The Bree Uplift is a particular structure in the direct footwall of the southwestern graben boundary fault system of the Roer Valley Graben, which has been firstly recognized at the base of the Cretaceous. To date fault activity around the Bree Uplift has been confined to the Subhercynian (late Cretaceous) inversion event or considered fading out during Tertiary times.

The revision of the existing geological data reveals that the Bree Uplift can still be recognized on the top-Tertiary map. This infers at least a late Tertiary activity, suggesting continuous fault activity in the graben boundary fault system not only on the major boundary faults but also on different splay faults, bounding individual fault blocks.

A high-resolution reflection seismic survey was carried out in 1999 over the Feldbiss fault system, the southern border of the Roer Valley graben, in Belgium. Six profile-lines with total length of 13982 m provided information on the 40-600 m depth range, covering Lower Pleistocene to Miocene strata with special emphasis on the Plio-Pleistocene Kieseloolite formation. Data quality depends on near-surface conditions and on degree of deformation in some fault zones, with better results for seismic detonator sources compared to vibroseis sources. The new data confirm the segmented character of the fault system with occurrence of fault bends, relay ramps and branching of overlapping fault sequences, testifying of the strong tectonic activity during the lower Pleistocene. Antiform structures along the Bichterweerd scarp, relaying the Feldbiss to the Geleen fault in the Meuse valley, are presented as a model for the Tertiary evolution of the Bree Uplift.