Module 3 Inv, Plate Tectonics
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Dec 6, 2023
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Plate Tectonics – Module 3 – GEO 1033
Purpose
Plate tectonics is a unifying framework for understanding the dynamic geology of the Earth. The theory posits
that the outermost layers of the Earth (the crust and uppermost mantle) make up the brittle lithosphere of the
Earth. The lithosphere is broken up into a number of thin plates, which move on top of the asthenosphere
(middle mantle). The asthenosphere is solid but flows plastically over geologic time scales.
This assessment guides you through an examination of patterns on Earth—the topography of the earth’s
surface above and below sea level, and the distribution of earthquakes and volcanic rock ages. You’ll then use
geologic data to determine long-term average plate motions.
To do this, you’ll use the program Google Earth, and Google Earth layers compiled from various sources. Please
answer EACH question, they are divided by subsections.
Skills
This assignment will help you practice the following skills that are essential to your success in this course / in
school / in this field / in professional life beyond school:
understanding basic disciplinary knowledge and methods/tools
applying basic disciplinary knowledge/tools to problem-solving in a similar but unfamiliar
context
analyzing
synthesizing
judging/evaluating and selecting best solutions and sources
creating/inventing an interpretation, solution, theory
Knowledge:
This assignment will also help you to become familiar with the following important content knowledge in this
discipline:
Plate Tectonic Boundaries and movement
Seismic and Volcanic evidence of Plate Boundaries
Age of the ocean crust
Criteria For Success
Be sure to watch the lecture videos about plate tectonics before starting the investigation
Step through the getting started with Google Earth section
Download Google Earth Pro to your desktop
Download the required kmz files from Blackboard to your desktop
Read the questions carefully and answer them fully relating what you are seeing to the
information in your lectures
Be mindful of grammar, spelling, and punctuation in your answers
Make sure to save and submit your assignment as a Word doc or pdf.
You can type directly into
this document.
Getting started with Google Earth
1.
On your computer, install the latest version of Google Earth Pro.
https://www.google.com/earth/about/versions/#earth-pro
2.
Once installed, open Google Earth, under the Tools/Options/3D View/ menu choose the “Decimal
Degrees” and Meters Kilometers” options and makes sure the “Use High Quality Terrain” box is
checked.
3.
Open the View menu. Go ahead and experiment with the options, but in general you should just have
the Tool Bar, Side Bar and Status Bar checked.
4.
Also on the View menu, hover over Navigation and you will see several options for the compass arrow
and slide bars in the upper right corner of the Google Earth screen. “Automatically” is a good choice as
it leaves a ghost of the image visible until you hover over it.
5.
Download the following kmz files from the module in Blackboard and save it/them to your desktop:
dynamic_earth_kmz_file
usgs_5.v2
6.
Load the kmz files into GE. You should be able to double-click on the filename and it will open within
GE, or, you can open it from your desktop in GE by using File/Open and navigating to the file.
7.
Once the DynamicEarth.kmz is loaded, click and drag to move it from “Temporary Places” to “My
Places.” Then save “My Places” by clicking File/Save/Save My Places. DynamicEarth.kmz will now be
available every time you open GE on this particular computer.
When you exit, GE you should save “My
Places” for the next time.
But you should manually save “My Places” whenever you make significant changes to it, as GE
does not auto save during a session.
8.
With an active Internet connection, you now have an interactive view of the earth! Take some time to
explore the Earth with Google Earth and figure out how the navigation works using the keyboard, your
touch pad and your mouse. For example: Zoom in and out, move N, S, E, W, grab and spin the globe,
etc. The resolution will change as you zoom. Clicking on the “N” of the navigation compass reorients
the view so north is “up.”
9.
At top left, “search” (and fly to) any place of interest. Zoom in and click on the “street view” icon
(orange stick figure under the compass at top right) to explore an area as if you were on foot
Zoom in to see individual buildings, roads, cars, etc. (Find the crew team and motorboat on Lake
Carnegie)
10. Go 3D – zoom into a significant topographic feature (e.g. Mount Everest, the Grand Canyon, Niagara
Falls). Hold the Shift key down and tilt the terrain using the Up/Down arrows to tilt the terrain, and spin
the terrain using the Right/Left buttons. Do the same thing for topographic features on the ocean floor.
Note that under Tools/Options/3D View you can increase the vertical exaggeration by up to 3x. This is
useful to emphasize subtle features, but is pretty scary when you look at the Grand Canyon that way!
