Sketching Block Diagrams

After successfully completing this exercise, students will be able to sketch geologic block diagrams of simple structures chosen by the instructor.

This exercise is designed to be used as an early 3D sketching exercise in a Structural geology course, though it could also be used in any other course where basic structures are studied. One key purpose is to help develop students' spatial visualization skills. We recommend that it follow this introduction to 3D sketching exercise.

Students watch videos of Dr. Hickson sketching two geologic block diagrams. Dr. Hickson talks about what he is doing as he sketches.

How to sketch a block diagram of flat layers (Quicktime Video 4.9MB May1 14)

How to sketch a block diagram of an upright anticline (Quicktime Video 13.3MB May1 14)

Students make sketches of block diagrams of structures of your choosing. These could include horizontal stratigraphy and an upright anticline, or could be of new structures, such as an upright syncline, asymmetrical folds, or anything else you like. We recommend building up gradually from simple structures to more complex ones.

Some students find this exercise relatively easy; others find it quite challenging. However, research shows that sketching helps build the spatial visualization skills that underpin this exercise (e.g., Gagnier et al., in review). You may wish to mention that to your students, to motivate and encourage them.

This exercise was developed as part of a set of exercises to support 3D visualization skills. These exercises had an intended order. Instructors can pick and choose the exercises, but the order we intended was as follows:

1. Introduction to 3D sketching
2. Sketching block diagrams
3. Sketching 3D Ripples and Dunes
4. Slicing cylinders
5. Slicing channels
6. Slicing fruit
7. Slicing rocks
8. Slicing fossils

We use a 4-point rubric to evaluate student sketches:

• 1 point for showing the (approximately) correct geometric pattern on each face of the block, and
• 1 point for correctly connecting layers that appear on multiple faces of the block.

Gagnier, Kristin Michod, Kinnari Atit, Carol J. Ormand, and Thomas F. Shipley. Comprehending Diagrams: Sketching to Support Spatial Reasoning: Topics in Cognitive Science (in review).