1. Summer 2006 Workshop
in Biology and Multimedia
for High School Teachers

2. Earth History - The Geologic Time Scale
Laurie St.Pierre
Sandwich High School
Sandwich, MA

3. The Age of the Earth 4.6 billion years old = 4,600,000,000
Image courtesy of NASA,

4. The earth’s 4.6 billion year history is divided into major units of time:
Precambrian Time
Paleozoic Era
Mesozoic Era
Cenozoic Era
Image created by Jason Brechko for Lake George Association (Lake George, NY)

5. Precambrian Time
4.6 billion years before present to 544 million years before present
Longest era with a sparse fossil record
Origin of earth’s crust, first atmosphere, and first seas
Earliest fossils of cyanobacteria use photosynthesis to produce oxygen
Ozone layer in the atmosphere is formed from oxygen
Image courtesy of
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

6. Paleozoic era
544 million years before present to 245 million years before present
Marine communities flourish
Early fishes develop
Origin of amphibians, insects & reptiles
Recurring ice ages/ Appalachians mountains form
Spore-bearing plants dominate
Images courtesy of:
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

7. Paleozoic era (continued)…
million years before present: Supercontinent of Pangea forms
248 million years before present: MASS EXTINCTION-90 % of all known families lost! c
Image courtesy of
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

8. Image courtesy of http://nascarulz.tripod.com/dinomain.html
Mesozoic Era
245 million years before present million years before present
The age of the dinosaurs!
Gymnosperms dominate land plant/ origin of angiosperms - flowering plants
Origin of mammals & birds
145 million years before present - asteroid impact? MASS EXTINCTION
Pangea begins to separate/ Rocky mountains form
Image courtesy of
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

9. 65 million years before present….
ASTEROID IMPACT!
Mass extinction of ALL dinosaurs and many marine organisms
End of the Mesozoic era
Image courtesy of NASA:
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

10. Image courtesy of: http://www.karencarr.com/gallery_Cenozoic_arch.html
Cenozoic Era
65 million years before present - today
Present era we live in
Continued evolution and adaptations of flowering plants, insects, birds, mammals
Mammals dominant
Major crustal movements & mountain building (Alps & Himalayan mountains form)
Image courtesy of:
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

11. And during the Cenozoic era…
The most primitive hominid (human ancestor) evolves - approximately 4.4million years before present
The first modern humans (homo sapiens) evolved approximately 100,000 years before present
Image courtesy of: