GEOL 102 Historical Geology

Spring Semester 2011
The Cenozoic Era I: Paleogene Geology

Phanerozoic Eon: 542 - 0 Ma

Although stratigraphers agree upon the names and dates of the Epochs of the Cenozoic, there has historically been considerable disagreement on the Periods of the Cenozoic:

This is the version shown in the graphic above. The "Quaternary" is formally reinstated as a "Period" that contained the Holocene and Pleistocene (and the latter has absorbed what was formerly the last stage of the Pliocene!) This follows an unsuccessful bid to create a "Quaternary Sub-Era". The "Tertiary" thus remains in limbo.

Cenozoic is by FAR the best known Era, representing only 1.4 % of Earth History, yet the most commonly encountered rocks on the Earth's surface and on the sea floor.

Paleogeography and Geology of the Paleogene:
Paleocene-Eocene: continuation of Laramide Orogeny in Cordillera (began in Maastrichtian, Late Cretaceous). Uplifted blocks and down-dropped basins in central west (Utah, Colorado, etc.): very large lake deposits of oil shales. Beginning of Yellowstone volcanism (a mantle plume underneath the American West)

Last epicontinental sea of North America (Cannonball Sea) in Paleocene: interior of continent has been fully emergent since then.

Paleocene-Eocene climates very warm, comparable to Cretaceous.

The Paleocene-Eocene Thermal Maximum:

Dramatic temperature drop during late Eocene:

Late Eocene/Early Oligocene: rifting of Atlantic separates Laurentia from Europe and Greenland from North America (end of Laurentia proper). Asia and North America remain physically connected by Bering Land Bridge (periodically emergent or submergent)

During Late Eocene: Chesapeake Bay impact:

Starting in the Eocene, and continuing into the Miocene, the Alpine Orogeny:

Late Oligocene: as Laramide Orogeny ends, extensive erosion of upper surfaces of Cordilleran Mountains and infilling of intramontane basins.

Throughout late Paleogene: Andean Orogeny (actually begins in Late K and continues to today) and earliest stages of Himalayan Orogeny.

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Last modified: 14 January 2011