How We Know What We Know:  The Tectonic Plates

 This exercise in an introduction to plate tectonics and the types of information used to support this theory.  The objective of the exercise is to give students an opportunity to see how the data is interpreted, and the opportunity to make their own interpretations.  By the end of the exercise, students should better understand of the theory of plate tectonics.

The Exercise:

Working in groups students will be assigned which map and which specialty they want to work with, either A) geochronology, B) seismology, C) volcanology,D) geography, or E) satellite geodessy.  The group will be assigned which plate you will work with, either 1) North American, 2) South American, 3) Pacific, 4) African, 5) Eurasian, or 6) Australian

- Examine your chosen specialty map  Specialty Groups:

Task 1: Look at your specialty maps and talk about what you see (concentrate on one specialty at a time, and then begin to compare them). What you look for will vary with data type. For the point data (volcanoes and earthquakes) you are looking for distribution patterns. For surface data (topography, gravity, seafloor age) you are looking for where the surface is high and where it is low. Work as a group. Let everyone talk about what they see. During this period concentrate on the whole world, not just the chosen plate.

Task 2: Now focus your attention on the boundaries of your assigned plate. Identify the nature of your data near the plate boundaries. Is it high or low, symmetric or asymmetric, missing or not missing, varying along the boundary or constant along the boundary, and etc. As a group, classify the plate boundaries based on your observations of your specialty data. Restrict yourselves to about 4-5 boundary types. At this point, do not try to explain the data; just observe!

Task 3 Assign a colored pencil color to each boundary type in your classification scheme for your specialty. Color your first plate boundary map to locate your specialty boundary types. If the data are asymmetric at a particular boundary type, devise a way of indicating that on your plate boundary map.  Each person should write down descriptions of their specialty plate boundary classifications. These maps and descriptions will be turned in at the end of the exercise.

- Examine your chosen Plate - Plate Groups:

Task 4: Each person should make a brief presentation to the rest of their group about their Scientific Specialty’s data and classification scheme. Your group may move to each map in turn while doing this.

Task 5: Compare the classifications of boundary type for your plate based on each type of data.  Are there common extents (along the boundaries) between the different classifications? Can your plate group come up with a new classification scheme that now includes data from all four Scientific Specialties? As above, assign a color to each of your plate boundary types. If a boundary is asymmetric, be sure to devise a way to represent the asymmetry. Mark the boundaries of your plate or plate grouping using your color scheme on your second Plate Boundary Map. Also write a description of the plate boundary classes you have used. The map and description should be turned in at the end of the exercise.

Whole Class Discussion
Two students from each Plate Group should make a presentation to the class. The first student should talk about their group’s plate boundary classification scheme. The second student should talk about how they classify the boundaries of their plate.
The instructor will conclude the exercise by summarizing the students’ observations and placing them in the context of accepted plate boundary types and plate boundary processes.

To be turned in by each student after the discussion:
1. Map with global plate boundaries classified using data from your chosen scientific specialty.
2. Descriptions of the plate boundary classifications devised for your specialty.
3. Map with your assigned plate’s boundaries classified using data from all four scientific specialties.
4. Descriptions of the plate boundary classifications devised by your plate group.