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
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 older ...
or
stage
Stage or stages may refer to:
Acting
* Stage (theatre), a space for the performance of theatrical productions
* Theatre, a branch of the performing arts, often referred to as "the stage"
* ''The Stage'', a weekly British theatre newspaper
* Sta ...
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 ago) ...
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 the Va ...
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 ...
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
Calpionellids are an extinct group of eukaryotic single celled organisms of uncertain affinities. Their fossils are found in marine rocks of Upper Jurassic to Lower Cretaceous age. They were planktic organisms with urn-shaped, calcitic tests t ...
species ''
Calpionellites darderi
''Calpionellites darderi'' is an extinct planktonic eukaryote and an important index fossil for the Lower Cretaceous stratigraphy. The first appearance of ''C. darderi'' marks the beginning of the Valanginian. It also defines the base of the "Cal ...
'' 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 b ...
) 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
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''
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 of ...
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
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
A university press is an academic publishing hou ...