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 geoch ...
, the Valanginian is an
age
Age or AGE may refer to:
Time and its effects
* Age, the amount of time someone or something has been alive or has existed
** East Asian age reckoning, an Asian system of marking age starting at 1
* Ageing or aging, the process of becoming olde ...
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
In the geological timescale, the Berriasian is an age/ stage of the Early/Lower Cretaceous. It is the oldest subdivision in the entire Cretaceous. It has been taken to span the time between 145.0 ± 4.0 Ma and 139.8 ± 3.0 Ma (million years a ...
Stage of the Lower Cretaceous and precedes the
Hauterivian
The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.9 ± 2 Ma and 129.4 ± 1.5 Ma (million years ago). The Hauterivian is preceded by t ...
Stage of the Lower Cretaceous.
Stratigraphic definitions
The Valanginian was first described and named by Édouard Desor in 1853. It is named after
Valangin
Valangin () is a former municipality in the district of Val-de-Ruz in the canton of Neuchâtel in Switzerland. On 1 January 2021 the former municipalities of Corcelles-Cormondrèche, Peseux and Valangin merged into the municipality of Neuchâ ...
, a small town north of
Neuchâtel
Neuchâtel (, , ; german: Neuenburg) is the capital of the Swiss canton of Neuchâtel, situated on the shoreline of Lake Neuchâtel. Since the fusion in 2021 of the municipalities of Neuchâtel, Corcelles-Cormondrèche, Peseux, and Valangin, ...
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 Fre ...
of Switzerland.
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
A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted ...
) 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 cuttle ...
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...
''
Acanthodiscus
''Acanthodiscus'' is an extinct ammonoid cephalopod genus from the order Ammonitida and included in the persphinctacean family Berriasellidae. The type species, named by Bruguière, 1792, is ''Acanthodiscus radiatus''.Saynoceras verrucosum'' and the major
marine transgression
A marine transgression is a geologic event during which sea level rises relative to the land and the shoreline moves toward higher ground, which results in flooding. Transgressions can be caused by the land sinking or by the ocean basins filling ...
Va3.
In the Tethys domain, the Valanginian stage contains five ammonite
biozone
In biostratigraphy, biostratigraphic units or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa, as opposed to a lithostratigraphic unit which is defined by the lithological properties ...
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. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of broad- ...
(flowering plants) are dated to the Late Valanginian.
References
Notes
Literature
*; (2004): A Geologic Time Scale 2004,
Cambridge University Press
Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by Henry VIII of England, King Henry VIII in 1534, it is the oldest university press in the world. It is also the King's Printer.
Cambr ...