TEST BANK FOR Laboratory Manual in Physical Geology.10th Edition By Richard M. Busch

Table of Contents
General Tips for Getting Started 2
Errata 4
Before You Teach a Laboratory 5
Pedagogical Model 7
Lab 1: Thinking Like a Geologist 8
Lab 2: Plate Tectonics and the Origin of Magma 23
Lab 3: Mineral Properties, Identification, and Uses 40
Lab 4: Rock-Forming Processes and the Rock Cycle 48
Lab 5: Igneous Rocks and Processes 54
Lab 6: Sedimentary Processes, Rocks, and Environments 61
Lab 7: Metamorphic Rocks, Processes, and Resources 72
Lab 8: Dating of Rocks, Fossils, and Geologic Events 77
Lab 9: Topographic Maps and Orthoimages 87
Lab 10: Geologic Structures, Maps, and Block Diagrams 99
Lab 11: Stream Processes, Landscapes, Mass Wastage, and Flood Hazards 116
Lab 12: Groundwater Processes, Resources, and Risks 127
Lab 13: Glaciers and the Dynamic Cryosphere 137
Lab 14: Dryland Landforms, Hazards, and Risks 146
Lab 15: Coastal Processes, Landforms, Hazards, and Risks 154
Lab 16: Earthquake Hazards and Human Risks 159
2
GENERAL TIPS FOR GETTING STARTED
Please consider these tips to help you use the Laboratory Manual in Physical Geology—
AGI/NAGT (10th edition) and this Instructor Manual more effectively.
1. Review the lab manual Instructor Resource Materials that are available to you,
and obtain the ones you need. You can find these resources online at
www.pearsonhighered.com/irc or you can contact your Pearson-Prentice Hall sales
representative at www.pearsonhighered.com/educator/replocator/
2. Review the Pedagogical Model upon which the lab manual is based (page 6).
3. Familiarize yourself with the following resource materials that are available to
your students:
• Pre-lab Videos created by Callan Bentley help students understand how to
successfully complete the lab activities by following a clear series of steps.
They can be accessed with the QR code on the cover flap of the lab manual or
at mygeoscienceplace.com
• GeoTools are cardboard and transparent rulers, protractors, grain size scales,
UTM grids, and more for students to cut out and use as needed. They can be
found at the end of the lab manual.
• A Math Conversion Chart, Introduction to SI Units, pictures of lab
equipment, and a map of North America are available in the Preface of the
lab manual (pages xi–xiv).
• TMYNTM, MasteringGeologyTM, and Learning CatalyticsTM, if used.
• QR Codes, which provide students with quick access to web sites they need
or may use in addition to resources provided in the lab manual.
4. Consider personalizing your students’ learning experience by using
MasteringGeologyTM, Learning CatalyticsTM, or TMYN (The Math You Need, When
You Need It) remedial tutorials.
MasteringGeologyTM is an online tutorial and homework program. Pre-lab video
quizzes can be assigned as formative assessments for you to analyze with a variety of
tools to isolate weaknesses and misconceptions of a student or class. This allows you
to build a plan for intervention and make the most of the time that students will have
in the laboratory. Learn more at www.MasteringGeology.com
Learning CatalyticsTM is pedagogical approach in which students use any webenabled
device of their choice (smart phone, tablet, laptop, etc.) to engage in
formative assessments (that guide learning) and summative assessments (that are used
for grading purposes) before, during, or after the laboratory. You can create or select
multiple choice questions for students to answer and/or you can create or select openended
questions that ask for numerical, written, or graphical responses. You can build
a seating chart, and then use the chart to see what students or groups of students have
answered specific items and how they answered them. You can assign questions for
students to answer synchronously during class/lab (one question is answered by each
student, but all students address the question at the same time), or in a self-paced
3
mode for formative or summative assessments. Learn more at
learningcatalytics.com/
TMYNTM is an online set of modular math tutorials for students in any
introductory geoscience, developed and managed by Jennifer Wenner (University of
Washington–Oshkosh) and Eric Baer (Highline Community College) with funding
from the National Science Foundation. You can assign the free modules for students
to use on their own, or you can assign them as formative or summative assessments.
You can also compare students’ pre-lab and post-lab ability to solve geological
problems involving mathematics and, thereby, measure the extent of their learning.
Learn more at serc.carleton.edu/mathyouneed/index.html
Please send comments, criticisms, and suggestions regarding the laboratory manual or
this instructor manual directly to Rich Busch, Department of Geology and
Astronomy, West Chester University, West Chester, PA 19383 or
[email protected]. Thank you!
4
ERRATA
Lab 2
On page 58, part “B” (Reflect and Discuss) is actually part “D.”
On page 68, part A, item 5b, the vector motions should be in mm/yr (not cm/yr).
