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Play-Doh Plates Original Source: Dr. Leslie Sautter (Dept. of Geology, College of Charleston) Grade Level: SC Standards: National Standards: 8th Grade IIIB1c,d,g; IIIB3j,k; IIIB4a,b Earth and Space Science Content Standard D: Focus Questions Prior to this activity, students should have studied lithospheric plates (Figure 1), including: the basic structure of the lithosphere (oceanic crust, continental crust, upper mantle) what comprises a plate (lithosphere = crust + upper mantle) how oceanic and continental crust are spatially related to one another (they are next to each other, NOT layered on top of each other) How are lithospheric plates structured? What are the interactions between plates at convergent plate boundaries? Objectives Students will: demonstrate their understanding of lithospheric plates. model convergent plate boundaries. Key Words Students should also have studied the different forms of convergent plate boundaries: oceanic-oceanic (Figure 2) oceanic-continental (Figure 3) continental-continental (Figure 4) plate, lithospheric plate lithosphere cross-section upper mantle oceanic crust, continental crust convergent boundary For each type of convergent boundary, they should have studied: the types of seafloor and/or continental features produced where the earthquakes would be located (shallow vs. deep focus earthquakes) what types of rocks are involved and formed (optional). Materials Per student group: 3 different colors of Play-Doh or similar type of modeling clay, salt-ceramic, etc., approximately ½ jar per color. (Each group must have the same 3 colors.) 3 color pencils (same colors at Play-Doh) 1 square piece of cardboard, ~ 8” x 8” Time Frame One to 50-minute class period for each part. Teacher Preparation This activity is useful as an assessment of students’ understanding of the structure of the lithosphere and lithospheric plates (Part I). For higher level students, understanding of plate boundary interactions may also be evaluated (Part II). Suggested Learning Environment Collaborative groups of 3-4 students. Multiple groups may each do the activity simultaneously, and then compare models. Relevant pages in Of Sand and Sea Chapter I, The Ocean Planet, p. 7-12. COASTeam Program, Project Oceanica, College of Charleston 1 Play-Doh Plates TEACHER PAGES Procedure 3. Name your plate and write a brief description of your plate. You may also name the continent and ocean(s) that are included. The steps that follow are included in the STUDENT PAGES. Additional information on the TEACHER PAGES is included in blue italics. 4. Draw a map of your plate, using the same scale as your model (the same dimensions as the cardboard, 8”x8”). Label any geographic or geologic features that you’ve created and described in your written summary. Part I Each student group will receive about ½ jar of each Play-Doh color. Your teacher will designate which color represents the upper mantle, which color represents the oceanic crust, and which color represents the continental crust. The darkest color should be the mantle, and the 5. Draw a light line on your map from one side of the map to the other, anywhere that the line would cross both the continent and the ocean. Label this line as A-A’ (one end of the line is A and the other end is A’). lightest color should be the continental crust. 1. Make a key in your science notebook of the Play-Doh colors and what each represents. a. What type of rock is found in each of these layers? Continental crust is composed primarily of 6. Imagine that you could cut straight into your model along the A-A’ line and view the cut surface from the side. This view is called a cross-section. Draw a diagram of what you think you’d find if you could view the crosssection along line A-A’. Label all the layers and color the map using the key you developed in step 1. Use the following guidelines to determine if the felsic (silica-rich) igneous rocks called granite. Oceanic crust is composed of mafic (iron and magnesium-rich) igneous rocks called basalt (near the surface) and gabbro (near the base). The upper mantle is composed of ultramafic (very iron and magnesium-rich) igneous rock, called peridotite. plate models are “correct.” The upper mantle should be on the bottom of the entire plate. The shape of the upper mantle = the shape of the plate. The upper mantle should not be exposed on the surface. It is always overlain either by oceanic crust or continental crust. The continental crust should be much thicker than the oceanic crust. It may have varying thickness. The oceanic crust should be thin, with little variation in thickness. If seamounts are included, they should be very small. The continental crust should be located next to (adjacent to) the oceanic crust. The 2 types of crust may not be layered one on top of the other – they should be side-byside. 