Virtual Geologic Mapping Exercise at Ben Levy
The Virtual Geologic Mapping Exercise at Ben Levy, western Ireland is designed to simulate a more advanced field mapping exercise. Students load a KML file in Google Earth that includes real outcrop data in the form of dots and orientation symbols. Students can click on each symbol for detailed outcrop information. Students use the Google Earth polygon tool to draw contacts and faults, and then draw colored polygons to show the aerial extent of the lithologic units within the field area. Once completed, the geologic map can be saved as a KML file and turned in (emailed) to the instructor. Students also draw a cross section to interpret the geologic structure of the field area, write lithologic descriptions of the units in the field area, and write a memoir or summary of the geology and geologic history of the field area.
The exercise uses Google Earth for investigating the field area and constructing the geologic map, a drawing program (like Powerpoint or Illustrator) to draw the cross section, and a word processing program for the lithologic descriptions and memoir/summary of the geology.
This course is designed as a more advanced mapping exercise in a typical undergraduate capstone field course. See the Virtual Geologic Mapping Exercise at Lough Fee for a comparable introductory mapping exercise.
Skills and concepts that students must have mastered
Students should know how to make basic rock and environmental interpretations from lithologic data. They should know what a geologic map looks like and represents. They should know what a cross section is, but will likely need some guidance on how to construct a cross section. Students typically require some guidance on how to write an organized and logical memoir/summary of the geology.
How the activity is situated in the course
This would be a more advanced mapping exercise in a capstone geology field course. The geology of the area includes complexities related to folds and faults that go beyond simple layercake stratigraphy. Students will master the mechanics of creating a geologic map, drawing a cross section, and writing supporting documentation.
This would likely be a 3-4 day field mapping exercise. Longer if students don't spend full days on the exercise.
Content/concepts goals for this activity
Exercise Tasks and Goals:
1. In Google Earth, virtually traverse the full field area, visiting outcrops (indicated by colored orientation symbols or dots) and collecting field data.
2. Build a geologic map in Google Earth by drawing contacts between lithologic units and drawing faults where necessitated by offsets in units. Draw polygons, colored by unit, to represent the interpreted regions for each lithologic unit. Fold axes and/or faults should be indicated. Upon completion, the full mapping area, as denoted by the large yellow polygon, should be colored. Neatness counts!
3. Interpret the geology of the field area by writing detailed descriptions of the lithologic units, constructing a cross section that interprets the geology of the area, and writing a memoir/summary of the geology and geologic history of the field area.
Higher order thinking skills goals for this activity
This exercise incorporates:
1. Analyzing and interpreting field data provided virtually
2. Synthesizing data to create a geologic map and cross section interpretation of the geology of the field area
3. Synthesizing background and field data to write a summary of the geology and geologic history of the field area.
Other skills goals for this activity
This exercise incorporates spatial thinking skills in construction of a geologic map and vertical cross section. It also incorporates professional writing skills in writing lithologic descriptions and a summary of the geology of the area.
Description and Teaching Materials
This virtual mapping exercise focuses on a .75 square kilometer field area just west of the town of Clonbur in western Ireland (Figure 1; approximate latitude: 53.53˚, longitude: -9.40˚). The basic geology consists of a layered sequence of Silurian clastic rocks that are stratigraphically above Neoproterozoic schists. Units are transposed and offset by younger faults. Virtual field investigations and construction of a geologic map will be facilitated by using the Google Earth virtual globe. The exercise works best with the web version of Google Earth, which can be accessed using the Chrome, Firefox, Opera, or Edge browsers.
Students open a KML file in Google Earth, which includes outcrop data collected from the actual Ben Levy field area. In Google Earth, outcrop data appears in the form of orientation symbols when students zoom close to the ground surface. Details for each virtual outcrop can be seen by clicking on the symbol. Students use this data to draw contacts, faults, and folds with the line tool in Google Earth, and then draw colored polygons to represent the aerial extents of the lithologic units. The working and completed geologic maps can be saved as KML files on the student's desktop.
Deliverables for the exercise include:
1. A completed geologic map (as a KML file)
2. A document with lithologic descriptions of each unit in the field area
3. A completed cross section that displays the student's interpretation of the geologic structure of the field area
4. A document that summarizes the geology and geologic history of the field area.
Web-based Google Earth is the preferred medium for creating the geologic map, although desktop Google Earth will work as well.
A drawing program like Powerpoint, Illustrator, or Google Slides is needed to construct a cross section.
A word processing program like Microsoft Word or Google Docs is needed to write the lithologic descriptions and the memoir/summary of the geology.
Teaching Notes and Tips
When using the Google Earth KML file, students need to zoom close to the ground surface to see the outcrops (orientation symbols). When students click on a symbol, outcrop information will appear in a pop-up window. Some pop-up windows include field or outcrop photos. Students should draw contacts between lithologic units and faults as lines in Google Earth, and then draw colored polygons in Google Earth to represent the aerial extent of the lithologic units within the field area. Students can also mark important points with Placemarks. Note that anything the students draw will appear at all zoom levels, but the outcrop data (orientation symbols) only appear when zoomed close to the ground surface. Students can iteratively save their working and final geologic maps from Google Earth to their desktop. Students should save multiple versions of their map as they work on it, so that they have backups.
The cross section can be drawn in a separate drafting program, and should not be drawn until the student's geologic map is completed. Students should use lithologic information and photos from the outcrops to complete their lithologic descriptions. The memoir/summary should describe the location of the field area, the depositional setting of the units, subsequent structural deformation features, and a brief geologic history of the area.
An Instructor packet with examples of the Deliverables can be requested from the author at: email@example.com
A related Virtual Geologic Mapping Exercise at Lough Fee (western Ireland) is available here: Lough Fee exercise
Students turn in a KML file of their completed geologic map, a completed cross section through the field area, a document with descriptions of the lithologic units, and a memoir or summary of the geology of the field area. Goals of the project area met if students turn in a neat and accurate geologic map, demonstrate that they understand the geology of the area by showing the dipping units, folds, and faults on their cross section, and provide documentation of the geology in their lithologic descriptions and memoir/summary.
An example grading rubric for the exercise can be downloaded here: ExampleGradingRubrics.pdf
References and Resources
Materials for this and other Google Earth exercises can be found at the author's website: https://www.whitmeyer.org/
The Symbols tool used to create the orientation symbols for Google Earth can be found here: https://educ.jmu.edu/~whitmesj/GEODE/symbols2/