The world, Oligocene, 35 Ma, Global Paleogeographic Views of Earth History, NAU
The world, Oligocene, 30 Ma, Paleogeography Through Geologic Time, NAU
North America, Oligocene, 25 Ma, Paleogeography and Geologic Evolution of North America, NAU
North America, Oligocene, 27 Ma, Regional Paleogeographic Views of Earth History, NAU
Southwestern U.S., Oligocene, 35-30 Ma, Geologic History of Western US, NAU (second map)
Oligocene, Palæos
Oligocene, Wikipedia
The Oligocene Epoch, University of California Museum of Paleontology
Geologic Time Table, Seafriends
See general sources above.
Oligocene, ~ 30 Ma, PALEOMAP project
Oligocene Epoch: Life, University of California Museum of Paleontology
Oligocene Flora, Fauna, Wikipedia
Oligocene Life category, Wikipedia
Terrestrial Life during the Oligocene, and Marine Life in the Oligocene, Smithsonsian National Museum of Natural History
A Collection of Eocene and Oligocene Fossils, Alan Morton
Global temperatures decrease by several degrees during the Oligocene. Glaciers cover Antarctica. Temperatures were generally decreasing from the early Eocene (about 50 Ma) until the last ice age, but the Oligocene featured a sharp drop in temperature that lasted 7 million years. This was followed by a sharp increase and the deglaciation of Antarctica. Global temperature during the Oligocene was still warmer than the present, however.
India and Africa continue to move north and lift all the mountain ranges of north Africa, Europe, the Middle East, and central Asia as part of the Alpine orogeny. The formerly large Tethys Ocean becomes the Mediterranean Sea as Africa closes in on Europe.
La Garita Caldera major volcanic eruption period. La Garita supervolcano, in southwestern Colorado, created the largest explosive event known. It released 5000 cubic kilometers of tephra (ash, cinders, and volcanic bombs).
Volcanism occurs in San Diego County at Mount Calavera (Carlsbad), and Morro Hill (Oceanside).
Climate changes due to rapid cooling, changing ocean currents, and the formation of polar ice sheets cause marine life to migrate toward the equator. Many marine species die out, and a minor extinction period occurs on land as well. A turnover occurs in mammals where many early types become extinct to be replaced by more modern mammals, including carnivores.
Apes first appear late in the Oligocene or in the Miocene. Parapithecus, found in Oligocene sediments of the Fayyum Oasis (Egypt), seems to be one of the earliest apes discovered so far. Other ape-like primates from the same area of Egypt include Propliopithecus and Aegyptopithecus. Kamoyapithecus was an early East African ape found in Kenya.
Paraceratherium, an Oligocene rhinocerous-like mammal, was the largest land mammal to ever live. It was over 5 meters tall at the shoulder and 8 meters in length.
© 2009, Mr. Varner.