Lab 5
On page 136, Figure 5.4, Step 3: for the description of pegmatitic texture, change “1 mm”
to “1 cm.”
On page 144, part A, change “Minerals Database (pages 000 – 000)” to “Minerals
Database (Pages 93–97).”
On page 152, part C, change “200 million years ago” to “190 million years ago.”
Lab 6
On page 185, part B, change “Photograph A” to Photograph B.”
5
BEFORE YOU TEACH A LABORATORY
BEFORE LAB BEGINS
1. Decide what activities your students should complete before and during the lab.
Most labs deliberately include more activities than your students could complete in a
single lab period, so you can choose the activities that you think will best enable your
students to learn what you expect them to learn in the lab time available.
2. Check the list of errata (page 4 in this Instructor Manual) for corrections that must
be made in the lab that you plan to use.
3. Assign pre-lab preparations for your students to complete. This may include:
a. Complete the first activity of the lab and by the start of the lab.
b. Watch the pre-lab video for the lab.
c. Take a pre-lab quiz using MasteringGeologyTM or other quiz of your design.
d. Complete assigned readings in the lab manual, class textbook, or other.
e. Know what activities must be completed by the end of the lab period.
f. Know what materials each student must bring to the start of the lab (as noted in
the blue boxes of the lab manual that start of each activity and as noted at the start
of each laboratory section of this Instructor Manual).
4. Review and assemble the Instructor Materials that you must provide during the
lab period. A list of the Instructor Materials is provided in this instructor manual, at
the start of each for each lab section. They are generic lists only and must be modified
by you to avoid confusion and know exactly what to assemble for the laboratory.
5. Review each activity and the Answers to Questions (provided in this instructor
manual) for each activity/question that you assign to your students. Some
questions have more than one right answer depending on how you have presented
material for students to read or explore.
6. Analyze pre-lab results, if you are assigned a pre-lab quiz using
MasteringGeologyTM or a similar program. Use that information to isolate
weaknesses and misconceptions of a student or class. Then build a plan for
intervention that makes the most of the time that students will have in the laboratory.
7. Develop the scope and sequence of the teaching/learning plan that you plan to
follow during the lab period.
a. What will you do at the start the lab period? For example, you may:
• Declare the scope and sequence of what students must do during the lab
period, how they are expected to do/record their own work yet work
and/or work in collaborative groups, and the safety practices that they
must follow.
• Review pre-lab weaknesses and misconceptions and/or use lab PowerPoint
to introduce the lab.
6
• Review how and where students obtain the materials they need (the
materials that you are providing in the lab).
• Address questions.
b. What will you do during the lab period? For example, you may:
• Allow students to work on activities at their own pace or according to your
other plan.
• Move about the room to be sure students/groups have the materials they
need and are on task.
• Address questions, use guiding questions of your own to help students
scaffold from the unknown to the known (or inability to ability), and
implement personal interventions as needed (especially relative to pre-lab
quiz results and special-needs).
c. What will you do near/at the end of the lab period? For example, you may:
• Review the results of each activity (item by item or the Reflect and
Discuss questions for formative purposes (i.e., to guide learning).
• Have students submit their individual worksheets for summative
assessment (evaluation for a grade).
• Have students complete a graded post-lab quiz.
• Have students address the Think About It questions linked to the lab
and/or the activities that they completed.
DURING THE LAB PERIOD
8. Carry out the plan that you developed above, in parts 7a and 7b.
AT/NEAR THE END OF THE LAB PERIOD
9. Carry out the plan that you developed above, in part 7c.
10. Grade materials and provide grades and feedback to students in a timely
fashion.
11. Reflect on any feedback about the lab that students may have volunteered and
use it to inform/guide your grading and future teaching.
7
PEDAGOGICAL MODEL
Each lab proceeds from items 1 through 4 and involves resources and assessments.
8
LABORATORY ONE
Thinking like a Geologist
BIG IDEAS: Geology is the science of Earth, so geologists are Earth scientists or
“geoscientists.” Geologists observe, describe, and model the materials, energies, and
processes of change that occur within and among Earth’s spheres over time. They apply
their knowledge to understand the present state of Earth, locate and manage resources,
identify and mitigate hazards, predict change, and seek ways to sustain the human
population.
THINK ABOUT IT (Key Questions):
• How and why do geologists observe Earth materials at different scales (orders of
magnitude)? (Activity 1.1)
• What materials, energies, and processes of change do geologists study?
(Activity 1.2)
• How and why do geologists make models of Earth? (Activity 1.3)
• How and why do geologists measure Earth materials and graph relationships
among Earth materials and processes of change? (Activity 1.4)
• How is the distribution of Earth materials related to their density?
(Activities 1.4, 1.5)
STUDENT MATERIALS
(Remind students to bring items you check below.)
