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Learning the layout of the Earth underneath the deep, blue seas

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Hook Why does the Earth look the way it does? Why are the oceans where they are? Where is the deepest part of the ocean?

Student Maps – 1 per group of 2 Color markers – 3 colors per group Rulers – 1 per group

1. On your own paper, predict where you think the deepest parts of the ocean are. Draw a picture of what you think an ocean’s profile would be from one side to the other. 2. Working in-groups of four, familiarize yourself with the legend of your map. How does your map show the depths of the ocean? 3.Using the markers provided, highlight/circle the deepest parts of the ocean. Find as many areas as possible that would be considered “deep” (more than 6000 m) 4. Highlight/circle the shallowest parts of the ocean (not including the continental shelves) with a different colored marker. Consider any thing less than 500 m as “shallow” 5. Are there any patterns that can be identified by the areas you have marked so far? 6. Starting at each shallow zone, draw lines from either side to the nearest deep zone. 7. How many zones of “shallow to deep” were you able to draw? 8. Compare your map with the map from another group. Do you notice any similarities? Any differences? 9. Compare your map with the Geologic Atlas provided to you by laying the Atlas over your map and lining up similar features (continents e.g.).

Discussions Questions/Extensions ......
Discussion Questions…

1. Do you see any relationship between age of the seafloor and depth of the ocean? Explain. 2. Why do you think the shallow areas are where they are? 3. Why do you think the deep areas are where they are? 4. Compare a map of the Atlantic Ocean with one of the Pacific Ocean. What are the similarities and differences between these two oceans? Why do you think they are like that?

EXTENSIONS… 1. Pick one region of “shallow to deep” on your map. Find and mark all places that are 1000 m deep. Connect these places with a line. 2. Find and mark all places that are 1500 m deep and connect them with a line, and then repeat this procedure for 2000 m, 2500m, and every multiple of 500 m on your map. 3. Compare your chart with a group that has done a different area of the map than yours. What differences do you notice? 4. Measure the distance between the shallow line and the deep line in your zone using a centimeter ruler. Measure the distance in centimeters and record this distance so that you can use it for a future calculation. This distance represents not only a scale of the distance for your zone, but it also represents time.

a) Make a prediction as to why distance might represent time? b) Are all shallow areas the same age? WHY? c) Are all deep areas the same age? WHY? d) Why are the zones different sizes?

5. You can make an approximation of the age of the seafloor at the various depths in your zone by using a simple ratio. If we believe the shallowest areas are the newest rock, then they are at time zero. The deepest areas would represent the oldest areas in the seafloor. From Scientific evidence the age of the rock in these deep areas is 180 million years. 6. You can calculate a ratio of distance to time using the following equation. _________ yr./cm = 180 million yr./Distance measured between shallow and deep. Using your measurements calculate the ratio. Record this value. 7. Now you know that so many cm is equal to so many million years. On your zone, mark the ages of the seafloor at 1-cm intervals.

e) How does the age data compare to the depth data? f) Can you give an explanation of why different zones are different shapes?

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