Bishop Tuff Degrees of Welding Google Earth tour

Jessica F. Larsen, University of Alaska, Fairbanks

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Summary

This is a kmz file that can be used in Google Earth to explore different outcrop locations along the LADWP road that goes into the Owens River Gorge. This file can be used as a "virtual outcrop" to supplement a number of possible activities developed by the instructor. The kmz file includes photographs and descriptions of the different outcrop locations as a function of relative depth in the ignimbrite. The descriptions are qualitative and discuss relative degrees of welding through observations of fiamme and devitrification textures. The descriptions also include photos of each outcrop location.

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Context

Audience

This is a "virtual outcrop" product that can be used as part of an activity, or during lecture, in any level course during a section or module covering volcanoes, eruption processes, and eruption products.

Skills and concepts that students must have mastered

Depending on how the instructor uses this kmz file, a range of skill levels would be needed. In a basic Geology 101 course, students should have some familiarity with the concept of stratigraphy and how ignimbrites are deposited on a basic level. Students will also need to understand the concept of conductive cooling timescales as a function of deposit thickness. Compaction processes and recrystallization timescales should also be introduced before employing the kmz file in an activity or lab exercise.

How the activity is situated in the course

This kmz file could be used as part of an activity or exercise developed by the instructor. It could be used in a stand alone way as a virtual outcrop during a lecture. This is appropriate for any undergraduate volcanology course or section of a general geology course covering volcanoes.

Goals

Content/concepts goals for this activity

The goal of providing this kmz file for instruction is as a virtual outcrop. Students can use this kmz file to examine photos of how the Bishop Tuff changes with depth as you travel through different sections along the Owens River Gorge road.

Higher order thinking skills goals for this activity

Depending on the context in which the kmz "virtual outcrop" file is used, students would need to be able to link what they see in the outcrop with depth and elevation data to models of how ignimbrites cool slowly, compact, and devitrify. The elevation data and photos could be used for more quantitative lab activities. In this case, students would need to apply concepts learned about how ignimbrites cool, compact, and recrystallize with depth and fiamme aspect ratio measurements to quantify cooling history with depth, and degree of welding through compaction.

Other skills goals for this activity

Description and Teaching Materials

The kmz file can be used in a stand alone way as a virtual outcrop, or during lecture. Or, the kmz file could be used to augment a lab exercise focused on cooling, compaction, and crystallization timescales in thick ignimbrite deposits. For example, the kmz file could be used as an "outcrop" representation of different degrees of welding observed through fiamme textures. If hand samples are available, students could estimate degree of welding from fiamme aspect ratios from the hand samples (or even possibly from the photos in the kmz file). Students could then apply their fiamme aspect ratio measurements to a simple estimate or scaling of degree of welding as a function of fiamme aspect ratio. Combined with the approximate elevation data given in the kmz file, students could make a semi-quantitative estimate of the depth profile tied with degree of welding through the Bishop Tuff, relevant to the Owens Gorge location.

The kmz file could also be used to introduce what students can expect to see if the course involves a physical field trip to the Owens Gorge and Long Valley area.

Owens Gorge .kmz file (KMZ File 73.6MB Jul10 19)

Teaching Notes and Tips

Access to Google Earth is required to use the kmz file.

Assessment

Assessment would be developed by the instructor depending on how they use the kmz file.

References and Resources

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