Bhutan, the Last Shangri-La: Sandwich Squash: How the Himalayas Were Formed
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By the end of this activity, students will:
1) Create and record a model of mountain formation.
2) Identify major mountain building formations.
3) Understand how the Himalaya Mountains were formed, why they are located near Bhutan and why they are becoming larger.
National Standards Science
1)Knows how features on the Earth's surface are constantly changed by a combination of slow and rapid processes (e.g., weathering, erosion, and deposition of sediment caused by waves, wind, water, and ice; sudden changes in the landscape caused by landslides, volcanic eruptions, and earthquakes)
2) Knows how land forms are created through a combination of constructive and destructive forces (e.g., constructive forces such as crustal deformation, volcanic eruptions, and deposition of sediment; destructive forces such as weathering and erosion)
1) copy of the program "The Living Edens: Bhutan"
2) 2 paper plates
3) 1 slice wheat bread per student group
4) 2 slices white bread per student group
5) grape jelly
6) nut butter (peanut or other)
7) drawing paper
8) colored pencils
9) Sharp knife
One to three class periods, including time to watch the video segments. The length of the sandwich activity will be about one 50 minute class period.
Students usually study mountain formation by drawings and the use of photographs. In this activity, students will make a model fold mountain, identify the internal structures then apply their discoveries to the mountains shown throughout the Bhutan video.
The continental plates constantly move on the mantle. When the plates come in contact with each other, one mass may slide beside each other, be pushed beneath the other or bend. The Himalayan Mountain range and topography of Bhutan is formed from the folding of rock masses where one plate is crashing into another. Additional geologic information is included in the procedures for the activity.
1. Distribute plates containing sandwich materials. Make sure each student has access to several sheets of white paper and colored pencils.
2. Place slice of white bread on the plate. Ask what position it is in. Discuss until
you get the answer "flat" or "horizontal."
3. Place layer of peanut butter on bread. Ask what position it is in. Ask which is
the oldest layer, ask what is the newest layer. Note that while the peanut
butter is flat, it is not completely flat. This relates to layers of rocks in road
cuts--while some are basically flat, there may be slight variations.
*After each layer is added, ask the questions about the position and what is oldest,
youngest, 2nd oldest and so on.
4. Place wheat bread on the peanut butter.
5. Put a thick layer of jelly on the bread.
6. Put the white bread on top.
7. Have student draw a simple side view of the sandwich and label it "Original
Rocks are deposited on the earth much like the layers on this sandwich. One layer is put on top of the other. What position are the layers originally deposited in? Once the students say "flat", you say they are correct and that they have learned one of the most basic rules of geology, something that took years to discover--the Law of Horizontality (sometimes called the Law of Original Position). This law says "Rock layers are laid down horizontally."
Ask the students which is the oldest layer, youngest layer, second youngest, etc. Once they have identified each, you say they are correct and they have discovered the second great law of geology, the Law of Superposition. This law states "If rock layers are not disturbed, the oldest layers are on the bottom and the youngest layers are on the top."
8. Have the students put the plate containing the sandwich with one side resting on a book and one side resting on the table. (The sandwich will be tilted.) Ask them what has happened to the sandwich. As soon as they have identified that it is tilted, ask them what caused the tilt. They will identify the that the plate was lifted. You say they are correct and point out there are many road cuts where rocks are tilted. The video shows many examples of tilted rock layers. Ask them what caused the tilt of the rocks. They will be able to identify that some force did it.
9. Have students draw a tilted sandwich and label it "Rock layers that are not flat have been moved by a force."
10. Tell the students that the layers of the sandwich represent the rock layers that could be found in an area. Geologists examine the layers and are able to make a good guess as to what happened in an area to form those rocks. This branch of science is called HISTORICAL GEOLOGY. You are to examine the following information and write a paragraph explaining what happened in the area to form the layers in this order.
*One possible explanation--Once there was a beach. The water in the area became higher and submerged the beach leaving a limestone layer behind. As the water rose, it became deep enough that the purer form, calcite, was deposited. Volcanic action entered the area pushing the water back. The volcanic lava then eroded into a new beach.
