Investigating Seafloor Spreading
Original Source: Dr. Leslie Sautter (Dept. of Geology, College of Charleston)
Grade Level:
SC Standards:
National Standards:
8th
IIIB3a,b,c,j,k; IIIB4c
Earth and Space Science Content Standard D
Focus Questions
should be at least 20 cm, but does not have
to be any specific length.
tape (any kind)
scissors
metric measuring device
crayons, paint, or markers – 6 colors (red,
orange, yellow, green, blue, violet)
graph paper (divisible by tenths)
1 cardboard tube, cut to the width of the
seafloor model’s paper (at least). Mailing
tubes or wrapping paper tubes work well.
small sample of basalt (if available)
For the Teacher:
overhead transparencies of Figures 1-4
from TEACHER PAGES
overhead transparencies of Tables 1-6 and
Graph 1 from STUDENT PAGES
overhead transparencies of Tables 1-6 and
Graph 1 from Teacher Answer Key
(optional), from TEACHER PAGES
Why isn’t the entire seafloor the same age?
How can seafloor age increase as distance
increases from a mid-ocean ridge?
What do the age differences of the ocean
floor tell us about motion of the seafloor?
Objectives
Students will:
calculate and graph the variable rates of
seafloor spreading through time, using a
seafloor model.
learn the concept of seafloor spreading.
describe the processes involved in creating
new seafloor at a mid-ocean ridge.
Key Words
mid-ocean ridge
magma, molten rock
basalt, igneous rock, mafic
oceanic crust
fissure
plate, lithosphere
divergence, divergent plate boundary
plate rate
seafloor spreading
tensional forces
Time Frame
One to two 50-minute class periods, depending
on how much of the construction of the seafloor
model and graphing is assigned as homework.
Suggested Learning Environment
Collaborative learning groups of 2-4 are
recommended, depending on amount of materials
available. At least two complete models (i.e.,
constructed by two collaborative groups) will be
required for later portions of the activity.
Materials
Per student group:
photocopies of STUDENT PAGES.
sheet of white paper (from banner roll),
~150 cm long, and at least 40 cm wide
corrugated cardboard. One edge of the
cardboard should be the same width as the
white paper. The length of the other edge
Relevant pages in Of Sand and Sea
Chapter I, The Ocean Planet, pp. 9-13
COASTeam Program, Project Oceanica, College of Charleston
1
Investigating Seafloor Spreading
TEACHER PAGES
Teacher Preparation
Borders between colors do not need to be
perfectly straight as shown in the figure, but
they should be perpendicular to the paper’s long
edge.
 Project Figure 1 to help guide the students.
 Here is where students could be assigned
Students will construct a model of a fictitious ocean
that is 4,600 km wide and 180 million years old.
Using this model, students will calculate halfseafloor plate rates as well as full-ocean seafloor
spreading rates based on the data provided. They
will also graph and summarize their results. The
seafloor spreading rates that will be calculated are
similar to rates found in several ocean basins,
including the Atlantic and Indian Oceans.
the time-consuming coloring duties as
homework.
2. Label each boundary between color bands with
the appropriate rock age in millions of years
(m.y.). Widths of the color bands vary (some
are narrow, some are very wide).
This activity may be confusing unless the teacher
has reviewed the material in advance and guides the
students through the process.
Using units of m.y.:
Units of “million years”, or “m.y.” are used to
avoid having long numbers with 7 or more digits,
as with 1,000,000 yr (or “one million years”).
Students should be familiar with converting from
kilometers (km) to centimeters (cm). The teacher
will need to review the conversion prior to
conducting the activity.
For example 23,000,000 yr would be expressed
as 23.00 m.y., and
131,530,000 yr = 131.53 m.y.
Students should also understand how to use the
seafloor model’s scale to calculate the distances of
the ocean floor the model represents (see Table 2).
What is 46.78 m.y. expressed in “yr”?
