Our Changing Earth: Geological Evolution
PURPOSE: To describe how the geologic features of the Earth have changed over
time.
ENGAGE: Have students think of their homes. Ask them the following questions about
their current home (if a child has not been in the home very long, have them think of a
place(building) that he has visited over the years, maybe a grandparent’s home or
school).
1.
2.
3.
4.
What does your home look like?
What did your home look like 5 years ago?
What artifacts exist that prove that your home has changed over time?
Think about the land around your home. How has it changed over the past 5
years?
5. What artifacts exist that would allow one to see that the land has changed over
time?
*Discuss these questions with the students after they are allowed to brainstorm the
answers about their own homes. Make sure to point out to students that just like their
homes have changed over time, the Earth has changed drastically over time.
EXPLORE: “Ask a Rock or Ask an Ice Core”
Set up the following stations for your students to explore evidence that supports
geological evolution of the Earth.
*Place students in small groups and allow them to rotate through each of the stations.
Have students use the Record Sheet to record their observations, data, and analysis
answers for each station. See student handout.
Station 1: Law of Superposition
In this station, students will use nonsense words to create a sequence from oldest to
youngest (oldest being the card on bottom that they start with and youngest being the
card on top that they end with). Students will start with the card that has the word TAR
and then figure out which card is next based on those letters. The next card in the
sequence uses one or two of the letters from the previous word to create the next word.
Because multiple words begin with the same letter as the previous word ends with, the
students will have to play around with the words to get the proper sequence. The
sequence ends up being TAR, RED, DOG, GEM, EMMA, MAT, TOE, and EEL. Once
the students are finished with the sequencing, they are to answer a series of questions
that relate the activity to the law of superposition. *Be sure to cut the cards BEFORE
you give them to the students—the cards are in the proper sequence on the master
copy. See handout for station materials.
Station 2: Relative Dating
Collect a variety of items of different ages (around 10). Make sure to get some objects
that are old and dirty and some that are shiny and new. The students will be asked to
put them in order of oldest to youngest. They will also be asked to justify the order of
the objects by describing the clues that led them to believe one object was older than
the other. This is much the same as relative dating that is used to date rock layers of
the Earth.
Station 3: Absolute Dating/Radioactive Decay
Students will perform a simulation of radioactive decay, the process used to perform
absolute dating on specimens. The students will use M & M s to perform the simulation.
New M & M s will be needed for each group that goes through the station (the M & M s
are eaten when they have “decayed”, therefore, none are left for the new group).
Station 4: Ice Cores
http://www.pbs.org/wgbh/nova/warnings/stories/
Students will use the website above to answer questions about the use of ice cores in
understanding geologic time. Computer access is necessary for this station.
Station 5: Continental Drift / Pangaea
Using cut-outs of the continents, students will attempt to recreate their version of
Pangaea. They will then predict what the Earth looked like between Pangaea and
present day. Students will need four copies of the continent shapes on green or white
paper, 4 pieces of blue paper to glue the shapes onto, glue, and scissors. A current
map of the world would be useful for students to get the continents in the correct place
for the present day time period.
Station 6: Unconformity
Students will explore and create unconformities using a sandwich that they will create.
The activity requires 2 slices of bread, sandwich spread (peanut butter, cream cheese,
jam), brown sugar, plastic serrated knife. This lab also draws in the concept of The Law
of Superposition.
Station 7: Chemical and Mechanical Weathering
Students will explore the concept of weathering by performing analyzing a series of
images that show the weathering of rocks. The students will analyze the images and
determine the type of weathering that has occurred. The students will then attempt to
come up what caused the weathering (ie, water, tree roots, or acid rain).
Go over the analysis questions and discuss the stations after the students have
finished.
EXPLAIN:
The students will use the attached worksheet to further their understanding of relative
dating, absolute dating, the Law of Superposition, Unconformity, Chemical and
Mechanical Weathering, and Continental Drift. After the students complete the
worksheet, go over the information as a class. Be specific in discussion of relative
dating, absolute dating, the law of superposition, unconformities, chemical and
mechanical weathering, and continental drift. Also take time to discuss how rock
formations occur and how they can be altered, thus creating confusion in the rock
record.
