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Representation and status

Color CMYK
siehe Betlis-Fm.
Color RGB
R: 160 G: 210 B: 120
lithostratigraphic Bed
Unit is in Use
local name (informal)


Banc de Büls
Strato di Büls
Büls Bed
Origin of the Name

Hinterbüls (SG), Churfristen

Historical Variants

Cephalopodenbank (Arn. Heim 1916), Ammonitenhorizont an der Basis des Valanginienkalkes (Haus 1937 in: Rutsch et al. 1966), Büls-Schichten (Kuhn 1997), Büls Beds = Büls Member (Föllmi et al. 2007)


Max. 5 m (Föllmi et al. 2007)


Fossil Content
  • ammonites

Hierarchy and sequence

Superordinate unit


Age at top
  • Early Valanginian
Note about top

Stephanophorus Zone / frühe campylotoxus-Zone (Wyssling 1986, Kuhn 1996)

Age at base
  • Early Valanginian
Note about base

späte Pertransiens-Zone

Dating Method

Ammoniten-Biostratigraphie (Wyssling 1986, Kuhn 1996, Föllmi et al. 2007).


Geographical extent
Vorarlberg, Ost- und Zentralschweiz.

Palaenography and tectonic

  • Neocomian
  • Cretaceous of the Helvetics
North Tethyan Shelf :
marge continentale européenne
Tectonic unit (resp. main category)
Kind of protolith
  • sedimentary


Kuhn Oliver (1996) : Der Einfluss von Verwitterung auf die Paläozeanographie zu Beginn des Kreide-Treibhausklimas (Valanginian und Hauterivian) in der West-Tethys. Diss. ETH Zürich

Die Phosphoritbildung der neudefinierten Büls-Schichten findet innerhalb der Pertransiens und Stephanophorus-Zone statt (Unter Valanginian), ...

Föllmi Karl B., Bodin Stephane, Godet Alexis, Linder Pascal, van de Schootbrugge B. (2007) : Unlocking paleo- environmental information from Early Cretaceous shelf sediments in the Helvetic Alps: stratigraphy is the key! Swiss J. Geosci. 100, 349-369

p.354: In distal parts of the platform, the lower Betlis Limestone is overlain by an up to 5 m thick and heterogeneous succession, which consists of sandy, glauconitic, hemipelagic carbonates and marl, which include a discrete level of phosphate nodules or a phosphatized hardground (Fig. 2; Fig. 3). This unit is identified both in different regions in Vorarlberg (Austria), as well as in eastern and central Switzerland (Hauswirth 1913; Heim 1910–1916; Haus 1937; Strasser 1979; Felber and Wyssling 1979) and has been defined as “Büls Beds” by Kuhn (1996).

The Büls Member is underlain either by sediments of the Vitznau Formation or of the lower Betlis Limestone (Fig. 2) and overlain by sediments of the hemipelagic Sichel Limestone of the Diphyoides Formation. In the case this latter member is absent, the Büls Member bundle with the overlying Gemsmättli Bed and forms a single phosphate-rich bed (Kuhn 1996). This is the case for example at the type locality of the Gemsmättli Bed in the Pilatus region (Wyssling 1986).

The Büls Member includes the oldest drowning unconformity within the Helvetic platform succession, and documents a first phase of highly reduced carbonate production on the platform (Föllmi et al. 1994, 2006). Its age is constrained by ammonite biostratigraphy in occurrences in Vorarlberg and eastern Switzerland and encompasses the late pertransiens and early campylotoxus zones (Wyssling 1986; Kuhn 1996).

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