46.78 m.y. = ______________ yr
 The answer is 46,780,000 yr.
 Be sure that students understand how to
Procedure
use the units of “m.y.”
The steps that follow are included in the STUDENT
PAGES. Additional information on the TEACHER
PAGES is included in blue italics.
3. Trim the paper about 5-7 cm beyond the edge
of the violet color band, so that the total length
of the paper is about 100 cm, or 1 m in length
(including the white edge at the end).
Part I: Constructing the Seafloor Model
(The teacher may assign a portion of the
construction as homework to save class time.)
1.
4. Cut the paper down the middle of its length, so
that you have two striped strips that are nearly
identical to one another. Each piece represents
a “half-seafloor.”
 Be sure students cut the paper along its
Your teacher will show on the overhead
projector an illustration of the seafloor model
for you to use as a guide for creating the model
(Figure 1). Look at Table 1 and use the data
from the “Width of Color Band on Paper”
(column a) to mark and color one of the long
sheets of white paper provided by your teacher.
length.
5. Cut the corrugated cardboard into two pieces so
that one edge of each piece is equal to the
COASTeam Program, Project Oceanica, College of Charleston
2
Investigating Seafloor Spreading
TEACHER PAGES
striped paper’s width (Figure 1, on the overhead
projector).
 Figure 1 should be projected again.
were dated to be less than 1 million years old (1
m.y.). The type of rock collected was basalt.
9. Your teacher may provide you with a sample of
basalt. Basalt is a black igneous rock with small
crystals that can rarely be seen by the naked
eye. Examine the sample provided by your
teacher.
6. Tape the cut edge of a cardboard piece to the
white end of one paper sheet. The paper should
be taped under the cardboard to hide the white
edge, so that the violet color band is adjacent
to the edge of the cardboard.
Repeat for the other piece of cardboard and
striped paper.

If students have not yet studied igneous rocks,
you may opt to skip the questions associated
with this step.
a.
7. Cut the cardboard tube so that the two pieces
are the widths of the half-seafloors. Tape the
other red end of each striped paper to a
cardboard tube (refer again to the projected
figure).

How is an igneous rock formed?
Igneous rocks are formed by the cooling and
crystallization of a magma.
b. What do the small crystal sizes of basalt
tell you about how it cooled?

What does your model represent?
You have now created two “half-seafloors” that are
nearly identical to one another. The color bands
indicate seafloor of varying ages (see Table 1).
Each color band represents rocks with ages that
range over a segment of time. For example, the
YELLOW color band is made of seafloor rock with
ages ranging from 40.10 to 67.70 million years old.
c.
Small crystal sizes indicate that the magma
cooled rapidly, preventing large growth of
crystals.
What does the dark color of basalt tell you
about its composition?
 Igneous rocks that are rich in iron (Fe) and
magnesium (Mg) are typically dark gray to
black. We call these rocks mafic igneous
rocks.
The cardboard pieces represent continents and the
cardboard tubes, are located at the model’s midocean ridge. When the two half-seafloors are
laid out together, with the mid-ocean ridge in the
middles and the continents on the ends, they will
represent a complete “slice” of an ocean basin that
is bounded by continents.
As rocks were collected farther from the ridge,
scientists discovered that basalt ages were
increasingly older. Eventually, enough data were
collected to construct a map similar to the striped
paper model.
10. As a class, decide what to name your ocean
basin, and label your seafloor model. Everyone
in the class has a “slice” of the same ocean
basin.
 This step is useful for the evaluation portion of
8. On a long table, or the floor, arrange the model
“seafloor” so that the striped sheets of paper
lie end to end, with the mid-ocean ridge in the
middle and the continents at the edges (see
Figure 2, on the overhead projector).
 Project Figure 2 to help guide the students.
the activity, when students compare their model
ocean basin to the Pacific Ocean.
 Remind students that the earth has one ocean,
but there are several ocean basins.
