SEQUENCE OF INTRODUCTORY PHYSICAL GEOLOGY TOPICS: WHEN SHOULD PLATE TECTONICS BE TAUGHT?

Traditionally, physical geology courses and textbooks are organized so minerals are taught first, and plate tectonics covered toward the end of the course. With the recent emphasis on inquiry-based teaching, and on viewing Earth processes as an integrated global Earth system, is this "traditional" sequence still the preferred teaching method? Are publishers reorganizing textbooks to capitalize on the "recent" Earth-system trend?

With the “traditional” sequence, plate tectonics acts as a “capstone” topic to explain how the previous subjects (e.g., volcanic activity) are related to the broader spectrum of Earth processes. It also allows the instructor to define, in detail, the causal mechanisms and "proof" of plate tectonics. In contrast, teaching plate tectonics first provides the student with the "big picture" early in the course. Subsequent topics can then be related to this overriding theme. As new concepts are introduced, students can place these topics into context, which allows for a deeper understanding of the interrelationships among geologic processes.

We surveyed 133 physical geology syllabi, from 114 colleges and universities, and 16 of the most recent editions of popular textbooks, to compare the teaching sequence of the following five topics: minerals, igneous rocks, volcanoes and volcanic activity, earthquakes, and plate tectonics. The most popular teaching sequence (41.7%) was the “traditional” approach: minerals, igneous rocks, volcanoes, earthquakes, and plate tectonics. The second most common sequence (26.8%) was the “recent,” approach: plate tectonics, minerals, igneous rocks, volcanic activity, and earthquakes.

Textbooks are also most commonly organized in the traditional sequence (31.2%). The recent approach was used in only 25.0% of the texts. However, a brief introductory chapter of plate tectonics and Earth processes was used in exactly half of the textbooks. This would suggest that authors and editors are compromising between the two. These data suggest that even though textbooks are beginning to reorganize chapter subjects, and authors are becoming more "Earth-system" oriented, the traditional method of teaching physical geology is still prevalent in college and university programs.