_____ laboratory manual with worksheets linked to the assigned activities
_____ laboratory notebook
_____ pencil with eraser
_____ metric ruler (cut from GeoTools sheet 1 or 2)
_____ calculator
_____ blue pencil or pen (Activity 1.3 only)
_____ drafting compass (Activity 1.3 only)
_____ several coins (Activity 1.3 only)
INSTRUCTOR MATERIALS
(Check off items you will need to provide.)
ACTIVITY 1.1: Geologic Inquiry
_____ none
9
ACTIVITY 1.2: Spheres of Matter, Energy, and Change
_____ none
ACTIVITY 1.3: Basketball Model of Earth’s Spheres
_____ drafting compasses (one per student)
_____ extra metric rulers (for students who forgot them)
_____ extra blue pencils (for students who forgot them)
_____ several coins/student: pennies, nickels, quarters, dimes
ACTIVITY 1.4: Measuring and Determining Relationships
_____ extra metric rulers (for students who forgot them)
_____ small (10 mL) graduated cylinders (one per group of students)
_____ waterproof modeling clay (at least 1 cubic cm. per student)
_____ gram balance (one per group of students)
_____ wash bottle or dropper bottle, filled with water (one per group)
_____ paper towels to clean up spills
ACTIVITY 1.5: Density, Gravity, and Isostasy
_____ extra metric rulers (for students who forgot them)
_____ gram balance
_____ wood blocks about 8 cm x 10 cm x 4 cm. Do not use cubes because they
float diagonally. Pieces of pine 2 x 4 studs work well. For variety, give
some groups pine and others a more dense wood like walnut (one block
per group of students).
_____ small bucket or plastic basin of water to float wood block (one per group of
students)
_____ paper towels to clean up spills
ACTIVITY 1.6: Isostasy and Earth’s Global Topography
_____ large (500 mL) graduated cylinders (one per group of students)
_____ pieces of basalt and granite that will fit into the large graduated cylinders
(one piece of each per group of students)
_____ gram balance
_____ wash bottle filled with water or dropper (one per group)
_____ paper towels to clean up spills
INSTRUCTOR NOTES AND REFERENCES
1. Metric and International System of Units (SI): refer to laboratory manual page xi.
2. Mathematical conversions: refer to laboratory manual page xii.
3. In Activity 1.5 of this laboratory, students explore the isostasy of a floating wood
block. You can make this more of a real-world inquiry by providing students with
two or more densities of wood. For example, pine and walnut work well because
10
students can easily see that the pine blocks float higher than the walnut blocks. This
makes it easier for students to conceptualize how isostatic differences between
granitic and basaltic blocks may explain Earth’s hypsographic curve.
4. Hydrous minerals of Earth's Mantle. Hydrous minerals include not only the obviously
hydrous minerals like gypsum, but also minerals like amphibole and pyroxene that
are "nominally hydrous" (actually hydrous even though they are generally regarded as
anhydrous). See David R. Bell and George R. Rossman's 1992 paper on this (Science,
v. 255, p. 1391–1397). Shortly after the Science article was published, Science News
quoted Bell and Rossman as estimating that the mantle may contain a volume of
water equal to 80% of the volume of the world's oceans. Even if this Bell and
Rossman estimate of mantle water seems high, one must still account for the hydrous
and nominally hydrous minerals in Earth's crust. Therefore, having students assume
that the solid Earth may contain water equal to 80% of the volume of the world's
oceans may be a conservative estimate.
For information on recycling of water into Earth's mantle, refer to: C. Meade and
R. Jeanloz. 1991. Deep-focus earthquakes and recycling of water into Earth's mantle.
Science 252:68–72.
11
LAB 1 ANSWER KEY
ACTIVITY 1.1: Geologic Inquiry
1.1A. Observation, analysis, and description of the parts of Figure 1.1
12
1.1B. Every part of Figure 1.1 shows objects that contain copper (Cu).
1.1C. Analyze Figure 1.1 and answer the following questions.
1.1D. 1. The best location for a new mine (pit) is location C, because the rocks there
have the same pink-red color in the false-colored satellite image as the rocks
of the current and old copper mine pits.
1.1D. 2. To see if location C is actually a good source for more copper ore, one must
go there to collect samples of the rock and determine if it contains copperbearing
minerals in profitable quantities to be mined.
13
ACTIVITY 1.2: Spheres of Matter, Energy, and Change
1.2A.
14
1.2B. answer sheet
15
1.2C. Completed Venn diagram
1.2D. Reflect and Discuss: Do you think that most change on Earth occurs within
individual systems, at boundaries between two systems, or at the intersections of
more than two systems? Why?
In general, one might expect that at the most change occurs at intersections of more than
two systems, because there are more varied materials and energy forms (than in one
system or the boundary between just two systems).
