Download Modeling Earth Interior

Amy Wagner
Modeling Earth’s Inerior
RL Moore Submission 2011
Lab Title: Modeling Earth’s Interior
Purpose: To calculate density and relate it to Earth’s interior layers. To construct a model of Earth using an appropriate
scale. To generate a graph that depicts Earth’s gradient and draw conclusions from the graph.
Materials: Density cubes (Copper, Brass, Aluminum, and Steel), ruler, Play Doh (four different colors), plastic knife,
string, triple beam balance, Microsoft Excel
Background:
Three centuries ago, the English scientist Isaac Newton calculated, from his studies of planets and the forces of gravity,
that the average density of the Earth is twice that of surface rocks and therefore that the Earth's interior must be
composed of much denser material. Our knowledge of what's inside the Earth has improved immensely since Newton's
time, but his estimate of the density remains essentially unchanged. Our current information comes from studies of the
paths and characteristics of earthquake waves traveling through the Earth, as well as from laboratory experiments on
surface minerals and rocks at high pressure and temperature. Other important data on the Earth's interior comes from
geological observation of surface rocks and studies of the Earth's motions in the Solar System, its gravity and magnetic
fields, and the flow of heat from inside the Earth.
The planet Earth is made up of three main shells: the very thin, brittle crust, the mantle, and the core; the mantle and
core are each divided into two parts. Although the core and mantle are about equal in thickness, the core actually forms
only 15 percent of the Earth's volume, whereas the mantle occupies 84 percent. The crust makes up the remaining 1
percent. Our knowledge of the layering and chemical composition of the Earth is steadily being improved by earth
scientists doing laboratory experiments on rocks at high pressure and analyzing earthquake records on computers.
Part I: Density of Earth’s Layers
Procedure:
1. Draw the Density Data Table (on the back of this page) in your composition notebook with a ruler. Make sure that you
include the title of the table.
2. The technician will obtain one of each of the four density cubes (Copper, Aluminum, Steel and Brass). Use the triple
beam balance to measure the mass of the object. Record this information in your data table.
3. The maintenance director will use a ruler to determine the volume of the cube in cubic centimeters. Round numbers to
the tenths place. Record this information in your data table.
4. Use the information collected to determine density and the layer of the earth represented.
5. Work with group members to answer the questions below the data table. Record your answer in your composition
notebook using complete sentences.
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Amy Wagner
Modeling Earth’s Inerior
RL Moore Submission 2011
Density Data Table
Density Cube
Mass (g)
Volume (cm3)
Density (g/cm3)
Layer of Earth
Represented
Copper
1
Aluminum
2
Steel
3
Brass
4
*Use the internet to find the actual densities of Earth’s layers and determine which layer each cube represents.*
Use complete sentences to answer the following question.
1.
What trend do you notice in the density of Earth’s layers?
____________________________________________________________________________________
____________________________________________________________________________________
2.
Why do Earth’s layers vary in density? How do you think they got this way?
____________________________________________________________________________________
____________________________________________________________________________________
3.
How do you think scientists were able to determine what the composition of Earth’s layers?
____________________________________________________________________________________
____________________________________________________________________________________
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Amy Wagner
Modeling Earth’s Inerior
RL Moore Submission 2011
Part II: Model of Earth’s Depth
Background:
The Earth's structure, scale and our place on it can be difficult to comprehend. Today we will use Play Doh to create a
physical model. We will also scale the data to make an accurate model of Earth.
At times it is difficult to visualize the relationships among numbers if they are in an inconvenient form or very big like
Earth. The data table on the left contains a list of measurements. This raw data can be converted into a form that is
easier to understand by dividing all the measurements by the value of the smallest (as shown in the table below). This
process is called normalizing the data. Now it is easier to see the third measurement is 19 times larger than the first
measurement.
Raw Data (mm)
Divided by
= Normalized data
0.0625
0.0625
1
0.125
0.0625
2
1.1875
0.0625
19
0.875
0.0625
14
Procedure:
1. Draw the “Calculated Measurements” Data Table in your composition notebook with a ruler. Be sure to include the title
of the data table.
2. Have the principle investigate obtain four different colors of Play Doh. The principle investigator should mass out the
amount proper amount of Play Doh for each layer- consult the data table. The measurement (grams) must be exact.
Return remaining clay.
3. Use the Play Doh you have massed to create a model of the earth and it’s layers.
4. Mass your model and measure the circumference of your model. Record this in your composition notebook.
5. Use plastic knife to cut Earth model in half.
6. Scale or normalize the data for the layer thickness of their model. Record in the “Calculated Measurements” data
table that you create in your composition notebook with a ruler. Below is a data table that models how you normalize
data.
