bbc.co.uk navigation

A London Clay landscape during the Eocene period

Eocene epoch

The Eocene began as a time of global warming, with temperatures across the planet soaring. Forests thrived and trees grew even in polar regions. Eventually, the Eocene became cooler and drier. As India continued to drift northwards, pushing against the Eurasian continent, the mass of rocks thrust up between them formed the Himalayas. At this time Africa was an island, not yet joined to the Middle East and Europe, but its own journey north was to trigger the formation of the Alps. Many species of grass evolved in the Eocene epoch, but were very limited in extent - today's grassy plains were still far in the future.

Began: 54.8 million years ago

Ended: 33.7 million years ago

What the Earth was like

A map of the Earth in the Eocene Epoch

Reconstruction of the Earth in the Eocene epoch, 54.8 million - 33.7 million years ago. Credit: Dr Ron Blakey, NAU Geology.

Causes of extinctions

During this period the following extinction level events are thought to have occurred.

Flood basalt eruptions Flood basalt eruptions
Flood basalt eruptions are a type of large-scale volcanic activity, both in terms of extent and duration, that can occur on land or on the ocean floor. A flood basalt may continue to erupt for tens of thousands - possibly millions - of years and the lava can cover hundreds of thousands of kilometres.
Impact events Impact events
Impact events, proposed as causes of mass extinction, are when the planet is struck by a comet or meteor large enough to create a huge shockwave felt around the globe. Widespread dust and debris rain down, disrupting the climate and causing extinction on a global, rather than local, scale.

Types of fossils formed in this period

About

The Eocene (symbol Eo ) epoch, lasting from 56 to 33.9 million years ago, is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. 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. 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.

The name Eocene comes from the Greek ἠώς (eos, dawn) and καινός (kainos, new) and refers to the "dawn" of modern ('new') fauna that appeared during the epoch.

Read more at Wikipedia

This entry is from Wikipedia, the user-contributed encyclopedia. If you find the content in the 'About' section factually incorrect, defamatory or highly offensive you can edit this article at Wikipedia. For more information on our use of Wikipedia please read our FAQ.

Geological time

  1. Origin of the Earth 4.6 billion years ago
  2. Archean era
  3. Cryogenian period
  4. Ediacaran period
  5. Cambrian period
  6. Ordovician period
  7. Silurian period
  8. Devonian period
  9. Carboniferous period
  10. Permian period
  11. Triassic period
  12. Jurassic period
  13. Cretaceous period
  14. Palaeocene epoch
  15. Eocene epoch
  16. Oligocene epoch
  17. Miocene epoch
  18. Pliocene epoch
  19. Pleistocene epoch
  20. Holocene epoch
  21. Present day

BBC News about Eocene epoch

  • Ancient giant penguin unearthed Scientists unearth a fossil in Peru of a giant penguin that lived some 36 million years ago, offering an insight into the birds' evolution.

BBC © 2013 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.