A tour of the Mariana Subduction System
Summary 
The material contained herein is designed to give the students a real world example of a convergent active margin. Many of the prominent topographic and subsurface features of the Mariana system are presented. These include faulting in the subducting plate, seamount subduction, mud volcanoes, arc volcano activity and volcanic hazards, and seafloor spreading in the backarc.
Learning Goals
It is intended that students come away from this lesson with a thorough understanding of the provinces of a convergent active margin as well as the processes taking place. Through the use of Google Earth they will have a good understanding of the geographic setting of the Mariana subduction system.
Context for Use
This mini-lesson is intended for use in a large introductory geology lecture class when discussing continental margins. It is anticipated that the students are familiar with plate tectonics. The lesson is intended to take ~25 minutes. A computer with an internet connection and powerpoint, Google Earth, and a web-browser is required. This lesson is currently designed to be used in parallel with a GeoWall lab in which 3-dimensional visualizations of the Mariana system are presented. This is however not necessary.
Description and Teaching Materials
This activity is presented using a self contained powerpoint file. Hyperlinks to Google Earth are currently setup for Mac OS X. Edit the hyperlinks to reflect the location of the Google Earth executable if you are using Windows. If you have a GeoWall available a 3-D visualization of the Mariana system that uses ArcScene is provided.
Powerpoint presentation (PowerPoint 57.5MB Apr3 07)
ArcScene GeoWall visualization of Mariana 3-D topography and earthquake distribution (zip archive) ( 884kB Apr3 07)
Teaching Notes and Tips
Familiarity with the Mariana system is important. When discussing the geography of the area the instructor should be familiar with the names of the principle volcanoes and islands in the region. The powerpoint contains some speaker notes that are intended to guide the discussion and suggest questions to pose to students. The included GeoWall visualization requires a GeoWall and ArcScene. When uncompressed the instructor will find an ArcScene file name Mariana in the Mariana folder.
Assessment
Assessment is achieved in two main ways. Firstly, the instructor is encouraged to make use of think-pair-share type activities rather than simply posing a question. This encourages the students to think about the material being presented. Secondly, the activity is currently used with a classroom response system. This gives every student the opportunity to answer questions anonymously. Based on the answers provided the instructor should be able to gauge student understanding and re-present key points as needed.
References and Resources
As mentioned above, understanding the geology of the area is key to presenting the material in an intelligible way. The Mariana system is discussed at length on the Margins web page (http://www.nsf-margins.org/). Much of the data presented in the lesson was collected during cruise EW0202 and EW0203 on the R/V Maurice Ewing. A web page has been set up to present the results of this cruise (http://www.geo.ua.edu/MARIANA/).