16
ACTIVITY 1.3: Modeling Earth Materials and Processes
1.3A. 1. See the completed basketball model below. Students should realize that it is
nearly impossible for them to draw separate lines for hydrosphere and
atmosphere (because they are so narrow compared to the diameter of the
basketball). The crust will be about the thickness of a pencil/pen line. You could
have students use another color of pencil for the crust (i.e., as done in red below).
17
1.3A. 2. The radius of the basketball model is 0.119m (119 mm), but the actual radius
of Earth is 6,371,000 m, so the ratio scale of model to actual Earth is 0.119 to
6,371,000. Dividing 6,371,000 by 0.119 reduces the ratio scale to 1:
53,537,815. Thus, the basketball model is 1/53,537,815th of the actual size of
Earth.
Fractional scale: 1/53,537,815 Ratio scale: 1:53,537,815
1.3B. MODELING LANDSLIDE HAZARDS
1. If you lift one end of the ruler, then the coin slides towards the opposite end.
2. The coin did not slide off of the ruler at the very second you started to lift one
end of the ruler, because there was friction between the coin and the ruler.
3. The coin start sliding when the force of gravity overcame the friction between
coin and ruler.
4. REFLECT & DISCUSS: When students describe how they would modify
the ruler and coin model, their answers will vary widely.
• Most will use different solid materials, such as rocks on a piece of marble.
• Some will introduce water.
• Some will introduce wind.
• Some will want to measure values and graph results.
ACTIVITY 1.4: Measuring and Determining Relationships
1.4A. The mathematical conversions (using the table on laboratory manual page xi) are:
1. 10.0 miles x 1.609 km/mi = 16.09 kilometers (or rounded to 16.1 km)
2. 1.0 foot x 0.3048 m/ft = 0.3048 meters (or rounded to 0.3 m)
3. 16 kilometers x 1000 m/km = 16,000 meters
4. 25 meters x 100 cm/m = 2500 centimeters
5. 25.4 mL x 1.000 cm3/mL = 25.4 cm3
6. 1.3 liters x 1000 cm3/L = 1300 cm3
1.4B. 1. 6,555,000,000 = 6.555 x 109 2. 0.000001234 = 1.234 x 10-6
1.4C. Students should be able to use a metric ruler (cut from GeoTools sheet 1 or 2) to
draw a line segment like this one that is exactly 1 cm long.
_____ 1 cm
1.4D. Students should be able to use a metric ruler to draw a square that is exactly
1 cm long by 1 cm wide. [Note that this is a two-dimensional shape called a
square centimeter, or cm2.]
1 cm
1 cm
18
1.4E. Students will have some difficulty drawing a three-dimensional cubic centimeter
on two-dimensional paper because the dimensions must be distorted to give the
drawing its perspective view. However, their drawing of a cubic centimeter
should be as close as possible to actual size. Some students will try to trace the
cubic centimeter in Figure 1.11B (which is correct, but must be traced exactly).
1.4F. Students should explain a procedure similar to this one and determine that water
has a density of about 1 g/cm3:
a. Fill a small graduated cylinder about halfway with water and record this
starting volume of water in the cylinder. The graduated cylinder will probably
be graduated in mL (which equals cm3), so students should record the starting
volume of water in cm3.
b. Weigh the graduated cylinder of water from step a and record the starting
mass of water in grams.
c. Add a small amount of water to the graduated cylinder and:
• Read and record this ending volume of water.
• Weigh and record this ending mass of water.
d. Use the following mathematical formula to determine the density of water:
Ending mass of water (g) – starting mass of water (g)
————————————————————————— = about 1 g/cm3
Ending volume of water (cm3) – starting volume of water (cm3)
1.4G. Students will determine that their clay has a density greater than 1 g/cm3. Most
brands are between 2 g/cm3 and 4 g/cm3. There are two main methods/procedures
that students use to determine this.
Method 1 procedures:
a. Construct a cubic centimeter of clay (1 cm3 of clay).
b. Weigh the cm3 of clay in grams. This is the grams per cubic centimeter
(density) of the clay.
Method 2 procedures:
a. Weigh a small lump of clay (that will fit in a graduated cylinder) and record
its mass in grams.
b. Fill the graduated cylinder about halfway with water and record the exact
starting volume of water in cubic centimeters.
c. Place the lump of clay into the water (do not splash) of the graduated cylinder
and record this ending volume of water in cubic centimeters.
d. Determine the volume of the clay by subtracting the starting volume of water
in the graduated cylinder (b) from the ending volume of water in the
graduated cylinder (c).
e. Determine the density of the clay by dividing the mass of the clay sample (a)
by the volume of the clay sample (d).
