|Classification of the Cenozoic|
11,700 BP to date
2.588 * to 0.012 mya
5.333 to 2.588 mya
23.03 to 5.333 mya
33.9 to 23.03 mya
56 to 33.9 mya
66 to 56 mya
The Tertiary was a geological age in the rank of a system (or a period ) that comprised the older and much longer section of the Cenozoic (the modern earth period). It began at the end of the Cretaceous 66 million years ago and lasted until the beginning of the Quaternary 2.6 million years ago. The climate on earth was much warmer in the Tertiary than it is today. After the mass extinction of the large dinosaurs and many other animal species at the end of the Cretaceous Period, the animal and plant world as we know it today developed mainly in the Tertiary.
The term tertiary should no longer be used within the official geological time scale . In practice (also in teaching), however, it is often still used. The current convention divides the tertiary into two ages and uses the terms paleogene for the older (66 to 23.03 mya ) and neogene for the younger (23.03 to 2.588 mya).
The climate of the Tertiary differed from that of the Quaternary due to the generally significantly higher global average temperatures. At the beginning of the Eocene , around 50 million years ago, the global temperature rose to the highest values (approx. 30 ° C) in the entire Cenozoic ("early Theocene climatic optimum"). There was a pronounced warm climate and the polar regions were ice-free. In the further course of the Eocene, however, the migration of the continents caused by plate tectonics (" continental drift "), especially the increasing isolation of the continent Antarctica, which drifted into the southern polar region, from the other southern continents (cf. → Gondwana ), the global heat transport (cf. → global conveyor belt ). This led to a cooling of the world climate at the end of the Eocene and from the Oligocene , about 35 million years ago, the glaciation of Antarctica began. In the early Miocene , around 20 million years ago, Antarctica was finally completely covered by an ice sheet. Only a few million years later, the Arctic began to freeze .
About 50 million years ago, the Indian continent collided with Asia, creating the Himalayan mountains and the highlands of Tibet . In addition, the formation or the main phases of formation of the Alps , the Apennines , the Carpathians , the Pyrenees and the Caucasus in Europe and the Andes in the South and the Rocky Mountains in North America took place in the Tertiary . The mountain formation in Eurasia went hand in hand with the extensive closure of the Tethys Ocean . The central areas of the Eastern Mediterranean and the Black Sea are small remnants of this former ocean basin.
The continental drift slowed down significantly in the Tertiary. The former Gondwana fell apart. Australia , which was then bound to the Antarctic , migrated northwards. In between, a deep oceanic rift formed. Land bridges existed between North America and Europe or between North America and Asia . Towards the end of the Tertiary, South America and North America merged into today's form.
fauna and Flora
The Tertiary is the time span between the mass extinction at the end of the Cretaceous Period , which also affected the great dinosaurs , and the beginning of the most recent Ice Age . The extinction could be the result of a meteorite impact , the so-called KT impact (Cretaceous Tertiary impact). At the beginning of the period, mammals replaced the reptiles as the dominant group of animals . Each epoch of the tertiary is characterized by characteristic leaps in development among mammals. Man's earliest recognizable ancestors, the hominoids Proconsul and Australopithecus , evolved. The modern forms of birds , reptiles, amphibians , fish and invertebrates were partly already formed at the beginning of the Tertiary or developed in its course. The marine animals, on the other hand - apart from the mammals - only underwent minor evolutionary changes. In the final phase of the Tertiary, the Pliocene, the beech population characteristic of the original Central and Western European forests already existed.
Terminology and nomenclature
The term tertiary comes from historical geology , i.e. the description of the history of the earth , and was introduced by Giovanni Arduino in 1760 . On the basis of his observations of geological strata in northern Italy, he distinguished between a primary ( basalt , granite , slate ), secondary (fossil calcareous deposits) and tertiary (more recent sedimentary deposits) epoch. Although Arduino originally only used this three-way division to mark different rock formations, the system was soon also used as a temporal grid. In 1828 Charles Lyell adopted this designation in his own, much more precise system. He subdivided the Tertiary based on the percentage of fossil mussel shell finds in the respective layers into Eocene, Miocene, older and younger Pliocene. Since this method was only suitable for the examined region of the Alps and the northern Italian plain, numerous other stratigraphic categories have been introduced in the period that followed.
The tertiary was deleted from the internationally valid geological time scale published by the International Commission for Stratigraphy in 2000 . In its place came the Paleogene (formerly: Old Tertiary) and the Neogene (formerly: Young Tertiary ) as periods in the Cenozoic (Earth Modern Age).