3D-printed models: tools for teaching 3D visualization of subsurface geology

Much of basic structural geology involves projecting data from maps of the Earth's largely two-dimensional (2D) surface into the opaque, three-dimensional (3D) subsurface. A key learning outcome is that students will be able to view a geologic map and visualize the landscape it represents and the shapes and relationships of geologic structures in the subsurface. Typically, this involves introducing students to tools that are used by professionals such as structure contours and stereographic projections. These techniques present students with challenges of scale, abstraction, and dimensionality. Challenges of scale involve the representation of macroscopic structures on printed pages. Challenges of abstraction involve representing physical features, such as rock formations or dipping surfaces, with idealized representations such as map patterns or sets of structure contours. Challenges of dimensionality involve mentally or mathematically projecting the real, but invisible, 3D subsurface world into 2D representations such as cross-sections and stereographic projections. Physical models offer the potential to ease some of these challenges, and advances in 3D-printing allow for the creation of sophisticated and highly customizable geologic models. Students will be able to directly observe otherwise hidden subsurface structural relationships by manually separating geologic domains. Write-on wipe-off surfaces allow students to draw structure contours directly on geologic structures. Due to the closure of printing facilities during the COVID-19 pandemic, several geologic models were published virtually using Seequent View, an interactive, web-based storytelling platform. The impact of 3D-printed models and their virtual equivalents on students' ability to visualize subsurface geology can be assessed using established survey instruments that test 3D visualization skills, and with metacognitive evaluations that assess students' perceptions of what they have learned.