Part A
The Proterozoic Eon
The Proterozoic is the single longest eon in Earth's geologic history. Plate tectonic processes (like plate subduction) were active during this time, helping continental masses develop and grow. For most of the Proterozoic, life on Earth was still very primitive, represented largely by single-celled cyanobacteria. This would change by the end of the Proterozoic, with the evolution of more complex multi-cellular life.
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Figure 9-2. The International Commission on Stratigraphy (ICS) defines the global units of the International Chronostratigraphic Chart that are the basis for the International Geological Time Scale. The official ICS geologic time scale used worldwide (left) and its Proterozoic section (right). |
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Proterozoic Geologic Time
Let's get started by look at a diagram representing Earth's entire history.
A simplified geologic time scale constructed from the 2019/05 ICS time scale is shown in Figure 9-3. It is not drawn to scale as its focus is including all of the Periods of the Phanerozoic Eon and all of the Epochs of the Cenozoic Era.
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Figure 9-3. A simplified geologic time chart compiled from the 2020/03 ICS version. |
* IMPORTANT *
Using the PDF link above, print a hard-copy version of this chart for use in this lab.
Refer to the simplified geologic time chart in Figure 9-3 to answer Quiz Me! questions A02 through A04.