Fault-bounded mountains and morphometric properties
This activity has benefited from input from faculty educators beyond the author through a review and suggestion process.
This review took place as a part of a faculty professional development workshop where groups of faculty reviewed each others' activities and offered feedback and ideas for improvements. To learn more about the process On the Cutting Edge uses for activity review, see http://serc.carleton.edu/NAGTWorkshops/review.html.
This page first made public: May 2, 2008
Skills and concepts that students must have mastered
How the activity is situated in the course
Content/concepts goals for this activity
They should also understand that they can develop and test their own morphometric properties, i.e., they are not restricted to those used by other geologists.
Higher order thinking skills goals for this activity
Other skills goals for this activity
Description of the activity/assignment
Bull, W.B., 1984, Tectonic Geomorphology: Journal of Geological Education 32, pp.310-324.
To prepare for the classroom exercise, the instructor briefly presents the concept that measurable landform properties can reflect the intensity of tectonic activity. We discuss that certain landforms and settings are particularly useful in these types of analyses, for example, fault-bounded mountains and piedmonts. The class goes through a quick review of dip-slip faults, fault scarps, and triangular facets, and the Tobin Range is introduced as a typical example of a fault-bounded mountain range. We then ask the question, what are the useful characteristics of these settings in terms of inferring tectonic activity?
To address the question, students work in groups of 2 or 3. Each group is given a set of topographic maps chosen from the following (the region can also be printed from CDs of digital, seamless topo.s, but the quad. names are provided for reference):
7.5 minute quad.s: Home Station Ranch , Jersey Summit , Kennedy Canyon, Mount Tobin , Needle Peak
15-minute quad.s: Mt. Tobin, Buffalo Springs, Cain Mountain
On each map set, two lengths along the fault scarps are marked. One is marked in red and one in purple. Each student group has a map set of a slightly different region, but all map sets have a red fault scarp and a purple fault scarp marked. The red fault scarps in all of the sets are those that have experienced more recent displacement.
Each group is asked to do the following:
1. List physical characteristics of each of the two fault-bounded mountains/piedmonts that are marked on your quad.s with different colors.
2. Decide among yourselves which fault-bounded mountains/piedmont has experienced more recent displacement.
3. Suggest morphometric properties that could be used to differentiate between the more recent and less recent displacement, and explain why each of your properties makes sense. Morphometric properties must be measurable from the topographic maps.
After about 10 minutes, the class reconvenes and we go through the first two questions as a class. Then, each group presents at least one morphometric property and explains their reasoning.
Once we have a list of properties that the class agrees on, the instructor presents and the class discusses the properties that Bull (1984) used in his research of the Tobin Range region, such as sinuosity, the ratio between the valley floor width and the total valley height, the development of triangular facets.
Designed for a geomorphology course
Addresses student fear of quantitative aspect and/or inadequate quantitative skills
Determining whether students have met the goals
Download teaching materials and tips
- Activity Description/Assignment (Acrobat (PDF) 28kB May2 08)