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The Eocene (IPA: / ˈ iː ə s iː n, ˈ iː oʊ-/ EE-ə-seen, EE-oh-[5] [6]) is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era.
Oligocene. Base of magnetic polarity chronozone C6Cn.2n. The Oligocene (IPA: / ˈɒlɪɡəsiːn, - ɡoʊ -/ OL-ə-gə-seen, -goh-) [4] is a geologic epoch of the Paleogene Period that extends from about 33.9 million to 23 million years before the present (33.9 ± 0.1 to 23.03 ± 0.05 Ma). As with other older geologic periods, the rock beds ...
More than 170 million years ago, Antarctica was part of the supercontinent Gondwana. Over time Gondwana broke apart and Antarctica as we know it today was formed around 35 million years ago. Over time Gondwana broke apart and Antarctica as we know it today was formed around 35 million years ago.
The other time was during the Cambrian Period, which ran from 538.8 million years ago to 485.4 million years ago. During the early Eocene, Australia [15] and South America [16] were connected to Antarctica. 53 million years ago during the Eocene Epoch, summer high temperatures in Antarctica were around 25 °C (77 °F). [15]
[14] [15] [16] Significant cooling took place in the final hundreds of thousands of years prior to the start of major Antarctic glaciation. [17] This cooling reached some threshold approximately 34 million years ago, [18] [19] [4] precipitating the formation of a large ice sheet in East Antarctica in response to falling carbon dioxide levels.
The icing of Antarctica began in the Late Palaeocene or middle Eocene between 60 [121] and 45.5 million years ago [122] and escalated during the Eocene–Oligocene extinction event about 34 million years ago. CO 2 levels were then about 760 ppm [123] and had been decreasing from earlier levels in the thousands of ppm.
Antarctica was also part of the ancient supercontinent of Gondwana, which gradually broke up by plate tectonics starting 110 million years ago. The separation of South America from Antarctica 30–35 million years ago allowed the Antarctic Circumpolar Current to form, which isolated Antarctica climatically and caused it to become much colder.
Antarctica provides a unique environment for the study of meteorites: the dry polar desert preserves them well, and meteorites older than a million years have been found. They are relatively easy to find, as the dark stone meteorites stand out in a landscape of ice and snow, and the flow of ice accumulates them in certain areas.