Discovering Plate Tectonics Lab
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School
Colorado State University, Fort Collins *
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Course
121
Subject
Geology
Date
Dec 6, 2023
Type
docx
Pages
7
Uploaded by PresidentSwan3772
GEOL 121
Name
Lab Section
L26
D
ISCOVERING
P
LATE
T
ECTONICS
Learning Objectives:
○
Summarize plate tectonics and demonstrate understanding of plate motions
○
Describe the features and processes found at different plate boundaries and
explain why they are found there
○
Developing geoscientific skills: analyzing/interpreting data; reading maps;
practicing quantitative skills; thinking in 3D
○
Understand that scientific inquiry is an ongoing/dynamic process; role of
evidence and technology in inquiry
Part 1: Expert analysis
(2pts.)
Geoscientists from different expertise areas will often collaborate to understand complex
problems. We are going to model this approach by having each of you become an expert on
one type of data. You will then share your understanding of that data with the rest of the group.
Instructions
:
Your TA will assign you one of the data sets listed below. Work with your expert group to
examine your dataset and answer the questions below.
Expert Groups (Circle Assigned Topic)
Seismology · Volcanology · Geochronology · Geography/Topography
1.
What is your data telling you? What do the symbols and colors mean?
Earthquakes/large historical earthquakes. The circles are the magnitude (bigger circle
= bigger earthquake) and the colors denote the depth of the hypocenter of the
earthquake.
2.
Compare your data to the Plate Boundary Map on the next page of this worksheet. Note any
differences or similarities.
The earthquake locations align with the location of all of the plate boundaries.
3.
How does your data act on or near plate boundaries? (Examples: narrow/straight/curved,
symmetric/asymmetric, deep/shallow, active/inactive, ridge/valley, etc)
Active plate movement causes earthquakes along the plate boundaries. The red dot
locations of the earthquakes seem to occur along ocean ridges and the colored dots
that are deeper look like they occur along continental ridges.
Discovering Plate Tectonics
GEOL 121
Part 2: Examining Known Plate Boundaries
You will now examine sets of maps that show four different boundary types: divergent,
transform, convergent with subduction, and convergent without subduction. Answer the
following questions for each boundary type.
A) Divergent Boundaries (2pts.)
There are two pages showing divergent boundaries. One shows the Mid-Atlantic Ridge, in
the center of the Atlantic Ocean. The other shows a comparison of mid-ocean ridges that are
spreading (creating new ocean crust) at different rates, to give you an idea of how different
divergent boundaries can appear.
1) Describe how each of the datasets (Seismology, Volcanology, Geochronology,
Geography/Topography) behaves at this plate boundary.
Seismology: The earthquakes along this ridge are shallow and they follow along the
line.
Volcanoes: No real pattern but they fall on the known plate boundary line.
Topography: You can see a visible young ridge along the plate line that gets older the
further you move from the ridge.
Geochronology: At the plate boundary the color denotes the area is younger and it is
spreading outwards getting older as it spreads.
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Discovering Plate Tectonics
GEOL 121
2) What are some distinguishing features at this type of plate boundary? What features
could you use to distinguish this boundary type from the others?
It has a distinct line of earthquakes along the known line, and you can see the
seafloor age gets older as you move towards the continents. The newest crust is right
at the plate line.
B) Transform Boundaries (2pts.)
There is one page showing a transform boundary along the western side of North America.
1) Describe how each of the datasets (Seismology, Volcanology, Geochronology,
Geography/Topography) behaves at this plate boundary.
The seismology shows earthquakes along the coast of California which correlates
with the location of the plate boundary. The spots where you can see volcanoes also
have slight correlation to the plate boundary lines. The topography shows the
younger oceanic crust in the shallower parts of the ocean along the coast/plate line
along with the younger seafloor age in the geochronology map.
2) What are some distinguishing features at this type of plate boundary? What features
could you use to distinguish this boundary type from the others?
A distinguishing feature is the volcanoes and earthquakes occur in a close proximity
to the plate boundary. Another is the age of the seafloor shows the crust at the plate
is younger.
C) Convergent Boundary with Subduction (2pts.)
There are two pages showing convergent boundaries with subduction: one near Fiji in the
southwestern Pacific Ocean, and one along the west coast of South America.
1)
Describe how each of the datasets (Seismology, Volcanology, Geochronology,
Geography/Topography) behaves at this plate boundary.
Similar to that of the coast of California. We can see earthquakes and volcanoes
along the plate boundary on the coast of South America. The volcanoes are more
concentrated unlike that of California. We know this is subduction because we see
3
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Discovering Plate Tectonics
GEOL 121
volcanoes along the boundary. The topography along the line of the plate
boundary looks to be close to sea level. The geochronology map shows the
spreading from the nearby Nazca plate which pushes the oldest areas closest to
the continent.
2) What are some distinguishing features at this type of plate boundary? What features
could you use to distinguish this boundary type from the others?
There is a high concentration of volcanoes above and below where the oldest part of
the seafloor is. The earthquakes are also significantly deeper than at other
boundaries weve looked at.
D) Convergent Boundary without Subduction (2pts.)
There is one pages showing a convergent boundary where subduction is not taking place in
the Himalayan Mountains where India is colliding with Eurasia.
1) Describe how each of the datasets (Seismology, Volcanology, Geochronology,
Geography/Topography) behaves at this plate boundary.
The earthquakes occur along the plate boundary. Because this is a convergent
boundary without subduction we do not really see any volcanoes along the plate
boundary. Because this boundary occurs mostly inland, we don’t really get much
information from the geochronological map. The topography shows the creation of
mountains along the boundary and because this is without subduction these are
mountains and not volcanoes.
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Discovering Plate Tectonics
GEOL 121
2)
What are some distinguishing features at this type of plate boundary? What features
could you use to distinguish this boundary type from the others?
There is a high concentration of mountains (rise in topography) along the plate
boundary along with a high concentration of shallow earthquakes.
Check in with your TA before proceeding to Part 3.
Part 3: Unknown Boundaries
Now that you have developed a mental model of what each of the datasets does at different
plate boundary types, your challenge is to use the data to identify some unknown boundaries.
A) Unknown Boundary 1 (2pts.)
1) What type of boundary is there in this map?
Divergent
3)
How do you know? What is your evidence?
Shallow earthquakes.
No volcanoes, young seafloor following plate boundary.
B) Unknown Boundary 2 (2pts.)
1) What type of boundary is there in this map?
Convergent with subduction
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Discovering Plate Tectonics
GEOL 121
2) How do you know? What is your evidence?
Trench theme in topography
High concentration of volcanoes and earthquakes along the plate boundary
C) Unknown Boundary 3 (2pts.)
1) What type of boundary is there in this map?
Divergent plate boundary
2) How do you know? What is your evidence?
Shallow earthquakes. Concentration of volcanoes at the continental ridge (Iceland).
The geochronological map shows the spreading away from the line, getting older as it
gets further from the boundary.
D) Unknown Boundary 4 (2pts.)
1) What types of boundaries is there in this map (there is more than one type)?
convergent with subduction and divergent
2) How do you know? What is your evidence?
Earthquakes varying between small and large, and we see some volcanoes which
shows we have a convergent boundary with subduction. The seafloor is also very
young in age.
6
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GEOL 121
Part 4: Reflection
(2pts.)
1) What are three things that you learned from this lab?
I learned how to properly read/interpret geochronology maps, how to properly
interpret topography maps and how to identify transform faults along divergent
plates.
2) What questions do you still have about identifying plate boundaries?
Is location of volcanoes always an indicator of a plate type?
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