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Determining the Geologic History of Rocks from a Gravel Deposit

Activity designed by Daniel Rolf Tucker, Melinda Riddler Tucker, and William Albert Rieck of the University of Southwestern Louisiana. Starting Point page developed by John McDaris.

This material is replicated on a number of sites as part of the SERC Pedagogic Service Project


Gravels deposited as a result of continental glaciation are used to teach introductory-level earth-science students the application of the scientific method in a cooperative learning mode which utilizes hands-on, minds-on analyses. Processes that involve erosion, transportation, and deposition of pebble- and cobble-sized clasts are considered by students in formulating and testing hypotheses. The wide variety of represented rock types forces the students to consider regional and local source terranes as well as what general type of sedimentary mechanism(s) was involved in formation of the deposit. Each student group is required to present an oral report on its findings. An optional written laboratory report of the experience of analyzing glacial gravels helps students to organize what they have learned and synthesize a general conclusion.

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Learning Goals

  • Have students apply the scientific method to identify rocks from glacial deposits, hypothesize how they got there and then test their hypothesis.
  • Give students an experience of active, hands-on inquiry.

Context for Use

The exercise was designed for use with elementary-education majors in an introductory earth science course. But, as long as the students have had some experience in identifying minerals and rocks, it is also applicable in middle and high school settings.

Teaching Materials

The instructor needs to secure sets of about a dozen specimens of varying lithologies for the students to identify. There should be as many sets of samples as there will be student groups. Most of the specimens should be esily identifiable to the novice, with a small number of more dificult samples. The samples should all be from the same location and should be representative of the rocks in the deposit.

The class is divided into groups of 3 students and the roles of analyzer, recorder, and reporter are assigned. The groups then try to identify as many of the specimens as they are able to given their skill level. They should also endeavor to draw specific conclusions about the history of the samples.

After the groups have identified the rocks in their specimen set, they are asked to use a geologic map to determine how the rocks came to be in the deposit where they were collected. Students should be expected to think about how the three mechanisms of sediment transport/deposition (running water, glaciers, wind) could have worked, individually and/or together, to form the deposit.

As an optional exercise, the instructor can also as each team whether their hypotheses about geologic history from the identification phase were correct or how they could determine this information. If not, supplemental work to repeat the exercise could be assigned.

Teaching Notes and Tips

A record of the authors' use of the activity in class is presented in Tucker et al., 1998 .


Student groups present their hypothesis and conclusions with the rest of the class orally after they have finished their investigations. The instructor can prompt the groups with questions to make sure they have come to a sound conclusion and supplemental work can be assigned if necessary.

References and Resources

Tucker, D.R., M.R. Tucker, and W.A. Rieck (1998). A Cooperative Learning Exercise Using Glacial Gravels , Journal of Geoscience Education, 46 (1), 41-44.

Wynn, C.M., and A.W. Wiggins, 1994, National science: Bridging the gaps, third edition: Needham Heights, Massachusetts, Ginn Press, 188 p.


Geoscience:Geology:Mineralogy, Igneous and Metamorphic Petrology

Resource Type

Activities:Project, Classroom Activity

Grade Level

College Lower (13-14):Introductory Level, Middle (6-8), High School (9-12)

Ready for Use

Ready to Use

Earth System Topics

Surface Processes:Glaciers, Weathering, Erosion, Mass Wasting, Solid Earth:Earth Materials:Minerals, Rocks


Solid Earth:Mineralogy, Petrology


Teach the Earth:Teaching Topics:Minerals, Teach the Earth:Teaching Environments:Intro Geoscience, Teach the Earth:Course Topics:Mineralogy, Petrology