When oceanographers began to sample the seafloor
and determine rock ages, mid-ocean ridge rocks
COASTeam Program, Project Oceanica, College of Charleston
3
Investigating Seafloor Spreading
TEACHER PAGES
It is important to know that not all plates have the
same rate of motion, so scientists calculate the rate
of each of the two half-seafloors on either side of
a mid-ocean ridge, then add them together, rather
than doubling one half-seafloor’s rate.
 Emphasize to students that the two plates on
Part II: Plate Rates and Seafloor Spreading
The seafloor of any ocean basin is the upper layer
of a plate. New seafloor – or oceanic crust – is
formed as the plate moves away from a fissure, or
large, elongate fracture in the seafloor. As the
fissure widens, magma rises up from the underlying
mantle onto the seafloor. The hot magma quickly
cools when it comes in contact with the cold
seawater, and crystallizes into solid rock along the
fissure. The mafic composition of the magma
produces a mafic igneous rock with very small
crystals (due to the rapid rate of cooling), forming
basalt.
either side of a mid-ocean ridge often have
different rates, but their model was
constructed so that the two half-seafloors have
identical rates.
11. Complete Table 1 (column d) by calculating the
“Total Seafloor Age” represented by each of
the 6 color bands of your model. These ages
are expressed in units of m.y.
The motion of two plates moving away from each
other at mid-ocean ridges is called divergence, and
results in a divergent plate boundary. This motion
is called seafloor spreading, named by the two
oceanographers who first studied it, Harold Hess
and Donald Dietz.
For example, the YELLOW color band total age
is 67.70 m.y. - 40.10 m.y. = ________ m.y.
 Refer to Teacher Answer Key, Table 1.
12. Using the information provided in Table 2,
calculate the model’s scale in the form:
1 cm = ___ km.
This scale means that 1 cm on your model is
equivalent to _______ km in the ocean it
represents.
The rate that a plate moves, or the “plate rate,”
can be determined using the formula for velocity:
where:
Rp = D/T
Rp is the plate’s rate (velocity) of motion
D is the distance from the mid-ocean ridge
T is time, or the age of the rock on the seafloor
Fill in all the blanks on Table two with the value
you calculate. The scale’s conversion factor
you will use in Table 3 is ____km/cm.
But there are two sides to this story! Divergent
plate boundaries have seafloor on both sides of the
mid-ocean ridge. In your model ocean, the two sides
of the ridge are mirror images of one another, so by
doubling the rate of one half-seafloor, the rate of
divergence, or the seafloor spreading rate of the
entire ocean basin can be calculated:
where:
 Refer to Teacher Answer Key, Table 2.
13. Using the scale’s conversion factor from Table
2, calculate the distance represented by each
color band, and complete Table 3 (column b).
Complete column c by adding the distance of
each color band to the distance from the
previous line. In other words, this number is a
cumulative distance from the mid-ocean ridge.
 Refer to Teacher Answer Key, Table 3.
Rss = 2(Rp)
Rss is the model ocean basin’s seafloor
spreading rate
Rp is the half-seafloor’s plate rate
COASTeam Program, Project Oceanica, College of Charleston
4
Investigating Seafloor Spreading
TEACHER PAGES
14. Transfer the data from Tables 1 and 3 to the
appropriate columns on Table 4 (as indicated).
Then, calculate the Half-Seafloor Plate Rate for
each color band, completing column c. Note that
rates in Table 4 should be expressed as km/m.y.
 Refer to Teacher Answer Key, Table 4.
17. Complete Table 6 (column b) by transferring the
data from Tables 3, as indicated. These data
will be used to graph the seafloor’s velocity
(rate).
 Refer to Teacher Answer Key, Table 6.
18. Using the data from Table 6, plot your data on
Graph 1 with “distance from ridge (km)” on the
y-axis (the independent variable) and “age of
seafloor (m.y.)” on the x-axis (the dependent
variable).
