Smithsonian National Museum of Natural History Geologic Time The Story of a Changing Earth
Presented by the Department of Paleobiology.
The Pliocene
Life in the Pliocene
Tectonics during the Pliocene
Climate Cycles during the Pliocene
Ostracode, a member of a group of crustaceans
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Climate Cycles during the Pliocene
Current research on Earth's orbital motions has resulted in detailed correlation of the sedimentary layers that were deposited in cycles during this time. These cycles are obvious in some rock strata and turn out to accurately record climate fluctuations caused by the orbital variations of the Earth. For example, paleoclimate research has shown that there was a warming phase at middle and high latitudes during the middle Pliocene (between 3.15 and 2.85 million years ago), accompanied by relatively stable tropical temperatures. This information is based on analysis of microfossils from deep-ocean cores, which give estimates of ancient sea surface temperatures. These can be used along with pollen samples from cores taken on land.

Changes in the ocean circulation patterns, along with the heat the oceans transport, accompanied the reconnection of South and North America and may have contributed to the middle Pliocene warm phase. Finally, in the late Pliocene, episodic climatic fluctuations continued along with a cooling trend. This represented the start of the Northern Hemisphere glaciation cycles that continued into the Pleistocene. An ice cap began to form in the north, although woody plants persisted even on the north shore of Greenland in some areas during the Pliocene.


Overview | Life in the Pliocene | Tectonics during the Pliocene
Climate Cycles during the Pliocene

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