From Virtual Field Trip to Geologically-Reasoned Decisions in Yosemite Valley

This study highlights a Geology of Yosemite Valley virtual field trip (VFT) and companion exercises produced as a four-part module to substitute for physical field experiences. The VFT is created as an Earth project in Google Earth Web, a versatile format that allows access through a web browser or Google Earth app with the sharing of an internet address. Many dynamic resources can be used for VFT stops through use of the Google Earth Engine (global satellite imagery draped on topography, 360° street-level imagery, user-submitted 360° photospheres). Images, figures, videos, and narration can be embedded into VFT stops. Hyperlinks allow for a wide range of external resources to be incorporated; optional background resources help reduce the knowledge gap between general public and upper-division students, ensuring VFTs can be broadly accessible. Like many in-person field trips, there is a script with learning goals for each stop, but also an opportunity to learn through exploration as the viewer can dynamically change their vantage at each stop (i.e. guided discovery learning). This interactive VFT format scaffolds students’ spatial skills and encourages attention to be focused on a stop’s critical spatial information. The progression from VFT to mapping exercise to geologically-reasoned decision-making results in high quality student work; students find it engaging, enjoyable, and educational.

Reframing Native Knowledge, Co-Managing Native Landscapes: Ethnographic Data and Tribal Engagement at Yosemite National Park

Several Native American communities assert traditional ties to Yosemite Valley, and special connections to the exceptional landmarks and natural resources of Yosemite National Park. However, tribal claims relating to this highly visible park with its many competing constituencies—such as tribal assertions of traditional ties to particular landscapes or requests for access to certain plant gathering areas—often require supporting documentation from the written record. Addressing this need, academic researchers, the National Park Service and park-associated tribes collaborated in a multi-year effort to assemble a comprehensive ethnographic database containing most available written accounts of Native American land and resource use in Yosemite National Park. To date, the database includes over 13,000 searchable and georeferenced entries from historical accounts, archived ethnographic notebooks, tribal oral history transcripts and more. The Yosemite National Park Ethnographic Database represents a progressive tool for identifying culturally significant places and resources in Yosemite—a tool already being used by both cultural and natural resource managers within the National Park Service as well as tribal communities considering opportunities for future collaborative management of their traditional homelands within Yosemite National Park. We conclude that the organization of such data, including inherent ambiguities and contradictions, periodically updated with data provided by contemporary Tribal members, offers a rich, multivocal and dynamic representation of cultural traditions linked to specific park lands and resources. Indeed, some Yosemite tribal members celebrate the outcomes as revelatory, and as a partial antidote to their textual erasure from dispossessed lands. In practice however, as with any database, we find that this approach still risks ossifying data and reinforcing hegemonic discourses relating to cultural stasis, ethnographic objectivity and administrative power. By critically engaging these contradictions, we argue that one can still navigate pathways forward—bringing Native voices more meaningfully into the management of parks and other protected spaces, and providing a template useful at other parks for collaboration toward shared conservation goals.

The Solitary Mountaineer

This chapter investigates John Muir's texts against the backdrop of privileged notions of exclusivity regarding race, gender, and class. It also highlight's Muir's astute environmental and political critique, as well as his passionate and sensual delving into a more-than-human world. The chapter points out how Muir both epitomized and complicated a dualistic mindset and actively promoted and aided tourism, arguing that city dwellers needed vacation time in the mountains. It describes how Muir grew politically engaged and became one of the most effectual advocates for the national parks, becoming instrumental in making wilderness accessible to white men. It also talks about Muir's book that was distributed to both West and East Coast readership, which includes carefully crafted narratives of his achievements and his adventures and promotion of tourism in Yosemite Valley.

Constraining post-glacial temperatures of rock avalanche deposits in the Yosemite Valley with cosmogenic noble gas and luminescence paleothermometry

<p>Yosemite Valley is renowned for its striking topography, with many sheer granite cliffs carved during past glaciations. At the base of these cliffs many large rock avalanche deposits can be found that were deposited since ice retreated from Yosemite Valley. Cosmogenic <sup>10</sup>Be measurements indicate that there are at least 10 different rock avalanche deposits that range in age from 13 to ~1 ka.</p><p>In this study, we estimate the time-averaged temperatures experienced by rocks from five of these rock avalanche deposits using cosmogenic noble gas and luminescence paleothermometers. These two systems yield independent estimates of valley floor temperatures during the Holocene, information that is useful for reconstructing the local environmental conditions since deglaciation.</p><p>Cosmogenic noble gas paleothermometry utilizes the fact that cosmogenic noble gases like <sup>3</sup>He experience thermally-activated diffusive loss at Earth surface temperatures in minerals like quartz. The concentration of cosmogenic <sup>3</sup>He in quartz relative to a cosmogenic nuclide that does not experience diffusive loss should therefore be a function of a rock’s thermal history over the duration of its exposure to cosmic ray particles. Apparent <sup>3</sup>He boulder exposure ages from these five rock avalanche deposits are 58 to > 98% younger than the corresponding <sup>10</sup>Be exposure ages. Preliminary models that combine these <sup>3</sup>He observations and sample-specific diffusion parameters indicate that effective diffusion temperatures (EDTs) recorded by <sup>3</sup>He in quartz are similar to or higher than the modern EDT from the instrumental record.</p><p>Like with the cosmogenic <sup>3</sup>He system, thermoluminescence (TL) paleothermometry of K-feldspars also relies upon the balance between steady signal build-up and thermally-activated loss. The difference is that TL derives from trapped electronic charge at defect sites within the feldspar crystal lattice that accumulates in response to natural background radiation. K-feldspar TL signals comprise a range of stabilities. The least stable sites will experience diffusive loss even at temperatures below 0 °C and the most stable sites will accumulate at upper crustal temperatures. By monitoring which sites are occupied and how long those sites have been accumulating charge, we estimate both the ambient temperature and the time spent at that temperature.</p><p>We compare and discuss the history of rock temperatures estimated from these two systems with implications for the post-glacial climate of Yosemite Valley.</p>