From Virtual Field Trip to Geologically-Reasoned Decisions in Yosemite Valley 1

7 This study highlights a Geology of Yosemite Valley virtual field trip (VFT) and companion exercises produced as a 8 four-part educational activity to substitute for physical field experiences. The VFT is created as an Earth project in 9 Google Earth Web, a versatile format that allows access through a web browser or Google Earth app with the sharing 10 of an internet address. Many dynamic resources can be used for VFT stops through use of the Google Earth Engine 11 (global satellite imagery draped on topography, 360° street-level imagery, user-submitted 360° photospheres). Images, 12 figures, videos, and narration can be embedded into VFT stops. Hyperlinks allow for a wide range of external resources 13 to be incorporated; optional background resources help reduce the knowledge gap between general public and 14 advanced undergraduate students, ensuring VFTs can be broadly accessible. Like many in-person field trips, there is 15 a script with learning goals for each stop, but also an opportunity to learn through exploration as the viewer can 16 dynamically change their vantage at each stop (i.e. guided discovery learning). This interactive VFT format supports 17 students’ spatial skills and encourages attention to be focused on a stop’s critical spatial information. The progression 18 from VFT to mapping exercise to geologically-reasoned decision-making results in high quality student work; students 19 find it engaging, enjoyable, and educational. 20


INTRODUCTION
The shifting landscape of the global COVID-19 pandemic in early 2020 brought unprecedented uncertainty and disruption to educators worldwide, particularly field educators (e.g.Arthurs, 2021;Phillips et al., 2021;Walker, 2021).
To promote safety and minimize virus spread, many national agencies, local governments, and universities changed rules and guidelines on a near-weekly basis, often implementing drastic procedural changes with little notice.Against this backdrop a hundred-plus intensive capstone field geology educational experiences (i.e."summer field" courses in the United States) hosted by universities around the world that were scheduled to run over the summer were forced to make a hard choice: Do we proceed?Some instructors held out hope of running their course (i.e."module" in the European use) only to have their camping permits denied at the last minute or shifting regulations cancel their field course altogether.Although a very small minority did actually run in-person courses with clearances and modifications to safely limit COVID-19 exposure (e.g.Rotzien et al., 2021), most instructors shifted to offering alternative courses in a remote or virtual format that would attempt to instill some of the field skills considered essential by employers and graduate advisors.
Field geology educators across the globe began organizing and meeting virtually in March 2020 as a forum on "Designing Remote Field Experiences" to assess resources readily available for use in remote field geology courses, what could be adapted from instructors' courses, and what could be created new with enough lead time to be implemented by others.Several working groups coordinated by affiliates of the National Association of Geoscience Teachers (NAGT) sprung up with sub-interests (learning objectives, building a community-based virtual field camp, virtual field trips, virtual worlds, virtual field geophysics, etc.).A clear challenge that repeatedly arose was how to virtually deliver the same depth of learning that in-person field experiences provide.
For the preceding three years University of California-Riverside's summer field geology course, hosted in Owens Valley, California, had a short one-day exercise where students were expected to use web-hosted lidar data to map geomorphic features such as debris fans, rockfalls, and glacial moraines in Yosemite Valley.This exercise was followed by a long day of driving over the Sierra Nevada to Yosemite Valley where students would participate in a multi-stop walk highlighting natural hazards including floods, rockfalls, and rock avalanches.In post-course surveys students cited the Yosemite activity and visit as one of their favorite aspects of the course, and the students' assessment results (scores) indicate the mapping products produced were some of the highest quality in the course.Out of this background familiarity and the possibility to create a long-lived teaching resource (i.e. with potential for broad international interest and usable with a site visit once in-person field instruction resumed), we developed a four-part Geology of Yosemite Valley educational activity (https://serc.carleton.edu/NAGTWorkshops/online_field/activities/237092.html; last accessed: 11 October 2021), advertised through the main NAGT working group, and made this activity publicly available in May 2020 through the Science Education Resources Center (SERC) website hosted by Carleton College (Figure 1).This paper is intended to provide an overview of the learning philosophies and technologies employed, with the hope that it promotes the creation of high quality virtual field trips (VFTs) appropriate for the general public, and highlights how VFTs can lead into advanced-level mapping and geologically-reasoned decision-making exercises suitable for third-year or fourthyear undergraduate courses.real-time editing) (Figure 2).

