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| This epoch is part of the Tertiary period and the Paleogene subperiod. |
| Pliocene |
| Miocene |
| Oligocene |
| Eocene |
| Paleocene |
The Eocene epoch (55-37 mya) is a major division of the geologic timescale and the second epoch of the Tertiary period in the Cenozoic era. The Eocene spans the time from the end of the Paleocene epoch to the beginning of the Oligocene epoch. The start of the Eocene is marked by the emergence of the first modern mammals. The end is set at a major extinction event that may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake BayThe Chesapeake Bay is the largest estuary in the United States. It lies off the Atlantic Ocean, surrounded by Virginia and Maryland. The Chesapeake Bay's watershed covers 64,000 milesē (165,760 kmē) in the District of Columbia and parts of six states: New. Still, as with other other geologic periodIn geology, a period or age is a time span of many millions of years that are assumed to have had similar characteristics. See geologic timescale for a list of geologic Periods and Ages. In general, the duration of Periods/Ages tends to get longer the furs, the strataInterstate road cutthrough limestone and shale strataeastern Tennessee In geology and related fields, a stratum (plural: strata is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers. Each layer that define the start and end of the epoch are well identified, but their exact dates are slightly uncertain.
The name Eocene refers to the "dawn" of modern ('new') mammalian fauna that appeared during the epoch.
The Eocene is usually broken into lower and upper subdivisions. The Faunal stages from youngest to oldest are:
Marking the start of the Eocene, the planet heated up in one of the most rapid (in geologic terms) and extreme global warming events recorded in geologic history, called the Paleocene-Eocene Thermal MaximumThe end of the Paleocene (55. 8 Ma) was marked by one of the most significant periods of global change during the Cenozoic, a sudden global change, the Paleocene-Eocene Thermal Maximum which upset oceanic and atmospheric circulation and led to the extinct or Initial Eocene Thermal Maximum (PETM or IETM). This was an episode of rapid and intense warming (up to 7°C at high latitudes) that lasted less than 100,000 years [1]. The Thermal Maximum provoked a sharp extinction event that distinguishes Eocene faunaFauna is a collective term for animal life, as distinct from Flora (plant life) Fauna is an ancient Roman goddess. from the ecosystems of the Paleocene.
Climates remained warm through the rest of the Eocene, although slow global cooling, which eventually led to the Pleistocene glaciations, started around the end of epoch as ocean currents around Antarctica cooled.During the Eocene, the continents continued to drift toward their present positions.
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 world and keeping global temperatures high. But when Australia split from the southern continent around 45 mya, the warm equatorial currents were deflected away from Antarctica, and an isolated cold water channel developed between the two continents. The Antarctic region cooled down, and the ocean surrounding Antarctica began to freeze, sending cold water and icefloes north, reinforcing the cooling.
The norhern supercontinent of Laurasia began to break up, as Europe, Greenland and North America drifted apart.
In western North America, mountain building started in the Eocene, and huge lakes formed in the high flat basins among uplifts.
Europe saw the Tethys Sea finally vanish, while the uplift of the Alps isolated its final remnant, the Mediterranean, and created another shallow sea with island archipelagos to the north. Though the North Atlantic was opening, a land connection appears to have remained between North America and Europe as the faunas of the two regions are very similar.
India continued its journey away from Africa, and began its collision with Asia, folding the Himalayas into existence.| Politics | Business | Finance |
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