Outcrop Mapping at Woodall Shoals, South Carolina-Georgia
Department of Physics, Geology and Astronomy, The University of Tennessee at Chattanooga
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Students work in groups of 3 or 4 to map relatively small parts of the outcrop at Woodall Shoals, which serves as a model of a complexly deformed high-grade metamorphic terrain. With the benefits of 100% exposure and a relatively small area, this provides a good introduction to mapping metamorphic rocks and associated structures.
This project is used in an upper level undergraduate field methods course that follows a course in structural geology.
Skills and concepts that students must have mastered
Students should be proficient in the identification of metamorphic rocks, making and noting field observations, representing spatial relationships in map projection, measurement of linear and planar features using a Brunton transit, recognition and/or interpretation of complex (well-exposed) structures, and traditional representation of features on a geologic map.
How the activity is situated in the course
This project is used only after students have gained considerable experience mapping deformed sedimentary rocks of the fold and thrust belt and low-grade metamorphic rocks of the western Blue Ridge. It is commonly also used at the conclusion of a field trip based on a geologic-transect of the Blue Ridge.
Content/concepts goals for this activity
Students will (1) apply knowledge of mineralogy and petrology to identify and distinguish among metamorphic lithologies, (2) apply knowledge of structural geology to recognize complex geologic structures associated with high-grade metamorphic rocks, and (3) practice and improve upon observation, measurement, and data-gathering skills.
Higher order thinking skills goals for this activity
Students will (1) interpret geometrically related features in the outcrop to infer the presence of structures that are not obvious, (2) interpret features in the outcrop to infer geologic processes, conditions of deformation, and sequences of events, and (3) practice and improve upon their spatial thinking skills required for map projection of the 3-dimensional outcrop surface.
Other skills goals for this activity
Students will practice and improve upon their ability to (1) work productively with others in a group and (2) draft a geologic map, both in the field (field map) and in the lab/office (final map, drafted with a computer).
Description of the activity/assignment
Mapping of complexly deformed high-grade metamorphic rocks in areas of relatively poor exposure, such as the southern Appalachian Blue Ridge, is very challenging. A traditional mapping project in such areas may be too difficult and frustrating for most undergraduate students and may be ineffective. Mapping parts of the outcrop at Woodall Shoals, with the benefits of 100% exposure and a relatively small area, provides a good alternative. This very large (2,000-square-meter) outcrop contains a full compliment of rock fabric and complex geologic structures typical of such areas. For purposes of the present exercise, it serves as a generic scale model of an exhumed high-grade terrain. The detailed map of the outcrop by Hatcher et. al. (1989, Georgia Geological Society Guidebook, v. 9, n. 3, Plate 3) is used as a solution to the exercise.
Determining whether students have met the goals
For part of the evaluation, students' map patterns are compared to that of Hatcher et. al. (1989, Georgia Geological Society Guidebook, v. 9, n. 3, Plate 3). Although a perfect match is not expected, the patterns should bear a reasonable resemblance. Other aspects of the evaluation consider the format and completeness of the map in terms of map symbols, density of structural symbols, explanation of symbols, rock names and lithologic descriptions, scale, north arrow and declination, title, author, group member names, date, etc. The evaluation can also consider observations of students' performance in the field and their contribution to the progress of their group. More information about assessment tools and techniques.
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