Determining the Geologic History of Rocks from a Gravel Deposit
This material was originally created for Starting Point:Introductory Geology
and is replicated here as part of the SERC Pedagogic Service.
- 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
Description and 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
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.