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Amy Wagner
Modeling Earth’s Inerior
RL Moore Submission 2011
Earth’s Layers Measurement Data Table
Actual Depth
Actual Volume
(km)
(x 109 km3)
Inner core
1216
7.5
2
Outer core
2270
170
46
Mantle
2885
906
242
Crust
5 to 20
21
6
Layer
Mass of clay in model (g)
Calculated Measurements
Layer
Clay color used
Actual layer
Actual layer depth
Layer in model
Layer thickness of
in your model
depth (km)
(normalized)
depth in (mm)
model (normalized)
Inner core
1216
Outer core
2270
Mantle
2885
Crust
25
Analyzing Data
String may be used to measure the circumference.
a. Mass of Earth Model __________ g
b. Circumference of Earth Model________ cm
1.
How does the data you collected from your model compare to Earth’s actual mass and circumference? (You may
refer to the figure on Page 2 of the lab to help you.)
2.
Is the model you made an accurate representation of Earth’s internal layers, why or why not. Be sure to fully
explain your answer.
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Amy Wagner
3.
Modeling Earth’s Inerior
RL Moore Submission 2011
What is something you learned about Earth’s internal layers by creating this model that you did not know
before?
Part III: Modeling the Geothermal Gradient in Earth’s Crust
Information:
The geothermal gradient is the rate of increasing temperature with respect to increasing depth in the Earth's interior.
Earth has different geothermal gradients based on the tectonic activity of aregion. In most areas of Earth the normal
geothermal gradient is 25 °C/km. In different areas, where there are increased tectonic activities, such as a rift zone or
divergent boundary, like the Mid Ocean Ridge, the gradient is 100 °C /km and a volcanic island arc such as Japan is 40
°C/km
Geologic Setting
Normal
Mid Ocean Ridge (Iceland)
Volcanic Island Arc (Japan)
Geothermal Gradient (°C/km)
25
100
40
Directions: (Use the data table on the back of this page as you work through the steps below).
1. Working with a partner use Excel and create the data table of your geothermal gradient using a depth of 0 through
value found in the data table (25 km). Plot the geothermal gradient of all three different geologic settings (normal
gradient and rift zone or volcanic island arc). Use an interval of 1 km on the x – axis.
2. Create a Scatter Plot type graph of Geothermal Gradient.
3. Title of Graph = Geothermal Gradient of Earth’s Crust, X axis = Depth (km), Y axis = Temperature ( oC)
4. Email a copy of your graph to your instructor.
Questions:
1. What is the relationship between temperature and depth?
2. Why is there so much heat beneath the surface of the Earth? (How was/is this heat created? Explain and give
multiple examples.)
3. What are some ways in which the Earth releases its thermal energy?
4. What trend or trends have you noticed about the geothermal gradients you have graphed?
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Amy Wagner
Modeling Earth’s Inerior
RL Moore Submission 2011
Depth
Depth (km)
Normal (25 C/km)
0
0
Rift Zone (80 C/km)
Mid Ocean Ridge (100 C/km)
0
0
1
25
80
100
2
50
160
200
3
75
240
300
4
4 x 25 =
4 x 80 =
4 x 100 =
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
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Amy Wagner
Modeling Earth’s Inerior
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RL Moore Submission 2011
Amy Wagner
Modeling Earth’s Inerior
RL Moore Submission 2011
Earth's Structure Misconceptions
1. Crust and Lithosphere (or plates) are synonymous terms
2. Asthenosphere is liquid (students are only familiar with liquid convection, not solid convection,
many secondary education earth science films also specifically refer to a molten internal layer,
and some fundamentalist religious groups specifically refer to the existence of a molten layer
that is hell's physical location).
3. Lower Mantle is liquid (for reasons similar to above).
4. Earth's core is hollow, or that large hollow spaces occur deep within Earth (a relict of older
cosmology and a mainstay of popular literature and Hollywood movies)
The Core
Summary:
The Earth's outer core has stopped rotating. The result is disruptions in the planet's electromagnetic
field, massive and dangerous electrical storms, and powerful solar generated microwaves that are
capable of melting the Golden Gate Bridge and which eventually will "cook" planet Earth.
In order to restart the liquid outer core's rotation a group of 'terranauts' must drill through the
Earth's crust and mantle then set off nuclear bombs to initiate core movement. Dr. Brazzleton has
developed a way to drill through rock using ultrasound waves. They make the journey to the inner
core in a craft named Virgil, which is capable of drilling through the hard and dense mantle rocks.
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Amy Wagner
Modeling Earth’s Inerior
Plate Boundaries
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RL Moore Submission 2011