Cycles during the Pliocene
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.
Life in the Pliocene |
Tectonics during the Pliocene
Climate Cycles during the Pliocene
Department of Paleobiology Home |
National Museum of Natural History Home
Smithsonian Institution Home