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

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.