Cenozoic

Mammals and the Modern World

Era Age (Myrs) Epoch

0.01Holocene

1.8Pleistocene

5.3Pliocene

23.8Miocene

33.6Oligocene

54.8Eocene

65Paleocene

144

206

248

290

323

354

417

443

490

543

2500

3800

Precambrian

Phanerozoic

Eon

Proterozoic

Archean

Hadean

Period

Quaternary

Tertiary

Neogene

Paleocene

Mississippian

Cenozoic

Mesozoic

Paleozoic

Cretaceous

Jurassic

Age of the Earth 4600 Myrs (4.6 Byrs)Source: Geological Society of America (1999)

Geologic Time Scale

Devonian

Silurian

Ordivician

Cambrian

Triassic

Permian

Pennsylvanian

Cenozoic

65-0 Myr

Highlights of the Cenozoic:Geology

1. Continents move into their current configurations. (Western NA remains active.)

2. Tethys Sea closes with the Alpine/Himalayan Orogeny.

3. Minor sea level fluctuations4. Temperature peaks in the Eocene

and drops through the Pliocene/Pleistocene Ice Age.

Highlights of the Cenozoic:

Life1. Mammals and angiosperms

(including grasses) diversify and dominate.

2. Mammals return to the sea.3. Two minor mass extinctions -

Eocene and Pleistocene/Holocene.4. Humans appear in the Pliocene

and by the late Holocene become a “geologic force”.

Cenozoic Geology

Late Cretaceous

Early Eocene

Late Eocene

Early Miocene

Late Miocene

Separation of

Antarctica&

Climate

Alpine/Himalayan Orogeny & the Closing

of the Tethys Sea

The Rise and Fallof the Western US

Subduction to San Andreas

Laramide Orogeny to Basin and Range

Subduction of the

Farallon Plate:

Origin of the San Andreas

Fault and the Gulf of California

Subduction of a

Spreading Ridge

The Laramide Orogeny(Rocky Mountains)

The Basin and Range

The Basin and Range

Curiosities: The Grand Canyon

<5 Myr Old!

Curiosities: Yellowstone

Curiosities: The Olympics

Curiosities:

Chesapeake Bay

Late Eocene

Curiosities: Central America

Central American Land Bridge

Climate - Hot

to Cold

Sea Level

Fluctuations

Transgression Regression

The Pliocene/Pleistocene

Ice Age

The Final

Ice Age

What Causes Ice Ages?

1. Position of the Continents• Changes to Ocean Currents• Closer o Poles

2. Orogenies / Uplift of Land Surface• Changes in air circulation• Increased erosion

3. Changes in Greenhouse Gases

Glacial Cycles within an Ice Age

What Cause

s Cycles?

Some Effects of the Ice

Changing Ecosystems