Teaching geologic map interpretation
Barbara Tewksbury (Hamilton College) Download a ppt presentation describing this approach (PowerPoint 34.2MB Sep22 10)
The approach that I used to use
- Define strike and dip and the various types of contacts. Help students visualize with Play-Doh.
- Start with planar contacts in areas having no topography; use lots of Play-Doh and paper models of inclined planar contacts to teach cross sections and apparent dip.
- Add topographic relief, and teach about the outcrop pattern of horizontal contacts, move on to vertical contacts, and then address inclined contacts and derive the rule of Vs.
- Bring out real world geologic maps, and have students apply what they have learned to interpret the maps and to draw cross sections.
- Move on to maps with folded contacts.
- Give students the opportunity to do their own mapping in the field.
A more successful approach using Google Earth
Raplee Anticline, Monument Upwarp, near Mexican Hat, Utah (37 09 15.44N, 109 49 20.24W). Click image to enlarge.
- Emphasize mapping before map interpretation in order to help students visualize, rather than memorize.
- Start by having students do geologic mapping in Google Earth before they know anything about strike, dip, or types of contacts.
- Have students work first with inclined units and contacts in areas with topographic relief, using Google Earth 3D view to develop an understanding of dip.
- Have students sketch simple cross sections of their own geologic maps and use Google Earth 3D view to help them visualize the relationships.
- Derive strike after students understand dip.
- Have students work with vertical contacts next, then horizontal contacts, and, finally, folded and faulted contacts.
- Give students lots of practice in mapping in Google Earth and creating their own cross sections in areas of increasing complexity.
- Follow with interpretation of existing geologic maps coupled with use of maps in the field.
Go to the first step: Visualizing inclined contacts
Download a kmz file of Google Earth placemarks (Zip Archive 3kB Aug26 10) that includes the places described in this set of web pages and in the Powerpoint presentation (PowerPoint 34.2MB Sep22 10) that describes this approach. if you are unable to download this .kmz file, you can copy the latitudes and longitudes of mapping examples and paste them into the "fly to" box in Google Earth.
Download a kmz file of other great locations for mapping (Zip Archive 5kB Aug26 10)
Go to Visualizing inclined contacts - Visualizing strike & dip - Visualizing vertical contacts - Visualizing horizontal contacts - Visualizing folds - Other mapping projects