Earth Science
Earth Dimensions Unit
Time: 117 minutes
Name___________________________________
Period ___ Start Date___________
Due Date __________
Planet Earth in Cross Section
Introduction:
Planet Earth is organized into layers of varying thickness. In this lab a model of the layers of the
earth will be constructed to scale using cash register tape. The tape will represent a “column” of the Earth
from its center to the outermost portion of its atmosphere. This cross-section model will be constructed to a
scale of 1 centimeter on the model equals to 100 kilometers on the actual Earth. NOTE: At this scale
one centimeter of register tape equals 100 kilometers. The average width of a line drawn by a sharp pencil
varies from 0.05cm to 0.08 cm. Therefore the width of a pencil used to draw layers will range in scale from
5 to 8 kilometers. How do you think this will affect your lab?
Background Information:
This solid, rocky planet becomes denser as one travels into its interior. Gravity has caused the planet
to differentiate, meaning that denser materials have been pulled towards Earth’s center. Relatively less
dense material migrates to the surface.
Ultramafic is a term used to describe rocks rich in iron and magnesium. These rocks are very dense.
Felsic is a term used to describe rocks rich in aluminum. These rocks are less dense.
What follows is a brief description of each layer beginning at the center of the Earth and working out
towards the atmosphere.
Inner Core – The solid, innermost sphere of the Earth. Examination of meteorites has led geologists to
infer that the inner core is composed of iron and nickel.
Outer Core – A layer surrounding the inner core which has the properties of a liquid. May be composed of
iron.
Mantle – A solid layer of ultra-mafic rock located below the crust. This is the thickest layer of the earth.
Asthenosphere – a partially melted layer of ultra-mafic rock in the mantle situated below the lithosphere.
Tectonic plates slide along this layer.
Lithosphere – The solid outer portion of the Earth that is capable of movement. The lithosphere is a rock
layer composed of the crust (felsic continental crust and mafic ocean crust) and the portion of the
mafic upper mantle situated above the asthenosphere.
Hydrosphere – Refers to the water portion at or near Earth’s surface. The hydrosphere is primarily
composed of oceans, but also includes, lakes, streams and groundwater.
Atmosphere – the layer of gas that surrounds our planet. Earth’s atmosphere is composed primarily of
nitrogen and is broken down into distinctive layers based on temperature profiles.
Troposphere – A 10 to 12-kilometer layer of the atmosphere next to the earth’s surface in which
temperature generally decreases rapidly with altitude and clouds form. Consists mostly of nitrogen
and oxygen.
Stratosphere – The layer above the troposphere in which temperature increases with an increase in
elevation. The stratosphere contains the ozone layer.
Mesophere – The layer above the stratosphere in which temperature decreases with altitude.
Thermosphere – The outermost layer of the atmosphere located above the mesosphere. In this layer,
temperature rapidly increases with altitude.
ES Planet Earth in Cross Section 10.2012
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Procedure:
1. Calculate the scale distances for the solid portion of the Earth and record in the table below.
To do this, divide the average thickness of a layer by 100 and ROUND TO THE NEAREST
TENTH. Scale: 1cm on the model = 100km on the actual earth.
Example: The radius of the inner core is 1271 km. Thus1271 km/100 equals a 12.7 cm
thick layer drawn on the register tape. Below is my mathematical explanation:
Set-up a
proportion
1 𝑐𝑚
100𝑘𝑚
=
?𝑐𝑚
1271𝑘𝑚
by 100km:
cross multiply so that: 100km(cm) = 1cm(1271km) now divide both sides
100km(cm)
100𝑘𝑚
=
1cm(1271km)
100𝑘𝑚
notice that the units cancel leaving 12.7cm.
Practice the mathematical explanation for these scale calculations.
Write the scale distances for all the layers in Data Table A in the Data section of the lab.
2. Refer to page 10 of the ESRT. Find the temperature at 1000 km intervals (1000, 2000,
3000, 4000, 5000, 6000). Complete the data table B in the data section of the lab.
3. Cut a 100 cm piece of register tape. You may wish to secure each end of the register tape
with masking tape.
4. Use a ruler and neatly draw a line perpendicular to the length of the tape 10 centimeters
from the left end, write your name in the space. This will be the center for the Earth.
Each layer will be measured from the new line you drew. See example below.
Center of Earth
10cm
Inner
Core
Outer
Core
Mantle
Register
tape
5. Using a pencil mark ALL of the layers of the Earth onto the register tape based on your
calculations in Data Table A. Begin from the center of the earth and add each successive
layer in order. Label each layer. Make thin pencil lines if needed. Use an arrow if you
cannot fit the word label on the line, as I have shown on the above example.
6. Refer to the background information on page one, and label onto the model the
composition of the inner core, outer core, mantle, asthenosphere and
lithosphere, ONLY. Composition example: the inner core is composed of iron and nickel.
7. Refer to the background information on page one, and label onto the model, liquid, gas or
solid for the inner core, outer core, mantle, asthenosphere and lithosphere,
ONLY.
8. Label onto the model the density of the inner core, outer core and mantle, ONLY.
Refer to page 10 of the ESRT.
9. Use Data Table B for your data and mark the temperature on the top edge of the paper
tape at 1000 km intervals. NOTE: When measuring, start at the boundary between
lithosphere/troposphere and measure deeper into the Earth’s layer.
ES Planet Earth in Cross Section 10.2012
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10. Color neatly, the inner core yellow, the outer core orange, the mantle red, the
asthenosphere light brown and leave the lithosphere white. Color the troposphere green,
the stratosphere light blue, the mesosphere dark blue and thermosphere violet. Color the
remaining space black.
Data Table A
Atmosphere
“Solid” Earth
Layer
Avg. Thickness
Inner Core
1271 km
Outer Core
2270 km
Mantle
2885 km
Asthenosphere
200 km
Lithosphere
100 km
Troposphere
12 km
Stratosphere
50 km
Mesosphere
80 km
Thermosphere
140 km
Scale in Centimeters
(cm)
Data Table B
Depth below
lithosphere/troposphere
boundary (km)
Scale
Distance
(cm)
Temperature
(C)
1000
2000
3000
4000
5000
6000
ES Planet Earth in Cross Section 10.2012
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Staple your paper model to the last page of this lab so that the paper un-folds, yet is
attached.
Questions:
1. List the layers of the solid Earth from least dense to most dense.
2. The actual average radius of the Earth is 6,378 km. A student found the radius
of the Earth to be 6730km, calculate the percent error of the student. Show the
E.S.A. below. Use your ESRT for the equation. Include both values in your
substitution numerator.
3. Mount Everest is the tallest mountain on Earth, rising 8.85 km above sea level.
How high (in centimeters) would Mount Everest appear on your register tape
model? Show your mathematical reasoning (example a proportion), include
units.
4. What causes the layers of the Earth to be ordered by density? Explain.
ES Planet Earth in Cross Section 10.2012
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