See attached handout
ELABORATE: “A Date with the Fossil Record”
Students will study a series of cards representing rock samples from a paleontologist
and determine the relative ages of the fossils in the rock samples. Next, the students
will create a timeline based on the order of the rock samples from oldest to youngest.
Use adding machine tape for the students to create their timelines and hang the
timelines vertically with the oldest rock layer at the bottom.
Note to Teacher: Each group will need a set of fossil cards and a fossil key for part 1
and a card with fossil ages for part 2. If possible, copy these on cardstock in color. To
save time, cut the fossil cards and fossil key apart and place in a zip-topped bag.
See student handouts.
EVALUATE:
1. Create a visual that answers this question: How has the surface of the earth
changed over time?
2. Complete the “Compare and Contrast: Absolute and Relative Dating” worksheet.
3. Suppose the continents had not drifted apart and you live on Pangaea today.
What would your life be like? Write a story about how your life would be different
such as driving to other countries, vacations, etc.
4. Create a model or visual to show what the surface of the earth will look 100
million years from now. Tell how the changes will take place and what impact
these changes will have on living things.
Additional Resources:
Great website for interactive continental drift and Pangaea.
http://www.discoverourearth.org/student/tectonics/continental_drift.html
ENGAGE, Part 2
Handout
Name ______________________________
Date _______________________________
My House: Then and Now
Think of your house and what it looks like right now. Now think of your house 5 years
ago. Answer the following questions about your house and the surrounding areas.
1. What does your home look like?
2. What did your home look like 5 years ago?
3. What artifacts exist that prove that your home has changed over time?
4. Think about the land around your home. How has it changed over the past 5
years?
5. What artifacts exist that would allow one to see that the land has changed over
time?
EXPLORE, Part 2
Station Cards
Ask a Rock or Ask an Ice Core Station #1
Directions: Place the layers of rock in the proper sequence.
Start with the layer labeled TAR. Use the letters to put the
layers in the proper sequence by matching ending letters of one
word to the beginning letters of the next. After sequencing the
cards, answer the following questions.
1. Which layer of “rock” is the oldest? Justify your answer.
2. Which layer of “rock” is the youngest? Justify your answer.
3. List the order of your sequence from oldest to youngest.
4. How does this simulation describe the layers of rock found
in the Grand Canyon?
Ask a Rock or Ask an Ice Core Station #2
Directions: Use the 10 items provided at the station. Arrange
the items in order from oldest to youngest. As you order the
items, take notes on the “clues” that help you figure out the
order of the objects. After ordering the objects, answer the
following questions.
1. List the order of the objects from oldest to youngest.
2. Discuss clues that led you to place the first object as the
oldest.
3. Discuss clues that led you to place the youngest object
last.
4. How might scientists use the age of fossils to date rock
layers?
5. Research the term index fossil. How might an index fossil
allow scientists to determine the age of rock layers?
EXPLORE, Part 2
Station Cards
Ask a Rock or Ask an Ice Core Station #3
Directions: Use the 25 M & M s and the cup for this station.
Place all the M & M s in the cup. Roll them out on the paper
towel. Record the number of M & M s that decayed and the
number that remain. The decayed M & M s are the ones with
the M up. The decayed M & M s may be eaten. Place the
remaining M & M s in the cup and repeat the process. Repeat
this process until all M & M s are decayed. Answer the
following questions when finished.
1. Create a graph with the information given in the lab. The
y-axis should be labeled “The Number of M & M s
Remaining” and the x-axis should be labeled “Toss
Number”.
2. Notice the shape of the line created by the data graphed.
Will the amount of radioactive substance ever be zero?
Justify your answer.
3. How do scientists use the amount of radioactive elements
found in rocks to determine the actual age of the rock?
4. Is the process of absolute dating using radioactive
elements error proof? Justify your answer.
5. How has the evolution of technology aided scientists in
their ability to date rock layers?
