VISITORS' USE OF THE LANDSCAPE TO UNDERSTAND GEOLOGIC TIME WHILE EXPERIENCING THE TRAIL OF TIME AT GRAND CANYON NATIONAL PARK

The new Trail of Time (ToT) interpretative exhibit at Grand Canyon National Park uses South Rim vistas to teach basic principles of geologic time and change. Visited by thousands daily, the ToT is a uniquely valuable setting for research on informal learning of geologic time and other basic geological concepts, as there have been very few studies of people's understanding of geological phenomena in natural areas. At the ToT, visitors are not only asked to comprehend a linear, horizontal timeline, but to correlate it with the strata exposed in the vertically oriented walls of the Canyon. This research addressed two questions: (1) How do Park visitors use elements of the geologic landscape of the Grand Canyon to explain fundamental principles of relative geologic time? and (2) How do visitors reconcile the relationship between the horizontal ToT timeline and the vertical encoding of time in Canyon strata?

Semi-structured interviews tracked participants' understanding of the ToT exhibit and of basic principles of geologic time. Application of Chi's (1997) verbal analysis method to the interview transcripts identified themes related to how the respondents utilized the landscape to answer interview questions. Results indicate that a majority of respondents comprehend principles of relative geologic time at Grand Canyon by utilizing (1) landforms, features, and processes observable from the rim at the time, termed the "observed landscape," and (2) past environments and geological processes not directly observed but inferred, termed the "inferred landscape." It was also determined that by applying the same integrated approach to the landscape, a majority of respondents are able to reconcile the horizontal ToT timeline with vertically encoded stratigraphic time. To gain deeper insight into the cognitive skills activated to correctly reconstruct geologic processes, Montangero's (1996) diachronic thinking model was applied to code responses into the three (Piagetian) schemes of (1) transformation, (2) temporal organization, and (3) interstage linkage. Results show that correct responses required activation of all three of these schemes. Appropriate application of these results can help inform future modifications of the ToT as well as other outdoor interpretive science exhibits.