2. Construct a model of a single lithospheric plate on top of the square of cardboard. You must include all three types of rock/colors of PlayDoh. For simplicity, include only 1 continent. Encourage students to make a simple model with one continent. The more complex, the more description they will have to do as the activity progresses! Be sure to check students’ progress, but do not correct them, as this is an assessment of their learning. Answer questions sparingly, encouraging them to “confer with their colleagues”. Do not provide students with Figures 1-4. COASTeam Program, Project Oceanica, College of Charleston 2 Play-Doh Plates TEACHER PAGES Continental crust may be situated in the middle of the plate, or along the edge of the plate (or both). Figures 2, 3, and 4 for guidance on the seafloor and continental features that should be described for each type of convergent plate boundary. Additional information is below. See Figure 1: a generalized cross-section of a plate. b. Describe what will happen during the convergence. Again, student responses will vary. Part II This activity may be added to Part I when more than one group has constructed a model and the models have been checked by the teacher. 1. c. Refer to Figures 2 and 3. Pair up with another group and exchange your models, maps and written summaries. Examine the other group’s model. When both groups are ready, each group should describe the model of the other group. d. Describe any new continental features that will be produced, and where they will occur. Refer to Figures 3 and 4. e. Clarify any confusion between model interpretations. melting of hot, hydrated rocks produces a mafic-composition magma, producing a basalt when it extrudes during volcanic eruptions. For oc-cont, the magma produced from the melting of hot, hydrated rocks produces a mafic-composition magma. But the pieces of the granite (felsic)-composition continental crust fall into the rising magma as the magma rises, producing an intermediatecomposition magma that produces andesite when it extrudes during volcanic eruptions. For cont-cont, there is little new rock formed, however old rocks are metamorphosed from the collision’s pressure. 3. Orient the two group models so that the two Convergent Boundaries are facing each other. Do not physically converge the models. 4. Predict what will happen if the two plates collide, or converge. In your notebook, write the answers to the questions below. The following abbreviations will be used for the three different types of convergent plate boundaries: oc-oc oceanic-oceanic convergence oc-cont oceanic-continental convergence cont-cont continental-continental convergence a. Describe any new rock that will be produced, and where it will occur. For oc-oc the magma produced from the 2. Each group should select one of the edges of the group’s own plate model. This will be referred to as the Convergent Boundary of the model. Describe any new seafloor features that will be produced, and where they will occur. f. What type or types of convergent plate boundary(ies) will occur? (Remember that if you have oceanic crust AND continental crust along one edge of a plate, that each will converge differently.) Will earthquakes occur? If so, where will they originate? Yes – there are many earthquakes associated with convergent plate boundaries. For oc-oc and oc-cont, the earthquakes will originate all along the subducting plate. These will be shallow, intermediate and deep-focus earthquakes. Student responses will vary, depending on the plate boundary interactions. Refer to COASTeam Program, Project Oceanica, College of Charleston 3 Play-Doh Plates TEACHER PAGES For cont-cont, the earthquakes will occur within the folded/faulted mountain chain being built from the collision. They are mostly shallow-focus earthquakes. Assessment For this activity, there are no specific assessment questions. Use the students’ PlayDoh models, maps, answers to questions from Step 4a-f, and cross-sections of the resulting convergent plate boundary to assess student understanding of convergent plate interactions. 5. Using the two Play-Doh plate models, carefully construct a new model of the resulting convergent plate boundary. Construct any seafloor or continental features generated by the type of convergence illustrated by the model. 6. Draw a map of your two-plate convergent boundary model. Label the surface features. 7. Draw a cross-sectional view along a line B-B’ that crosses the plate boundary (perpendicular to the plate boundary). Again, Figures 2, 3, and 4 illustrate the features that should be included for each of the types of convergent plate boundaries. . Source: Dr. Leslie Sautter, Project Oceanica, Dept. of Geology and Environmental Geosciences, College of Charleston, SC. website: http://oceanica.cofc.edu email: [email protected] phone: 843-953-5586 Funding for the COASTeam Program was provided by the South Carolina Sea Grant Consortium. http://oceanica.cofc.edu/coasteam/ COASTeam Program, Project Oceanica, College of Charleston 4 Play-Doh Plates TEACHER PAGES Figure 1. Cross-section diagram of the lithosphere. (Figure from Of Sand and Sea, by P. Keener-Chavis and L. Sautter) Figure 2. Cross-section diagram of an oceanic-oceanic convergent plate boundary. (Figure from Of Sand and Sea, by P. Keener-Chavis and L. Sautter) COASTeam Program, Project Oceanica, College of Charleston 5 Play-Doh Plates TEACHER PAGES Figure 3. Cross-section diagram of an oceanic-continental convergent plate boundary. (Figure from Of Sand and Sea, by P. Keener-Chavis and L. Sautter) Figure 4. Cross-section diagram of an continental-continental convergent plate boundary. (Figure from Of Sand and Sea, by P. Keener-Chavis and L. Sautter) COASTeam Program, Project Oceanica, College of Charleston 6