Tertiary
From Wikipedia, the free encyclopedia
The Tertiary is a a term for a geologic period 65 million to 1.8 million years ago. The Tertiary covered the time span between the superseded Secondary period and an out-of-date definition of the Quaternary period. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Tertiary extinction event, at start of the Cenozoic era, spanning to beginning of the most recent Ice Age, at the end of the Pliocene epoch.
Contents |
[edit] Historical use of the term
The term Tertiary was first used by Giovanni Arduino in 1759. He classified geologic time into primitive (or primary), secondary, and tertiary periods based on observations of geology in northern Italy.[4] Later a fourth period, the Quaternary, was applied. In 1828, Charles Lyell incorporated a Tertiary period into his own, far more detailed system of classification. 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 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, later the use of mollusks was abandoned from the definition and the epochs were renamed and redefined.
[edit] Geological events
Tectonic activity continued as Gondwana finally split completely apart, and India collided with the Eurasian plate. South America was connected to North America toward the end of the Tertiary. Antarctica — which was already separate — drifted to its current position over the South Pole. Widespread volcanic activity was prevalent.
[edit] Climate
Climates during the Tertiary slowly cooled, starting off in the Paleocene with tropical-to-moderate worldwide temperatures and ending up with extensive glaciations at the end of the period.
[edit] Life form events
At the beginning of the period, mammals replaced reptiles as the dominant vertebrates. Each epoch of the Tertiary was marked by striking developments in mammalian life. The earliest recognizable hominoid relatives of humans, Proconsul and Australopithecus, also. Modern types of birds, reptiles, amphibians, fish, and invertebrates were either already numerous at the beginning of the period or appeared early in its history. Modern families of flowering plants evolved. Marine invertebrates and non-mammal marine vertebrates experienced only modest evolution.
[edit] References
- ^ Retallack, G.J. (1997). "Neogene Expansion of the North American Prairie". PALAIOS 12 (4): 380-390. http://links.jstor.org/sici?sici=0883-1351(199708)12%3A4%3C380%3ANEOTNA%3E2.0.CO%3B2-Q. Retrieved on 2008-02-11.
- ^ Zachos, J.C.; Kump, L.R. (2005). "Carbon cycle feedbacks and the initiation of Antarctic glaciation in the earliest Oligocene". Global and Planetary Change 47 (1): 51-66.
- ^ Krijgsman, W.; Garcés, M.; Langereis, C.G.; Daams, R.; Van Dam, J.; Van Der Meulen, A.J.; Agustí, J.; Cabrera, L. (1996). "A new chronology for the middle to late Miocene continental record in Spain". Earth and Planetary Science Letters 142 (3-4): 367-380. http://linkinghub.elsevier.com/retrieve/pii/0012821X96001094. Retrieved on 2008-03-01.
- ^ Carl O. Dunbar, Historical Geology, 2nd ed. (1964), John Wiley & Sons, New York, p. 352
| Paleogene period | ||
|---|---|---|
| Paleocene epoch | Eocene epoch | Oligocene epoch |
| Danian | Selandian Thanetian |
Ypresian | Lutetian Bartonian | Priabonian |
Rupelian | Chattian |
