Transcript Geologic Time - lyneezajacbeck

Geologic Time
Pre-Concept Map Activity
Using a sheet of copy paper, sketch a
concept map of “Earth’s History”
 No one else thinks exactly the same as
you, so no two maps should be the same
 Put the most general topics at the top and
get more specific as you flow downwards
 Link ideas together with lines
 Write a few words or a phrase on the line
that explains why the two ideas are linked
together

Snickers Lab
1. What is the oldest layer of the Snickers?
How do you know?
2. What is the youngest layer of the
Snickers? How do you know?
3. Which is older, the peanuts or the
caramel? How do you know?
4. With your lab group, decide on the steps
to making a snickers bar.
GEOLOGIC HISTORY
THE RULES OF THE DATING GAME
© Copyright 2005 - 2006 M. J. Krech. All rights reserved.
Time
What
is
time?
Time is…
Either
relative or
absolute
Time is: a measured period during
which an event, process, or
condition exists or continues.
One Year =
the time it
takes the
Earth to
complete one
orbit around
the Sun.
Geologic Time
Based on the
same time units
 Generally much
greater periods
of time
 100,000 years
 1,000,000 years

Dating Techniques
One ways in which geologists look at
time: Relative Dating
Relative Dating is..
What happened first?
What happened next?
…the measure
of a sequence
of events
without
knowing the
exact date at
which the
events
occurred.
Principles of Relative Dating




Principle of Superposition
Principle of
Cross-Cutting
Principle of Inclusions
Principle of Unconformities
Principle of Superposition


The youngest
rocks are on the
top.
The oldest rocks
are on the
bottom.
Q#1
Principle of Superposition
 Which
rocks are
older?
 Which
rocks are
younger?
Principle of Cross-Cutting


Volcanic vents cutting across
sedimentary rock layers Which is youngest?
Any feature that
cuts across another
rock or structure is
younger than what it
cuts across.
You can't cut
something until that
something exists,
therefore the cut has
to be younger.
Q#2
Principle of Cross-Cutting
What
is
younger?
The rocks
or the
fault line?
Principle of Inclusions

Rock layers which contain other rocks
are younger than the inclusion.
The
inclusion
(the other
rocks)
is older!
Q#3
Principle of Inclusions
Which is older? The rock layer or the
rocks included in the layer?
Principle of Unconformities
Unconformities are surfaces
that represent gaps in the
geologic record.
Principle of Unconformities
missing rock layer = missing time
Rock Symbols
Q#4 Where's the missing sediment?
How
do
you
know?
Q#5 Where's the missing sediment?
How
do
you
know?
Q#6
What happened first?
How
do
you
know?
Q#7
Where is the youngest rock?
How
do
you
know?
Q#8
Where is the unconformity?
How
do
you
know?
Q#9
What rock layer is the oldest?
How
do
you
know?
Q#10
Which is younger?
The fault or the rock layers?
How
do
you
know?
Does this diagram show
Q#11
an unconformity?
How
do
you
know?
Q#12
Which is younger?
The rock layer or the inclusion?
How
do
you
know?
The End
BONUS: What do you see here?
“Understanding a Million” Activity
How long would it take to count to a million?
Well, counting once per second (easy at the
start, but tough when you reach the
hundred thousand mark), eight hours per
day, seven days per week (no weekends
off), it would take you a little over a
month to count to one million!
“Understanding a Million” Activity
One possible way to actually see a million individual objects is to use a
computer and print out a million asterisks. Using a word processor
on a computer, type out one page filled with nothing but asterisks.
Print the page and count the number of asterisks there are on the
page. Divide this number into one million to see how many pages it
will take to print one million asterisks. Print out the right number of
pages and put them all up on one wall. Then you will be able to see
one million objects all at once!
Once you have seen a million asterisks, calculate how many
classroom walls, like the one you used, it will take to put up
one billion asterisks (Don't actually do it. It will take too much
paper!)
Or just for fun, see how many candles you can put on a birthday cake
and then try and figure out how large a birthday cake you would
need to celebrate Mother Earth's birthday!
Chart Observations


“first humans appeared on Dec 31st, 9:24 PM
and one second before midnight ‘Voyage of
Christopher Columbus’ - Year 1492″.
Now: The first second of New Year’s Day Widespread development of science and
technology; emergence of global culture;
acquisition of the means of self-destruction of
the human species; first steps in spacecraft
planetary exploration and the search of
extraterrestrial intelligenc.
Geologic Time Activity
Compare geologic time to
the length of a football
field, which is 100 yards
long. Earth formed about
4.6 billion years ago.
That's 4,600,000,000! If
you divided 4.6 billion by
100, then each yard
equals 46,000,000 years,
and each ten yard section
equals 460,000,000
years.
Geologic Time Activity
•
Making a Time Line
Print out or draw a model of a football field. (Note: The "print out" option provides you with a scale
model of a 25-yard section of a football field and two end zones. You will need 4 copies of the 25yard section but only 1 copy of the end zones.) Starting at the left (4.6 billion years ago) and
"moving forward in time," label the 10-yard lines in years. Then, using different colored markers,
draw a horizontal line to show the beginning and end of each of the following periods and eras.
1.
2.
3.
4.
5.
6.
Cenozoic Era (65 million years ago [mya] to present)
Triassic (245-208 mya), Jurassic (208-146 mya), and Cretaceous (146-65 mya) periods
Paleozoic Era (570-245 mya)
Proterozoic Era (2500-570 mya)
Archaean Era (3800-2500 mya)
Hadean Era (4600-3800 mya)
•
Option: Make a circle, pie diagram, or clock that shows the amount of time in degrees (there are
360 degrees in a circle) or in percentages for the following:
a clock of the 4.6 billion year history
a clock of the Mesozoic (Triassic, Jurassic, and Cretaceous)
a clock of the Mesozoic to the present.
1.
2.
3.
Geologic Time Activity
•
•
1.
2.
3.
4.
5.
6.
Finding an Event in Time
Many important events have occurred since Earth formed 4,600
million years ago (mya). Below is a list of some of those events.
Your task is to mark on a time line when those events took place. If
you haven't already done so, you might want to begin with the
"Geologic Time Activity." That activity provides a scale model of a
football field that can be used for this activity.
Mark the spot on the time line with an "X" where the following
important events in Earth's history occurred.
first microscopic life (3.6 bya)
first multicellular life (900 mya)
first oxygen appears in atmosphere (1.9 bya)
first land plants appear (450 mya)
formation of the Himalayas begins (30 mya)
formation of the Atlantic Ocean begins (150 mya)
Geologic Time Activity
• In the example below, we
have used the footballfield model for our time
line. On it we have
marked the first
appearance of dinosaurs
(225 mya), the
disappearance of
dinosaurs (65 mya), and
the first appearance of
homo sapiens (1/2 mya).
Geologic Time Activity
• Option: As a group activity, it might be fun to create a geologic time
line on the floor of your classroom or a hallway. First, you will need
to measure the length of the place you have chosen to make your
time line. Second, determine how many inches, feet, or yards
represent a given number of years by dividing 4.6 billion by the
length of your "time line."
• To mark the events in Earth's history, you might prepare a sign
representing each event and have students hold the signs and stand
in the proper time spots on your geologic time line. (4.6 billion years
is a big number to represent. To prevent the need for "studentmarkers" to stand on top of one another, you may want to use a very
large space, such as a gym or a sidewalk for your time line.)