 Kilometers and millions of years are used when
15. Because seafloor motion occurs at a rate similar
to the growth of fingernails (and faster!),
oceanographers most often use the units cm/yr.
Thus, the data from Table 4 must be converted
so that the units are cm/yr. For example, if you
have calculated a rate of 40 km/m.y., the
conversion would be as shown below.
plotting these data, so the numbers are not so
large.
a.
40 km =
40,000 m = 4,000,000 cm = 4 cm
1 m.y.
1,000,000 yr
1,000,000 yr
1 yr
Answer: 40 km/my = 4 cm/yr
b. Note that both axes are labeled, including
the units used.
 Students may need assistance with the
conversion from km/m.y. to cm/yr, as shown in
c.
the example above.
 Remember that there are 1000 m in a kilometer
and 100 cm in a meter.
a.
Connect data points with a line, starting at
the origin (0,0).
 Refer to Teacher Answer Key, Graph 1.
19. Compare your graph with the Half-Seafloor
Plate Rate data from Table 4 (column c). In
your science notebook answer the following
questions:
Convert your data from Table 4 to complete
Table 5 (columns a, b, and c).
 Refer to Teacher Answer Key, Table 5.
16. For the model seafloor in this activity, the
“seafloor spreading rate” is twice (2x) the halfseafloor “plate rate.”
a.
Be sure to include the zero point, as it
represents the mid-ocean ridge, where
distance = 0 km, and age = 0 m.y.
a.
What does the slope of each line segment on
your graph represent?
 The slope of each line segment represents
D/T or velocity (plate rate).
Complete Table 5 (column d) by calculating
the Seafloor Spreading Rate during each
color band. Now your units are cm/yr.
b. If one segment of the line is steeper than
the other, what does that mean?
 It means that the plate rate was faster for
 Refer to Teacher Answer Key, Table 5.
that period of time.
Again, in real ocean basins, rate of motion for each
plate must be determined separately, and added
together to calculate the ocean’s spreading, or
growth rate.
c.
Based on your data, did the rate of seafloor
spreading remain constant through time?
How do you know?
COASTeam Program, Project Oceanica, College of Charleston
5
Investigating Seafloor Spreading
TEACHER PAGES
 The line segments vary in slope (on the
graph), indicating that the plate rate was
not constant through time.
Part III: Simulating Seafloor Spreading
20. Roll up each half-seafloor until the cardboard
continent is reached. Place a wooden dowel
through each of the 2 half-seafloor tubes.
d. How old is your model ocean?
 The model ocean is 180 m.y. old.
e.
Four students are needed to demonstrate the
process of seafloor spreading. Select your
group.
What is the distance from the ridge to the
continent (in km) for your half-seafloor?
 The distance is 2300 km (represented on
the model by 92 cm).
f.
Arrange the two half-seafloor rolls with the
dowels as shown in Figure 3a (not as shown in
Fig. 3b!). Two students face each other, and
each holds the ends of two dowels.
What is the overall average rate of seafloor
spreading for the half-seafloor? Express
your answer first in km/m.y., then in cm/yr.
 Make sure that students have their paper rolls
 To calculate the average rate, students
oriented as shown in Figure 3a, not as shown in
Figure 3b.
should divide the total distance (ridge to
continent) by the total amount of time (age).
Thus, the answer is
2300km/180m.y. = 12.78 km/m.y.
or
230,000,000cm/180,000,000yr = 1.28 cm/yr
g.
A third and fourth student each hold the end of
one of the continental pieces. Place the edges
of the two continental pieces together, with the
paper rolled up beneath them, hidden from the
surface.
What is the average rate of seafloor
spreading for the entire ocean basin?
21. Before unrolling the seafloor, simulate the
initial rifting (fracturing) of the continent to
produce a small fissure (only 4-6 inches wide).
Violet paper should be exposed in the fissure.
 Students should multiply the answer for the
half-seafloor (previous question) by 2.
