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GLS100 LAB: PLATE TECTONICS
Discovering Plate Boundaries Part I
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. Answer
all questions in clear complete sentences unless otherwise stated.
Objectives:

Locate and define plate boundaries from geographic, radiometric, seismic and
volcanic data.

Interpret sea-floor spreading and subduction from geographic, radiometric,
seismic and volcanic data.

Develop a hypothesis from a single set of data.

Explain your interpretation to others.

Evaluate and modify a hypothesis to incorporate additional data

Define the location of major tectonic plates

Identify physiographic features related to specific plate boundaries

Interpret processes occurring along different types of plate boundaries
In lecture you will learn how the theory of Plate Tectonics evolved from Wegner's earlier
hypothesis of Continental Drift as geoscientists acquired and applied new data. In the
first two labs you will use some of these data to both locate and identify plate
boundaries.
INTRODUCTION
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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 their boundaries.
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EXERCISE 1
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.
Specialists and Related Data
Specialist
Geochronology
Volcanology
Geography
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
Seismology
indicates depth of earthquakes: red = 0-33 km, green 70 -300 km, blue
300-700
EXERCISE 2
You will each have a blank world map 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. DO NOT DRAW BOUNDARIES NOT SUPPORTED BY
YOUR DATA!
Step 2: Reorganized into groups containing one or more specialist from each category.
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EXERCISE 3
1. Following the order given in the specialists list take turns explaining to each other
your data and your reasoning behind your placement of the 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.
4. Answer the following questions:
a. Which maps are the most limiting and Why?
b. Which map is a more comprehension indicator of plate boundary locations?
Why?
c. Which maps seem to locate boundaries where they don’t exist? Explain.
d.
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Step 3: Review and class discussion.
NOTES:
Credits: This lab has been modified from Discovering Plate Boundaries by Dale S.
Sawyer, Department of Earth Science at Rice University
Terminology:
Continental Crust: The thick buoyant crust composing the continents.
Continental crust has the over-all composition of the common igneous rock
granite.
Divergent Boundary: A plate boundary where plates are pulling apart.
Geochronology: The branch of geology concerned with ordering and dating of
earth materials and events in the Earth's history.
Oceanic Crust: The crust composed of denser dark igneous rock (basalt) that
underlies the ocean basins.
Plate Tectonics: The theory that the Earth’s rigid outer layer, the lithosphere is
broken into a number of plates, each of which moves over the underlying plastic
layer (asthenosphere). Plates converge, diverge and slide past one another
where their edges (boundaries) meet.
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Radiometric Dating: Determining the age of earth materials or objects by using
the decay rates of radioactive elements. The absolute age of earth materials are
obtained through radiometric dating.
Seismology: The study of earthquakes.
Sea-floor Spread: The process occurring along oceanic divergent boundaries
where new oceanic crust is created. When plates pull apart magma generated
from the underlying mantle wells up to fill the space, thereby creating new
oceanic crust.
Subduction: The process along converging boundaries involving oceanic crust
where one plate dives beneath the other and is consumed in the underlying
mantle. This is a destructive plate boundary because crust is destroyed.
Quiz: Learn the terms above and the names of all plates
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