Purpose:
Islands are structures having a great variety of features. One of the best ways to show these features is by the use of a contour map. A contour map is a model of a given section of land that uses lines to show constant heights above sea level. These lines show the pattern of heights for an Island as it rises above sea level. First make a clay model of an Island rising out the ocean. Then you will construct a contour map from this model. Finally, you will compare the contour map with the original Island model.
Procedure
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A. Materials: Modeling clay (four colors, nondrying), flour, plastic knife, pencil paper
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B. Flatten a piece of clay of one color into a smooth, flat sheet about 1 cm thick and measuring about 10 cm an each side. Sprinkle some flour on the table where your are working to keep the clay from sticking to it. Flatten the other three colors into similar sheets. Stack the four sheets of clay one on top of the other. Sprinkle the surface of each sheet with some flour to keep it from sticking to the other.
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C. Carefully curve the stack of sheets into an island. Keep the trimmings together by color, as best as you can, so the clay can be used again. Make one side of your island a steep cliff the opposite side should slope more gradually to the sea. Use your fingers to help shape the island to make it look natural.
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D. Now place the island near the middle of a sheet of paper. Push a pencil, point down, through the center of the mountain and twist the pencil once or twice to make a mark on the paper underneath. Remove the pencil. Then lightly trace around the base of your island with the pencil. Peel off the bottom layer and place the remainder of the island inside the first drawing. Look down through the hole you made in the island to make sure it is lined up with the mark on the paper. Trace around the remainder of the island again. Repeat this procedure until all layers have been erosion traced. The flat peak of your island represents the top of the last layer. Place a dot on the paper to represent the flat peak of your island. You now have a contour map of your island.
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E. Rebuild your clay island by putting the layers together as they were in the beginning. Using the clay model and the contour map of the model, answer the following questions in the manner directed by your teacher.
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1. If each layer represented 50 meters in height, how high would the peak of your island be?
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2. Looking at your contour map, what increase in height up the island does each line represent? This increase is called the contour interval.
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3. On the map, how can you tell which side of the island has the most erosion?
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4. On the map, how can you tell which side has the gradual slope to the sea?
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5. What shape do the contour lines have which show the presence of a valley?
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6. What shape do the contour lines have which show the presence of a ridge?
Summary:
In your own words, compare a contour map to the island features which the contour lines show.
Faulkner’s Island, located 3 miles south of Guilford Connecticut, was formed by retreating glaciers. At present it has not been determined whether it was created during the retreat of the Wisconsin glacier or the earlier Illinois glacier. The island, approximately 40 feet high, is approximately 1400 feet long and 250 feet wide at its widest point. It is a drumlin composed of unconsolidated glacial sediments (Till) which are clearly seen along the steep sloping sides of the island.
Faulkner’s Island Research Projec
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(figure availabe in print form)
(figure availabe in print form)
(figure availabe in print form)