The Dry-Erase Cube: Teaching Structural Geology in Three Dimensions

Teaching structural geology and its three-dimensional aspects may be as much a challenge for the instructor to teach it as it is for the students to learn it. A cube made of white opaque high-density plastic, which serves as dry- (or wet-) erase material, makes teaching and learning three-dimensional geology much easier and fun. Maps, cross sections and block diagrams can be drawn (and erased!) and seen in three dimensions, and compared with their two-dimensional projections on paper. For example, the cubes are very useful for teaching the concept of apparent dips, which is essential in the construction of cross sections and block diagrams, and is confusing to many students. Plotting apparent dips on block diagrams is especially difficult, because of the distortion caused by the projection. The dry-erase cube provides an intermediate step. Students can first draw the actual apparent dip on the cube and subsequently construct the same angle on the projection of the block on paper. This can be made especially easy if the edges of the cube have the same length as the edges of an isometric block diagram on paper, so that they can simply be lined up.

Several dry-erase cubes can be placed adjacent and on top of each other, so that multiple levels of maps, and parallel and perpendicular cross sections can be constructed. The relationship between maps and cross sections is then clearly visible. The cubes are also an aid in the understanding of stereographic projections, because structural data can be made visible as three-dimensional planes and lines before they are plotted. The dry-erase cubes are not only useful for geoscience teachers, but or anyone teaching or dealing with geometries and block diagrams, e.g. engineers and mathematicians, geologists in the petroleum or mining industries, hydrologists and K-12 teachers.