Download Geologic History

An Old-y but a Goody!
• The Earth is estimated to be 4.5 billion years old.
• Lots of things have happened in that time.
• Divide this time span into pieces based on fossil and isotope
evidence.
• Each section of Earth
history is marked by
key events.
Geologic History
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Unit Essential Question:
How does Earth’s past give clues to its present and future?
Presentation Objectives:
Life begins
Dinosaurs
Mammals
Etc.
§ Differentiate between eons, eras, periods, and epochs.
§ Explain how the geologic time periods are named.
Meet The Eons
• An eon is the longest time unit, which is measured in
billions of years.
• Hadean, Archaean, Proterozoic, Phanerozoic
The Archaean and
Proterozoic are often
grouped together and
referred to as the
Pre-Cambrain.
Meet The Eras
• An era is a subunit of the Phanerozoic, which is
measured in hundreds of millions to billions of years.
• Paleozoic, Mesozoic, and Cenozoic
• -Zoic means life
• Paleo = old
• Meso = middle
• Ceno = recent
Periods of Time
• A period is a subunit of an era, which is measured in tens
of millions to hundreds of millions of years.
Let’s Get A Closer Look!
• Many of these periods were
named after the location
where the rocks of this time
where first found and studied.
Jura Mountains, Europe
Let’s Make A Scale Model!