THE SEMIOTICS OF STRATIGRAPHIC DIAGRAMS

Semiotics is the study of symbols and their use or interpretation. One framework of semiotics draws upon sub-topics of linguistics and describes three types of symbolic relations: (1) syntax - interrelations between symbols, (2) semantic - the relation between the symbols and the object they represent and (3) pragmatic - the relation between the symbols and their user. When teaching geology students, educators train students on the semantics of geologic representations, such as topographic maps, seismic sections, structural geologic maps, and stereonets. In the present study, we investigate the symbolic relations of simple, stratigraphic cross-section diagrams. Cross-sections are used in introductory courses and textbooks to teach students basic principles of geology, including superposition and cross-cutting relationships. Pilot data suggested that non-science majors may interpret rock symbols based on non-geologic knowledge rather than the typical appearance of a rock texture. For example, geologists represent limestone with a symbol of stacked bricks. Non-science majors interpret this symbol as everyday bricks. This simple semantic error while interpreting the rock symbol may interfere with students’ interpretation of the syntax of the cross-sections. We tested this first by disembedding the rock symbols from a simple cross-section diagram and asking geology and non-geology majors to evaluate the relative age of the rock symbols. Non-geologists arranged the symbols based on semantic relations to everyday objects, while geologists arranged the symbols using the syntax of a transgressive stratigraphic sequence. Preliminary results from a second study involving students’ interpretation of simple stratigraphic diagrams are also included.