Name _______________________
Geologic Time
Chapter 17 section 1
(This is transcribed from a Prentice Hall
read only slide show.)
Geologic Time Scale:
Slide Number
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Information
To understand ________, it is important
to realize that our
______________________.
Modern methods of
______________________ put Earth’s
age at _________________________.
This immense time span is hard to
comprehend. Guess about how long it would
take just to count to 4.5 billion if you could
count one number per second without
stopping. __________
An appreciation for the magnitude of
geologic time is important because many of
_________________
________________ that
__________________ are needed for
significant changes to occur.
It took _______________________ to
create these mountains and it will take
_______________
________________________________.
Geologists have divided all of Earth history
into units of varying magnitude. Together
they comprise ____________________.
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The _________________ provides a
framework for arranging events of the
_________________.
_______ represents the
_________________
_______.
The _________ that began about
_____________ is called the Phanerozoic,
__________________.
The
________________________________
_
of Phanerozoic eon contain an
______________
__________________________.
The Phanerozoic eon is divided into units
called ______.
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The era names refer to import differences
in dominant life-forms.
 ______zoic refers to ancient life.
Example Trilobite fossils.
 _____zoic refers to middle life.
 _____zoic refers to recent life.
Each era is divided into smaller units called
_________.
The changing fossil record also played an
important part in establishing each of the
periods.
Periods may be divided into epochs. Seven
epochs are names for the periods of the
Cenozoic era.
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The epochs of other periods usually are
just _____
______________________________.
The _____________________, which
ended just 10,000 years ago, coincides with
a time span commonly known
________________________.
The detail on the time scale does not begin
until about 540 million years ago, the date
for the _____
______________________________.
The vast expanse of time prior to the
Cambrian Period is divided into three eonsthe _______, the ___________, and the
_______________.
This greater than 4 billion-year span is also
commonly called the ________________.
About what percent of Earth’s 4.5 billionyear history is represented by Precambrian
time? _____
Why are the eons of Precambrian time not
divided into numerous eras and periods?
One reason is that __________________
was soft-bodied and therefore the fossil
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record is meager compared to the
Phanerozoic eon.
In addition, much of the Precambrian rock
record is buried beneath younger rocks
and/or altered by metamorphism.
The Grand Canyon’s ancient Vishnu schist is
buried beneath a huge pile of Paleozoic
rocks.
Which is the greatest expanse of time?
_______
Which is a subdivision of an epoch?
___________
Mesozoic is an example of ________.
Eons are divided into these _________.
Which is the smallest time span on the
geologic time scale? _______
Cambrian and Jurassic are examples of
________.
The age of the Earth is about:
________________
The Phanerozoic eon began about years
ago.
We are presently living in the
____________ era.
The Hadean, Archean, and Proterozoic are:
______
________________________________
_______
________________________________
__.
Which era of the Phanerozoic eon has the
most periods? _________________
Eocene, Pleistocene, and Holocene are
examples of: __________