EXPLORE, Part 2
Station Cards
Ask a Rock or Ask an Ice Core Station #4
Directions: Use the following website to aid in the understanding of how
scientists use ice cores to understand geologic evolution and climate
changes. http://www.pbs.org/wgbh/nova/warnings/stories/
1. Where do scientists obtain ice cores from?
2. What time span can ice cores tell us about from geologic time?
3. Choose Ice Core Timeline. Choose Global Warming.
a. Which gases are tracked in this ice core to support the idea of global
warming?
b. How much ice accumulation is represented in this graph taken from ice core
data?
c. What relationship is shown between the rise in atmospheric gas and
temperature?
4. Choose Volcanic Activity.
a. What is Toba?
b. How does the volcanic ash and sulfur compounds affect our climate?
c. What would happen if a volcano the size of Toba erupted today?
5. Choose Temperature.
a. Which isotopes are analyzed in an ice core sample to allow scientists to
predict the temperature of an area thousands of years ago? Describe this
analysis process.
b. By how much has the temperature risen since the last ice age?
6. Choose Climate Change.
a. Does global climate shift gradually or can it shift rapidly? Justify your answer
by giving an example from the link.
b. What was the name given to the freak period and how long did it last?
7. Choose Dating.
a. How does the snow found in an ice core differ if it came from the summer
versus the winter?
b. What do scientists measure to determine when seasons occurred?
c. Describe what is seen and can be interpreted by the image of the ice core
analysis from China.
8. Choose Sea Storminess.
a. How can the ice core information be used to describe the disappearance of
the Vikings in Greenland?
b. Where does the excess sodium come from at the poles?
9. Choose Air Pollution.
a. What is trapped in the ice cores that show the human impact on the Earth as
a result of burning fossil fuels (give the name of the chemicals)?
b. What act has reduced the levels of sulfates and nitrates found in ice cores?
10. Choose Radioactivity.
a. What event occurred that led to radioactive material being found in ice cores
that were collected at the South Pole? Why is this alarming?
EXPLORE, Part 2
Station Cards
Ask A Rock/Ask An Ice Core Station #5
Directions:
1. Cut out the four sets of the continent shapes.
2. Use one set to recreate your version of Pangaea (the
super-continent). Glue the continents onto one sheet of
blue paper to create Pangaea. Label this map “Pangaea.”
3. Use the second set of continent shapes to create a map of
the current position of the continents on Earth. Glue the
shapes to the second blue piece of paper. Label this map
“Now.”
4. Compare the two maps that you have created. Create a
third map of what the Earth may have looked like in
between Pangaea and now. Glue the pieces to the third
blue sheet of paper and label this map “Between.”
5. Answer the following questions using the three maps.
a. Why do you think scientists believe that the
continents were once one big landmass?
b. What might have caused this landmass to drift apart?
c. What scientist first proposed this idea of the
continents being one large landmass and drifting
apart (Hint: You may wish to use the internet or your
textbook to find this answer)?
6. Use the fourth set of continents to create a final map
showing what you think the Earth will look like 250 million
years in the future. Glue the pieces to the last piece of
blue paper and label this map “Future.”
7. Write a paragraph to explain why you think the continents
will move as you have pictured in your “Future” map.
EXPLORE, Part 2
Station Cards
Ask a Rock or Ask an Ice Core Station #6
Unconformity
Angular Unconformity
An unconformity is a mystery to scientists. An unconformity is
a gap in the geologic record that occurs when rock is eroded
exposing older rock and then new rock forms on the much
older rock. The layering of new rock onto much older rock
leaves a gap in the geologic record. In this lab, you will create
a rock layer and then identify unconformities.
Directions:
1. Cut the two pieces of bread in half to create 4 pieces of bread.
2. Carefully spread one of the spreads on a piece of bread. This
process is the deposition of sediment.
3. Place a piece of bread on top of the spread. Brush the crumbs off
the top of the second piece of bread.
4. Create your next layer of rock by spreading brown sugar over the
top of the bread. Make sure the layer is evenly spread.
5. Place the 3rd piece of bread on top of the brown sugar.
6. Spread another layer of sandwich spread on top of the 3rd piece of
bread and then place the last piece of bread on top.
