Cutting Edge > Courses > Sedimentary Geology > Sedimentology, Geomorphology, and Paleontology 2014 > Teaching Activities > Measuring Sedimentary Structures for Paleocurrent Reconstruction

Measuring Sedimentary Structures for Paleocurrent Reconstruction

Kyle Fredrick, California University of Pennsylvania
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Summary

This is a combination field/lab exercise for an upper-level Sedimentology course. Students will use Brunton compasses to collect structural and sedimentological data. Orientation data will be analyzed using Rose diagrams.

Context

Audience

This exercise is used in an upper-level (400-level) course, Sedimentology and Stratigraphy, at a primarily undergraduate institution. Most students in the class are expected to be juniors and seniors.

Skills and concepts that students must have mastered

Students should be competent at taking field notes and creating adequate field sketches. They should already understand the principles of grain-size variation, bedding, and transgression/regression. They should be familiar with sedimentary structures, but not necessarily proficient in identifying them. They should be practiced in using a Brunton compass, but again, not necessarily proficient.

How the activity is situated in the course

This is a stand-alone exercise that is conducted the week after a mid-semester field trip. It is designed to take up to two one-hour class periods and then completed on the students' own time to finish their write-up.

Goals

Content/concepts goals for this activity

Sedimentary structure recognition
Field observations and note-taking
Paleocurrent analysis
Rose diagrams

Higher order thinking skills goals for this activity

Analysis of data
Synthesis of data for paleogeographic interpretations
Defending hypotheses and creating alternative models

Other skills goals for this activity

Spatial reasoning
Peer-to-peer critical reading/writing
Proficiency with Brunton compass
Field sketching and general field skills
Analyzing frequency plots
Comparing varying methods of data display

Description and Teaching Materials

This exercise is founded upon a field trip that we take for Sedimentology, to Ohiopyle State Park. It is a one-day field trip to a location about 45 minutes from our campus, usually taking a full Saturday (8-10 hours).
On the trip, students will use the topographic map to locate themselves and to note our field stops. The first, and most obvious location is at Cucumber Falls on the western side of the park. It is easy to access and has terrific exposure from undercutting that has created several measurable cantilevers. Large cross-bed sets are easily measured here. Also, students will be able to see the channel fills, which they should recognize as key to their interpretation for other, less obvious sites.
After the field excursion, we spend the following two class periods introducing Rose diagrams and the students compile their data. They engage with their partners and ask questions of the instructor. The hope is that they vet their hypotheses and begin crafting a rough draft of their write-up by the second class period. They are then given additional time to complete their brief write-up (I give until the beginning of the next week).
Student Handout for Paleocurrent Lab (Acrobat (PDF) 2.3MB Jun11 14)
Word version of Handout (Microsoft Word 2007 (.docx) 390kB Jun11 14)
Blank Rose Diagram (Microsoft Word 2007 (.docx) 50kB Jun11 14)
Ohiopyle Map (Acrobat (PDF) 2MB Jun11 14)

Teaching Notes and Tips

This exercise is purposefully vague in some important places. Namely, there is not a lot to back up the use of Brunton compasses or completing sketches in the field. These are skills that students should be comfortable with before endeavoring to complete this exercise. Additionally, the Rose diagram compilation is not explained at length. It is explained as a "simple" procedure, that we'll do as a class. I find that it is easier to deliver this technique with a small data-set in class and have them complete it to replicate one that I've already done. If theirs matches mine, they are ready to move on to their own data.

Assessment

Students are graded on their write-up and the completion of their supporting documents. This is a short writing assignment and will mostly be used to engage their analytical skills. The rubric is a 25-point scale from which 15 points are attributed to their ability to communicate a reasonable geologic interpretation.
Not included in the documentation is a follow-up, where we will discuss the different interpretations among the different groups.

References and Resources

Ohiopyle Map: http://www.mappery.com/map-of/Ohiopyle-State-Park-map
Pottsville Sandstone explanation from USGS: http://mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=PAPAp%3B6
Official page of Ohiopyle State Park: http://www.dcnr.state.pa.us/stateparks/findapark/ohiopyle/

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