The Mountain View area of the Stillwater Complex as a field teaching model
I. S. McCallum,
University of Washington, Dept. of Earth and Space SciencesAuthor Profile
<! -- start vocab summary -->
Two sections in the Mountain View of the Stillwater Complex are readily accessible for field-based teaching of petrologic and geochemical principles: (a) a section through the Ultramafic series in the vicinity of the old Mouat Chrome Mine and (b) a section through the Banded series exposed on the mine road ¾ mile south of the junction with the West Fork USFS road. Both sections provide ideal field settings to demonstrate a number of relatively simple concepts that we commonly discuss in abstract terms in the classroom.
<! -- end vocab summary --> Used this activity? Share your experiences and modifications
I will assume that most students in this group who make the trip to the Stillwater Complex are geology majors and do so after a year of traditional geology classes, i.e., they will have been exposed to mineralogy, petrology, structural geology and stratigraphy, and that they will have knowledge of the basic sciences equivalent to a full year of mathematics, physics and chemistry.
Skills and concepts that students must have mastered
Prior to the field visit, and preferably in a classroom setting near the actual site, students should attend a short tutorial on the general geology of the complex. In this tutorial there should be an attempt made to emphasize why rocks of this type, in general, and the Stillwater Complex, in particular, have played such a large role in petrologic thought. On the assumption that most students need reminding of what minerals look like and how textures are described, a brief summary of the basic mineralogy of mafic cumulate rocks should be provided
How the activity is situated in the course
This is a field trip designed to demonstrate and tie together concepts we talk about in the classroom.
Content/concepts goals for this activity
The fundamental objective is to have the students realize that rocks are much more than collections of minerals and that the mineral assemblages and rock sequences conform to simple basic scientific principles. A major objective is to have students make semi-quantitative observations of the rocks with a view to understanding basic petrologic principles such as fractional crystallization, magma mixing, assimilation, compaction, and fluid migration. The exposed sequences examined by the students provide superb examples to which more advanced students can apply the principles of thermodynamics and phase equilibria to actual rocks. The Ultramafic sequence also allows the students to make an estimate of the total reserves of Cr ore associated with the main Cr seam in the complex.
Higher order thinking skills goals for this activity
This activity involves analysis of data, formulation of hypotheses, synthesis of ideas, and critical evaluation of competing models and hypotheses.
Other skills goals for this activity
Description of the activity/assignment
Two sections in the Mountain View of the Stillwater Complex are readily accessible for field-based teaching of petrologic and geochemical principles: (a) a section through the Ultramafic series in the vicinity of the old Mouat Chrome Mine and (b) a section through the Banded series exposed on the mine road ¾ mile south of the junction with the West Fork USFS road. Both sections provide ideal field settings to demonstrate a number of relatively simple concepts that we commonly discuss in abstract terms in the classroom. To this end, the Mountain View field site has many advantages: it is readily accessible to large numbers of students, the rocks are well exposed and unaltered, detailed maps are readily available, there is a very large petrologic and geochemical database, a number of seminal papers on this area have been published, the mineralogy is simple and the constituent minerals in all rock types are easily identified with a simple 10x hand lens. In addition, this area demonstrates the importance of the Stillwater Complex as a major economic resource.
Determining whether students have met the goals
Students have met the goals of the activity if they are engaged in the activity and can come up with creative, but plausible, ideas for how the complex formed that are based on observations made at the field site.More information about assessment tools and techniques.
Teaching materials and tips
- Activity Description/Assignment (Microsoft Word 53kB Jul29 08)
- The Stillwater Complex: A review of the geology (Microsoft Word 1.4MB Jul29 08)
- Stillwater Stratigraphic Column (Acrobat (PDF) 130kB Jul29 08)