Transcript Geologic Time Scale NOTES

GEOLOGIC
TIME
SCALE
A method for
organizing Earth’s
history
The Earth is 4.6 Billion years old…
That amount of time is hard to
imagine…
With over 30 million seconds in a
year, it would take 150 years to
count 4.6 billion seconds on a
clock!
To count to a billion, it would take 95.1 years
if you count a number every 3 seconds
To walk a billion steps, you would go around
the equator 15.278 times at 2 feet per step
To make a billion dollars, you would need
to make $100 a day for 27,397.26 years
Historical Geology: A Glimpse of the Earth's Past. United Learning. 2002. unitedstreaming. 4 January 2007 <http://www.unitedstreaming.com/>
The Geologic Time Scale
A system of dating Earth’s
history by combining
GEOLOGY with
BIOLOGICAL
EVENTS
The Geologic Time Scale uses :
Relative Time
And
Absolute Time
Pre-Cambrian and Paleozoic Eras. AIMS Multimedia. 1982. unitedstreaming. 4 January 2007 <http://www.unitedstreaming.com/>
distinguished by a feature (ex: Ice Age)
 shorter than epoch
usually lasting a few million to a hundred million
years
•Short time spans
•Subdivisions of the periods
•Created based on ROCK and FOSSIL evidence
•Most common in most recent era-WHY?
‣Based on major geologic disturbances of
Earth’s crust
‣Time when a single rock system was
formed
‣Tens of millions of years
Broad
Hundreds of millions of years
Based on life characteristics;
biologic events
Longest division; many hundreds of
millions of years long
Two or more eras form an Eon
Based upon the presence of visible
life
TLC Elementary School: Prehistoric Earth. Discovery Channel School. 2004. unitedstreaming. 4 January 2007 <http://www.unitedstreaming.com/>
Arranged
chronologically
Oldest events at
the bottom
Most recent
events at the top
NOW…
• Read about your era on the geologic time scale
• Complete the questions you have been assigned
• Work on the timescale activity while you wait
• Teach your era to your group
• Get the notes for the other eras
Life formed from non-living
matter after the Earth cooled.
4.0 Billion years ago, the surface cooled forming
solid crust
H2O vapor condensed & fell as rain
Much CO2, H2, CH3, CO, SO2, and N gas
No oxygen or ozone
Energy from lightning and UV from the sun caused
Chemical reactions formed organic materials
1920’s
A.I. Oparin
Primitive earth had reducing atmosphere
Atmosphere favored production of organic compounds
First organisms were coacervates
Blue-green algae like organisms
1950’s
Miller and Urey
University of Chicago experiment
Same ideas as Oparin used in lab
Darling, David. The Encyclopedia of Astrobiology Astronomy and Space Flight. 31 Januayr 2006http://www.daviddarling.info/encyclopedia/O/Oparin.html>.
• Theory
was tested by
Miller-Urey Experiment
• Scientists
recreated the
conditions of the early Earth to
show how materials of life could
form from non-living materials
Henahan, Sean. From Primordial Soup to the Prebiotic Beach.. Access Excellence. 2002. 16 December 2002<http://ww.accessexcellence.org/WN/NM/miller.html>
This apparatus recreated conditions on a
young
Earth, proving that
complex molecules
could have been created
on early Earth
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85% OF EARTH’S HISTORY!!
MOLTEN EARTH FORMS
SURFACE COOLS
PRIMITIVE ATMOSPHERE
(NO FREE O2 GAS)
• OCEANS FORM
• LIFE BEGAN
• HYDROTHERMAL OCEAN VENTS
• Nutrient rich
• PROKARYOTES (BACTERIA)
• LATER CYANOBACTERIA
(STROMATOLITES)
• Photosynthesis; O2 released
• Ozone created
• THEN, EUKARYOTES AND SOFT BODIED
MULTICELLULAR ORGANISMS
• OCEAN LIFE EXPANDED
• LIFE MOVED TO LAND
• Plants (except flowering)
• Fungi
• Insects
• Reptiles
• MASS EXTINCTION
• Largest ever
• 90% organisms become extinct
• Ocean life completely changes
Numbers of marine species
increased greatly
A relatively short time during
the Paleozoic Era
Diversity of living things increased
dramatically
Most living species have ancestors
from the Cambrian period
Video clip from: Historical Geology: A Glimpse of the Earth's Past. United Learning. 2002. unitedstreaming. 6 January 2006 <http://www.unitedstreaming.com/>
Fossil location in Canadian Rocky
Mountains
Fossils from the “Cambrian Explosion”
Area thought to have been
under water, near the equator
Special because of age & shape of
fossils of ‘soft-bodied’ animals
Video clip from: Greatest Discoveries with Bill Nye: The Origin and Evolution of Life. Discovery Channel School. 2005. unitedstreaming. 6 January 2006
<http://www.unitedstreaming.com/>
Why is the Burgess Shale so
important?
What does the Burgess Shale
provide evidence for?
Video clip from: Greatest Discoveries with Bill Nye: The Origin and Evolution of Life. Discovery Channel School. 2005. unitedstreaming. 6 January 2006
<http://www.unitedstreaming.com/>
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DINOSAURS
MARINE LIZARDS
BIRDS
PLANTS
• Conifers
• Flowers
MASS EXTINCTION
• Dinosaurs
• Many plants and animals
MESOZOIC ERA
TRIASSIC PERIOD (225-180 MYA)
Pangaea (supercontinent) formed
MESOZOIC ERA
JURASSIC PERIOD (180-135 MYA)
Pangaea starts to separate
MESOZOIC ERA
CRETACEOUS PERIOD (135-65 MYA)
Continents in modern positions
MESOZOIC ERA
CRETACEOUS PERIOD (135-65 MYA)
Mass Extinction: 50% of all plant and animal
groups die out
Alvarez’s Meteor Impact Theory- 10 km wide
meteorite hits Earth
HOW COULD A METEORITE IMPACT
CAUSE A MASS EXTINCTION?
• The impact caused shock waves, tidal waves, and sent a
tremendous amount of dust into the atmosphere
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As the dust re-entered the Earth’s atmosphere, it would have
instantly heated the atmosphere causing tremendous forest fires
Dust from impact blocked out the sun and caused major climate
change and plants to die
Plants, animals, etc. went extinct due to the climate changes and
competition between organisms
• MAMMALS
• PRIMATES
HUMANS
• CLIMATE CHANGES
• Ice ages
• Caused migrations and
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•
extinctions
GEOLOGIC CHANGES
• Mountains
• Volcanoes
CIVILIZATION
The Great
Ice Age
A SIXTH MASS EXTINCTION?
• Are we the cause of a sixth mass extinction that is currently taking
place?
• Round Table Discussion