THE TOPOGRAPHIC SAND BOX, A TOOL FOR IMPROVED UNDERSTANDING AND VISUALIZATION OF TOPOGRAPHIC MAPS

Understanding topographic maps and visualizing the 3-D information contained is a common challenge for introductory earth science students. To address this problem, a laboratory mapping exercise has been developed using a set of sand box models (four to five for a 20-student class). Each model is constructed to exhibit one or more topographic features (e.g. steep vs. shallow slopes, hill, valley, ridge, depression). All contain a shoreline which serves as the zero elevation reference. Working in small groups, the students begin by constructing contour lines on the surface of the sand. The next task is to construct a paper map. This requires measuring the size of the sand box and devising an appropriate scale for the paper map. When completed, each map is labeled with much of the same supporting information that accompanies a standard topographic map: written scale, scale bar, north arrow, contour interval, etc. The exercise also includes the labeling of several bench mark elevations, discussion of precision and accuracy of the bench marks, construction of a topographic profile, and labeling of topographic features on the map. “Aerial” photographs are taken of all of the boxes and are shared with the entire class. When all of the maps have been completed, the class is taken on a tour/discussion of all of the sand boxes. To provide further practice and reinforcement, a follow-up exercise is assigned which uses a topographic map draped over the 3-D topography in Google Earth. Informal observation of students at work suggests a higher level of engagement than was seen during a paper-based contouring exercise. Student enthusiasm also appears to be improved.