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| Tertiary period | |
|---|---|
| Name | Tertiary Period |
| Color | #ffcc99 |
| Time start | 66 |
| Time end | 2.58 |
| Time unit | million years ago |
| Caption | Generalized timeline showing major events attributed to the Tertiary |
Tertiary period The Tertiary period is a historical term for the early Cenozoic interval spanning from the end of the Cretaceous mass extinction to the onset of the Quaternary. Originally used in 18th–19th century stratigraphy by figures such as Charles Lyell and Gottfried Wilhelm Leibniz-era collectors, the label became entrenched in works by institutions like the Geological Society of London and textbooks by authors associated with the British Museum (Natural History), before formal chronostratigraphic terminology evolved under bodies such as the International Commission on Stratigraphy.
Historically, the term was popularized in the 19th century by John Phillips and William Smith as part of a fourfold scheme alongside the Primary, Secondary, and Quaternary; early adopters included the Royal Society and contributors to the Encyclopædia Britannica. Nineteenth- and early twentieth-century maps from the United States Geological Survey and publications by the British Geological Survey used "Tertiary" to group strata now assigned to epochs defined in later work by the International Union of Geological Sciences and the International Commission on Stratigraphy. Debates among stratigraphers such as Charles Lyell, Adam Sedgwick, and later Albert Einstein-era scientific correspondents influenced adoption and eventual replacement of the term in formal nomenclature.
In classical usage the Tertiary encompassed multiple epochs later formalized as the Paleocene, Eocene, Oligocene, Miocene, and Pliocene; these units were refined through biostratigraphic work by researchers associated with institutions like the Natural History Museum, London and the Smithsonian Institution. Global stage names such as the Thanetian, Ypresian, Priabonian, Chattian, Aquitanian, and Zanclean were integrated into chronologies produced by the International Commission on Stratigraphy and correlated with regional scales like the European Land Mammal Ages and the North American Land Mammal Ages. Radiometric tie points using techniques developed by laboratories at California Institute of Technology and Massachusetts Institute of Technology and magnetostratigraphy correlated with records from the Ocean Drilling Program refined boundaries and allowed reassignment of intervals into the Paleogene and Neogene systems.
During the Tertiary interval the continental configuration evolved under models advanced by proponents of plate tectonics such as Alfred Wegener-inspired researchers at the Scripps Institution of Oceanography and the Lamont–Doherty Earth Observatory. Major events included continued northward drift of fragments like the Indian Plate and collision with the Eurasian Plate producing uplift of the Himalayas and altering monsoon patterns studied by teams from Columbia University. The opening of the North Atlantic Ocean and widening of basins such as the Bay of Bengal and Gulf of Mexico followed seafloor spreading documented by marine expeditions including the Deep Sea Drilling Project. Regional tectonics produced mountain building in the Andes, changes in the Mediterranean Sea connections, and the formation of corridors like the Bering Land Bridge that influenced faunal exchange documented by researchers from the American Museum of Natural History.
Tertiary climates featured marked shifts from early warm intervals such as the Paleocene–Eocene Thermal Maximum—investigated by teams at Lamont–Doherty Earth Observatory and ETH Zurich—to cooler, more seasonal conditions culminating in establishment of ice sheets on high latitudes analyzed in studies from University of Cambridge. Atmospheric carbon dioxide reconstructions by laboratories at University of Oxford and Woods Hole Oceanographic Institution track greenhouse declines, while proxy records from sites cored by the Integrated Ocean Drilling Program show changes in ocean circulation, the development of the Antarctic Circumpolar Current linked to the opening of the Drake Passage, and regional transitions from tropical forests to grasslands examined in work by University of California, Berkeley and University of Michigan paleoecologists.
Faunal and floral turnovers during the Tertiary include radiation of mammals (e.g., Perissodactyla, Artiodactyla, Primates), diversification of birds documented by fossils in collections at the Natural History Museum, London and the Field Museum, and expansion of angiosperm-dominated floras studied by paleobotanists at the Royal Botanic Gardens, Kew. Key evolutionary events include origins of modern groups like cetaceans traced through sequences found near Wadi Al-Hitan and research by teams from Yale University and Harvard University, and the rise of grazing-adapted mammals with tooth morphologies analyzed in museums such as the Smithsonian Institution National Museum of Natural History. Localized extinctions and turnover events correlate with isotope excursions identified by researchers at University of California, Santa Cruz and shifts in ocean chemistry recorded by the Integrated Ocean Drilling Program.
Tertiary strata host economically important resources; Tertiary petroleum systems were documented in basins explored by companies like Chevron and ExxonMobil and studied at universities such as Texas A&M University, while coal deposits of Tertiary age fueled industrial growth in regions cataloged by the United States Bureau of Mines and the British Geological Survey. Phosphate and evaporite deposits associated with Tertiary basins have been exploited by firms including Rio Tinto Group and informed by regional surveys from the United Nations programs. Paleontological discoveries from Tertiary localities—fossil mammals from La Brea Tar Pits, primate fossils from sites investigated by teams from University of California, Berkeley and Stony Brook University, and marine vertebrates curated at the Natural History Museum of Los Angeles County—have been pivotal for museums, academic collections, and public exhibits.
The term's legacy persists in historical literature, museum labels, and regional practice even as formal stratigraphy adopted the Paleogene and Neogene divisions through resolutions of the International Commission on Stratigraphy and publications from the International Union of Geological Sciences. Contemporary geological syntheses by authors affiliated with institutions such as the Geological Society of America, American Geophysical Union, and major university presses use the updated framework while noting the historical utility of the Tertiary in classical mapping and monographs produced by entities like the British Geological Survey and the United States Geological Survey.
Category:Geological periods