two facies of the Naaldwijk Formation (Walcheren Member). The geophysical transect was calibrated using existing nearby drill hole data, so that a continuous snapshot of the subsurface was gained. Therefore this research also contributes to the recent genesis of this part of the Dutch coast.