19
1.4H. 1. Clay sinks in water because it is more dense than water (it has a density
greater than 1 g/cm3).
2. Some students will try to flatten the clay into a sheet that can float on the
surface tension of the water. Other students will try to make a boat or a clay
sphere. (If students are having great difficulty getting the entire lump of clay
to float, then you can ask them to consider how the Navy gets steel to float—
i.e., it makes the steel into ship shapes.)
3. When students eventually make a ship shape (or sphere) and get their clay to
float, then they should realize that the clay floated because it took on a new
shape with a larger volume. This decreased the density of the clay and
increased its buoyancy.
1.4I. Reflect and Discuss:
The hydrosphere (liquid water) is less dense than the lithosphere, so it sits on top
of the lithosphere. The atmosphere is the least dense of them all, so it occurs
above them. In summary, the spheres are most dense at Earth's center and less
dense with position away from Earth's center. Many students will draw this
relationship and label the spheres.
1.4J. RATES:
1. a. 1.6 km x 1,000,000 mm/km = 1,600,000 mm
6 million years = 6,000,000 yr
So: 1,600,000 mm ÷ 6,000,000 yr = 0.2666666 mm/yr
= 2.666666 x 10-1 mm/yr
b. 0.2666666 mm/yr times the age of the student in years = answer
2. 60°C ÷ 3.9 km = 15.38°C/km
1.4K. Single Line Graph
20
1. The amount of CO2 in the atmosphere at Mauna Loa Observatory, Hawaii has
increased every decade since 1962.
2. The values for carbon dioxide increase as the years increase, and the line has
a positive slope.
1.4L. Bar Graph
1.4M. Two-line Graph
1. The relationship revealed in this graph is that there is a close correlation
between atmospheric carbon dioxide (ppmv) and global temperature. When
carbon dioxide levels are, the temperature is high. When carbon dioxide is
low, then the temperature is low. Over the past 400,000 yr, both factors have
risen and fallen together in cycles lasting about 100,000 yr. Carbon dioxide
concentrations did not exceed 300 ppmv in any of those natural cycles or drop
below 180 ppmv in any of those natural cycles.
1.4N. Reflect and Discuss
Graph K and M show that since at least 1962, carbon dioxide levels have been
higher than at any time in the past 400,000 years and reached a level of 393 ppmv
in 2012. Graph L shows that the rate of carbon dioxide increase is also rising.
One can expect the level and rate to increase in the future by extrapolating the
graphs into the future. Also, based on Graph M, the levels of carbon dioxide in
our atmosphere are greater than at any time in the past 400,000 years. Graph M
also shows that global temperature and carbon dioxide concentrations rise and fall
together, so one can infer that abnormally high global temperatures will
accompany the abnormally high carbon dioxide levels of the future.
21
ACTIVITY 1.5: Density, Gravity, and Isostasy
1.5A. Student answers will vary according to the type of wood. However, students
should realize that they can determine the mass of the wood block by weighing it
in grams (g). They should be able to determine the volume of the wood block by
using a ruler to measure its three linear dimensions in cm, and then multiplying
the dimensions together to find the volume in cubic centimeters (cm3). The
density of the wood block is its mass in grams divided by its volume in cubic
centimeters.
1.5B. Bear in mind that the proportions of wood above and below the waterline will
vary according to the type of wood. Pine floats higher than walnut. Exact
measurements recorded by students will also vary according to type of wood and
size of the block.
1.5C. The exact form of equations will vary from student to student. The common form
is:
Hbelow = (Ρwood ÷ Ρwater) Hblock
1.5D. The exact form of equations will vary from student to student. Using the equation
above (answer to Question 17), the common form would be:
Habove = 1 – [ (Ρwood ÷ Ρwater) Hblock ]
1.5E. The density of water ice (in icebergs) is 0.917 g/ . The average density of (salty)
ocean water is 1.025 g/ .
1. % below = (0.917 g/cm3 ÷ 1.025 g/cm3) 100% = 89.5%
2. % above = 100% – [(0.917 g/cm3 ÷ 1.025 g/cm3) 100%] = 10.5%
3. Students will generally find that their grid estimations of the percentages of
the iceberg below and above sea level are consistent with their calculations
above.
4. As the top of the iceberg melts, its submerged base will rise to establish a new
isostatic equilibrium.
1.5F. Where mountains have been eroded, their “roots” are still rising very slowly, so
ancient shorelines become elevated above the levels where they originally
formed.
22
ACTIVITY 1.6: Isostasy and Earth’s Global Topography
1.6A. Student values for the density of pieces of basalt that they personally analyze will
vary from about 2.9 g/cm3 to 3.3 g/cm3. However, they should still determine that
the average density of all 10 basalt samples is about 3.1 g/cm3.
