Transcript Earth History - Life Sciences Outreach at Harvard

Summer 2006 Workshop
in Biology and Multimedia
for High School Teachers
Earth History The Geologic
Time Scale
Laurie St.Pierre
Sandwich High School
Sandwich, MA
The Age of the Earth
4.6 billion years old
=
4,600,000,000
Image courtesy of NASA, http://en.wikipedia.org/wiki/Image:The_Earth_seen_from_Apollo_17.jpg#file
The earth’s 4.6 billion
year history is divided
into major units of time:
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Precambrian Time
Paleozoic Era
Mesozoic Era
Cenozoic Era
Image created by Jason Brechko for Lake George Association (Lake George, NY)
http://www.lakegeorgeassociation.org/geology_facts.htm
Precambrian
Time
• 4.6 billion years before present to
544 million years before present
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•
•
•
Longest era with a sparse fossil
record
Origin of earth’s crust, first
atmosphere, and first seas
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Earliest fossils of cyanobacteria
use photosynthesis to produce
oxygen
Ozone layer in the atmosphere is
formed from oxygen
Image courtesy of http://www.sharkbay.wa.gov.au/tourism/what_to_see_and_do/images/stromatolites_lge.jpg
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
•
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: http://discover.edventures.com/images/termlib/p/paleozoic/support.gif,
http://en.wikipedia.org/wiki/Trilobites
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
Paleozoic era
(continued)…
•
286 - 248 million years
before present:
Supercontinent of Pangea
forms
c
•
248 million years before
present: MASS
EXTINCTION-90 % of all
known families lost!
Image courtesy of http://www.ig.utexas.edu/research/projects/plates/teaching_ideas.htm?PHPSESSID=def1b9
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
•
•
•
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Mesozoic Era
245 million years before present 65 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 http://nascarulz.tripod.com/dinomain.html
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
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: http://www.nasaexplores.com/show2_912a.php?id=01-074&gl=912
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
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: http://www.karencarr.com/gallery_Cenozoic_arch.html
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
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: http://www.wilderdom.com/images/evolution/8.jpg