Page 385 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

Chapter 12 The Dynamic Planet 349
Percentage of Earth’s history
11.7%
Present major extinctions
Eon
Earth’s history
Last 570 million years
Era
Millions of years ago
Era
Period
Epoch
Millions of years ago
CENOZOIC
•1st humans
•1st large mammals
QUATERNARY
MESOZOIC
Pleistocene
Neogene
•1st
hominids TERTIARY
Pliocene
Miocene
PALEOZOIC
Paleogene •1st grasses •Himalayan orog
Holocene
Oligocene
eny Eocene
•Earth’s modern atmosphere evolves
Late
•Major extinctions (65 m.y.a.)
•Laramide orogeny •Nevadan orogeny
CRETACEOUS
•Atlantic basin rifting •Dinosaurs at maximum •Flowering plants
Paleocene
Middle
JURASSIC
•1st birds and mammals
Early
•Major extinctions (210 m.y.a.)
TRIASSIC
•Pangaea forms
•Beginning of age of dinosaurs
•Major extinctions (250 m.y.a.) (largest) PERMIAN
•Alleghany orogeny
88.3%
65.5 251
542 900
1600
2500
3000
3400
3800 4100
4600 Holocene Epoch
88.3% Precambrian Eon
0.01 2.6 5.3 23.0 33.9 55.8 65.5
145.5
200 251
299 323
359.2
416 443.7
488.3
542
Late
PENNSYLVANIAN
•1st reptiles
Middle
•The living atmosphere
•1st photosynthesis– cyanobacteria
Early
•1st chemosynthesis–
bacteria microfossils
•The evolutionary atmosphere
•Oldest known Earth rock (4000)
•Oldest known Moon rock
MISSISSIPPIAN
•1st winged insects
•Major extinctions (370 m.y.a.)
DEVONIAN
•1st trees; amphibians
SILURIAN
•1st land plants; insects
•Major extinctions (440 m.y.a.)
ORDOVICIAN
CAMBRIAN
•1st fish and shellfish
11.7% Phanerozoic
1.4% Cenozoic Era 4.0% Mesozoic
Era
Eon 6.3% Paleozoic
Era
PRECAMBRIAN
▲Figure 12.1 Geologic time scale, showing highlights of earth’s history. Dates appear in m.y.a. (millions of years ago). The scale uses currently accepted names of time intervals, except for the Hadean Eon, which, while not an official designation, is the proposed name for the period before the Archean. The six major extinctions or depletions of life forms are shown in red. In the column to the left, note that the Precambrian Eon spans 88.3% of geologic time. [Data from geological Society of America and Nature 429 (May 13, 2004): 124–125.]
Animation
Applying Relative Dating Principles
Hadean Eon
PHANEROZOIC
ARCHEAN
PROTEROZOIC
PALEOZOIC
MESOZOIC
Carboniferous
PRECAMBRIAN
11.7%
5.4%
CENOZOIC
1.4%