Walker Lake Area Glacial Geomorphology

Sarah R. Hall, College of the Atlantic

Calla Schmidt, University of San Francisco

Becca Walker, Mt. San Antonio College

Initial Publication Date: August 31, 2020

Summary

Students visit Walker Lake (Eastern Sierras) to identify and map glacial geomorphic features. From their field and remote observations of the landscape, they subsequently make interpretations about formation processes of several geomorphic features and generate a geomorphic map. Students also determine the relative ages of glacial features using their geomorphic map and by analyzing boulders from different moraines in the field area.

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Learning Goals

Content/Concept Goals:

Students will...

  • Identify glacial geomorphic features in the field and make interpretations about the processes that formed and modified them.
  • Create a geomorphic feature map using field observations and remote imagery.
  • Apply relative dating techniques to determine the relative ages of glacial features and consider the limitations of the dating techniques utilized.


Higher Order Thinking Skills Goals:


Other Skills Goals for this Activity:

Students will..

  • Develop a method for recording data in the field.

Context for Use

Audience:

This activity was completed during the 2-week summer E-STEM Field Course with ~20 undergraduate students interested in environmental science.

Prerequisite Skills and Concepts:

Students should be familiar with reading and interpreting topographic maps (identifying ridges, saddles, drainages, the significance of spacing of contour lines), glacial landscape features (at least know of the terms/processes), and have seen aerial imagery before. Recommend using Unit 2, Part 3 (Yosemite Activity) from the GETSI Mass Wasting module as a pre-trip exercise.

How the Activity is Situated in the Course:

This activity follows an introduction to glacial geomorphology. This is also great as a stand-alone activity (doesn't have to be part of a field course, could be its own field trip). It also works great as a remote lesson. Could pair with topographic profiling (by hand or using GIS or Google Earth software) to make profiles across moraine crests to look at shape as another estimate of relative dating techniques. Can map moraines from aerial imagery in GIS as well. View the E-STEM field course timeline for more information about how this activity is situated in the course.

Description and Teaching Materials

In part 1 of the exercise, students map several kinds of geomorphic features on an aerial image and/or topographic map of the field site as they observe the landscape from the crest of a moraine. In part 2 of the exercise, students collect a variety of field data to assess the relative ages of moraines in the area, including lichen cover; "ping vs. thud" characteristics of boulders; size of boulders; shapes of moraines; soil development on different moraines; amount and type of vegetation on different moraines; etc. Office work involves making an office copy of their geomorphic map and using the spatial relationships between the moraines that they mapped to infer relative ages, then graphically representing their field data to (a) assess whether or not their field data agree with their map interpretation of relative ages; (b) comment on the efficacy of various field data sets in assessing moraine relative ages for this field site.

Student Handout

Bloody Canyon Student Handout (Microsoft Word 2007 (.docx) 15kB Apr24 20)

Materials:

  • Printed moraine map (shown in Figure 1)
  • Printed topographic map (shown in Figure 2)
  • Tracing paper/vellum paper and tape
  • Colored pencils
  • Rock hammer
  • Hand lens
  • Pencil/eraser
  • Mapboard
  • Rulers
  • Compass
  • GPS (optional)
  • Camera (optional)

Teaching Notes and Tips

Remind the students to stay hydrated and to wear protective clothing (sun hat, long pants, shirt, and close toed shoes)– this is at a higher elevation than many students are use to (2500m).

Have students work in pairs. Give them a time limit, a limit to how far they should map, and a clear meeting location. Laying out a long measuring tape works well for students to track their progress. You can have all of the students map the same area, or some students map different transects. This pairs well with the Botanical Transect Mapping activities.

Start the activity by observing the landscape as a class and discussing some of the prominent geomorphic features: moraines, lakes, cirques, bogs, colluvial cones, etc. Have the students draw these features on their basemap (on tracing paper/vellum paper over the aerial imagery) while observing the landscape. Another option is to map directly onto the topographic maps. Make sure they can locate the moraines in the landscape, on the aerial images, and on the topographic maps.

We parked the vans here: 37.872565, -119.158775. This location is between two moraines; both crests are easily accessible on foot. We gathered at the crest of the moraine to the north, found a large enough area to sit and map while facing ~north. This is a good place to ask students to locate themselves on the map as you can see Walker Lake from the moraine crest.


Assessment

  • Assess the geomorphic feature map with the rubric for the Mapping Badge.
  • Assess the written summary, drawing of relative ages and evidence, and data table with the rubric for the Field Notes Badge.

References and Resources