Thus, the answer is
2 x 1.28 cm/yr = 2.56 cm/yr
A fissure is an elongate fracture. When a
fissure occurs, the heated rock below melts
(due to the release of pressure) to form magma.
The magma rises to fill in the crack. The
composition of the magma is mafic. As the
magma cools and crystallizes, basalt is formed.
a. Explain what the violet paper represents.
b. Based on your data table, how old is the
rock that was originally formed when the
fissure was produced?
 The violet paper represents seafloor that is
h. Seafloor spreading rates of the North
Atlantic Ocean have varied between 2 and 4
cm/yr, whereas the East Pacific Rise in the
Pacific Ocean has a rate of over 10 cm/yr.
How does your model ocean compare with
these actual spreading rate averages?
 The model most closely approximates the
North Atlantic.
180 million years old, or formed 180 m.y.a.
 The seafloor formed at the fissure is
composed of basalt.
COASTeam Program, Project Oceanica, College of Charleston
6
Investigating Seafloor Spreading
TEACHER PAGES
22. Continue to “create new seafloor” by very slowly
diverging the two plates. Be sure that the
same color of paper (= same age of rock) is
“forming” at the ridge at the same time. As
new seafloor is “formed at the ridge,” call out
the ages. When the divergence simulation is
completed, the “red” seafloor will be located at
the mid-ocean ridge.
 Emphasize that students are simulating the
b. What type of crust is produced at the
ridge?
 Oceanic crust is formed at the ridge.
c.
 The magma that formed the basalt most
likely is located in the mantle, directly
beneath the ridge axis.
growth of their model ocean by having rifted a
continent, and by diverging the two plates. New
seafloor was formed in the process.
d. What color represents the oldest seafloor?
 The oldest rock would be the first rock that
had extruded, which is represented by the
purple color band.
This model approximates the ages of the North
Atlantic’s seafloor. The model ocean basin is scaled
to the North Atlantic as well.
e.
What color represents the youngest
seafloor?
 The red color band extruded last and
23. Answer the following questions in your science
notebook.
a.
Where is the source of the magma that
formed the seafloor rock?
represents the youngest rock. This rock
could have been formed last week!
Do the different colors represent rocks of
different compositions? What composition
or compositions of rocks form as an ocean
floor “grows”?
f.
As distance from the ridge increases, what
happens to the age of the seafloor?
 The age of the seafloor increases with
increasing distance from the ridge.
 No, the colors do not represent different
compositions of rock. All the rock produced
at the ridge is basalt.
Summarize your observations and discoveries by
answering the questions on the next page.
COASTeam Program, Project Oceanica, College of Charleston
7
Investigating Seafloor Spreading
TEACHER PAGES
Questions (Assessment)
Use your observations of the Earth’s lithospheric plates and the relationship of plate boundaries to seafloor
features to answer the following questions. Your teacher will provide information of how to format your
answers.
Use the students’ responses to questions 9, 19 and 23 (written in their science notebooks) to assess their
understanding of the activity.
 Were all tables and graphs completed accurately?
Students will apply the knowledge gained from this activity in the next activity “Age of the Ocean Floor,” which
uses actual seafloor age data.
1) Examine your graph of the Half-Seafloor Plate Rate (Graph 1). During what range of time did the plate
move fastest? Answer with a range of time, such as “between 10 and 20 million years ago.”
 The seafloor has been spreading most rapidly during the last 40 m.y.
 Students may be more specific, stating that between 20 and 40 million years ago the rate was
fastest.
2) When was the plate movement slowest? Again, answer with a range of time.
 From 40 to 67 m.y. ago, the seafloor spreading rate was at its slowest.
3) Write a 1 page description of how your ocean grew, starting 180 million years ago. In your description,
explain what occurred during seafloor spreading (including the type of rock formed) and how the spreading
rates varied through time.