1.6B. Student values for the density of pieces of granite that they personally analyze
will vary from about 2.7 g/cm3 to 3.2 g/cm3. However, they should still determine
that the average density of all 10 granite samples is about 2.8 g/cm3.
1.6C. 1. Habove = 5 km – [ (3.1 g/cm3 ÷ 3.3 g/cm3) 5 km ] = 0.3 km
2. Habove = 30 km – [ (2.8 g/cm3 ÷ 3.3 g/cm3) 30 km ] = 5.0 km
3. 5.0 km – 0.3 km = 4.7 km
4. The calculated value of 4.7 km in part c is close to the actual difference
between the average height of the continents and the average depth of the
oceans on the hypsographic curve in Figure 1.11.
1.6D. Reflect and Discuss: Earth has a bimodal global topography because its granitic
continental blocks of lithospheric rock have an average density that is less than
the average density of basaltic sea floor rocks. Thus, on average, the continental
blocks sit about 4.53 kilometers higher in the mantle than the basaltic blocks.
Oceans cover the basaltic blocks, but the tops of continental blocks remain above
sea level.
1.6E. Reflect and Discuss: As a mountain forms, it establishes a level of isostatic
equilibrium in the denser mantle—a sort of “mantle line” (like the waterline on an
iceberg). In other words, most of the mountain is a submerged “root,” just as most
of an iceberg is its “root” below sea level. As a mountain is eroded, its root rises
to establish a new level of isostatic equilibrium.
1.6F. Reflect and Discuss: Students can take and defend any inference, but the best and
most correct inference is one that is supported by data and good logic. The most
correct proposal (according to their work in this laboratory) is a compromise
hypothesis stating that:
Blocks of Earth’s crust (actually lithosphere) have different densities (Pratt) and
different thicknesses (Airy), so they sink to different compensation levels.
23
LABORATORY TWO
Plate Tectonics and the Origin of Magma
BIG IDEAS: Tectonics is the study of global processes that create and deform
lithosphere. Plate tectonics is the theory that Earth’s lithosphere is broken into dozens of
plates (thin curved pieces). The plates are created and destroyed, move about, and interact
in ways that cause earthquakes and create major features of the continents and ocean
basins (like volcanoes, mountain belts, ocean ridges, and trenches).
THINK ABOUT IT (Key Questions):
• Is the lithosphere beneath your feet really moving? (Activity 2.1)
• What causes plate tectonics? (Activities 2.2, 2.3)
• How are plate boundaries identified? (Activities 2.4, 2.5, 2.6, 2.7)
• How and at what rates does plate tectonics affect earth’s surface?
(Activities 2.4, 2.5, 2.6, 2.7)
• What are hot spots, and how do they help us explain plate tectonics?
(Activity 2.8)
• How and where does magma form? (Activity 2.9)
STUDENT MATERIALS
(Remind students to bring items you check below.)
_____ laboratory manual with worksheets linked to the assigned activities
_____ computer with Internet access (Activities 2.1 and 2.8 only)
_____ laboratory notebook
_____ pencil with eraser
_____ metric ruler (cut from GeoTools sheet 1 or 2)
_____ protractor (cut from GeoTools sheet 4)
_____ calculator
_____ plastic ruler or popsicle stick (Activity 1.2)
_____ colored pencils (red and blue)
_____ visual estimation of percent chart (cut from GeoTools sheet 1 or 2)
INSTRUCTOR MATERIALS
(Check off items you will need to provide.)
ACTIVITY 2.1: Plate Motion Inquiry Using GPS Time-Series
_____ extra metric rulers (for students who forgot them)
24
ACTIVITY 2.2: Is Plate Tectonics Caused by a Change in Earth’s Size?
_____ extra metric rulers (for students who forgot them)
ACTIVITY 2.3: Lava Lamp Model of Earth
_____ extra blue pencils (for students who forgot them)
_____ extra red pencils (for students who forgot them)
_____ extra plastic rulers or popsicle sticks, so each student has one
_____ Silly Putty TM
_____ lava lamp (turned on at least one hour ahead of time) and/or lava lamp
video clip
ACTIVITY 2.4: Paleomagnetic Stripes and Seafloor Spreading
_____ extra metric rulers (for students who forgot them)
ACTIVITY 2.5: Atlantic Seafloor Spreading
_____ extra metric rulers (for students who forgot them)
_____ extra blue pencils or pens (for students who forgot them)
_____ extra red pencils or pens (for students who forgot them)
ACTIVITY 2.6: Using Earthquakes to Identify Plate Boundaries
_____ extra metric rulers (for students who forgot them)
_____ extra red pencils or pens (for students who forgot them)
ACTIVITY 2.7: San Andreas Transform-Boundary Plate Motions
_____ extra metric rulers (for students who forgot them)
ACTIVITY 2.8: Hot Spots and Plate Motions
_____ extra metric rulers (for students who forgot them)
ACTIVITY 2.9: The Origin of Magma
_____ extra metric rulers (for students who forgot them)
_____ hot plate (one per group of students)
_____ sugar cubes (two per group of students)
_____ dropper with water or dropper bottle (one per group of students)
_____ aluminum foil (one sheet per group of students) or foil baking cups (two
per group of students)
