1. The Geologic Time Scale

2. Part 1

3. The Geologic Time Scale

4. The Geologic Time Scale
The Geologic Time Scale is a system of chronological measurement that relates stratigraphy to time. Stratigraphy is a branch of geology which studies rock layers and layering (stratification.) It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy includes two related subfields: lithologic stratigraphy or lithostratigraphy, and biologic stratigraphy or biostratigraphy, and is used by geologists, paleontologists, and other earth scientists to describe the timing and relationships between events that have occurred throughout Earth's history.

5. The Geologic Time Scale
This scale divides geologic history into units, with the following subdivisions:
Eons are the greatest expanse of time. There are three (or four) eons:
Hadean - the first eon
Precambrian - further subdivided into the Achaean and Proterozoic eons
Phanerozoic - the most recent and current eon
Eras are subdivisions of an eon. For example, the eras of the Phanerozoic eon are:
the Cenozoic (“recent life”)
the Mesozoic (“middle life”)
the Paleozoic (“ancient life”)
Eras are further subdivided into periods.
Periods are further subdivided into epochs.

6. The Geologic Time Scale
Eon Eras Periods Epochs

7. The Geologic Time Scale

10. The Geologic Time Scale
Geologic time is divided into two eons, but one of these is divided into sub-eons.
the Precambrian (ancient) Eon
the Achaean Sub-Eon
the Proterozoic Sub-Eon
the Phanerozoic (current) Eon

11. The Geologic Time Scale
In this two eon-system, the Precambrian Eon can be said to have began with the creation of the Earth about 4.5 billion years ago and ended about 542 million years ago.
The Achaean Sub-Eon began with the creation of the Earth and ended about 2.5 billion years ago.
The Proterozoic Sub-Eon began about 2.5 billion years ago and ended about 542 million years ago.
The Phanerozoic Eon began about 542 million years ago and continues to the present day.

12. The Geologic Time Scale
Eons are further divided into Eras.
Archean Eon
Eoarchean Era
Paleoarchean Era
Mesoarchean Era
Neoarchean Era
Proterozoic Eon
Paleoproterozoic Era
Mesoproterozoic Era
Neoproterozoic Era
Phanerozoic Eon
Paleozoic Era
Mesozoic Era
Cenozoic Era

13. The Geologic Time Scale
The Phanerozoic Eon is further divided into Periods.
Phanerozoic Eon
Paleozoic Era
Cambrian Period
Ordovician Period
Silurian Period
Devonian Period
Carboniferous Mississippian Period
Carboniferous Pennsylvanian Period
Permian Period
Mesozoic Era
Triassic Period
Jurassic Period
Cretaceous Period
Cenozoic Era
Tertiary Period
Quaternary Period

14. The Geologic Time Scale
The Cenozoic Era is further divided into Epochs.
Cenozoic Era
Tertiary Period
Paleocene Epoch
Eocene Epoch
Oligocene Epoch
Miocene Epoch
Pliocene Epoch
Quaternary Period
Pleistocene Epoch
Holocene Epoch

15. LAB

16. Lab- The Geologic Time Scale

17. The Geologic Time Scale
Figure 11.19
The Geologic Time Scale