ACTIVITY DESCRIPTION
All created features for a given project appear in a Table of Contents and can be reordered by the creator but not viewers.A publicly-shared project can be downloaded by a third-party user; it can also be copied such that a thirdparty creator can edit and adapt someone's project as their own (for example adding their own built-in quiz assessments for their students).
Three types of features can currently be added to projects: fullscreen slides, lines or shapes, and placemarks.
(1) Fullscreen slides fill the entire screen and are not geotagged.The creator can upload a background image or video and overlay text with hyperlinks.Because of the lack of geotagging, fullscreen slides work best as title slides or interstitial slides that intentionally pull focus away from the more interactive Google Earth environment (for example to highlight a figure or concept).
(2) Placemarks are geotagged points in Google Earth's global environment and are the most versatile feature that can be created.A key advantage of placemarks in an Earth project is that not only is the viewer flown to the point on the globe, but the precise view (zoom level, view orientation, imagery) that the creator selects.The view can be a top-down or oblique 3D vantage of Google Earth's elevation model-draped satellite imagery or pulled from Google Street View's extensive ground-level photosphere imagery (outward looking 360° zoomable imagery).User-submitted photosphere imagery can also be incorporated if the use is consistent with their Creative Commons license.VFT creators can use the Google Street View app on a smartphone or tablet to create and submit their own photospheres, which can be readily used as well.The creator can add text, hyperlinks, images, and videos into a sidebar that helps explain the particular view selected for the placemark.There is a more advanced option to directly edit the sidebar's html, which allows for custom widths, styles, and the addition of features like audio narration or embedded quizzes.
(3) Lines or polygons can be drawn on the standard 3D view of Google Earth with different widths, colors and transparencies, which may be helpful for highlighting a specific feature like a fault or landslide.Similar to the placemark functionality, a sidebar box can have text or images describing the feature and a custom view can be tagged.Each line appears as an item in the Tables of Contents so this would be an unwieldy way to annotate many features in a small area (creating and embedding a figure would be more effective).It is not possible to create lines or polygons within a photosphere view.

VFT Walkthrough
When the viewer (student) clicks on the provided Geology of At any point, navigation allows the student to go forward or backward or pull up the Table of Contents to revisit a past stop.To maximize accessibility to a wide variety of knowledge levels, text in the VFT is extensively hyperlinked to external web resources like Wikipedia or the U.S. Geological Survey.If a student is familiar with terms such as "subduction zones" or "partial melting" then they can read on, whereas another student who is not familiar with those terms readily has access to the information needed to understand.A student works through each of the 44 stops, reading the text and connecting the views to annotated figures and videos provided.In some places small exercises are suggested using the built-in measure tool (measuring area or distance).A student that needs to dive deeper into the hyperlinks and background information will need more time to complete the VFT (~3 hours), while a more knowledgeable student may be able to work through it in under 2 hours.
Yosemite Valley was a fortunate place to design a VFT, as the heavy visitation and high interest meant that many existing resources could be adapted rather than being created new.Google Earth's "3D Buildings" layer (phototextured 3D models derived from low-flying aerial photogrammetry) in Yosemite Valley is of exceptional quality (for example, able to resolve individual trees or boulders), on par with current coverage in major cities and other popular outdoor recreation areas.The National Park Service has a wide variety of professionally-produced informative YouTube videos on Yosemite, including many on geology topics, that we incorporated with attribution.Similarly, most of the valley's main trails and viewpoints have Google Street View coverage.We created many new figures to best pair with specific vantages (Figure 3).
To be most broadly applicable, we designed this VFT without any assessment.Students get participation credit for completing the VFT; if they are less diligent or skip stops they are more likely to need to revisit the VFT later to complete the other activity parts.Teachers could create their own quizzes hyperlinked at different stops, even linking them directly to their records of scores if they had that functionality.
While the VFT could be conducted as a guided tour with an instructor leading the class through the field trip in a lecture format (this would probably take less time), the simplicity of the format and opportunities for deeper learning are greater if students are allowed to guide themselves (1-2 hours).Like many in-person field trips, the Google Earth Web project format strikes an effective balance between purpose-driven stops with targeted learning goals and opportunities for learning through exploration.While the particular vantages, text, images, and videos are presented in a structured format to deliberately guide a student, at any point a student can break the script by zooming in, rotating their view, walking a trail, or even searching for additional photospheres.Afterwards, the