_____ crucible tongs (one per group of students)
_____ permanent felt-tip marker (one per group of student)
INSTRUCTOR NOTES AND REFERENCES
1. Metric and International System of Units (SI): refer to laboratory manual page xi.
2. Mathematical conversions: refer to laboratory manual page xii.
25
3. To model Kinetic Theory, place small plastic or glass marbles in a clear plastic box or
tray on an overhead projector. Hold the model still and elevated at one end, so the
marbles form a close-packed array resembling a crystalline solid structure. Vibrate
the model slightly to model a rise in kinetic energy and to start moving the marbles
apart, as if melting is initiating. Vibrate the model more to model a greater rise in
kinetic energy and to cause all of the marbles to move about independently, as if total
melting or vaporization has occurred. (To model crystallization by decreasing kinetic
energy, repeat these tasks in reverse.) Note: be sure to remind students that plumes of
Earth’s mantle are rock, not liquid magma or lava.
4. One lava lamp, or two, or three? Most lava lamps must be lighted for at least one hour
before they exhibit active and obvious convection. It helps to have two or more lamps
that have been turned on at different times, so the “lava” (wax) has varying amounts
of kinetic energy. This helps students understand kinetic theory and how unequal
amounts of heating affect the development and rate of convection. A lava lamp video
clip is provided on the IRC-DVD. Note: be sure to remind students that Earth’s
mantle is rock, not liquid magma or lava.
5. Decompression melting. To help students visualize decompression melting, have
them mix corn starch and water to make a corn starch suspension. Then have them try
to roll some of the suspension into a ball and watch the suspension flow through their
fingers. So long as the suspension is under pressure (i.e., while it is being rolled into a
ball), it remains in a solid-like state. When the suspension is not under pressure (i.e.,
when a ball of suspension is placed on the palm of a hand), it flows in a liquid state.
This is NOT decompression melting, but it helps students understand that pressure
can prevent flowing even in materials that are normally fluid.
6. To model mantle plumes and hot spots, make a model of Earth’s compositional
layering first by placing clear corn syrup in a clear plastic cup (to represent Earth’s
mantle) and then by adding a few mm of water on top of it (to represent Earth’s
crust). To prepare material for a mantle plume, heat a small amount of corn syrup
(with a few drops of red food coloring) on a hot plate. Fill a dropper with the hot red
corn syrup, and then squeeze some of it out onto the bottom of the plastic cup
containing the cool syrup and water. Watch as the hot red corn syrup rises through the
cooler corn syrup to form a long narrow plume and a pool of red syrup just beneath
the water (crust). This is especially useful for having students entertain ideas about
the origin of hot spots.
7. Flux melting. In the smelting industry, the term “flux” refers to materials such as
“fluxstone” that are added to raw ore in order to lower the fusion (melting)
temperature and produce slag. Experimental petrology has demonstrated that water
lowers the fusion temperature of some minerals commonly found in granite, basalt,
and peridotite, thereby initiating partial melting at lower, “wet solidus” temperatures.
26
8. Water in Earth's mantle. For information on recycling of water into Earth's mantle,
refer to: C. Meade and R. Jeanloz. 1991. Deep-focus earthquakes and recycling of
water into Earth's mantle. Science 252:68–72.
9. San Andreas fault slip rate.
For a published estimate of the recurrence interval for very large earthquakes
along the San Andreas fault north of San Francisco (221 +/– 40 yr), see: T.M. Niemi
and N.T. Hall. 1992. Late Holocene slip rate and recurrence of great earthquakes on
the San Andreas fault in northern California. Geology 20:195–198. During the
recurrence interval, the accumulated strain would be about 3.2 m (10 ft). However,
Niemi and Hall (1992) also estimated that the Late Holocene rate of movement on the
fault is about 2.4 cm/yr.
For a published estimate of the recurrence interval for very large earthquakes
along the San Andreas fault zone 70 km northeast of Los Angeles, California, see:
T.E. Fumal, S.K. Pezzopane R.J. Weldon II, and D.P. Schwartz. 1993. A 100-Year
Average Recurrence Interval for the San Andreas Fault at Wrightwood, California.
Science 259:199–203. They calculated a recurrence interval of about 100 years, a slip
rate of about 2.5 cm per year, and a slip per very large earthquake of about 4 meters.
