1. Identify and describe the geometric characteristics of the four basic fold interference patterns (Types 0-3) and explain how they form through superposition of multiple fold generations.
2. Use 3D modeling tools to recreate superposed folds, manipulate variables like hinge line orientations and axial surface angles, and analyze resulting interference patterns in map, cross-section, and 3D views, and using stereonets.
3. Interpret the implications of fold interference for deformation history, including changes in kinematic conditions and challenges in mapping fold orientations in multiply deformed terrains.

This activity, "Exploring Fold Interference Patterns Using Visible Geology," is a roughly 2-hour guided inquiry lab designed for upper-level undergraduate students in a Structural Geology or Tectonics course. It requires students to apply foundational concepts of fold anatomy, classification, and superposition principles before beginning. The core of the lab involves using the Geology Explorer module , part of the Visible Geology web-based application, to build 3D models, apply and manipulate fold parameters (F1 and F2), and recreate the four basic fold interference patterns (Type 0-3). Students must demonstrate technical proficiency with the 3D modeling web-based application and utilize disciplinary skills like stereonet analysis to interpret their models. The final output is a short report summarizing their construction and interpretation of the models' geometric and tectonic implications.

Visible Geology teaching activity_exploring_fold_interference_patterns.pdf (Acrobat (PDF) 729kB May15 26)

Visible Geology teaching activity_exploring_fold_interference_patterns.docx (Microsoft Word 2007 (.docx) 7.2MB May15 26)

• Based on the specific geometries applied during events by the students, outcomes can vary widely. I would suggest encouraging the students to experiment to find the best combinations, which will lead to increased understanding compared to following very explicit instructions.
• To save and share their work in Visible Geology, students are encouraged to log in with their Google Account.

The assessment criteria are designed to directly evaluate student mastery of the three specified learning goals through a combination of 3D model construction, visual evidence, and analytical interpretation.

• The first goal assesses the understanding of the geometric characteristics of the four-fold interference patterns (Types 0-3) and the principles of superposition, requiring clear, correctly labeled screenshots of each pattern.
• The second goal evaluates the demonstrated proficiency in using the Visible Geology web-based application for model construction and analysis, with deliverables including screenshots of the undeformed and F1 fold models, and an accurate stereonet plot identifying the F1 fold axis.
• The third goal focuses on analytical and interpretive application, linking model outcomes to real-world geological processes, which is assessed through accurate and thorough short-answer responses to the questions regarding fold parameter effects, tectonic implications (Question 5), and a final reflection.

• Prior to the lab, students should read the "Superposed Folding" section of the PSGT textbook (Chapter 8, approximately pages 27-29), focusing on the principles of fold superposition, the four interference types, and their tectonic significance.
• Reference: van der Pluijm, B. and Marshak, S. (2020). Processes in Structural Geology & Tectonics. University of Michigan.
• Optionally, review earlier sections on fold anatomy and classification for foundational terminology (e.g., hinge lines, axial surfaces, interlimb angles).
• For tips, tricks and how-to videos for using Visible Geology, check out the Visible Geology Help & Resources.