11. On the Google Earth tool bar, click the clock-with-an-arrow icon to explore historical imagery in an area
of interest (views through time of the Princeton campus, for example)
12. By clicking and dragging, you can move things that you have found and want to save, from the “Search”
menu into “My Places.” You can also re-organize “My Places” by adding and deleting items, changing
the order of things, making subfolders, etc.
13. Explore the built-in items under the Layers menu at bottom left, and Dynamic Earth layers in your
Places menu.
14. Expand and contract the folders and subfolders, turn various items on and off, etc. For example, with
the Dynamic Earth/Volcanoes of the World layer displayed, left-clicking on a volcano brings up an
information box about it.
Part I
Seismic Patterns
Expand the “Seismicity” layer item and click “on” the “USGS 5.4+ epicenter 1986-2015” layer to show the
epicenters of large earthquakes (those with magnitudes ≥ 5.4).
1.
Describe any patterns you see in the distribution of earthquake epicenters over the Earth’s surface. You
will need to move around the Earth to explore the different locations—do they form lines, arcs, circles
or clusters? Are patterns connected or disconnected?
A pattern seen of earthquakes with a magnitude greater than 5.4 is they are clusters along coastlines and
island ridges. The pattern also forms lines and arcs as it clusters.
2.
The different colors refer to the depths of the earthquakes. What color are the shallowest earthquakes?
The deepest?
The shallowest earthquakes are orange and the deepest are red.
3.
Look closely at and around the Earth’s ridges (Mid-Ocean Ridge in middle Atlantic) and trenches
(southeast Pacific). The earthquake depth patterns associated with these features are different.
The trenches show a pattern of deeper earthquake magnitudes.
4.
Complete the chart below. Using the earthquake depths as evidence.
Near Ridges
Near Trenches
Lithosphere Thickness (evidence)
Thinnest near mid-ocean ridges, plates are pulling
apart
Lithosphere Thickness (evidence)
Thicker in oceanic trenches where plates are
converging
Describe the depth or range of depths of
earthquakes and distribution (symmetric or
asymmetric)
Usually associated with shallow depths; symmetric
Describe the depth or range of depths of
earthquakes and distribution (symmetric or
asymmetric)
Deep focus earthquakes; asymmetric and scattered
along the subduction zone
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Near Ridges
Near Trenches
Is there a pattern to the depth distribution?
Depth pattern is shallow
Is there a pattern to the depth distribution?
Depth pattern is deeper
Part II
Volcanoes & Volcanic Patterns
Leaving the earthquake layer on, click on the “Volcanoes of the World, Global Volcanism Program” layer.
5.
Describe the relationship between the locations of most active volcanoes and locations of earthquakes.
The relationship is horizontal along the boundaries of the plates.
6.
What types of volcanoes are typically found along plate boundaries as opposed to intraplate
volcanoes?
Typically, composite volcanoes are found along plate boundaries opposed to intraplate which are found further
away from plate boundaries.
7.
What are some common hazards associated with volcanic eruptions?
There are many hazards which include pyroclastic flows (dense mixture of ash and hot gases), pyroclastic
(rocks), poisonous gases, landslides, mudflows, tsunami, and climate change.
Part III
Plate Boundaries
Unclick all the layers, and then click on the “plate boundary model” layer.
This shows plate boundaries and
the names of major plates.
8.
Find the boundary between the African and South American plates.
Where is this plate boundary,
relative to the coastlines of Africa and South America?
The plate boundary is parallel to the coastlines.
9.
Now click the other layers on and off so that you can see relationships between plate boundaries and
these features. If you did not have the “plate boundary layer” available to you, how could you
determine where this plate boundary was? Be sure to consider topography as well as the earthquake
and volcano layers. List several ways and be specific.
Look to see where evidence of plates pulling apart and coming together is happening and creating
earthquakes, volcanoes and/or trenches.
10. What type of deformation is occurring as a result of this boundary, if any? What type of structures or
features would you expect to see, be specific?
This is a divergent plate boundary where they are pulling part and we can expect to find rift valley/mountain
ridges.
11. Travel westward across the South American plate to its boundary with the Nazca plate.
Where is this
plate boundary, relative to South America?
The boundary runs parallel along South Americas west side.
12. If you did not have the “plate boundary layer” available to you, how could you determine where this
plate boundary was? List several ways and be specific.
Look at earthquake activity and the depth pattern
Look for arcs and chains of volcanic activity
Look for areas of mountain ridges or new ocean floor for subduction and spreading
Download the kml file from USGS website and upload file on Google Earth.
