Mapping Plate Tectonic Boundaries

Students will review the concept of plate tectonics in relationship to topography, volcanoes, and earthquakes.

1. Presence of deepening earthquakes inboard of the plate boundary.
2. Presence of a volcanic arc, inboard of the plate boundary.
3. Presence of an oceanic trench.

1. Presence of a mid ocean ridge.
2. Presence of volcanoes within a rift.
3. Presence of shallow earthquakes.

1. Presence of offset mid-ocean ridges
2. Presence of offset land masses (e.g., Haiti/Cuba)
3. Presence of shallow earthquakes along a topographically defined lineament.

1. Volcanoes unassociated with plate boundary topography.
2. A chain of seamounts in bathymetry

1. The relative age of continental land masses and oceanic crust based upon the morphology of the land. i.e., Oceanic crust appears young because of its sharp undistorted tectonic margins. Continental crust appears much more random in topography because it's long history of many plate tectonic events.
2. The presence of continental shelves as evidence of sea level change and as evidence for differences in crustal density.
3. Students can analyze earthquake depths to describe the geometry of plate boundaries by plotting earthquake depths along a profile line crossing the different types of plate boundaries.

• Students will learn to interpret color hillshade maps of the Earth.
• Students will gain experience utilizing map scale bars and legends.
• Students will practice using data to make inferences.

Notes on Datasets:
The GIS data utilized when I created these maps (in 2011) include the following datasets:
Topography: NOAA ETOPO-1 Global Relief Map (1 km resolution) dataset with ice. https://www.ngdc.noaa.gov/mgg/global/global.html
Volcanoes: Locations of active volcanoes from the Smithsonian's Global Volcanism Program:
http://volcano.si.edu/list_volcano_holocene.cfm
Earthquakes: I downloaded the global record of earthquakes from before year 2000 that were greater than Magnitude 4.5 locations and depths information using the earthquake catalogue now located at: https://earthquake.usgs.gov/earthquakes/search/

Notes on the Worksheet Questions:
The included worksheet is only a guide. It is aligned with how I usually run this activity, but could easily be modified to shorten the activity or to make it more in-depth.

Other Notes:

• Many more earthquakes have occurred since 2000 and could be added to the maps. Additionally, one could scale the earthquakes by magnitude, which I have not done here so that the topography would not become obscured. This map does not include earthquakes smaller than M4.5, if included (not available globally), it would be hard to read the map, but the plate boundaries that have only sparse earthquakes would show up better.
• A common issue that the students and I run into with the volcano data is that it only includes eruptions that have either been witnessed or studied geologically, therefore most underwater volcanoes along the mid ocean ridges are not on the map.
• The topography of Transform boundaries is hard to discern on the continents and easy to see in the Ocean basins.

1. Reserve enough time to project the included world topographic map on the white board of the classroom and let each group come to the front of the class and add 1-2 plate boundaries to the map and to explain to the class what data led them to that conclusion. This will undoubtedly lead us to realize that some groups made errors, or missed some boundaries, which creates good teaching moments.
2. I will also collect the worksheets to check attendance and will generally grade the assignment, taking off only a few points for incomplete explanations and poorly formed ideas and then utilizing these misses as teaching points when reviewing for exams or moving back into lecture mode. E.g., reviewing common mistakes missed on the last activity.
3. I also will check that each group mapped the plate boundaries and include that in their worksheet grade.