3D Model of a Geologic Map
200-level undergraduate course, "Introduction to Geologic Structures." This course is a pre-requisite for most upper-level undergraduate geoscience courses in the core curriculum, including Structural Geology. It has a pre-requisite of an introductory level Geology course.
Skills and concepts that students must have mastered
Students need to be familiar with the concepts of unconformities and igneous intrusions
How the activity is situated in the course
This activity builds on previous exercises interpreting geologic maps of dipping beds, of angular unconformities, and of simple igneous intrusion. See the "references and resources" section at the bottom of this page for links to some of these previous activities.
We do this exercise in class, allowing students to talk to each other and/or to ask questions of the instructor and TAs.
Content/concepts goals for this activity
Students will be able to construct a cross-section through a geologic map that includes an unconformity and / or one or more planar igneous intrusions.
Higher order thinking skills goals for this activity
Students will be able to decipher cross-cutting relationships on a geologic map.
Other skills goals for this activity
3D spatial visualization
Description and Teaching Materials
I provide students with a geologic map of the region illustrated in the 3d Play-Doh model shown here, including a line of cross-section that cuts across the map in the long dimension.
Science of Learning: Why It Works
Three-dimensional models can help to improve students' understanding of geological phenomena. Physical models, such as playdough models, serve as analogies to geological features and geologic maps. Analogies support the development of spatial thinking skills by allowing the student to draw from their knowledge and apply it to new cases (e.g., Gentner 1983). For example, students can reason from what they can experience when carving off pieces of playdough to how erosion will reveal geological structures). Analogical learning also applies to "mapping" -- that is, relating -- the features of models onto real world phenomena (e.g., this layer of playdough corresponds to a layer of sandstone). Physical models provide analogies to real-world phenomena, support cognitive offloading, and promote spatial accommodation.
Practice constructing spatial analogies can help students develop the mental models that allow them to recognize new cases of familiar concepts in the field. When instructors provide accurate physical models of geologic features, students can self-assess their understanding by comparing their mental model -- or their own physical model -- to the instructor's physical model. When students make their own physical models, these models serve as a means of "inscription," in much the same ways that mapping and sketching do: they allow for students to record their conceptual understanding of a natural phenomenon (Mogk and Goodwin, 2012). However, unlike mapping and sketching, a playdough model allows for this record to be three-dimensional, like the phenomenon itself, which can reduce the cognitive demands inherent in the process of inscription by reducing the need to generate a 2D representation of 3D space (Newcombe, 2012). In addition, physical models support spatial accommodation: when a student compares their (mental or physical) model of a phenomenon or region to their instructor's model and recognizes a difference between the models, the student is prompted to revise their mental model (Davatzes et al., 2008). When the change required is spatial the student may use the feedback directly to revise the model. When the change is significant, the student may need to completely discard their old model and construct a new one. Playdough models of geological structures can thus serve as the basis for improved mental models.
Teaching Notes and Tips
Showing students the Play-Doh model is a formative assessment for the students. It allows them to compare their mental model of the geologic map to a 3D physical model of the same region. I also collect their cross-sections.
References and Resources
This exercise builds on previous activities in the course, including:
Davatzes et al. (2018). Learning to form accurate mental models. Eos, 99, https://doi.org/10.1029/2018EO091643. Published on 07 February 2018.
Gentner, D. (1983). Structure-mapping: A theoretical framework for analogy. Cognitive Science, 7(2), 155–170.
Mogk and Goodwin (2012). Learning in the field: Synthesis of research on thinking and learning in the geosciences, in Earth and Mind II: A synthesis of research on thinking and learning in the geosciences, edited by Kim A. Kastens and Cathryn A. Manduca. GSA Special Paper 486:131-163. DOI: 10.1130/2012.2486(24)
Newcombe, N. S. (2012). Two ways to help students with spatial thinking in geoscience. Geological Society of America Special Papers, 486, 85-86.