Biostratigraphy of the Crystal Peak Dolomite, Ibex, UT

Benjamin F Dattilo
Indiana University Purdue University Fort Wayne
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Students participated in measuring a section and collecting samples for real research.
It is part of a flexible field course
Prior student experience varies widely in this course.

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This activity was one day out of a 14 day senior-level field course "Regional Geology". The course is offered every 2 years and is open to majors of all levels and for honors students as a necessary component (lecture + lab + field) of their introductory geology course.

Skills and concepts that students must have mastered

Minimal: all students were assumed to have had physical geology. Some students had had several courses in geology and paleontology.

How the activity is situated in the course

This activity occupied one day out of 14 in a wide-ranging field trip. The exercise does not depend on other exercises.


Content/concepts goals for this activity

Sequence stratigraphy
Section measuring techniques
Sample collection and hygeine for micro paleontology

Higher order thinking skills goals for this activity

Inferrence with respect to biostratigraphy--how do you date a sandstone that, itself, contains no fossils?

Other skills goals for this activity

Working in groups
use of jacob staff
Drawing a stratigraphic section in the field

Description of the activity/assignment

This activity involved students in an actual research project. Prior to conducting the fieldtrip, the first conodonts were retrieved from a few samples of the Crystal Peak Dolomite, which lies above the Watson Ranch Quartzite and below the Eureka Quartzite; both "quartzite" (sandstone) units are unfossiliferous. The Crystal Peak samples revealed an unusual conodont fauna which offered promise for refining the stratigraphic placement of the Eureka Quartzite. At this time the stratigraphic section had not been measured, though the locations of each sample had been marked on the outcrop. The fieldtrip happened to coincide with the next opportunity to actually measure the section, log the stratigraphic positions of these previously-collected samples, and collect additional samples to refine the stratigraphic pattern first recognized. The following outline is generalized


Much of the preparation for this activity could be done before the fieldtrip began.

First, the stratigraphy and biostratigraphy of the Ibex region is well known and a pre-lecture with handouts were provided by James Miller, one of the co-researchers who specializes in Conodont stratigraphy of the region.

Other helpful steps in preparation would include providing students with an orientation to conodonts, including a little time examining them under a microscope and studying photographs of key species expected in the section. In this case, the species that might mark the base of the Mohawkian.

Pre-trip Activity (spring 2009)

Students can be provided with an opportunity to contribute to sampling strategy. In this case, some samples had already been collected (labelled A, B, C . . . without the context of a measured section), and conodonts had already been identified from these samples (by Ray Ethington). Provide the students with this information, combined with knowledge of the specific biostratigraphy in question. At this point, allow students to choose the interval of interest--where do we need to collect more samples? Where would additional samples likely NOT improve the precision of correlation? Why?

Field Activity (Spring 2009 after finals)

With this introduction, students were presented at the outcrop section. Students were divided into three groups and took turns 1) using Jacob staff to measure the strata and place marks at regular intervals up outcrop; 2) drafting a stratigraphic section and describing the strata in a field notebook; and 3) recording the stratigraphic horizons of previously-collected samples, and collecting additional samples according to plan. Each of these activities is closely monitored by an instructor, so it requires three instructors to complete.

Followup Activities (spring 2010 Sed Strat course).

This activity was conducted as part of a two-week field excursion in the spring of 2009. Grades were due at the end of the two weeks, so followup activities were not incorporated into the course. However, many of the students who attended this field course are geology majors who will take sedimentology-stratigraphy course (tought by ME the same instructor) in the spring of 2010. This will provide an opportunity for students to take combine their field observations and photos with conodont data extracted from the samples that they collected and perhaps participate directly in the publication process.

The fact that this was a real research project elicited a high level of enthusiasm from the students.

Determining whether students have met the goals

Students are evaluated using 1) direct observation of student performance in the field 2) on site questioning and 3) students field notes turned in after activity..

More information about assessment tools and techniques.

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