Graham Cracker Plate Tectonics Purpose 1. To identify and demonstrate the forces that shape the features of the Earth 2. To understand how plate boundaries interact with each other and the features created as they drift atop the slow moving asthenosphere. 3. To represent the natural world by creating models and analyzing their limitations Materials 1 Graham Crackers Cake frosting Wax paper I Piece of Fruit Rollup Small cup of water 1 Plastic knife Napkins or paper towels Background Information The main force (push or pull) that shapes our planet s surface over long periods of time is the movement of the Earth s outer layer (crust). This outer layer of crust is divided into plates that move very slowly at rates of several centimeters per year. That is about how fast your fingernails grow! Movements deep within the Earth, carry heat from the hot interior to the cooler surface, causing the plates to move (convection). As the plates move, the continents also move or drift over the Earth s surface. The movement of the Earth s plates, especially at the plate boundaries where the plates meet, produces features on the continents and on the ocean floor. Looking at the World map, you may have noticed that the continents seem to fit together like a jigsaw puzzle. In the early 1900 s, a German scientist named Alfred Wegener developed a hypothesis to explain this observation. He found evidence that the continents that existed millions of years ago moved together. As the continents collided, they formed one large landmass or supercontinent called Pangea. The supercontinent later broke apart to form our modern World map.
Terms Pangaea name of the single landmass that broke apart about 250 million years ago also termed whole Earth. Plates sections of the lithosphere that make up the outermost layer of Earth. Plate Tectonics Theory the theory that states the Earth s plates move in a constant, slow motion and interact with each other to produce features of the Earth. Lithosphere the rigid layer that includes the uppermost mantle and crust. Asthenosphere uppermost plastic-like layer of the mantle that is just below the lithosphere. Continental crust the thicker but less dense area of the Earth s lithosphere that lies beneath the continents. Oceanic crust - the thinner but more dense area of the Earth s lithosphere the lies beneath the oceans. Convection the transfer of heat by movements of a current through a fluid. Convergent boundary places where the plates push together; mountains often form where continental plates collide and shift. Subduction when an oceanic plate collides with a continental plate, the more dense oceanic plate moves under the less dense continental plate; volcanoes often form when subduction occurs. Divergent boundary - places where plates are moving apart, forming rift valleys (on land) and sea floor spreading (at the bottom of the ocean) (see textbook p.287). Transform boundary places where plates slide past each other horizontally; the sliding motion causes earthquakes. Answer the questions using your knowledge from this activity, your text and other handouts. Procedures, Observations, and Questions Spread about a 1cm thick layer of frosting on the wax paper. Carefully break your graham cracker into 4 sections. Place one graham cracker on the layer of frosting. Dip the end of the other cracker in the cup of water for about 1 second and gently place it small end to small end with the other cracker. Push the dry cracker and wet cracker together. Draw and label your observations in the space below. (use arrows to show the direction of movement)
1. What type of boundary does this model? 2. What land feature does this model? 3. What are some limitations of this model? 4. Which layer(s) of the Earth are represented by the graham crackers? 5. Which layer of the Earth does the frosting represent? 6. Carefully remove the two crackers, smooth the frosting with the knife and place two dry crackers long side by long side on the frosting. Slide the crackers past each other from side to side. Draw and label your observations in the space below. (use arrows to show the direction of plate movement) 7. What type of boundary does this model? 8. What catastrophic event is normally caused by this motion? 9. Explain the process that causes the Earth s plates to move?
10. Carefully remove the crackers and smooth the frosting. Take two crackers and place them long side by long side on the frosting. Gently pull the crackers apart just a few millimeters. Draw and label your observations in the space below. (use arrows to show the direction of plate movement) 11. What type of boundary and landform does this model represent? 12. Carefully remove the crackers and smooth the frosting. Place one dry cracker on the frosting, divide the fruit roll-up into four pieces and then place one piece of fruit rollup on the frosting next to the side of the cracker. Push down gently on the fruit rollup, then gently push the cracker towards the fruit rollup until it starts to slide over the rollup. Draw and label your observations in the space below. (use arrows to show the direction of plate movement) 13. What type of boundary does this model? 14. What is the process called that is being modeled and what is the land formation that can be caused by this plate movement? 15. Remove the cracker, smooth the frosting, and place two pieces of fruit roll-up side by side on the frosting, now gently push down and pull away both crackers at the same time. Draw and label your observations in the space below. (use arrows to show the direction of plate movement) 16. What type of boundary and landform does this model represent?