Smithsonian National Museum of Natural History Geologic Time The Story of a Changing Earth
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The Pliocene
Life in the Pliocene
Tectonics during the Pliocene
Climate Cycles during the Pliocene
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Tectonics during the Pliocene
The Pliocene began with the catastrophic origin of the Mediterranean Sea. The Mediterranean Basin had been dry since the Miocene, replaced by grasslands. However, at the beginning of the Pliocene it was reflooded when a tectonic barrier near the Straits of Gibraltar was breached, allowing water from the Atlantic Ocean to pour into the basin, probably catastrophically. North and South America were connected 3.4 million years ago by the formation of the Panamanian Isthmus, due to the eastward movement of the Caribbean plate. This closed the Balboa Portal between the Atlantic and Pacific Oceans, creating significant changes in the marine environment by separating these two oceans.

The continents were in nearly their present-day positions by the Pliocene. The Indian plate continued to move northward under the Asian plate, further elevating the Himalaya Mountains. Other areas of mountain-building around the old Tethys Ocean involved the Caucasus region in Asia, which also generated large orographic changes in climate due to the rain-shadow effect. In North America, the Cascades, Rockies, and Appalachian Mountains experienced continued or renewed uplift, along with the Colorado Plateau. The Sierra Nevada and Alaskan Ranges were forming as well. Mountain-building was also taking place in Europe, including the Alps. All these orogenies affected global climate and worked with astronomically controlled climate cycles to create cooler and more unstable conditions relative to the Miocene.


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

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