The information on this page is a summary description.
The full formal description is available here: Vaals Formation
| Abbreviation | VAA |
| Parent unit | Chalk group |
| Child units | Asdonk Member, Sonnisheide Member, Raren Member, Cottessen Member, Gemmenich Member, Vaalsbroek Member, Beusdal Member, Terstraten Member, Benzenrade Member |
| Lithological description | In the type area, the unit comprises six members with a total thickness of about 150 m, to which W.M. Felder & Bosch (2000) added a seventh, the Benzenrade Member. – Raren Member (thickness between 12 and 18 m): predominantly laminated, yellow to greyish-green, glauconitic fine- grained sands, in channel fills. In places lenticular sandstone bodies occur with rich faunas, interfingering in westerly direction with silty fine-grained sands and sandy silts. – Cottessen Member (thickness up to 10 m): cyclic alternation of yellow to greyish-green, glauconitic laminated channel fills, and light grey-brown, fine-grained sandy silts to silty fine-grained sands. Occurring locally are fossil-rich sandstone banks; towards the west, a facies change similar to that in the Raren Member occurs. The top corresponds to a fossiliferous, dark grey-green glauconitic horizon. – Gemmenich Member (thickness about 10-12 m): similar to Cottessen Member. – Vaalsbroek Member (thickness 4-6 m): cyclic alternation of yellow to greenish-grey, glauconitic, laminated fine-grained sands without silt, and glauconitic, silty, fine sands with extensive bioturbation. – Beusdal Member (thickness between 14 and 25 m); cyclic alternation of poorly indurated, yellow to greyish-green, glauconitic laminated fine sands without silt and glauconitic, silty, fine-grained sands with extensive bioturbation. – Terstraten Member (thickness up to about 15 m): greyish-green, silty fine-grained sandy silts with glauconite. Base characterised by poorly indurated, light grey, fine-grained sandy silt with fossil hash, in particular the bivalve Cucullaea subglabra. – Benzenrade Member: see W.M. Felder & Bosch (2000) |
| Age | Early Early Campanian to early Late Campanian by ammonoid and coleoid cephalopods: Belemnitella praecursor, Bt. m. mucronata, Gonioteuthis granulataquadrata, G. q. quadrata, Scaphites hippocrepis II-III, Trachyscaphites spiniger, Pachydiscus duelmensis, P. launayi, Eupachydiscus levyi, Hoplitoplacenticeras marroti, H. cf. coesfeldiense, Glyptoxoceras vaalsiense, and Baculites vaalsensis. |
| Thickness | Total thickness up to about 150 m. |
| Area of occurrence | Type area in direct vicinity of the Vaalserberg, southeast of Vaals (Limburg, The Netherlands). |
| Type locality | Stratotypes: – Raren Member: road cutting along Sandbergweg, Aachen-Vaalserquartier, Germany (co-ordinates 308.700/200.600). – Cottessen Member: road cutting along Holle Weg at Cottessen (Limburg, the Netherlands) (co-ordinates308.200/194.540). – Gemmenich Member: road cutting between Terstraten and grenspaal 7, Bleiberg (Plombières), Liège province (Dutch co-ordinates 196.120/307.300). – Vaalsbroek Member: road cutting at Mechelen-Overgeul (Limburg, the Netherlands) (co-ordinates 311.820/192.200). – Beusdaal Member: road cutting between Sippenaeken and Teuven, Liège province (Dutch co-ordinates 306.830/192.240). – Terstraten Member: road cutting east of Terstraten on the Belgian-Dutch border, near grenspaal 6) (co-ordinates 307.420/196.420). – Benzenrade Member: outcrop at Den Dael on the Putberg between Benzenrade and Ubachsberg (Limburg, the Netherlands) (co-ordinates 195.800/318.820). |
| Alternative names | |
| Authors | Dusar, M. & Lagrou, D. |
| Date | 07/06/2010 |
| Cite as | Dusar, M. & Lagrou, D., 2010. The Vaals Formation, 07/06/2010. National Commission for Stratigraphy Belgium. https://ncs.naturalsciences.be/lithostratigraphy/Vaals-Formation |
| Additional information | Formerly described as “Smectite de Herve” (Dumont,1832) , “Système hervien”(Dumont, 1850) “Assise de Herve” [Rutot (1894), Leriche (1929), Marlière (1954)], “Vaalser Groenzand” or Hervian (Netherlands Geological Survey, 1957). Recent references: Albers (1976), Albers & Felder (1979), Jagt (1989), Kennedy & Jagt (1995, 1998), Jagt (1999), Felder & Bosch (2000). Complementary data (M. Dusar, 2011): The Vaals Formation is occurring in the Belgian – Dutch – German boundary area and the eastern Pays de Herve, mostly in the form of greensand. Further to the west, the Vaals Formation is often completely eroded by channels filled with chalks belonging to the Gulpen Formation or may consist of bluish weathering clays as in the Hallembaye quarry north of Visé, displayint the so-called ‘Smectite de Herve’ facies. On the eastern part of the Brabant Massif, the Vaals Formation is represented by patches of coarse residual deposits. The Vaals Formation is more extensively developed in the Campine Basin, where the lithostratigraphic subdivision of the type area cannot be distinguished. Instead, a two-fold subdivision has been made, which further west at the western margin of the Campine basin and on the Brabant Massif evolves into the chalks of the Nevele Formation. This new subdivision of the Vaals Formation is described in more detail on this website. Also, the Benzenrade Member, added to the Vaals Formation by Felder & Bosch (2000) in the area between the type area and the southern margin of the Roer Valley Graben, is considered as a separate unit, laterally equivalent of the Gulpen Formation, the new Dorne Formation (see separate description on this website). |
