Download GLS100 LAB: PLATE TECTONICS Discovering Plate Boundaries

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GLS100 LAB: PLATE TECTONICS
Discovering Plate Boundaries
Physical Geology Lab I – Dr. Lindley S. Hanson
Name:__________________________________________
Specialty assigned:_____________________________
The purpose of this lab is to understand the application of various map data to the development of the Plate
Tectonics Theory, and to apply the scientific method.
Objectives:
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Locate and define plate boundaries from geographic, radiometic, seismic and volcanic data.
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Interpret sea-floor spreading and subduction from geographic, radiometic, seismic and volcanic data.
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Develop a hypothesis from a single set of data.
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Explain your interpretation to others.
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Evaluate and modify a hypothesis to incorporate additional data
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Define the location of major tectonic plates
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Identify physiographic features related to specific plate boundaries
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Interpret processes occurring along different types of plate boundaries
In lecture we’re learning how the theory of Plate Tectonics evolved from Wegner's earlier hypothesis of Continental
Drift as geoscientists acquired and applied new data. In this lab you will use some of these data to both locate and
identify plate boundaries.
INTRODUCTION
Plate tectonics is probably the most important unifying theory in geology. The theory states that the Earth's rigid
outer layer, the lithosphere, is broken into several mobile plates that interact along their boundaries. Plates converge,
pull apart, and slide past one another causing a variety of features and events to occur along the boundaries where
they meet.
EXERCISE
Step I: Interpreting data
You will be assigned one of the specialties listed in the Table 1 and will be given a map with data pertaining to your field.
Study your map. Discuss with members of your group the meaning of the data. Look for any linear trends or relationships
that might represent a boundary between two plates.
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Specialist
Geochronology
Volcanology
Geography
Seismology
Specialists and Related Data
Map and Data
Absolute ages of rock composing the floor of the oceans. Numbers corresponding to color key
represent millions of years before present.
World distribution of volcanoes. Red dots indicate historically active volcanic features.
Large Map: Physiographic map of the world.
Small map: Elevation in meters above and below sea level
Earthquake Locations 1990-1996 (magnitude 4 and greater). Color indicates depth of earthquakes:
red = 0-33 km, green 70 -300 km, blue 300-700
Exercise 1:
You will each have a blank map of the Earth with the names of the major plates labeled. However, the plates themselves
are not outlined. With a pencil lightly dash the boundaries on the map. Then as a group discuss your hypotheses and
create a group map with boundaries clearly drawn in pencil. Correct your map and prepare yourself to present it and your
supporting hypotheses to others in the class.
Step 2: Reorganized into groups containing one or more specialist from each category.
Exercise 2:
1. Following the order given in the specialists list take turns explaining to each other your data and
placement of plate boundaries.
2. Once everyone understands the data presented by each specialist, reevaluate your map. Have you drawn
any hypothetical boundaries in locations that are not supported by the other sources of data? Remember a
theory must be supported by all the data, or their
must be a logical explanation why all the data might not fit.
3. Redraw your map: Using the data from all specialists redraw all plate boundaries on a clean world map.
On the back of the map list all criteria your group used to define the boundaries.
Step 3: Displaying the Relative Motion of plates along their Boundaries
There are three types of boundaries (convergent,
divergent, and transform) based on the relative
movement of the plates across them. As a group
discuss what boundaries can be identified as either
convergent or divergent.
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Exercise 3: State below how the data are used to identify each boundary.
1. Convergent Boundary:
a. Describe how the type of convergent boundary is indicated by the distribution and depth of
earthquakes:
b. List the landforms typically developed along a convergent boundary.
c. Describe the distribution of volcanic features along a convergent boundary.
2. Divergent Boundary:
a. Describe how a divergent boundary is indicated by the distribution and depth of earthquakes:
b. List the landforms associated with a divergent boundary.
c. Describe the distribution of volcanic features along a divergent boundary.
Step 4 -- Final Task: Learn the names of the plates and their location.
NOTES:
Credits: This lab has been modified from Discovering Plate Boundaries by Dale S. Sawyer, Department of Earth Science at
Rice University in Houston, Texas.