An Inquiry-Based Approach to Learning Petrology Using Student-Generated Data

submitted by

Karl Wirth Macalester College
Author Profile

This is a partially developed activity description. It is included in the collection because it contains ideas useful for teaching even though it is incomplete.

The Petrology course at Macalester College is designed around a semester-long project. All laboratory and classroom activities within the course are directed toward understanding and solving a real-world problem, the origin and evolution of an intrusion in northern Minnesota. Emphasis is on using multi-disciplinary approaches, modern instrumentation, and student-generated data. After completing the course, students exhibit improved quantitative skills, reasoning, and understanding of fundamental petrologic processes.
GSA Poster (Acrobat (PDF) 107.6MB Nov14 03)

Learning Goals


Higher Order Thinking Skills:

problem-solving, hypothesis testing, integrating diverse observations and data, relations between rocks and data

Other Skills:

databases, sample preparation, instrumentation, spreadsheets, writing, oral presentation


Instructional Level:

undergraduate majors

Skills Needed:

introdroductory earth science

Role of Activity in a Course:

This is an example of a semester-long project that integrates many of the aspects of a petrology course

Data, Tools and Logistics

Required Tools:

standard tools for teaching petrology (microscopes, computers) as well as some instrumentation (e.g., AA, XRD, XRF, ICP). A comprehensive suite a related rocks that illustrate fundamental petrologic processes is also needed; it is preferred that students can collect the samples in the field.

Logistical Challenges:

This approach is time-consuming for the student and the instructor, resulting in less content breadth in the course, but much greater depth.


Evaluation Goals:

After completing the course students exhibit greater facility working with large datasets, integrating diverse observations, and improved writing and oral presentation skills. However, this has not been rigorously tested.

Evaluation Techniques:


The project begins early in the semester when students are provided a suite of rocks, a map, and a lithostratigraphic column from the Sonju Lake Intrusion. Students work as a group to describe and classify the rocks using hand specimens and thin sections. This is followed by detailed petrographic analysis, which provides data about mineral textures, compositions, and proportions. Explanations of the origin and evolution of the intrusion are constructed from the petrographic data and then tested using mineral (SEM-EDS) and whole-rock (XRF) chemical data collected by the students. The explanations of the origin and evolution of the intrusion are further evaluated and revised. Finally, students test their hypotheses using numerical models (MELTS and trace element models) to model their geochemical data. Students present their findings to the rest of the class in oral format and submit written reports.