11. Ask students if they want to see the volcano "erupt." Have someone punch a hole into the sandwich through the middle of the top layer. If you press gently on the top layer of bread, both hands flat on either side of the hole, the jelly comes up and out making a good volcano simulation. Note that the jelly has gone through a layer to get on top. This shows another rule of geology. If a rock layer cracks through an existing layer, it is younger than the layer it cracks through. Have the students draw a picture of a layer that an underlying layer has cracked through and label. There are no volcanoes active in the Himalayan Mountain range at present due to the thickness of rock.
12. Explain that forces in the earth can come from either the side or below. We will simulate the force coming from the side. Squeeze the sandwich together fairly rapidly so that it is crushed. Take a SHARP knife and cut the sandwich in half across the folds. Use toothpicks to identify the structures. Draw the interior making sure to show the layers and what has happened to them. Let the students draw for several minutes.
13. Tell the students that the things they see in the sandwiches have names and that they should label their drawings. Tell them they can re-draw the sandwich if necessary. Draw the following on the board. Most sandwiches will have all of these.
Anticline. This is an upfold. (It can be remembered because if you draw a line across the middle, it forms a series of A's.) Anticlines, synclines and monocline form fold mountains like the Appalachians, Rockies and Himalayas.
Breached anticline. Due to the stress on the rocks, cracks form at the top of the anticline allowing erosion to occur. The top wears away causing a circular indent (sometimes with an end valley) to form. Dome mountains, such as the Adirondacks of New York were formed this way. This will occur in the future in the Himalayas.
Syncline. This is a downfold. It is usually found next to an anticline.
Recumbent fold. A fairly rare type of fold (in real rocks) that shows up surprisingly often in the sandwiches. It is nothing more than an S fold.
Monocline. This is a fold where one side either drops or goes up. The other side is flat.
14. When the sandwich is crushed quickly, breaks in the bread occur. These represent faults. Many, but not all, sandwiches will show these small breaks. The faults will be one of two types. Have students find faults in sandwich.
To present the different faults, discuss how one side goes up and one side goes down. Draw up and down arrows on the sides of the two fault type diagrams (see finished drawings below).
To present how to identify the two types, tell students that they are a kid on one side of the fault and a lot of money (or an A for the semester) is on the other side. "If you were a NORMAL kid, which of the two fault types below would you choose to go across?" The students will choose the fault that is easiest to climb. This is a NORMAL FAULT. Normal kids climb normal faults.
Ask "Which fault would you have to THRUST yourself into the air to get across?" This is a THRUST FAULT. The thrust fault is on the right and the normal fault is on the left.
Both the thrust fault and the normal fault, when found in a series and on a larger size, can form mountain ranges. This type of mountain is a FAULT-BLOCK MOUNTAIN. We can see a small example of this by looking at a pile of books. When they fall over, there is a block of book, then a fault, then a book and so on. The Grand Teton Mountains are a classic example of this. Have students fill in the following chart: (It is filled it in for this sheet)
15. The third type of fault is the same type as the San Andreas fault of California. This happens when the two sides slide beside each other but do not go up or down. This is called a LATERAL FAULT. Simulate this fault by rubbing the two halves of your sandwich back and forth against each other.
Once the sandwiches have been rubbed, have them look for the smooth, shiny surfaces in the peanut butter. In rocks these are called SLICKENSIDES. When the great forces push the rocks against each other, the surfaces are polished. Also note the complete jumble of the layers that have been moved around. In most lateral faults (and many normal or thrust faults) the forces cause this jumble of rocks at the fault line. The forces may be so great that new rock types are formed in the crack. Rocks formed this way are usually METAMORPHIC though metamorphic rocks are formed other ways as well.
16. As a final activity, have the students draw a mountain scene from the Bhutan video. The drawing should show the inside structures that would cause the mountains to form with the features labeled.
This Dynamic Earth http://pubs.usgs.gov/publications/text/dynamic.html This is an online book with illustrations of many geologic mountain building processes.
Ask a Geologist http://walrus.wr.usgs.gov/ask-a-geologist/ A direct source where professional geologists will answer student questions.
Students may be assessed though their participation in making the model, identifying the features and through the labeling of their drawings. The in-activity drawings and post-activity analysis of the Himalayan interiors should be evaluated by the correct labeling of geologic features.
1) Younger students will be able to identify the different folds and faults though the geologic terms may need to be changed to labels such as up-folds, down-folds and faults. Students should be encouraged to look for signs of geologic activity in rock outcroppings where they live.
2) Older student groups can research other mountain ranges in the world and identify how they were formed and the structures that make them.