A FIELD-BASED EXPLORATORY ACTIVITY TO INTRODUCE SEDIMENTARY PROCESSES

At a community college, most students are already familiar with (and curious about) the surrounding landscape, but many who take the Introduction to Geology course are also “science-phobic.” In this setting, exploratory field activities offer students the opportunity to learn new concepts by studying familiar areas, drawing on their natural curiosity and lessening their fear. As an introduction to sedimentary rocks and processes, students are guided through a two-stage field laboratory in a local canyon, the Farmington Glade.

In the first stage, students examine sediments in a dry wash, describe the sorting, rounding, and composition of grains, and relate these properties to the source, method of transport, and depositional environment of the sediment.

In the second stage, the students make similar observations about the Paleocene Ojo Alamo Formation, a fluvial sandstone that forms the canyon walls. Students perform a cobble count, sketch cross-beds and channels in the outcrop, and discover abundant petrified wood within the formation and discuss reasons for its presence. A follow-up discussion in the field helps students combine this information to deduce the source, transport, deposit, and additional information about the formation.

This lab achieves multiple learning goals. Students gain content knowledge about sedimentary processes, skills in observing and measuring features of sedimentary rocks, and deductive reasoning skills to draw conclusions based on their observations. Perhaps most importantly, students realize that they are fully capable of understanding the science, and many become less fearful and more committed to the course after this activity.

In evaluations, students comment, “Can we have more labs like the Glade?” Additionally, students consistently achieve higher scores on this lab and on quizzes involving sedimentary processes than on other, non-field-based labs. The familiarity of these local features and exploratory nature of the lab clearly enhances students’ enjoyment of the activity and retention of the content. Although this particular outcrop is limited is area, this activity could easily be altered to accommodate a different region: streambeds are ubiquitous and sedimentary rocks are commonly exposed even in regions with little outcrop.