Tertiary ( ) is a widely used but obsolete term for the
geologic period from 66 million to 2.6 million years ago.
The period began with the demise of the non-
avian
Avian may refer to:
* Birds or Aves, winged animals
*Avian (given name) (russian: Авиа́н, link=no), a male forename
Aviation
*Avro Avian, a series of light aircraft made by Avro in the 1920s and 1930s
*Avian Limited, a hang glider manufactur ...
dinosaurs in the
Cretaceous–Paleogene extinction event
The Cretaceous–Paleogene (K–Pg) extinction event (also known as the Cretaceous–Tertiary extinction) was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago. With th ...
, at the start of the
Cenozoic Era
The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configurat ...
, and extended to the beginning of the
Quaternary glaciation at the end of the
Pliocene Epoch
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58[geologic time
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 geochron ...](_blank)
system, but it is essentially the merged
Paleogene and
Neogene periods, which are informally called the Early Tertiary and the Late Tertiary, respectively. The Tertiary established the Antarctic as an icy island continent.
Historical use of the term
The term Tertiary was first used by
Giovanni Arduino during the mid-18th century. He classified geologic time into primitive (or primary), secondary, and tertiary periods based on observations of geology in
Northern Italy. Later a fourth period, the
Quaternary, was applied.
In the early development of the study of geology, the periods were thought by
scriptural geologist
Scriptural geologists (or Mosaic geologists) were a heterogeneous group of writers in the early nineteenth century, who claimed "the primacy of literalistic biblical exegesis" and a short Young Earth time-scale. Their views were marginalised and ...
s to correspond to the Biblical narrative, the rocks of the Tertiary being thought to be associated with the
Great Flood
A flood myth or a deluge myth is a myth in which a great flood, usually sent by a deity or deities, destroys civilization, often in an act of divine retribution. Parallels are often drawn between the flood waters of these myths and the primaeval ...
.
In 1833,
Charles Lyell
Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known as the author of ''Principles of Geolo ...
incorporated a Tertiary Period into his own, far more detailed system of classification, based on
fossil mollusks he collected in Italy and Sicily in 1828-1829. He subdivided the Tertiary Period into four epochs according to the percentage of fossil mollusks resembling modern species found in those
strata. He used
Greek names: Eocene, Miocene, Older Pliocene, and Newer Pliocene.
Although these divisions seemed adequate for the region to which the designations were originally applied (parts of the
Alps
The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Sw ...
and plains of Italy), when the same system was later extended to other parts of Europe and to America, it proved to be inapplicable. Therefore, the use of mollusks was abandoned from the definition and the epochs were renamed and redefined.
For much of the time during which the term 'Tertiary' was in formal use, it referred to the span of time between 65 and 1.8 million years ago. The end date of the Cretaceous and the start date of the Quaternary were subsequently redefined at c. 66 and 2.6 million years ago respectively.
Modern equivalents
The Tertiary period lies between the
Mesozoic Era
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretac ...
and the
Quaternary Period
The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
, although it is no longer recognized as a formal unit by the
International Commission on Stratigraphy.
The span of the Tertiary is subdivided into the
Paleocene (66–56 million years
BP), the
Eocene (56–33.9 million years BP), the
Oligocene (33–23.9 million years BP), the
Miocene (23–5.3 million years BP) and the
Pliocene (5.3–2.6 million years BP), extending to the first stage of the
Pleistocene, the
Gelasian Stage.
References
External links
*
{{Authority control
Cenozoic