Facies and Lithologies
The Rupel Formation can be 250 meters thick at maximum. During the Rupelian age the Netherlands (and Belgium) were covered by a shallow sea, which became deeper towards the northwest. In the northwest, the sedimentary facies can be more than 500 m deep marine, while in southeastern parts of the Netherlands the formation has a near coastal facies.
The formation is subdivided in four members: the Bilzen Member (yellow-white glauconiferous fine sand, containing fossils), the Boom Member (a thick clay deposit, containing loam layers and septaria), the Eigenbilzen Member (strongly layered sands) and the Ratum Member (sand, clay and loam, appears only in the east of the Netherlands).
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