7. Cut your sandwich in half so that you can draw the layers on your
Record Sheet.
8. Indicate the youngest and oldest layer of your rock formation on
the Record Sheet.
9. Note any unconformities that exist by drawing them on the Record
Sheet.
10. Using the diagram at the top of this card, try to create an angular
unconformity (Hint: you can cut the pieces again). Draw your
angular unconformity on the Record Sheet.
EXPLORE, Part 2
Station Cards
Ask a Rock or Ask an Ice Core Station #7
A
D
B
E
C
F
Chemical Weathering: the process that breaks down rock through
chemical changes. Examples of chemical weathering include water
dissolving certain minerals in rock, exposure to oxygen from the air
reacting with chemicals in the rock, exposure to carbon dioxide from the
air reacting with chemicals in the rock, or acids from plants or acid rain
reacting with the chemicals in the rock.
Mechanical Weathering: Weathering that occurs when rock is
physically broken down into smaller pieces. This could include trees
growing into a rock and splitting it, ice freezing in cracks and causing the
cracks to expand, abrasion from smaller particles and water, or pressure
being applied on top of or underneath the rock.
Directions: Classify each picture shown above as chemical or
mechanical weathering. Use the description of each type of weathering
provided to aid in the classification. Try to determine exactly what may
have caused the weathering (ie, if the rock has a crack and a tree is
growing in the rock then the tree’s roots would be causing the rock to
crack open). Record your information on your Record Sheet.
EXPLORE, Part 2
Materials for Station 1
Name ___________________________________
Date ____________________________________
Station 1: Cards for the Law of Superposition Activity
TAR
RED
DOG GEM
EMMA MAT
TOE
EEL
EXPLORE, Part 2
Materials for Station 5
Name ___________________________________
Date ____________________________________
EXPLORE, Part 2
Student Handout
Name ___________________________________
Date ____________________________________
Record Sheet for Ask a Rock/Ask an Ice Core
Station 1: The Law of Superposition
Questions:
1.
2.
3.
4.
Station 2: Relative Dating
Record your “clues” here:
Questions:
1.
2.
3.
4.
5.
Station 3: Absolute Dating
Toss Number
Graph:
Number Decayed
Number Remaining
EXPLORE, Part 2
Student Handout
Name ___________________________________
Date ____________________________________
Questions:
1.
2.
3.
4.
5.
Station 4: Ice Cores
Questions:
1.
2.
3. Choose Ice Core Timeline. Choose Global Warming.
a.
b.
c.
4. Choose Volcanic Activity.
a.
b.
c.
5. Choose Temperature.
a.
b.
6. Choose Climate Change.
a.
b.
7. Choose Dating.
a.
b.
c.
8. Choose Sea Storminess.
a.
b.
9. Choose Air Pollution.
a.
EXPLORE, Part 2 continued
10. Choose Radioactivity.
a.
Station 5: Continental Drift
*Attach your 4 maps and your paragraph to this record sheet. Be sure to label the maps
as directed at the station.
Questions:
a.
b.
c.
Station 6: Unconformity
Place your drawings in the boxes indicated below.
Drawing of Rock
Youngest to Oldest
Unconformities
Layers
Angular
Unconformities
Station 7: Chemical and Mechanical Weathering
Image A
Chemical
or
Mechanical
Image B
Image C
Image D
Image E
Image F
Source or
Cause of
Weathering
EXPLAIN, Part 2
Handout
Name ___________________________________
Date ____________________________________
Creating a Rock Sequence
Using the sequence of historical events below, complete the cross-section diagram to show the
events according to the principle of superposition. Use the symbols given in the key, and label
each layer according to its place in the sequence,
(A)
(B)
(C)
(D)
The ocean covers the area; coral thrive and limestone deposits are formed.
Mud washes in and is later pressed into layers forming shale.
Coral thrive again. Limestone forms.
A normal fault occurs.
(E) Sand is deposited and later cemented.
(F) Coral deposits occur, forming limestone.
(G) The entire area is uplifted above the ocean, and the coral-rich limestone erodes.