13. What type of deformation is occurring as a result of this boundary, if any?
If referring to the boundary in question 11, ductile and brittle deformation can be present causing the
folds and faults.
14. What type of structures or features would you expect to see, be specific?
You would expect to see mountain ranges, subduction zones, trenches and patterns of earthquakes and
volcanoes.
Part IV
Plate motion
Unclick all the layers, and then click on the “Seafloor Age” layer.
This shows the age of the ocean floor
layers.
Look across the mid-Atlantic ridge between the South American plate and the African plate.
15. How many years does each colored band represent? __10 million_________
On average, continental crust is 2 billion years old; the oldest rocks are 3.8 billion years old, and some of the
grains in those rocks are even older.
16. What is the age of the oldest seafloor? ____160 million years____
17. On average, which is oldest – the continents or the ocean basins? __Continents__
18. Find the North American plate, the African plate, and the Mid-Atlantic Ridge that marks the boundary
between them. What happens to the age of the seafloor as distance increases away from the Mid-
Atlantic Ridge?
The age is older.
19. Is crust being created or destroyed at this plate boundary (and other spreading ridges)? _created_
20. Is this plate boundary divergent, convergent, or transform? __divergent_____
21. Focus on the northern Atlantic Ocean, near the east coast of the US and the northwest coast of Africa.
How long ago did the northern Atlantic Ocean begin to open up or start spreading? Describe your
reasoning.
Between 140-150 million years ago according to the color.
22. Did the northern Atlantic Ocean basin start opening at the same time as the southern Atlantic Ocean
basin (the area between to the south end of South America and Southern Africa)? How much older or
younger is the northern Atlantic basin than the southern Atlantic basin?
Describe your reasoning.
Atlantic Ocean basin is older by about 20 years due to the color difference.
23. From the Mid-Atlantic ridge, choose either the South American plate side or the African plate side. Click
on “Tools” and then “Ruler” to click and measure the distance from the mid-ocean ridge of the various
ages of the oceanic crust.
Be sure to choose kilometers for your unit of measure.
24. Describe the motion of your chosen plate relative to the Mid-Atlantic ridge, based on this seafloor age
data, the direction of motion, the average speed (s=distance/time) and whether or not speed and
direction has been constant over time.
Part V
Apply what you have learned—the Pacific Plate
Turn your attention to the Pacific plate. Note that the Pacific Ocean is comprised of several plates; we want
to focus on the very large Pacific plate (not the Nazca plate, or Cocos plate, or Philippine plate or other
plates.) The Pacific plate is “born” underwater at the East Pacific rise, the spreading ridge west of South
America. It is being destroyed at convergent boundaries around its northern, western, and southern
boundaries. NOTE: No instructions are provided for using the different layers. You should be familiar with
them by now. If needed you can go back and review.
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25. Is the East Pacific Rise spreading faster or slower than the mid-Atlantic Ridge and how can you tell –
without doing any calculations? Has the rate been constant over time?
The East Pacific Rise is spreading faster and you can tell without any calculations because it is hotter and
therefore supports more fluidity. It is consistently spreading quickly over time and that is why there is no ocean
trench and just a smooth volcanic summit at East Pacific Rise.
26. Describe the motion of the Pacific plate relative to the East Pacific Rise, based on this seafloor age data
– direction of motion, average speed and whether or not speed and direction has been constant over
time.
27. Based on the evidence of plate motion, explain how supercontinents form and how they rift apart.
Plate motion supports supercontinents forming and rifting apart by the geological forces created at all the
plate boundaries i.e., subduction, ocean spreading. The plates are flowing on top of land masses eventually
having seeing oceans spread and/or land masses fusing together.
Part VI
Crustal Deformation
28. This section requires some critical thinking as you will NOT be using Google Earth for this short section.
Thinking back over this activity and what you have learned about plate tectonics and plate motion,
consider other effects it has on the Earth. Include a brief discussion on the effects plate tectonics has
on crustal deformation. Make sure you include stress, strain, folds, faults and any other features you
can think of. Discuss the types of forces needed to create the features, the time it would take and so
on.
Plate tectonics move and create forces that shape geological features across the globe both under and above
water. Crustal deformation happens when forces exceed the internal strength of rocks, physically changing
their shapes. These forces are called stress, and the physical changes they create are called strain. Folds and
faults are two types of deformations that happen in the earths crust. A fold happens when layered rocks bend
and twist in a vertical movement. Faults are the detachment of layered rocks in a horizontal movement. These
processes effects the climate that can be on earth and shape landmarks such as the Himalayan Mountains and
San Andreas Fault. Understanding the tectonic forces building up in the earth’s crust helps to predict the next
major earthquake, volcano, or other natural disaster that would occur subsequently.
