GeoScape: An instructional rock garden for inquiry-based cooperative learning exercises in introductory geology courses

Journal of Geoscience Education, Mar 2003 by Calderone, Gary J, Thompson, J Robert, Johnson, Wayne M, Kadel, Steve D, Et al

The map pattern represents a faulted plunging anticline and syncline duplex that has been eroded to a nearly horizontal surface. This structure is overlain by horizontal layers that have been "eroded" to form a butte and mesa topography (see Figure 3 Post-erosion volcanism has formed a cinder cone on the mesa. A lava flow emanates from the cone and flows down the face of the eroded mesa. A dry stream valley traverses the northeastern portion of the map area and is constructed to illustrate the pattern formed by tilted layers as they cross the drainage.

Although the basic design of the map pattern is "set in stone", a number of other features have been left intentionally vague to allow individual instructors to change the interpretation for different courses or different sections of the same course. The fault, for example, is purposefully ambiguous on the map. We can change the rake of slickensides information that we give to the students to consequently change the fault from dip-slip to strike-slip. If we choose to make the fault dip-slip, we can further change the dip direction that we give to students to alter the hanging wall designation and thus, the type of fault.

Similarly, the details of the igneous and metamorphic complex at the core of the plunging anticline are left vague to allow variation in the interpretation of this area. For example, veins of quartz emanating from the granite body can crosscut the metamorphic rocks to make the granite/quartzite contact intrusive; or, we can eliminate these and force the granite/quartzite contact to be nonconformable. Likewise, there are no geopetal structures in the vertically dipping quartzite-phyllite-marble sequence. We can thus provide information to the students to vary the interpretation of the sedimentary protoliths from a transgressive to a regressive marine near-shore sequence. Additionally, sedimentary structures and fossils can be added to, or subtracted from, the sedimentary layers to vary depositional environments and create geologic time scale correlations if desired.

The actual scale of GeoScape was problematic. Our chief academic objective was to landscape an area large enough so that the students would have to do field work and check contacts and other relationships. We also desired, however, to have an area that was feasible to map during a lab period (2.5 hours) or in parts of several lab periods. Further complicating the issue was that of cost. Larger areas simply cost more to cover with gravel and flagstone. The compromise that best suited our goals and budget was an area of about 4400 ft^sup 2^ (see Figure 1). The area is large enough to easily accommodate a typical lab class of 24 students engaged in mapping exercises. The area has also been used to illustrate three dimensional structures in lecture classes consisting of about 48 students.

CONSTRUCTION OF GEOSCAPE

Prior to construction, the faculty and staff at Glendale College surveyed the map pattern of Figure 2 onto the ground and chose the appropriate flagstone and gravels from the stocks of local suppliers. Most of GeoScape was constructed in approximately one week by a commercial contractor working closely with the geology faculty.