Eocene

Late EoceneMiddle EoceneEocene EpochEarly EoceneUpper EoceneMiddleGeiseltalianEocene periodlatest Eocenemid-Eocene
The Eocene Epoch, lasting from, is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era.wikipedia
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Paleocene

PalaeoceneLate PaleocenePaleocene epoch
The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch.
The name is a combination of the Ancient Greek palæo- meaning "old" and the Eocene Epoch (which succeeds the Paleocene), translating to "the old part of the Eocene".

Oligocene

Late OligoceneOligocene epochEarly Oligocene
The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch.
The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch.

Eocene–Oligocene extinction event

Grande CoupureEocene-Oligocene Boundaryat about the same time
The end is set at a major extinction event called the Grande Coupure (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay.
The transition between the end of the Eocene (33.9 Ma) and the beginning of the Oligocene is marked by large-scale extinction and floral and faunal turnover (although minor in comparison to the largest mass extinctions).

Chesapeake Bay impact crater

Chesapeake BayChesapeake Bay craterChesapeake Bay Impact Structure
The end is set at a major extinction event called the Grande Coupure (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay.
The Chesapeake Bay impact crater was formed by a bolide that impacted the eastern shore of North America about 35.5 ± 0.3 million years ago, in the late Eocene epoch.

Ypresian

Early EoceneLower EoceneEarly
The Ypresian stage constitutes the lower, the Priabonian stage the upper; and the Lutetian and Bartonian stages are united as the middle Eocene.
In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene.

Priabonian

MP 17HeadonianPriabonian stage
The Ypresian stage constitutes the lower, the Priabonian stage the upper; and the Lutetian and Bartonian stages are united as the middle Eocene.
The Priabonian is, in the ICS's geologic timescale, the latest age or the upper stage of the Eocene epoch or series.

Paleogene

PalaeogenePaleogene PeriodLower Tertiary
The Eocene Epoch, lasting from, is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era.
This period consists of the Paleocene, Eocene, and Oligocene epochs.

Cenozoic

Cenozoic EraCainozoicAge of Mammals
The Eocene Epoch, lasting from, is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era.
The Cenozoic is divided into three periods: the Paleogene, Neogene, and Quaternary; and seven epochs: the Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene.

Geologic time scale

geologic timescalegeologic timeperiod
The Eocene Epoch, lasting from, is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era.

Lutetian

MP 11Lutetian stageMP 13
The Ypresian stage constitutes the lower, the Priabonian stage the upper; and the Lutetian and Bartonian stages are united as the middle Eocene.
The Lutetian is, in the geologic timescale, a stage or age in the Eocene.

Popigai crater

PopigaiPopigai diamondsPopigay crater
The end is set at a major extinction event called the Grande Coupure (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay.
A large bolide impact created the 100 km diameter crater approximately 35 million years ago during the late Eocene epoch (Priabonian stage).

Bartonian

Bartonian ageMP 16Auversian
The Ypresian stage constitutes the lower, the Priabonian stage the upper; and the Lutetian and Bartonian stages are united as the middle Eocene.
The Bartonian is, in the ICS's geologic time scale, a stage or age in the middle Eocene epoch or series.

Azolla event

800,000 years of arctic azolla bloomsa particularly swift reduction
At the beginning of the middle Eocene an event that may have triggered or helped with the draw down of carbon dioxide was the Azolla event at around 49 million years ago.
The Azolla event is a scenario hypothesized to have occurred in the middle Eocene epoch, around, when blooms of the freshwater fern Azolla are thought to have happened in the Arctic Ocean.

Crocodile

crocodilescrocodiliancrocodylid
A few of these proxies include the presence of fossils native to warm climates, such as crocodiles, located in the higher latitudes, the presence in the high latitudes of frost-intolerant flora such as palm trees which cannot survive during sustained freezes, and fossils of snakes found in the tropics that would require much higher average temperatures to sustain them.
They separated from other crocodilians during the Eocene epoch, about 55 million years ago.

