NOVICE UNDERSTANDING OF 3D BLOCK DIAGRAMS: UNPACKING MISCONCEPTIONS ABOUT BASIC DEPOSITIONAL ENVIRONMENTS

Proper understanding of simple visualizations is key to students’ future understanding of complex visualizations. Unfortunately, not all geoscience diagrams are intuitive to students, some show significant and persistent misconceptions. One type of diagram that instructors report students having difficulty with is 3D block diagrams of basic depositional environments. The present study was conducted to characterize the errors novices make when first learning with this diagram. The specific diagram used in this study was a simple block diagram of a depositional environment where the ocean rose over time. The diagram included three rock types: conglomerate, sandstone, and siltstone.

Participants (N=56) were instructed to make twelve relative age judgments between different pairs of points on the diagram. Participants also made the same judgments on a scaffolded diagram designed to make the horizontal nature of time salient. The scaffolded diagram was identical to the first, except that an ash layer was added below the siltstone; participants were told the ash layer was the result of a volcanic eruption. Overall performance on the basic diagram was poor (44% correct). Adding the ash layer appeared to aid participant’s understanding as overall performance was better than when no ash layer was present, t(55) = 3.78, p < .001. However, improvement was not seen across all types of comparisons. When the judgment required reasoning across different rock types, there was no effect of the ash layer, t(55) = 1.26, ns. Judgements improved only when the two points were separated by the ash layer, t(55) = 5.31, p < .001.

Results suggest that many participants have a basic misconception that all material of the same rock type is deposited at the same time. While the ash layer increased the number of questions participants answered correctly, it did not alter this misconception. Participants seemed to understand that everything below the ash layer was older than everything above the ash layer, however, they did not necessarily understand how the rest of the materials were originally deposited. Future work in this area seeks to find ways to support learning about the gradual accumulation of rock in the absence of visual discontinuities and to further characterize misconceptions.