(H) The area is again covered by the ocean, and mud washes in, forming shale.
(I) A disconformity marks the change from limestone to shale.
(J) Magma moves up through the existing rock layers and crystallizes to form a dike.
Limestone
Analysis:
Sandstone
Shale
Basalt
Igneous Intrusion
1. If a fossil is marked by the star, is the fossil older or younger than the layer above
it? The layer below it?
2. How might a scientist determine the age of the rocks using the age of the fossil?
3. What type of dating would be used to determine the age of the rocks by using the
fossil?
4. How might scientists use the uranium-238 content to date the rocks? What is
this type of dating called?
5. How might scientists use the carbon-14 content to date the fossil? Why is
carbon-14 used for fossils and uranium-238 used for rocks?
6. Why is the intrusion considered an unconformity?
7. What other types of unconformities exist?
8. How could chemical and mechanical weathering affect this rock sequence?
9. Which of the types of rock would be most affected by acid rain, a type of
chemical weathering?
10. Which of the types of rock would be most affected by intense winds, a type of
mechanical weathering?
11. How would continental drift explain this rock sequence being found on both
South America and Africa?
12. Would you expect to find a fossil matching the one found in this rock sequence in
both places? Justify your answer.
ELABORATE, Part 2
Handout
Name ___________________________________
Date ____________________________________
A Date with the Fossil Record
Task: A paleontologist from Utah has sent you 9 samples from a series or rock layers.
She needs your help in determining the relative age of the fossils. Another lab is using
radioactive dating to determine the absolute age of the fossils and the results will not be
available for several weeks. The paleontologist needs your information immediately.
You know from previous work that the rocks of Sample 2 are the oldest.
Materials: nine cards representing the rock samples, pencil, strip of adding machine
tape, markers, fossil key, fossil dates, calculator (if needed)
Procedure: Determining Relative Age
1. Carefully study the cards and the fossil key you have been given. Beginning with
Sample 2, arrange the fossil cards from oldest to youngest. If needed, try
different arrangements until you get them in order. Remember: After an
organism becomes extinct, it does not reappear in younger rocks.
2. Complete the following data table by recording the samples in order from bottom
to top (oldest to youngest) in the first column. The information for Sample 2 has
been done for you. Use the fossil to identify the fossils and write their names in
order by age from left to right in the top row of the table. Beside each sample,
write an X in the appropriate column to indicate which fossil(s) are present in
each sample.
Order of
Samples
Sample
# ____
Sample
# ____
Sample
# ____
Sample
# ____
Sample
# ____
Sample
# ____
Sample
# ____
Sample
# ___
Sample
#2
Name of Fossil Organism
Trilobite
Ptychopariida
X
Analysis: Determining Relative Age
1. Based on the information in your table, which fossil is the youngest?
______________________________________________________________________
______________________________________________________________________
2. Look at the X’s in the table. What would you conclude if there was an X outside the
pattern?
______________________________________________________________________
______________________________________________________________________
3. Does the information you have so far tell the exact age of a particular fossil? Why or
why not?
______________________________________________________________________
_______________________________________________________________________
4. What information does relative dating provide to paleontologists?
______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Procedure: Creating the Timeline
1. Now you are going to prepare a timeline for the paleontologist in Utah with the dates
from the radioactive dating lab. When looking at the information from the lab, you
discover that the dates are no longer attached to the appropriate rock samples. Since
the process of absolute dating is very expensive, you can’t pay to have it done again.
Then, you realize that since you have determined the relative ages of the samples, all
you have to do is arrange the dates from oldest to youngest and record the dates in your
table from oldest to youngest.
2. Use colored markers or pencils and the adding machine tape provided to make your
timeline. Your timeline should include the dates, fossil names, and fossil drawing.
Analysis: Creating the Timeline
1. Based on absolute dating, which fossil organism lived for the longest period of time?
______________________________________________________________________
Which fossil organism lived for the shortest period of time?
______________________________________________________________________
Explain your answers.
______________________________________________________________________
______________________________________________________________________
. ______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
2. How could you use the information on your timeline be used to determine the age
range of the Ammonite?