Azolla

Azollaceaemosquito fernaquatic ferns
With the equable climate during the early Eocene, warm temperatures in the arctic allowed for the growth of azolla, which is a floating aquatic fern, on the Arctic Ocean.

Antarctic ice sheet

Antarctic ice capAntarcticAntarctica
During this decrease ice began to reappear at the poles, and the Eocene-Oligocene transition is the period of time where the Antarctic ice sheet began to rapidly expand.
The icing of Antarctica began in the middle Eocene about 45.5 million years ago and escalated during the Eocene–Oligocene extinction event about 34 million years ago.

Eocene Thermal Maximum 2

ETM-2Elmo horizonEocene Layer of Mysterious Origin
The hyperthermals in the early Eocene, notably the Palaeocene–Eocene Thermal Maximum (PETM), the Eocene Thermal Maximum 2 (ETM2), and the Eocene Thermal Maximum 3 (ETM3), were analyzed and found that orbital control may have had a role in triggering the ETM2 and ETM3.
It appears to be the second major hyperthermal that punctuated the long-term warming trend from the Late Paleocene through the early Eocene (58 to 50 Ma).

Green River Formation

Green RiverFossil Lake
In western North America, mountain building started in the Eocene, and huge lakes formed in the high flat basins among uplifts, resulting in the deposition of the Green River Formation lagerstätte.
The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes in three basins along the present-day Green River in Colorado, Wyoming, and Utah.

Arctic Ocean

ArcticArctic SeaArctic coast
With the equable climate during the early Eocene, warm temperatures in the arctic allowed for the growth of azolla, which is a floating aquatic fern, on the Arctic Ocean. The end of the PETM was met with a very large sequestration of carbon dioxide into the forms of methane clathrate, coal, and crude oil at the bottom of the Arctic Ocean, that reduced the atmospheric carbon dioxide.
The seafloor began spreading from the Gakkel Ridge in the Paleocene and Eocene, causing the Lomonosov Ridge to move farther from land and subside.

Antarctica

AntarcticAntarctic continentReference Elevation Model of Antarctica
At the beginning of the period, Australia and Antarctica remained connected, and warm equatorial currents mixed with colder Antarctic waters, distributing the heat around the planet and keeping global temperatures high, but when Australia split from the southern continent around 45 Ma, the warm equatorial currents were routed away from Antarctica.
In the Eocene epoch, about 40 Ma Australia-New Guinea separated from Antarctica, so that latitudinal currents could isolate Antarctica from Australia, and the first ice began to appear.

Geological period

periodperiodsgeologic period
As with other geologic periods, the strata that define the start and end of the epoch are well identified, though their exact dates are slightly uncertain.

Even-toed ungulate

artiodactyleven-toed ungulatesCetartiodactyla
These modern mammals, like artiodactyls, perissodactyls and primates, had features like long, thin legs, feet and hands capable of grasping, as well as differentiated teeth adapted for chewing.
The oldest fossils of even-toed ungulates date back to the early Eocene (about 53 million years ago).

Eucalyptus

eucalypteucalyptus treeeucalypts
The earliest definitive Eucalyptus fossils were dated from 51.9 Mya, and were found in the Laguna del Hunco deposit in Chubut province in Argentina.
The fossils are from the early Eocene (51.9 Mya), and were found in the Laguna del Hunco deposit in Chubut province in Argentina.

Antarctic Circumpolar Current

West Wind DriftcircumantarcticAntarctic circumpolar
Another major contribution to the expansion of the ice sheet was the creation of the Antarctic circumpolar current.
Published estimates of the onset of the Antarctic Circumpolar Current vary, but it is commonly considered to have started at the Eocene/Oligocene boundary.

Geology of the Himalaya

Himalayan orogenycollisionGeology of the Himalayas
Another possible atmospheric carbon dioxide increase could be during a sudden increase with metamorphic release during the Himalayan orogeny, however data on the exact timing of metamorphic release of atmospheric carbon dioxide is not well resolved in the data.
An almost complete stratigraphic record ranging from the Upper Proterozoic to the Eocene is preserved within the sediments of the TH.