The Geologic Time Scale

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The Geologic Time Scale
Geologic Time Scale
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Geologic Time Scale
Geologic Time Scale Subdivisions of Earth's
history by pure Time and by Rocks
deposited during an interval of time
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Geologic Time Scale
Divisions Eons (largest) Phanerozoic ---
--- shelly fossils 542 my Proterozoic ---
--- modern tectonics 2.5 by Archean ------
oldest rocks 4.0 by Hadean
------ origin of Earth 4.6 by
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Geologic Time Scale
Precambrian is an informal term for
everything prior to the Cambrian
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Geologic Time Scale
Divisions Eras only Phanerozoic
subdivided based on appearance of fossils
bounded by mass extinctions
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Geologic Time Scale
Divisions Eras (largest) Cenozoic - new
life Mesozoic - middle life Paleozoic - ancient
life
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Geologic Time Scale
Periods (fundamental unit) Geologic
column originally divided as Time-Rock
units.
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Geologic Time Scale
Periods (fundamental unit) Geologic Time
units bear the names of their corresponding
Time-Rock units.
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Geologic Time Scale
Time Scale was developed piece-meal Units
were recognized locally Bounded by regional
unconformities Based on fossil assemblages
Named for local geography (tribes)
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Geologic Time Scale
19th C Naturalists Characterized their own rocks
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Geologic Time Scale
Allegheny
19th C Naturalists Characterized their own rocks
Catawbian
Wataugan
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Geologic Time Scale
Type section where the unit was
originally defined. Independent workers
Around Europe 19th Century
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Geologic Time Scale
Ordovician
Type sections
Cambrian
Silurian
Devonian
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Geologic Time Scale
Time scale assembled by
Principle of Superposition Principle of
Fossil Succession Correlation
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Geologic Time Scale
Characteristics of the Time Scale There is
not a single, complete section anywhere!
Scale was originally all relative. Absolute
time was added later.
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Geologic Time Scale
Same principles applied for Epochs Ages
Biologic component more important Cenozoic
Epochs were originally based on of modern
mollusc species. Work on Series Stages
continues today
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Geologic Time Scale
What to know. Geologic Time Scale from class web
page Practice on Blank Eons (dates)
Eras (for Phanerozoic dates) Periods
(Miss, Penn, Tertiary) Do not have to
know who, where when of naming.
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Geologic Time Scale
What to know. Geologic Time Scale from class web
page Practice on Blank Eons (dates)
Eras (for Phanerozoic dates) Periods
(Miss, Penn, Tertiary) Do not have to
know who, where when of naming.
My personal guarantee Question 1 on Test 1
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Queens Two Cover Jacks Three Poker Play Maybe Day
Some Over Come
Honey Please Plate My On Eggs Put
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Complete Geologic Section can be assembled though
correlation. For example Arizona - Utah
Grand Canyon
Zion
Bryce Canyon
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Grand Canyon
Zion
http//3dparks.wr.usgs.gov/coloradoplateau/images/
bryce_strat.jpg
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Grand Canyon
Zion
http//3dparks.wr.usgs.gov/coloradoplateau/images/
bryce_strat.jpg
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Cambrian - Jurassic
Grand Canyon
Zion
http//3dparks.wr.usgs.gov/coloradoplateau/images/
bryce_strat.jpg
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Zion
Brice Canyon
http//3dparks.wr.usgs.gov/coloradoplateau/images/
bryce_strat.jpg
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Cambrian - Quaternary
Zion
Bryce Canyon
Grand Canyon
http//3dparks.wr.usgs.gov/coloradoplateau/images/
bryce_strat.jpg