.
______________________________________________________________________
______________________________________________________________________
Sample 4
Sample 4
Sample 5
Sample 6
Sample 1
Sample 2
Sample 3
Sample 9
Sample 8
Sample 7
Fossil Key
Fossil Key
Fossil Key
Trilobite
Trilobite
Trilobite
Ammonite
Ammonite
Ammonite
Seed Plant
Leaf
Seed Plant
Leaf
Seed Plant
Leaf
Bony Fish
Bony Fish
Bony Fish
Crinoid
Crinoid
Crinoid
Shark
Shark
Shark
Fossil Ages
Provided by the Lab
Fossil Ages
Provided by the Lab
Fossil Ages
Provided by the Lab
437.8 mya
437.8 mya
437.8 mya
514.7 mya
514.7 mya
514.7 mya
151.6 mya
151.6 mya
151.6 mya
87.3 mya
87.3 mya
87.3 mya
285.3 mya
285.3 mya
285.3 mya
5.8 mya
5.8 mya
5.8 mya
253.7 mya
253.7 mya
253.7 mya
58.9 mya
58.9 mya
58.9 mya
180.2 mya
180.2 mya
180.2 mya
ELABORATE, Part 2
Answers
Order of
Samples
Name of Fossil Organism
Trilobite
Sample
#6
Sample
#8
Sample
#4
Sample
#3
Sample
#9
Sample
#7
Sample
#5
Sample
#1
Sample
#2
X
X
X
Order of Dates:
(Youngest on top)
5.8 mya = Sample 6
58.9 mya =Sample 8
87.3 mya = Sample 4
151.6 mya = Sample 3
180.2 mya = Sample 9
253.7 mya = Sample 7
285.3 mya = Sample 5
437.8 mya = Sample 1
514.7 mya = Sample 2
Crinoid
X
X
X
Seed Plant
Leaf
X
X
X
X
X
Ammonite
X
X
X
Bony Fish
X
X
X
Shark
X
X
X
EVALUATE, Part 2
Transparency
Create a visual that answers this question:
How has the surface of the Earth
changed over time?
Think . . .
Draw . . .
Explain . . .
How you would answer this question?
EVALUATE, Part 2
Handout
Name ___________________________________
Date ____________________________________
Compare and Contrast
I am investigating . . .
Absolute Dating
and
Relative Dating
How are they alike?

_____________________________________________________
_____________________________________________________

_____________________________________________________
_____________________________________________________

_____________________________________________________
_____________________________________________________

_____________________________________________________
_____________
How are they different?
 _____________________________________________________
_____________
Teacher Resource #2
Terms Used
Absolute Dating: any method of measuring the age of an event
or object in years. the actual age for a rock or mineral
Continental drift theory: theory that states that the gradual
shifting of Earth’s plates causes continents to change their global
positions over time
Correlation: the matching up of rock layers from different
locations
Convergent plate boundary: the boundary formed by the
collision of two lithospheric plates.
Daughter Isotope: the stable isotope that results from
radioactive decay
Divergent plate boundary: the boundary between two tectonic
plates that are moving away from each other.
Half-life: the time needed for half of a sample of radioactive
substance to undergo radioactive decay.
Isotope: an atom that has the same number of protons(or the
same atomic number) as other atoms of the same element do but
that has a different number of neutrons (thus a different atomic
mass)
Law of superposition: states that the oldest rocks lie on the
bottom and the youngest rocks are on top of any undisturbed
sequence of sedimentary rocks.
Parent Isotope: an atomic nucleus that is undergoing decay
Plate tectonics: the theory that explains how large pieces of the
Earth’s outermost layer called tectonic plates move and change
shape.
Radioactive Dating: the process by which the age of a rock is
determined by measuring the amount of radioactive isotopes
present in the rock or rock sample
Radiometric dating: the method used for absolute dating.
Radioactive decay: the process in which a radioactive isotope
tends to break down into a stable isotope of the same element or
another element.
Relative dating: uses information about rock layers and the
fossil record to determine the age relationships between rocks
Unconformity: gaps in the rock record.