Virtual Geologic Mapping Exercise at Lough Fee

Steve Whitmeyer, James Madison University

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Summary

The Virtual Geologic Mapping Exercice is designed to simulate an introductory 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 line 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 Ilustrator) to draw the cross section, and a word processing program for the lithologic descriptions and memoir/summary of the geology.

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Context

Audience

This course is designed as an introductory mapping exercise in a typical undergraduate capstone field course. It could also be used as an introductory laboratory exercise by removing some of the additional components, like the cross section, lithologic descriptions, or memoir/summary of the geology.

Skills and concepts that students must have mastered

Students should know how to make basic rock interpretations 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 one of the first mapping exercises in a capstone geology field course. The geology of the area is fairly straightforward, but it teaches students the mechanics of creating a geologic map, drawing a cross section, and writing supporting documentation.

Activity Length

This would likely be a 3-day field mapping exercise. Longer if students don't spend full days on the exercise.

Goals

Content/concepts goals for this activity

Exercise 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. 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

Exercise files:

Exercise Description:

The Virtual Geologic Mapping Exercise focuses on a 2.5 square kilometer field area along the eastern shore of Lough Fee in County Galway, western Ireland (approximate latitude: 53.579˚, longitude: -9.799˚). The basic geology consists of a layered sequence of Silurian clastic rocks that overlie Neoproterozoic schists. Units are dissected and offset by younger faults. Virtual field investigations and construction of a geologic map are 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, and Edge browsers.

Students open a KML file in Google Earth, which includes outcrop data collected from the actual Lough Fee 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 and faults 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.

Technology Needs

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 outcrops have camera symbols, which indicates that field or outcrop photos are included in the pop-up window. 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, along with information in the Supplementary Data file, to complete their lithologic descriptions. The memoir/summary should describe the location of the field area, the depositional setting of the units, and a brief geologic history of the area.

An Instructor packet with examples of the Deliverables can be requested from the author at: whitmesj@jmu.edu

Assessment

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 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: Virtual_Geologic_Mapping_Exercise_Rubric.pdf (Acrobat (PDF) 36kB May17 20)

References and Resources

All of the files related to this exercise can also be found at the GEODE site:
http://csmgeo.csm.jmu.edu/Geollab/Whitmeyer/geode/Lough_Fee/

The Symbols tool used to create the orientation symbols can be found here:
http://csmgeo.csm.jmu.edu/Geollab/Whitmeyer/geode/symbols/




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