El Capitan Cross-Cutting Relationships Exercise
Part II of the activity leverages the novel Geologic Map of the Southeast Face of El Capitan (Putnam et al., 2014;2015) as an advanced real-world relative dating exercise.El Capitan is one of the most famous landmarks in Yosemite, an imposing, nearly kilometer-high vertical-walled monolith of exposed intrusive rock steeped in the history of rock climbing.With the help of rock climbers and gigapixel photographs, geologists mapped intrusive units with 8 different chemical compositions projected onto a vertical plane with great detail and precision (10 cm accuracy for most contacts).While some of the units may be time-transgressive (e.g.multiple generations of pegmatite dikes) or coeval (overlapping geochronologic ages and gradational contacts), relationships are consistent enough that students can screenshot a particular region of the map and interpret the relationships to sort the 8 units from oldest to youngest (Figure 4).A solution file is available through the SERC website with verified instructor credentials.
With author permission, a version of the geologic map (Putnam et al., 2014) was edited to remove details such as the geologic summary, correlation of mapped units, and geochronology so that students could focus on the mapped relationships.An El Capitan stop on the VFT provides the necessary background that students need to understand the basics of this geologic puzzle exercise.The concepts of cross-cutting relationships, gradational contacts, included fragments, and magma mixing are introduced, using relatable examples where possible (a cracked phone screen for cross-cutting relationships) and students are provided an embedded link to download the modified map.Because students could search for the geologic map and companion journal article, this exercise works best as an in-session group exercise with lenient grading.Emphasis should be placed more on the locations the students decide to screengrab to highlight the least ambiguous relationships and their explanations provided.
Many cross-cutting relationship exercises given to students may involve sorting the timing of layered units, unconformities, folds, faults, and dikes.This El Capitan exercise is made more challenging by focusing on eight intrusive units with limited spatial layering and real world relationships of varying ambiguity.

Geomorphic Mapping of Yosemite Valley Exercise
In Part III of the activity students are tasked with producing a geomorphic map of the Quaternary (mostly Holocene) surficial deposits in Yosemite Valley using Google Earth Pro (desktop version)(Figure 5).Features to be mapped include deposits of talus (i.e., rockfall), debris fans, rock avalanches, and glacial moraines, as well as river terrace risers.The VFT highlights examples of each of these deposit types with additional background concerning processes and linked hazards (rockfall, flooding, debris flows), including historic events.All the instructions and data links needed for this mapping exercise are contained within the Google Earth KMZ provided to students.An example of each deposit type or feature to be mapped is provided to students in the folder structure that they will use to submit their final map (as a KMZ courses.In the process of mapping, most students (82%; 18 out of 22) recognize that nearly all of the valley walls have talus or debris flow deposits at their base; many (64%; 14 out of 22) recognize the variable density of river terrace risers along the length of the valley.

Geologically-Reasoned Decision-Making in Yosemite Valley Exercise
Part IV of the activity builds on the detailed geomorphic mapping the students did in Part III, which in turn builds on the knowledge gained in Part I's VFT.In a KMZ file students are provided with two real-world hazard extents that Yosemite National Park uses for planning and preparedness: the known extent of the January 1997 flood in the valley, approximating a 100-year flood, and a rockfall hazard extent that considers talus slopes and isolated boulders but not rock avalanches (Stock et al., 2014) (Figure 5).Students immediately recognize that some places in Yosemite Valley are expected to be susceptible to both floods and rockfall, and that most of the valley floor is susceptible to one of the hazards.Looking at the hazard extents overlain on the Google Earth satellite imagery, students can readily see what existing park infrastructure is within or near the hazard extents.
Students are tasked with using both their geomorphic mapping and the hazard extents to (1) provide recommendations for existing Yosemite Valley infrastructure that could be relocated to a less hazardous location, and (2) identify locations that would be suitable for additional development with varying levels of risk (e.g, a hotel, visitor center, storage facility, or parking lot).Students turn in a KMZ file indicating their recommendations and a technical report written as if they were consulting for the park (an oral presentation would be an effective format too).It is emphasized that the recommendations students provide must be well-reasoned and geologically-sound.Students should consider the nature of the respective hazards (e.g.rockfalls occur instantly and without warning and can be fatal, floods in the valley are predictable several days out and are rarely fatal) and the facility use (parking lots in flood zones can perhaps be evacuated with limited damage, a seldom-visited storage yard is better near a rockfall hazard zone than a campsite, etc.) when providing their recommendations.Students get particularly invested seeing how the numerous facilities are placed throughout the valley.By the end of the exercise they gain an appreciation of the limited real estate available for further development in the valley, that natural hazards are an active part of Yosemite Valley, and that there are considerable challenges associated with making decisions that affect the safety of over 4 million people a year.