LAB 2 ANSWER KEY
ACTIVITY 2.1: Plate Motion Inquiry Using GPS Time-Series
2.1A. Answers will vary. For example, although most students in the United States live
on the North American Plate, some live on the Pacific Plate.
2.1B. Answers will vary and must be checked on an individual basis.
27
2.1C. Students will have some difficulty generalizing about the general motion of North
America and South America, but most will agree on the general motion of Africa
and Europe.
2.1D. Reflect and Discuss: Most discussions of plate tectonics describe how the
Atlantic Ocean is developed around a divergent plate boundary (Atlantic Mid-
Ocean Ridge), so North America and South America are moving away from
Europe and Africa. The generalized plate motion vectors above (black arrows)
seem to confirm that. Therefore, students generally use the above map to say that
it supports the Plate Tectonic Theory.
ACTIVITY 2.2: Is Plate Tectonics Caused by a Change in
Earth’s Size?
2.2A.
28
2.2B.
2.2C. 1.
2. Some students will notice that the percentages of convergent and divergent
boundaries is nearly equal and that the percentage of transform boundaries is a
bit less. However, most will conclude that there is roughly one-third of each
kind of plate boundary and that Earth’s size is staying about the same.
3. 510,000,000 km2 ÷ 3.4 km 2 /yr = 150,000,000 yr (or 1.5 x 107 yr)
2.2D. Reflect and Discuss: Based on the answers to questions above, there is evidence
for about equal amounts of crustal compression, tension, and shear. Thus, it seems
reasonable that Earth’s size is not changing (i.e., Earth is staying about the same),
and plate tectonics is not driven by a change in Earth’s size. Some students will
come to the likely conclusion that for Earth to remain the same size, there must be
mantle convection, whereby lithosphere is created at divergent boundaries,
recycled back into the mantle at convergent boundaries, and neither created nor
recycled at transform boundaries. Most students will know about Earth’s hot
interior and will at least suggest that it is processes inside of Earth that are causing
its change in size. Their descriptions of those processes will vary widely, and
should not be graded with one strict answer in mind at this point. Their
conceptions serve as working hypotheses for future parts of the lab.
29
ACTIVITY 2.3: Lava Lamp Model of Earth
2.3A. 1. See the completed table below.
2. Rheidity is the time it takes for a solid material under stress to lose its elasticbrittle
behavior, entirely, and just permanently deform (flow) like a viscous
fluid. So a rheid is a solid material that can change from viscoelastic behavior
to just viscous behavior. Silly Putty has such behavior, so it is a rheid.
3. Reflect and Discuss: Brittle solid rocks of the lithosphere may exhibit viscoelastic
behavior and even shatter when they exceed their elastic limit (as in an
earthquake). However, when the same rocks subduct into the mantle and are
subjected to intense forces over long periods of time (and are hot), they can
flow as a viscous fluid.
2.3B. Students must observe a convecting lava lamp (that has been heating at least one
hour) or a movie clip of a convecting lava lamp to answer these questions.
1. The “lava” moves from the base of the lamp to the top of the lamp, where it
sits temporarily before sinking back to the bottom of the lamp.
2. Lava at the base of the lamp is heated by the light bulb. As the lava is heated,
its kinetic energy level rises, which causes the lava to expand to a slightly
greater volume and lower density. When the density of lava is less than the
surrounding fluid, the lava rises.
3. Lava at the top of the lamp is cooling. As it cools, its kinetic energy level
decreases, which causes the lava to contract into slightly less volume and
higher density. When the density of lava is greater than the surrounding fluid,
the lava sinks.
4. convection
30
2.3C. 1. Earth’s mantle is like a lava lamp, because:
• mantle rocks are unequally heated like lava in the lava lamp.
• mantle rocks are heated at the base of the mantle, like lava in a lava lamp
is heated at the base of the lava lamp.
• it has warmer rocks that rise like lava in a lava lamp.
• it has cooler rocks that sit atop the mantle or sink back into the mantle, like
the masses of cooling lava at the top of the lava lamp.
2. Earth’s mantle is different from a lava lamp, because:
• the mantle is rock, not lava or wax.
• the mantle is heated by Earth’s outer core, but the lava lamp is heated by a
light bulb.
• the mantle convects more slowly (i.e., cm/year) than the lava lamp
(cm/second or cm/minute).
2.3D. By comparing lab manual Figures 2.4 and 2.3, students should observe that:
1. the warmer, less dense mantle rocks (red in Figure 2.6) mostly occur beneath
divergent plate boundaries and hot spots.
2. the cooler, denser mantle rocks (blue in Figure 2.6) mostly occur beneath
continents.
2.3E. Reflect and Discuss: The nature and detail of student cross sections will vary, but
it should be at least a labeled, simple sketch like the one below.
31
ACTIVITY