 Key points that students should include:
the initial rifting of the continent and earliest formation of oceanic crust 180 million years ago.
cooling and crystallization of magma to form basalt and oceanic crust.
Formation of oceanic crust at the mid-ocean ridge
Divergence from the mid-ocean ridge
the different time periods (the ranges of time that different rates occurred).
Source: Dr. Leslie Sautter, Project Oceanica, Dept. of Geology and Environmental Geosciences, College of Charleston, SC.
Contributions to this activity were made by Elizabeth King Rhodes and Shelley Aksomitas.
website: http://oceanica.cofc.edu email: [email protected] phone: 843-953-5586
Funding for the COASTeam Program was provided by the South Carolina Sea Grant Consortium. http://oceanica.cofc.edu/coasteam/
COASTeam Program, Project Oceanica, College of Charleston
8
Investigating Seafloor Spreading
TEACHER PAGES
Figure 1. Layout of the half-seafloor model with continent attached.
The “seafloor” is 92 cm in length and represents 2,300 km of the fictitious ocean basin. The letters
“R,O,Y,G,B,V” represent red, orange, yellow, green, blue and violet, respectively. The cardboard tube is
attached to the Red end of the paper.
cardboard tube
continent
R
O
Y
G
B
V
|-------------------------------------------------92 cm----------------------------------------|
Figure 2. Layout of the full seafloor model (Parts II and III) with continental pieces.
ridge (2 cardboard tubes)
continent
V
continent
B
G
Y O R
R
O Y
G
B
V
COASTeam Program, Project Oceanica, College of Charleston
9
Investigating Seafloor Spreading
TEACHER PAGES
Figure 3. Set-up of seafloor rolls for Part IV.
Assemble model this way….
….not this way!
Figure 4. Depiction of the full seafloor model as it is “diverging.”
continent
COASTeam Program, Project Oceanica, College of Charleston
10
Investigating Seafloor Spreading
TEACHER PAGES
Teacher Answer Key
Table 1. Calculating seafloor ages for each color band.
Subtract the youngest age from the oldest age for each color band on your model. This “Total Seafloor
Age in Color Band” indicates the period of time that elapsed while the plate was moving away from the
mid-ocean ridge.
Color Band
a) Width of
Color Band
on paper
b) Youngest
Age of
seafloor
c) Oldest
Age of
seafloor
d) Total Seafloor
Age In Color
Band
(cm)
(m.y.)
(m.y.)
(m.y.)
RED
15.00
0.00
20.10
20.10
ORANGE
15.00
20.10
40.10
20.00
YELLOW
7.00
40.10
67.70
27.60
GREEN
30.00
67.70
131.90
64.20
BLUE
10.00
131.90
147.70
15.80
VIOLET
15.00
147.70
180.00
32.30
TOTAL “Half Seafloor”
92.00
COASTeam Program, Project Oceanica, College of Charleston
11
Investigating Seafloor Spreading
TEACHER PAGES
Table 2. Using the model scale.
The paper model uses the scale 92 cm = 2,300 km.
If:
92 cm on the model = 2,300 km in the actual ocean
Then:
1 cm = 25 km
Now, enter the number above into all the blank spaces below:
1 cm on the model = 25 km in the ocean the model represents
We can express the scale as being “25 kilometers per centimeter.”
So, the scale’s conversion factor is:
25 km/cm
To calculate, use the ratio:
92 cm
1 cm
Solve for x:
x=
or:
x=
x=
=
2300 km
x km
(1 cm * 2300 km)
92 cm
2300 cm*km
92 cm
25 km (centimeters cancel out)
Thus, 1 cm = 25 km
This is the same thing as saying there are 25 km per cm on the
map, or having a scale conversion factor of 25 km/cm.
COASTeam Program, Project Oceanica, College of Charleston
12
Investigating Seafloor Spreading
TEACHER PAGES
Table 3. Calculating distances.
Use the scale’s conversion factor from Table 2 to calculate the width of seafloor for each color band
segment (column b). Add the distances together (column c) so that the distance increases from the ridge
along the model seafloor.
