Activity of the Month – December, 2007 Sedimentation Rates ...oceanleadership.org › files ›...
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Teaching for Science • Learning for Life TM | www.deepearthacademy.org Activity of the Month Summary Students calculate sediment rates at different sites on the ocean floor. They have the opportunity to explore a real-life application of rate calculation and what really counts as “fast” in geologic time. Learning Objectives Students will be able to: • Read and interpret drill site maps. • Estimate and calculate the rates of sedimentation at various places on the ocean floor. National Science Education Standards • Standard D: Earth and Space Sciences Ocean Literacy Essential Principles 1. The Earth has one big ocean with many features. 2. The ocean and life in the ocean shape the features of the Earth. Target Age: Grades 6-8 Time: One class period Materials • Student pages (included) • Graph paper • Rulers • Calculatiors (optional) • Pencils Background The ocean floor is constantly changing. Not only are Earth’s tectonic plates moving underneath it, but sediments from above are constantly raining down on it. These sediments include formerly living organisms that have drifted down through the water column, minerals that have precipitated out of the water and terrigenous matter, or material washed or blown out from land. All of these materials Activity of the Month – December, 2007 Sedimentation Rates on Shatsky Rise fall onto the ocean floor at varying rates, which are affected by how close the seafloor is to shore, depth of the water, chemistry of the water, ocean currents, and volcanic events. We can study and compare these rates by closely examining sediment cores obtained by scientific ocean drilling. What to do 1. Hand out student pages and have students look at the maps, which show an area in the Pacific Ocean called the Shatsky Rise. We will focus on four different locations (Site 1209, 1210, 1211, 1212) where cores have been drilled and recovered from the seafloor. Ask students: Where do you think sedimentation rates will be fastest and why? Where do you think they will be slowest and why? 2. The core images on the student pages show sediments that were deposited during the same time period. These cores were taken at different depths, but they all show similar color changes. Lead a class discussion to encourage students to become familiar with core observation. Ask students: a. Where is the older sediment? The younger sediment? (older at the top) b. What might cause a change in color in the core? c. If we know from fossil evidence that a sharp change from light to dark sediment is a horizon that is the same age for all of the cores, then why are they not at the same depth? (different rates of sediment raining down)
Transcript of Activity of the Month – December, 2007 Sedimentation Rates ...oceanleadership.org › files ›...
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ce • Learning for Life
TM | w
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.deepearthacademy.org
Activity of the Month
Summary
Students calculate sediment rates at different sites on the ocean floor. They have the opportunity to explore a real-life application of rate calculation and what really counts as “fast” in geologic time.
Learning Objectives
Students will be able to:
• Read and interpret drill site maps.
• Estimate and calculate the rates of sedimentation at various places on the ocean floor.
National Science Education Standards
• Standard D: Earth and Space Sciences
Ocean Literacy Essential Principles
1. The Earth has one big ocean with many features.
2. The ocean and life in the ocean shape the features of the Earth.
Target Age: Grades 6-8
Time: One class period
Materials
• Student pages (included)
• Graph paper
• Rulers
• Calculatiors (optional)
• Pencils
Background
The ocean floor is constantly changing. Not only are Earth’s tectonic plates moving underneath it, but sediments from above are constantly raining down on it.
These sediments include formerly living organisms that have drifted down through the water column, minerals that have precipitated out of the water and terrigenous matter, or material washed or blown out from land. All of these materials
Activity of the Month – December, 2007Sedimentation Rates on Shatsky Rise
fall onto the ocean floor at varying rates, which are affected by how close the seafloor is to shore, depth of the water, chemistry of the water, ocean currents, and volcanic events. We can study and compare these rates by closely examining sediment cores obtained by scientific ocean drilling.
What to do
1. Hand out student pages and have students look at the maps, which show an area in the Pacific Ocean called the Shatsky Rise. We will focus on four different locations (Site 1209, 1210, 1211, 1212) where cores have been drilled and recovered from the seafloor.
Ask students:
Where do you think sedimentation rates will be fastest and why?
Where do you think they will be slowest and why?
2. The core images on the student pages show sediments that were deposited during the same time period. These cores were taken at different depths, but they all show similar color changes. Lead a class discussion to encourage students to become familiar with core observation.
Ask students:
a. Where is the older sediment? The younger sediment? (older at the top)
b. What might cause a change in color in the core?
c. If we know from fossil evidence that a sharp change from light to dark sediment is a horizon that is the same age for all of the cores, then why are they not at the same depth? (different rates of sediment raining down)
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edimentation R
ates on Shatsky R
ise
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3. Ask students: Does looking at the cores change your opinion of their sedimentation rates?
