Transcript Day 28

Day 28
What are destructive Earth processes?
Destructive processes break down old
landforms. examples: weathering; erosion;
tectonic plates sinking and melting
What are constructive Earth processes?
Constructive processes build new land
forms. examples: mountain building;
deposition; new crust formation
Daily Warm-Up Exercises
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Mini Geologic Time Lines
(Part 3)
Investigation 6
It's About Time
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Mini Time Lines
Each pair will make a time line on addingmachine tape.
Your time line should be 4.5 meters long to
show all of Earth history. We will only use
70 cm.
What scale will we need to use to represent
4.5 billion years?
1 mm = 1 million years
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Geological Eras
Geologists have divided Earth's history into
four eras based on the kinds of organisms
that existed at the time.
•Cenozoic
•Mesozoic
•Paleozoic
•Precambrian
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Geological Periods
Geologists further divided the eras into
periods based on major events that took
place in Earth's crust. For example, the
Mesozoic Era is divided into three periods.
•Cretaceous period
Mesozoic Era
•Jurassic period
•Triassic period
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Now
 Turn to the Earth History Time Line on
page 51. Your task is to divide your 4.5meter adding-machine tape into eras and
periods. Our time line will be 70 cm.
 Draw a line at one end of your tape and
label it "Now."
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Quaternary Period
The Quaternary period started 1.6 mya.
How many millimeters is that?
1 million years = 1 millimeter, so
1.6 million years = 1.6 millimeters
Draw a line 1.6 mm from the Now line and
label that tiny section the "Quaternary
Period."
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Tertiary Period
The Tertiary period started 66 mya.
How many millimeters is that?
1 million years = 1 millimeter, so
66 million years = 6.6 centimeters
Draw a line 6.6 cm from the Now line and
label that section the Tertiary Period."
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VERY IMPORTANT!!!
All measurements must be made from the
Now line.
The zero end of the ruler must always stay
on the Now line.
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Mark Eras
When you finish all the periods, go back
and draw a heavy line to mark the
beginning of each era.
Label the era by writing its name across the
periods.
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