Designing Virtual Field Trips with Google Earth Web
The Projects feature of Google Earth Web is a robust and adaptable format for semi-immersive virtual field trips that can be created with relative ease and presented intuitively.Instructors and students alike can learn the basics of project creation in about 15 minutes, making it an efficient format for instructors and also suitable for students to create their own VFT as part of a course's final project.The VFT can be made readily available on web-connected tablets (via Google Earth) or computer (via web browser such as Google Chrome) using a simple web link.The abundant fair-use imagery available through the Google Earth Engine (topography-draped satellite, 360° street-level, user-submitted 360° photospheres) often means VFT creators do not have to start from scratch.Using a 360° camera or the Google Street View app the VFT creator can also upload their own photospheres.The ability to not only geotag a field trip stop as a point on a map, but to curate a precise starting view for that stop (e.g.zoom level, oblique 3D vantage, particular view orientation in a photosphere) allows the creator to draw attention to the vantage most directly relevant to the learning goals for that stop.Text, images, and videos can be added to a sidebar supporting the stop's view; annotated photos of a similar or identical view can be particularly illustrative.However, each stop's view is not fixed, allowing the viewer to explore "off-script", which can improve their situational awareness and opportunities for independent learning.Advanced creators can customize the html for a given html stop, providing an opportunity to add custom icons, narration, and built-in quizzes.Though less self-contained, hyperlinks offer an opportunity to send students to external web addresses for background information (e.g.Wikipedia), quizzes or surveys (e.g.Google Forms), and even web-hosted 3D models of outcrops or hand samples (e.g.Sketchfab, V3Geo).
As a result of the COVID-19 pandemic, Google Earth Web VFTs were created for several locations instructors would otherwise be taking students on physical field trips, such as Greece (Evelpidou et al., 2021b) and Colorado (Mahan et al., 2021).A notable pre-pandemic general public-focused implementation of Google Earth Web Earth projects as VFTs is "Streetcar 2 Subduction" hosted by the American Geophysical Union (Rowe et al., 2020; https://www.agu.org/streetcar2subduction).On their dedicated web page eight separate Earth projects are linked that cover geological field trips in the San Francisco Bay Area, building on the classic field trip guidebook "A Streetcar to Subduction and Other Plate Tectonic Trips by Public Transport in San Francisco" by Wahrhaftig (1984).While these trips are fully functional as VFTs, they include information on transportation and safety logistics, and are designed as self-guided walking tours.Because there is often cellular data reception in these urban-adjacent field trip areas, a selfguided participant can use their GPS position (as a blue dot) to navigate from one stop to the next within the VFT frame, and access the text, annotated images, and videos provided at each stop along the way.There is a vast collection of existing field trip guidebooks that could be adapted into immersive VFTs to reach a broader audience.Currently there are several limitations of the Google Earth Web project format that are worth discussion.There is no functionality to add georeferenced layers to a Google Earth Web project, such as a geologic map that could be turned on or off over a landscape or a folder of data points that are distinct from field trip stops.Analysis is limited to measuring distances and areas.Google Earth Web also currently does not have the ability to switch between different imagery dates, a stellar feature on Google Earth Pro (desktop) that better highlights landscape changes (e.g.before and after a wildfire).If there was a more straightforward way to cache all imagery and media related to a project, the VFT could be taken to remote field locations and actually be used as more of an interactive field trip guide.At the moment there does not seem to be a way to directly embed 3D models into Google Earth Web project sidebars; we attempted to embed web-hosted Sketchfab, SketchUp, and 3D PDF models but were blocked by script or cookie permissions.The ability to add an embedded 3D scan of a rock sample or a detailed outcrop model would likely add to a VFT viewer's experience (these can still be hyperlinked though).Adapting the Google Earth Web project format to Google Earth VR would certainly boost the immersiveness of a VFT, but at the cost of being a less accessible format for many due to the specialized equipment currently needed for VR (e.g.Hagge, 2021).For public outreach efforts and student engagement it would also be beneficial if statistics could be accessed about the number of viewers and how long they viewed the VFT.Google Earth has been around for over twenty years and software development continues to actively be supported, but as with any format, longevity is not guaranteed.