4. The data in the first student page chart show depths and the age of the sample at different depths. Have students fill in the chart and graph age versus depth for all drilled cores for Site 1209,1210, 1211, 1212 on a single set of axes. (See answer graph below) (Note that they will need to add together the thickness of each layer to find the total depth at the bottom of each layer.)
Ask students:
Is the sediment accumulating at a constant rate in each core?
5. Ask students:
How can you calculate the sedimentation rate (m/million years) for each core?
What is that sedimentation rate?
Have students fill in the second table on the student page, the Sedimentation Rate Chart. Be aware that the thicknesses represent the total thickness for each layer, while all the ages are in millions of years from the present. To calculate rates, students will need to find the difference between each two consecutive ages.
6. Hold a class discussion about the results they found.
Ask students:
a. How does the location of the site affect sedimentation rates? Some ideas to get the students thinking might include:
i. How close is the site to land?
ii. What is the temperature of the water likely to be?
iii. What are the major ocean currents in the area, and which way do they flow?
iv. Is there volcanic activity in the area?
b. How does water depth affect sedimentation rates?
c. These cores each show the Paleocene Eocene Thermal Maximum. Ask students to research this time period. How much time does it represent?
d. The Shatsky Rise has moved considerably over the past 120 million years. (See Figure F4, Leg 198 Initial reports: http://www-odp. tamu.edu/publications/198_IR/chap_01/c1_ f4.htm#772164). If the Pacific Plate (upon which the Shatsky rise rests) moves northwestward at an average rate of approximately 8 cm/year, how far has it traveled in 120 million years? How could this movement affect sedimentation rates?
Submitted by Heather Miller • Greely Middle School, Cumberland, Maine • School of Rock, July 2007
Age vs. Depth
0
50
100
150
200
250
300
350
400
0 20 40 60 80Age (Ma.)
Dep
th (
met
ers)
Site 1209
Site 1210
Site 1212
Site 1211
Answer Graph:
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edimentation R
ates on Shatsky R
ise
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Answer KeyD
epth
* vs. Ag
e Ch
art
Site: 1209
Water D
epth
: 2387 mS
ite: 1210 W
ater Dep
th: 2573 m
Site: 1212
Water D
epth
: 2681 mS
ite: 1211 W
ater Dep
th: 2907 m
Age (M
a.)T
hickness of S
ediment Layer
(meters)
Depth* at the
Bottom
of each S
ediment Layer
Thickness of
Sedim
ent Layer (m
eters)
Depth* at the
Bottom
of each S
ediment Layer
Thickness of
Sedim
ent Layer (m
eters)
Depth* at the
Bottom
of each S
ediment Layer
Thickness of
Sedim
ent Layer (m
eters)
Depth* at the
Bottom
of each S
ediment Layer
0
0
0
00
5.82
78.3
78.3
83.9
83.960.1
60.147.5
47.5
18.2
33.2
111.5
29.5
113.42.9
63.04.8
52.3
29.9
2.3
113.8
1.8
115.20
63.011.2
63.5
33.7
14.9
128.7
9.1
124.30
63.016.4
79.9
43.6
17.8
146.5
16.4
140.70
63.010.1
90.0
49.7
34.9
181.4
23.6
164.36.9
69.914.1
104.1
55
14.9
196.3
17.5
181.85.7
75.610.6
114.7
60
23.5
219.8
25.6
207.413.4
89.08.8
123.5
64.97
15.5
235.3
12.5
219.910.7
99.78.9
132.4
68.6
29.7
265.0
24.9244.8
36.4136.1
26.3158.7
71.3
N
A
NA
38.8283.6
21.6157.7
N
A
NA
75.7
N
A
NA
64.4348.0
33.7191.4
N
A
NA
*meters below
seafloor
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edimentation R
ates on Shatsky R
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Answer KeyS
edim
entatio
n R
ate Ch
art
Site: 1209
Water D
epth
: 2387 mS
ite: 1210 W
ater Dep
th: 2573 m
Site: 1212
Water D
epth
: 2681 mS
ite: 1211 W
ater Dep
th: 2907 m
Age (M
a.)T
hickness of S
ediment Layer
(meters)
Sedim
entation R
ate (meters per
million years)
Thickness of
Sedim
ent Layer (m
eters)
Sedim
entation R
ate (meters per
million years)
Thickness of
Sedim
ent Layer (m
eters)
Sedim
entation R
ate (meters per
million years)
Thickness of
Sedim
ent Layer (m
eters)
Sedim
entation R
ate (meters per
million years)
0
0
00
0
5.82
78.3
13.45483.9
14.41660.1
10.32647.5
8.1615
18.2
33.2
2.681729.5
2.38292.9
0.23424.8
0.3877
29.9
2.3
0.19661.8
0.15380
011.2
0.9573
33.7
14.9
3.92119.1
2.39470
016.4
4.3158
43.6
17.8
1.79816.4
1.65660
010.1
1.0202
49.7
34.9
5.721323.6
3.86896.9
1.131114.1
2.3115
55
14.9
2.811317.5
3.30195.7
1.075510.6
2
60
23.5
4.725.6
5.1213.4
2.688.8
1.76
64.97
15.5
3.118712.5
2.515110.7
2.15298.9
1.7907
68.6
29.7
8.181824.9
6.859536.4
10.02826.3
7.2452
71.3
N
A
NA
38.814.37
21.68
N
A
NA
75.7
N
A
NA
64.414.636
33.77.6591
N
A
NA
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edimentation R
ates on Shatsky R
ise
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Student Page
Figure 2. Maps of Ocean Drilling Program site locations for this activity.
