LEARNING CYCLE APPROACH TO INVESTIGATING MODERN BEDFORMS

Bedforms provide the link between flow conditions and sedimentary structures that are preserved in the geological record. Students in an undergraduate sedimentary-geology course investigate this link through an early-semester field trip to observe bedforms in a small barrier beach/inlet/tidal-delta complex in mid-coast Maine and to relate these bedforms qualitatively to formative flows. The exercise uses a learning-cycle approach of prediction, observation and comparison to identify and correct student misconceptions.

As background for the exercise, students are introduced to the concepts of flow regime and bedforms in class, using abundant field photographs. They then complete homework using photographs to practice identification of bedforms and interpretation of formative flows. Several days prior to the trip, students are provided with an aerial photograph of the site and asked to make predictions about what bedforms and orientations they expect to find in 6-8 designated sub-environments (e.g., foreshore, backshore, inlet channel, proximal and distal flood-tidal delta) and why. During the trip, students visit these same sub-environments at low tide and describe, map and photograph the actual bedforms and interpret the formative flows. They then compare their observations with their predictions and self-evaluate their conceptions and misconceptions.

An advantage to this approach is that students have an observational framework and a set of predictions when they visit the field, focusing their efforts and learning on the link between bedforms and flow. By comparing their predictions and observations, students not only self-correct many of their misconceptions, but also provide the instructor insight into their thinking. The exercise sets the stage for subsequent interpretation of paleoflow conditions from sedimentary structures and of lateral and vertical variations of facies in the sedimentary record. Although specific to the mesotidal barrier setting in coastal Maine, the exercise and its approach may serve as an example that can be adapted to other settings.