APPLYING TUFTE'S PRINCIPLES OF GRAPHIC DESIGN TO GEOSCIENCE TEXTBOOK ILLUSTRATIONS

Edward Tufte has written extensively (and passionately) about principles underlying graphic design, used both to display and to explain complex processes and quantitative information. His design principles can be summed up as “simplicity of design and complexity of data” (Tufte, 1983). Grady (2006) specifies Tufte's concepts further: use design in the service of the content; display the general and particular, and macro and micro together; eliminate “chart-junk;” use graphics to learn more about the processes and narratives they represent; emphasize the smallest effective difference; and use similar templates to display variation and change.

We applied Tufte's principles to diagrams of processes widely used in geoscience textbooks, including the earth's radiation budget, the rock cycle, and the water cycle, among others. We were surprised at the variability of the diagrams representing these fundamental processes. Our analysis shows that excellent diagrams have these features: a key for explaining important symbols; a combination of accurate pictures and short text that visually reinforce the main ideas and provide concise explanations; informative use of color and symbols such as arrows; and a clear path that guides the reader to the next process or conclusion. Confusing diagrams share these features: vagueness or over-simplification in some cases and over-complexity in others; apparently “realistic” design elements that do not accurately represent the nature of the processes; “chart-junk;” numbers without units; and confusing spatial locations. The best illustrations elegantly convey information that cannot be described in text whereas others confuse students and reinforce common misconceptions they bring to introductory geoscience classes.

Our findings suggest that geoscience diagrams require some geo-specific design principles, in addition to Tufte's more general ones: consider the spatial location of processes in the earth and on the diagram; try to make diagrams and their parts unambiguously either realistic or symbolic; position arrows with care; and clarify the quantitative data. In addition to illustrating good and bad design principles and their consequences, we will attempt to create diagrams that exemplify Tufte's principles.