Cenozoic Era
Mammals and the Modern World
Geologic Time Scale
Eon
Cenozoic
65-0 Myr
Era
Period
Quaternary
C
e
n
o
z
o
i
c
P
h
a
n
e
r
o
z
o
i
c
0.01
1.8
Neogene
5.3
23.8
Tertiary
33.6
Paleocene
54.8
65
M
e
s
o
z
o
i
c
Cretaceous
144
Jurassic
Triassic
Permian
P
a
l
e
o
z
o
i
c
Pennsylvanian
Mississippian
Devonian
Silurian
Ordivician
Cambrian
P
r
e
c
a
m
b
r
i
a
n
Age (Myrs)
206
248
290
323
354
417
443
490
543
Proterozoic
2500
Archean
3800
Hadean
Age of the Earth 4600 Myrs (4.6 Byrs)
Source: Geological Society of America (1999)
Epoch
Holocene
Pleistocene
Pliocene
Miocene
Oligocene
Eocene
Paleocene
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 fluctuations
4. Temperature peaks in the Eocene and drops
through the Pliocene/Pleistocene Ice Age.
Highlights of the Cenozoic:
Life
1. 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
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
Causes
Cycles?
Some Effects of
the Ice
Changing
Ecosystems