Geoscience in Two-year Colleges > Activities > Well Core Analysis: Capstone Activity for Historical Geology

Well Core Analysis: Capstone Activity for Historical Geology

Original activity developed by Robert H. Blodgett, Austin Community College using a graphic logging form modified from one created by Alan J. Scott.
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Summary

As a capstone laboratory project for introductory historical geology, the class is divided into groups of 3 to 5 students to analyze a sedimentary rock core and associated geophysical log. Each group graphically describes and interprets 24 feet of split core, along with a gamma log for the same interval. The class is provided with hand lenses, binocular microscopes, , spray wash bottles, dilute HCl, a logging form, and with selected research papers on textures, structures, and fossils found in the core, regional paleogeography, and on the tectonics and paleooceanography at the time of deposition. Each group gives a 15-minute presentation of their core interval to the entire class and submits a graphic log for the interval. All students submit a two-page report summarizing their own observations and interpretations of the core interval. Assessment is based on a combination of the group presentation and individual report.

Learning Goals

The primary goal is for students to experience the thrill and excitement of scientific discovery in a project that integrates observational and interpretive skills to reconstruct Earth history. Secondary goals include improving each student's ability to work in a group, apply critical thinking to evaluate sedimentological, paleontological, mineralogical, and geophysical observations, formulate hypotheses to explain observations, integrate observations with published scientific literature, and to synthesize and communicate ideas both in writing and in an oral presentation.

Context for Use

End-of-the-semester laboratory project suitable for:
  1. A freshman-level introductory course in historical geology at either a 2-year or 4-year college
  2. An undergraduate- or graduate-level stratigraphy or sedimentology course

Students should have completed previous laboratory or field exercises on the identification and interpretation of sedimentary rocks, sedimentary structures, and fossils.

Total laboratory time is 6 hours with the core available for student use outside of the scheduled class time in a 4-hour open laboratory session.

A well core for this exercise might be obtained from an oil or mining company, or through a state geological survey. College alumni working for energy or mining companies, consulting firms, or government agencies may be able to arrange for donation of part of a core to the college. The U.S. Geological Survey Core Research Center in Denver (http://geology.cr.usgs.gov/crc) is also a potential source of information on well cores.

This exercise could be modified to use well cuttings, instead of core, with more emphasis on textural trends, mineralogy, and possibly microfossil identification.

Description and Teaching Materials

Mechanics

Lab 1 (1.5-hr) – introduction to subsurface methods, including constructing graphic well logs and interpreting geophysical logs; Orientation to well core (e.g. labeling, marks indicating orientation of core, depth measurements on core box, markings produced in coring and preparation of core) and geophysical log.

Lab 2 (1.5 hr) – safety briefing followed by selection of groups; each group begins description of two boxes of core, each with 9 feet of split core; Emphasis is on learning to use the logging form and describing the "big picture" for the entire 18-feet of core; Professor acts a consultant to guide students in observing and interpreting textures, grain-size trends, structures, fossils, and minerals. Students are offered a selection of photocopied research papers that can borrowed and read before the next lab session. Other references are included as *.pdf files on Blackboard.

Lab 3 (1.5 hr) – completion of core description and preparation for group presentation; Professor continues role as a consultant using the Socratic method to guide observations and interpretations.

Lab 4 (1.5 hr) – each group gives a presentation to the entire class gathered around the group's boxes of core. Each group has 10 minutes for a presentation and 5 minutes for questions. The professor summarizes and adds to each group's presentation once it is complete. Students submit individual 2-page papers on their core interval.

Equipment and supplies

Dilute hydrochloric acid in a dropper bottle (1 per group)
Hand lenses (1 per student)
Meter sticks with a scale in inches (1 per group)
Plastic spray bottles with water (identical to those used for misting plants - 1 per group)
Binocular microscopes (optional - 1 per group)
Photocopied (or *.pdf copies) of references containing illustrations and interpretation of body and trace fossils, sedimentary structures, plate tectonics, paleogeography, paleoclimatology, and paleoceanography (if applicable) help students place the core in a local, regional, and global context.

Teaching Materials

Student Handout for Well Core Project (Microsoft Word 304kB Jun11 10)
Graphic Logging Form (Microsoft Word 242kB Jun11 10)

Teaching Notes and Tips

The professor should be in the classroom interacting with students while they are describing the core. Students at first may be overwhelmed with the tasks; An example of how a short section of core would be described helps give students the confidence to proceed with the exercise. Continual discussion between the professor and the student groups is needed to ensure that they complete tasks in the allotted time. Safety guidelines regarding the use of dilute acid and microscopes should be reviewed at the start of the exercise.

Assessment

Rubrics can be used to evaluate group presentations and individual reports. Interaction between the professor and students during laboratory sessions helps assess if students have developed observational and interpretive skills. Comments on a end-of-semester written course evaluation will indicate if students have experienced thrill and excitement in the project.

References and Resources

Sample examination of well core and cuttings
Swanson, R.G., 1981. Sample examination manual: Tulsa, OK, American Association of Petroleum Geologists Methods in Exploration Series.
Standard symbols for graphic logs
Nilsen, T.H., Lindquist, T. and Cobb, J.C., 2006. Lithologic patterns for stratigraphic columns and cross sections, in Walker, D.J. and Cohen, H.A., eds. The geoscience handbook, AGI data sheets (4th edition), p. 42-44.
Interpretation of wireline geophysical logs
Bohling, Goeff, and Doveton, John H., 2002 Reading the rocks from wireline logs: Lawrence, KS, Kansas Geological Survey, updated 2003 - online tutorial and software at http://www.kgs.ku.edu/PRS/ReadRocks/portal.html

Doveton, John H., 1994. Geologic log interpretation: Tulsa, OK, Society of Economic Paleontologists and Mineralogists Short Course No. 29, 169 p. [ http://scnotes.sepmonline.org/content/sepscgli/1.toc]

Lewis, D.W., 1984. Practical sedimentology: Stroudsburg, PA, Hutchinson Ross Publishing Co., 227 p.

Interpretation of trace fossils in core

Chamberlain, C. Kent, 1978. Recognition of trace fossils in cores, inBasan, Paul B., ed., Trace fossil concepts: Tulsa, OK, Society of Economic Paleontologists and Mineralogists Short Course No. 5, p. 133-183. http://scnotes.sepmonline.org/content/sepsctfc/1/SEC5.body.pdf

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