Color Band
a) Seafloor Width,
measured on
the model
b) Seafloor Width,
represented by
the model
c) Distance from
ridge of
oldest rock
(cm)
(km)
(km)
RED
15.00
375.00
375.00
ORANGE
15.00
375.00
750.00
YELLOW
7.00
175.00
925.00
GREEN
30.00
750.00
1675.00
BLUE
10.00
250.00
1925.00
VIOLET
15.00
375.00
2300.00
Column b values are calculated by multiplying column a values by 25 km/cm (the scale of the map):
15.00 cm * 25 km/cm = 375.00 km
Column c values are the cumulative distance, meaning the distance from each segment is added to the
previous value.
For example:
The value of 750.00 km in column c was calculated by adding the ORANGE “Seafloor Width” value (column
b) of 350.00 km to the RED “Distance from the ridge” value (column c) of 350.00 km, or:.
375.00 km + 375.00 km = 750.00 km
Then the YELLOW “Seafloor Width” of 175.00 km was added to the previous distance of 750.00 km to
calculate the cumulative distance of 925.00 km.
COASTeam Program, Project Oceanica, College of Charleston
13
Investigating Seafloor Spreading
TEACHER PAGES
Table 4. Calculating half-seafloor plate rates.
Calculate the model’s half-seafloor plate rates through time, first using the units “kilometers per million
years”, or km/m.y.
Color Band
a) Seafloor
Width
(km)
b) Age
Difference
(m.y.)
c) Half-Seafloor
Plate Rate
(km/m.y.)
(from Table 3)
(from Table 1)
RED
375.00
20.10
18.66
ORANGE
375.00
20.00
18.75
YELLOW
175.00
27.60
6.34
GREEN
750.00
64.20
11.68
BLUE
250.00
15.80
15.82
VIOLET
375.00
32.30
11.61
Table 5. Calculating seafloor spreading rates in cm/yr.
Plate rates are usually expressed using the units “centimeters per year,” or cm/yr. Seafloor spreading
rate is two times the half-seafloor plate rate, since there are two plates involved and they are moving
apart at the same rate (in your model ocean).
Color Band
a)Seafloor
Width
(cm)
b) Age
Difference
(yr)
c) Half-Seafloor
Plate Rate
(cm/yr)
d) Seafloor
Spreading
Rate
(cm/yr)
RED
37,500,000.00
20,100,000.00
1.87
3.73
ORANGE
37,500,000.00
20,000,000.00
1.88
3.75
YELLOW
17,500,000.00
27,600,000.00
0.63
1.27
GREEN
75,000,000.00
64,200,000.00
1.17
2.34
BLUE
25,000,000.00
15,800,000.00
1.58
3.16
VIOLET
37,500,000.00
32,300,000.00
1.16
2.32
COASTeam Program, Project Oceanica, College of Charleston
14
Investigating Seafloor Spreading
TEACHER PAGES
Table 6. Summarizing your data.
Complete the table below, using your calculations from Table 3. Use this table to
make your graph, below.
Color Band
a) Oldest Age of Seafloor
in Color Band
(m.y.)
b) Distance from ridge
of oldest rock
(km)
(from Table 1)
(from Table 3)
RED
20.10
375.00
ORANGE
40.10
750.00
YELLOW
67.70
925.00
GREEN
131.90
1675.00
BLUE
147.70
1925.00
VIOLET
180.00
2300.00
s
Half
Half-Seafloor
– Seafloor
Plate Rate
Seafloor
Spreading
2500
Distance from Ridge (km)
Graph 1. Graphing HalfSeafloor Plate Rate.
Use data from Table 6 to graph
the variations in half-seafloor
plate rates.
2000
1500
1000
500
0
0
50
100
Age of Seafloor (m.y.)
COASTeam Program, Project Oceanica, College of Charleston
15
150
200