Sedimentology and facies distribution of Pleistocene cold‐climate aeolian and fluvial deposits in the Roer Valley Graben (southeastern Netherlands)

The Roer Valley Graben (southeastern Netherlands) is an area of tectonic subsidence that contains a 35 m‐thick record of fine‐grained Middle‐ and Upper‐Pleistocene deposits. The sedimentary structures of these sediments were studied using undisturbed sediment cores and cone penetration tests. This enabled a reconstruction of the depositional environment. Seven sedimentary facies were distinguished, ranging from sandy fluvial deposits to loamy aeolian deposits and organic sediments. Wet‐aeolian sand‐sheet and loam deposits are the two most widespread facies. The aeolian sand is characterized by horizontal alternating bedding, attributed to deposition of sand and silty sand on an alternating wet and dry surface. The loam is usually massive and interpreted as a reworked loess deposit. In the sediment sequence, a shift can be observed from a dominance of fluvial deposits to an alternation of fluvial and aeolian deposits and finally, to predominantly aeolian deposits. The majority of the sediments have been deposited during successive Middle‐ and Late‐Pleistocene glacial periods. It is argued that a high groundwater table, attributed to local subsidence and climatic conditions, was the main factor determining the local depositional environment and preservation potential of the sediments in the Roer Valley Graben. Copyright © 2004 John Wiley & Sons, Ltd.