Transcript Living Things - Ms. D. Science CGPA

Earth’s History – 7th Grade
Ms. De Los Rios
4.4
Essential Question: How do Scientist study Earth’s past?
What is the Geologic Time Scale?
How has Earth Changed Over Geologic Time?
Geologic Time
Pgs. 158-163
My Planet Diary pg. 158
Earth’s History In A Day
Suppose you could squeeze all of Earth’s 4.6-billion-year history into
one 24-hour day. The table shows the times at which some major
events would take place.
1. Write the letter for each
event on the clock diagram.
2. Did anything surprise you
About the data? If so, what?
________________________
________________________
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What is the Geologic Time Scale? Pg. 159
r. 159 3rd
The history of the Earth covers an enormous length of time.
Scientists have developed new terms to identify long periods.
Because the time span of Earth’s past is so great,
geologists use the geologic time scale to show Earth’s
history.
The geologic time scale is a record of the geologic events and the
evolution of life forms as shown in the fossil record.
Geologic Time Scale pg. 161
In the geologic time scale, scientists
have placed Earth’s rocks in order by
relative age (when rocks were formed)
Then, they divided geologic time into parts,
based on times in Earth’s history when there
were major changes in life forms.
1st Precambrian Time- The earliest part
of the geologic time scale.
•Covers 88% of Earth’s history
•The longest of the geologic time scale,
ended 542 million years ago.
•Few fossils survived from this period.
Dividing Geologic Time pg. 161
Scientists divided the time between
Precambrian Time and the present into
three long units of time called eras.
3 Eras are:
•
•
•
Paleozoic Era
Mesozoic Era
Cenozoic Era.
Dividing Geologic Time pg. 161
Moreover, scientists subdivided eras
into units of geologic time called
periods.
• The Paleozoic Era is made up of 6
periods
Dividing Geologic Time pg. 161
•the Mesozoic Era is made up of 3
periods
•The Cenozoic Era is made up 3
periods.
•The last of these, the Quaternary
Period, continues to the
present time.
Assess Your Understanding Pg. 161
1a. Define The geologic time scale is a record of __________ and
__________.
b. Sequence-Number the following periods in order from earliest to
latest.
Neogene ________
Jurassic ________
Quaternary ________
Triassic _________
Cretaceous _________
c. Draw Conclusions-Refer to My Planet Diary and Figure 2. During
which period did modern humans arise?
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How Has Earth Changed Over Geologic Time? Pg. 162
Scientists use the principle of uniformitarianism to help
explain Earth’s past.
This principle explains that geologic processes that operate
today are the same ones that operated in the past.
Natural processes such as weathering, erosion,
and plate tectonics have reshaped Earth’s surface. The
distribution of land and water on Earth’s surface has changed
over time.
How can scientist infer about events in Earth’s history?
Using fossils, evidence from rock layers, and radioactive
dating,
Geologic Time – pg. 162-163
The Evolving Earth
The timeline shows how Earth has changed over time.
Identify each development with the period in which it occurred.
Assess Your Understanding
pg. 163
1a. Explain How does uniformitarianism help scientists who are
Studying Earth’s past?
______________________________________________________
______________________________________________________
b. How do scientists study Earth’s past? Use an example from this
chapter in your answer.
______________________________________________________
______________________________________________________
I get it! I know that the ways Earth has changed over geologic time
include____________________________________________
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