Part VII
Continental Drift versus Plate Tectonics
29. Describe the relationship between continental drift and plate tectonics.
Continental drift is the theory that land masses move slowly around earth. Land masses sit on top of plates
which are constantly in motion.
30. What evidence was used to support continental drift?
Evidence used to support continental drift is the continents aligning to fit together, fossil placement across
continents, and paleoclimate indicators.
31. What evidence was used to support plate tectonics?
Evidence used to support plate tectonics is earthquakes, volcanoes and age of seafloor.
32. What are the three types of plate boundaries?
The three types of plate boundaries are divergent, convergent and transform.
33. What are the key features associated with each boundary?
Divergent plate boundaries are where plates pull apart and create ridges. Convergent plate boundaries move
toward each other and collide creating subduction zones and trenches. Transform plate boundaries slide past
each other creating faults and shallow earthquakes.
Part VIII
The Role of Plate Tectonics
34. Review the overall activity, what role does plate tectonics play in modern geology? (This includes
everything from rock types to earthquakes and volcanoes to mountain building, climate change to
evolution of life.)
Plate tectonics affects modern and future geology in the way the land masses on earth lay and how far apart,
close or nonexistent areas of the world can be. It affects fault movement and the frequency that earthquakes
and volcanoes can happen and create other disasters such as tsunamis.
Save your completed assessment, make sure you name is on the document and submit the completed file as a
Word document or pdf in Blackboard.
Grading
All questions will be graded for completeness, grammar, punctuation, and critical thinking according to the following
rubric:
.
Exceeds Expectations
(3pts)
Meets Expectations
(2pts)
Does not Meet
Expectations (1pt)
Grammar and Punctuation
Answers have less than 5
total errors in grammar,
spelling, punctuation
Answers have more than 5
and less than 10 errors in
grammar, spelling,
punctuation
Answers have more than
10 errors in grammar,
spelling, punctuation
Critical Thinking
All answers are well
thought out using multiple
lines of evidence from
Google Earth
Most answers are well
thought out using at least 2
lines of evidence from
Google Earth
Answers are not well
thought and/or use no
evidence from Google
Earth
Follows Directions
All directions were
followed
Most directions were
followed
Directions were not
followed
Completeness
All questions are answered
thoroughly, and all are
complete.
Most questions are
answered thoroughly and
no more than 3 are
incomplete.
Most questions are
incomplete.
Total
Resources
Plate boundary model
(KMZ File 66kB Aug14 14)
Plate boundary model with orogens
(KMZ File 79kB Aug14 14)
Data source: Bird, Peter (2003) An updated digital model of plate boundaries, Geochemistry Geophysics
Geosystems, 4(3), 1027; converted into Google Earth format by Thomas Chust (Ludwig-Maximilians-Universitat
Munchen).
USGS 5.4+ epicenters colored by depth.kmz
(KMZ File 1.5MB Dec25 16) 'USGS Earthquakes 5.4+ 1986-2015,
colored by depth']
Data source: compiled from USGS NEIC catalog http://earthquake.usgs.gov/earthquakes/search/
USGS Earthquakes 1.0+ for the past week, plotted by depth, updated every 5 minutes
(KMZ File 440bytes
Aug14 14)
USGS Earthquakes 2.5+ for the past 30 days, plotted by depth, updated every 15 minutes
(KMZ File 442bytes
Aug14 14)
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File source: http://earthquake.usgs.gov/earthquakes/feed/v1.0/kml.php
Seafloor age 10 my isochrons
(KMZ File 227kB Aug14 14)
Seafloor age 5 my isochrons
(KMZ File 9.6MB Aug14 14)
Data source: Muller, R. D., W. R. Roest, J. Y. Royer, L. M. Gahagan, and J. G. Sclater. 1997. Digital isochrons of
the world's ocean floor.J. Geophys. Res. 102:3,211-3,214; AND Müller, R.D., Sdrolias, M., Gaina, C. and Roest,
W.R., 2008, Age spreading rates and spreading asymmetry of the world's ocean crust, Geochemistry,
Geophysics, Geosystems, 9, Q04006, doi:10.1029/2007GC001743.
Holocene Volcanoes
(KMZ File 534bytes Aug14 14)
Data source: Smithsonian Institution Global Volcanism. http://www.volcano.si.edu/learn_products.cfm?p=9