Exercise on the Mesozoic/Cenozoic Development of the North American Cordillera
This assignment is intended to have students use the map reading skills they have learned in previous labs and their understanding of the lower crust and upper mantle derived from classroom lectures and demonstrations to develop a three-dimensional picture the Southern Canadian Cordillera. I try to incorporate the notion of temporal change by asking students to describe the region at different times in the past and to speculate what the region would look like if certain tectonic events happened in the future.
Key words: tectonics, Cordillera,subduction, fold thrust belts
This assignment is the final project for a course entitled Earth's Interior: Its character, dynamics, and development. The course is taught at the 200 level, and it is required of all majors. I developed this course after a change in major requirements meant that many of our students were graduating without taking structural geology.
Skills and concepts that students must have mastered
I use Keary, Klepeis, & Vine as the text, and we have worked through all but the final chapters of three chapters of the book when students begin the project. Throughout the semester, we have focused on the Canadian Cordillera as a type example of trailing margin sedimentation, foreland basin sedimentation, fold-thrust belt structure, and metamorphism. Students have completed labs on stereographic projections, first motion diagrams, rock fabrics, geologic maps, trailing margin sedimentation, continental transform faults, and fold-thrust belts before beginning this exercise.
How the activity is situated in the course
This is the culminating project for this course, and students have the final two weeks of class, our reading period, and part of the exam period to complete the project. That includes two weekly laboratory periods where I discuss student's progress with them and guide them toward materials in the text, materials posted on BlackBoard, or earlier labs.
Content/concepts goals for this activity
The goal of this exercise is to have students compile published geophysical data and geologic maps to understand the structure and tectonic of the Canadian Cordillera. This belt is, in my view, an interesting and well-known archetype of an orogenic belt.
Higher order thinking skills goals for this activity
In building a complete picture of the belt, students must synthesize data and ideas as they evaluate competing models for the development of the belt.
Other skills goals for this activity
Working in groups and writing are other skill goals for this activity.
Description and Teaching Materials
For this project, students use two of the Continent-Ocean Transects constructed for the Decade of North American Geology and contemporaneous centennial of the Geological Society of America: the Centennial Continent-Ocean Transect #7, B-2 Juan de Fuca Plate to Alberta Plains and the Centennial Continent-Ocean Transect #9, B-3 Juan de Fuca Spreading Ridge to Montana Thrust Belt. One could develop a similar exercise for different continent-ocean transects.
Student handout for Exercise on the Mesozoic/Cenozoic Development of the North American Cordillera (Microsoft Word 2007 (.docx) 27kB May4 12)
Teaching Notes and Tips
Some students take to this project without any hesitation. Others require some guidance. I have included a series of 'things to think about' questions, and I often work through them with individual students or groups of students.
The evaluation is rather subjective and qualitative, but I look especially for how closely students have examined the primary materials and developed an internally consistent picture of the orogen, how well students have drawn upon concepts from readings and lectures to support their arguments, the extent to which they have consulted with their cohorts, and how clearly and concisely they convey their thoughts.
References and Resources