Download Data Analysis - Net Start Class

Science 8
Mapping Activity
You Floor Me!
EQ: How do we use models to study the
Earth?
Targeted Skills
Information Literacy
 Collect Information
 maps
Thinking and Reasoning
 Creative Thinking
 sequence
 Problem Solving/Decision making
 perform calculations
Enduring Understanding
Earth is a dynamic system.
Changes result from the interaction between matter and
energy.
Concepts Important to Know and Understand
Earth models, internal/external forces
Broad Brush Knowledge
maps, images, graphs, charts, convection currents, plate
tectonics
Core Objectives
11. Identify forces and processes that shape features of
Earth, and predict changes that may result.
Purpose: To determine the rate of seafloor spreading.
Expert Information: Prior to World War II, most geologists thought that the ocean floor was
mostly flat and featureless, but wartime military inventions helped scientists uncover its true
structure. To help protect the country’s borders, the U.S. was very interested in creating
devices that could detect submarines under the surface of the water. Sonar is a device that
uses sound waves to detect the surroundings beneath a given point. The military used sonars to
track submarine movement along the ocean floor and used them extensively in the Pacific and
Atlantic Oceans. Apart from finding submarines, scientists working for the government also
made detailed maps of the ocean floor, which they determined is not flat and has a lot of
different elevations. Most notably, geologists found a huge volcanic mountain range in the middle
of the Atlantic Ocean, which they called the Mid-Atlantic Ridge.
Over time, magma rises to the surface and becomes lava as it oozes out of the center of
the ridge and hardens. Rock samples gathered along the Mid-Atlantic Ridge indicated that the
youngest rock is found at the center of the ridge and the oldest rock is closer to the area where
the ocean floor meets the continents. Half of the newly formed basalt is pushed toward
America, while the other half moves towards Europe.
The second major military invention was the magnetometer. These instruments were
created to detect the presence of iron on enemy submarines that were near the Navy boats.
Using magnetometers, geologists accidentally discovered that basalt, which forms the ocean
floor, contains iron. As the magma cools and crystallizes it aligns itself with the earth’s magnetic
poles. In the 1950’s, this instrument was used to determine that there were magnetic strips of
basalt on the floor of the Atlantic Ocean. Not only did the magnetic strips align with the ridge,
but the strips were a mirror image of each other. By analyzing this rock, scientists have
determined that Earth’s magnetic field reverses every 500,000 – 700,000 years. Geologists
inferred from this information that the Atlantic Ocean is getting larger.
© 2006 Plano ISD/Klein ISD 2007
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Procedure
1. Using a centimeter ruler make a small mark 1 cm to the right of the Mid-Atlantic Ridge. Draw a
line parallel to the Mid-Atlantic Ridge. This line represents a layer of rock deposited 13 million
years ago. Label this line 13.
2. Repeat step 1 drawing a line to the left of the Mid-Atlantic Ridge. Label this line 13.
3. Using a centimeter ruler make a small mark 3.5 cm to the right of the Mid-Atlantic Ridge. Draw a
line similar to the Mid-Atlantic Ridge. This line represents a layer of rock deposited 53 million
years ago. Label this line 53.
4. Repeat step 3 drawing a line to the left of the Mid-Atlantic Ridge. Label this line 53.
5. Using a centimeter ruler make a small mark 7 cm to the right of the Mid-Atlantic Ridge. Draw a
line similar to the Mid-Atlantic Ridge. This line represents a layer of rock deposited 117 million
years ago. Label this line 117.
6. Repeat step 5 drawing a line to the left of the Mid-Atlantic Ridge. Label this line 117.
© 2006 Plano ISD/Klein ISD 2007
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Data Analysis
Years Old
Measured Distance (cm)
13,000,000
1
53,000,000
3.5
117,000,000
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Actual Distance (cm)
Rate of Ocean Spread (cm/year)
1. Convert the measured distance of line 13 in cm to actual distance in cm by multiplying by
30,000,000. Enter the answer into the data table.
2. Calculate the rate of seafloor spreading by dividing the actual distance by the age, 13,000,000
years. Enter the answer into the data table.
3. Convert the measured distance of line 53 in cm to actual distance in cm by multiplying by
30,000,000. Enter the answer into the data table.
4. Calculate the rate of seafloor spreading by dividing the actual distance by the age, 53,000,000
years. Enter the answer into the data table.
5. Convert the measured distance of line 117 in cm to actual distance in cm by multiplying by
30,000,000. Enter the answer into the data table.
6. Calculate the rate of seafloor spreading by dividing the actual distance by the age, 117,000,000
years. Enter the answer into the data table.
Interpretation
1. Considering the answer to #6, how much further is the United States from the Mid Atlantic
Ridge now than it was the year you were born? How much further is the United States from
Europe now than it was the year you were born?
2. If you took a cruise to Spain, how much longer or shorter would your trip be than Columbus’ trip
in 1492? (remember your measurement in #6 was only to the Mid Atlantic Ridge)
3. What must be happening on the other side of the globe?
4. Considering what you know about Pangaea, describe the Atlantic Ocean 250 million years ago. 250
million years in the future?
5. What are the limitations of this model?
© 2006 Plano ISD/Klein ISD 2007
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Scale
1 cm measured distance = 300 km actual distance
or
1 cm measured distance = 30,000,000 cm actual distance
updated 06/04/2002
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