1. Geological Time Scale

2. Geological Time Scale
Division of Earth’s history into time units based largely on the types of life-forms that lived only during certain periods.

3. Eon
A unit of time equal to a billion years
longest subdivision in the geologic time scale that is based on the abundance of certain types of fossils and is subdivided into eras, periods, and epochs.

4. Era
Second-longest division of geologic time; is subdivided into periods and is based on major worldwide changes in types of fossils.
A division of geologic time , longer than a period and shorter than an eon.

5. Period A division of an Era
Third-longest division of geologic time; is subdivided into epochs and is characterized by the types of life that existed worldwide.

6. Epoch A division of a period
Next-smaller division of geologic time after the period; is characterized by differences in life-forms that may vary regionally.

7. Precambrian - Comprises about 88% of geologic time
Longest part of Earth’s history, lasting from 4.0 billion to about 544 million years ago.
First multicelled organisms
First one-celled organisms
Origin of Earth

8. Paleozoic Periods First jawless fishes Trilobites dominant
Ordovician(490 million years ago)
Cambrian (540 million years ago)
"""Age of Invertebrates"""
First jawless fishes
Trilobites dominant
First organisms with shells

9. Paleozoic
Devonian417 million years ago
Silurian 443 million years ago
"""Age of Fishes"""
First insect fossils
Fishes dominant
"

10. Paleozoic Permian 290 years ago
Carboniferous: Pennyslvanian 323 million years ago
Carboniferous: Mississippian 354 million years ago
"""Age of Amphibians"""
Extinction of trilobites and many other marine animals
First reptiles
"
Large Amphibians abundant.

11. Mesozoic Cretaceous 144 million years ago
Jurassic 206 million years ago
Triassic 248 million years ago
"""Age of Reptiles"""

12. Mesozoic
First flowering plants
First birds
Dinosaurs dominant.

13. Cenozoic
Tertiary Era
Periods
Pliocene 5.3 million years ago
Miocene 23.8 million years ago
Age of Mammals

14. Cenozoic Periods
Oligocene million years ago
Eocene 54.8 million years ago
Paleocene 65 million years ago
Exitintion of Dinosaurs and many other species

15. Cenozoic
Quaternary
Holocene .01 million years ago
Pleistocene 1.8 million years ago
Humans Develop