A. ODP drilling sites in the western Pacific. The Shatsky Rise sites are in the red box.
B. Ocean bathymetry and ODP drilling sites at Shatsky Rise.
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edimentation R
ates on Shatsky R
ise
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Student Page
Figure 2. Photos of cores from Shatsky R
ise in the Pacific Ocean. The cores w
ere recovered from
sites drilled during Ocean D
rilling Program Leg 198.
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edimentation R
ates on Shatsky R
ise
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Student PageD
epth
* vs. Ag
e Ch
art
Site: 1209
Water D
epth
: 2387 mS
ite: 1210 W
ater Dep
th: 2573 m
Site: 1212
Water D
epth
: 2681 mS
ite: 1211 W
ater Dep
th: 2907 m
Age (M
a.)T
hickness of S
ediment Layer
(meters)
Depth* at the
Bottom
of each S
ediment Layer
Thickness of
Sedim
ent Layer (m
eters)
Depth* at the
Bottom
of each S
ediment Layer
Thickness of
Sedim
ent Layer (m
eters)
Depth* at the
Bottom
of each S
ediment Layer
Thickness of
Sedim
ent Layer (m
eters)
Depth* at the
Bottom
of each S
ediment Layer
0
0
0
00
5.82
78.3
83.9
60.147.5
18.2
33.2
29.5
2.94.8
29.9
2.3
1.8
011.2
33.7
14.9
9.1
016.4
43.6
17.8
16.4
010.1
49.7
34.9
23.6
6.914.1
55
14.9
17.5
5.710.6
60
23.5
25.6
13.48.8
64.97
15.5
12.5
10.78.9
68.6
29.7
24.936.4
26.3
71.3
N
A38.8
21.6
NA
75.7
N
A64.4
33.7
NA
*meters below
seafloor
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ce • Learning for Life
TM | w
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edimentation R
ates on Shatsky R
ise
8
Student PageS
edim
entatio
n R
ate Ch
art
Site: 1209
Water D
epth
: 2387 mS
ite: 1210 W
ater Dep
th: 2573 m
Site: 1212
Water D
epth
: 2681 mS
ite: 1211 W
ater Dep
th: 2907 m
Age (M
a.)T
hickness of S
ediment Layer
(meters)
Sedim
entation R
ate (meters per
million years)
Thickness of
Sedim
ent Layer (m
eters)
Sedim
entation R
ate (meters per
million years)
Thickness of
Sedim
ent Layer (m
eters)
Sedim
entation R
ate (meters per
million years)
Thickness of
Sedim
ent Layer (m
eters)
Sedim
entation R
ate (meters per
million years)
0
0
00
0
5.82
78.3
83.960.1
47.5
18.2
33.2
29.52.9
4.8
29.9
2.3
1.80
11.2
33.7
14.9
9.10
16.4
43.6
17.8
16.40
10.1
49.7
34.9
23.66.9
14.1
55
14.9
17.55.7
10.6
60
23.5
25.613.4
8.8
64.97
15.5
12.510.7
8.9
68.6
29.7
24.936.4
26.3
71.3
N
A38.8
21.6
NA
75.7
N
A64.4
33.7
NA
