In the
geologic timescale
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronol ...
, the Valanginian is an
age or
stage of the
Early or Lower Cretaceous. It spans between 139.8 ± 3.0
Ma and 132.9 ± 2.0 Ma (million years ago). The Valanginian Stage succeeds the
Berriasian Stage of the Lower Cretaceous and precedes the
Hauterivian Stage of the Lower Cretaceous.
Stratigraphic definitions
The Valanginian was first described and named by
Édouard Desor in 1853. It is named after
Valangin, a small town north of
Neuchâtel
, neighboring_municipalities= Auvernier, Boudry, Chabrey (VD), Colombier, Cressier, Cudrefin (VD), Delley-Portalban (FR), Enges, Fenin-Vilars-Saules, Hauterive, Saint-Blaise, Savagnier
, twintowns = Aarau (Switzerland), Besançon (France), ...
in the
Jura Mountains
The Jura Mountains ( , , , ; french: Massif du Jura; german: Juragebirge; it, Massiccio del Giura, rm, Montagnas da Jura) are a sub-alpine mountain range a short distance north of the Western Alps and mainly demarcate a long part of the Frenc ...
of
Switzerland
). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...
.
The base of the Valanginian is at the first appearance of
calpionellid species ''
Calpionellites darderi'' in the stratigraphic column. A global reference section (a
GSSP) had in 2009 not yet been appointed.
The top of the Valanginian (the base of the Hauterivian) is at the first appearance of the
ammonite
Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...
genus ''
Acanthodiscus''.
Subdivision
The Valanginian is often subdivided in Lower and Upper substages. The Upper substage begins at the first appearance of ammonite species ''
Saynoceras verrucosum'' and the major
marine transgression Va3.
In the
Tethys domain, the Valanginian stage contains five ammonite
biozones:
* zone of ''
Criosarasinella furcillata''
* zone of ''
Neocomites peregrinus''
* zone of ''
Saynoceras verrucosum''
* zone of ''
Busnardoites campylotoxus''
* zone of ''
Tirnovella pertransiens
''Tirnovella'' is an extinct subgenus of ammonoid cephalopod, from the early Cretaceous.
Use in Stratigraphy
The group is often used as an index fossil, with '' Tirnovella alpillensis'' being used to define border between the Berriasian and t ...
''
Flora
The oldest fossils that can definitely be attributed to the clade
Angiospermae
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
(flowering plants) are dated to the Late Valanginian.
References
Notes
Literature
*; (2004): A Geologic Time Scale 2004,
Cambridge University Press.
External links
GeoWhen Database - ValanginianMid-Cretaceous timescale
and ühttp://stratigraphy.science.purdue.edu/charts/Timeslices/5_JurCret.pdf Jurassic-Cretaceous timescale], at the website of the subcommission for stratigraphic information of the ICS
Stratigraphic chart of the Lower Cretaceous
at the website of Norges Network of offshore records of geology and stratigraphy
*02
Geological ages
Cretaceous geochronology
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