Comparison to Other VFT Formats
ArcGIS Online allows multiple layers of vector data to be viewed on a single customizable map interface (though currently custom raster layers are not supported) and provides the ability to analyze and filter the data (e.g.Earth Web with an overview map and field stops that can be selected from a table of contents, but lacks the key ability of associating a discrete view with each stop. Arizona State University hosts many publicly accessible VFTs built in the SmartSparrow software platform (Mead et al., 2019; https://vft.asu.edu/).These trips are largely photosphere-centric with built-in links to video and image popups, and links to additional photosphere stops; the result is an immersive experience with high production value (there are even ambient bird sounds) in a completely self-contained format.Several educators have been experimenting with using videogame platforms (e.g.Minecraft, itch.io) to allow exploration-based field simulations in both scanned real world sites and fictional environments (Needle et al., 2021;Rader et al., 2021); these formats typically require more commitment on the part of the educators to design and implement but can be engaging, allow interaction between students, and mimic the freedom of mapping a region for the first time.Virtual Reality (VR) experiences offer the most immersive VFT possibilities by allowing the viewer to have the virtual environment surround them (e.g.Peterson et al., 2020;Hagge, 2021;Métois et al., 2021); unfortunately, the specialist VR goggles, software, and computer are likely unavailable to most students at home and students will almost certainly need to take turns in a classroom setting.
Arguably one of the more flexible formats for presenting VFTs remains a custom html webpage; this format allows embedding of maps (e.g.ArcGIS Online, Google My Maps) and 3D outcrop or rock sample models (e.g.Sketchfab), as well as external web links or links to download supporting materials (e.g.Bond and Cawood, 2021).

Building Effective Learning Through VFTs
Undoubtedly a major advantage of VFTs is their immediate accessibility to locations around the globe and beyond.
Additionally, VFTs through Google Earth provides opportunities for students to participate in cognitively engaging and interactive learning experiences, which have been found to improve student outcomes in STEM courses (Freeman et al., 2014;National Research Council, 2011).In a recent meta-analysis synthesizing the findings from 225 studies, Freeman and colleagues (2014) found that interactive and active learning experiences, such as those provided by VFTs, are better for students' STEM learning than pedagogical experiences that rely heavily on didactic instruction (e.g.lecture-based instruction).
VFTs using Google Earth allow for students to engage in guided discovery learning (Mayer, 2004).Virtual learning environments based solely on discovery learning allow students to independently explore and solve problems with little to no guidance (Lee and Anderson, 2013;Mayer, 2004).However, one drawback to this type of learning environment is that it can be a source of extraneous cognitive load, especially when it comes to users with limited knowledge about geology and conducting fieldwork.Cognitive load refers to the load that performing a particular task imposes on the cognitive system (e.g.Paas and Van Merrienboer, 1994;Sweller, 2011).The amount of information one's cognitive system can process at a given moment is limited.Thus, the presentation of too much information, some of which is unnecessary information when it comes to solving the task, can result in artificially increasing the cognitive resources needed to process the relevant content.This is referred to as extraneous cognitive load by Sweller (2010), and it results in decreasing the efficiency and efficacy of the learner's cognitive system (see review of cognitive load theory by Paas et al., 2010).With the aim of reducing the learner's cognitive load, the embedded instructional prompts that the Google Earth VFT format affords enables the instructor to promote guided discovery of the environment by allowing for the integration of direct instruction into discovery learning (e.g. Lee and Anderson, 2013;Mayer, 2004).This direct instruction provides students with the scaffolding (i.e.additional learning supports that can eventually be decreased with increasing ability) necessary to navigate and learn from such a perceptually and informationally rich environment (e.g. Lee and Dalgarno, 2011).
Google Earth-based VFTs are also an effective means to scaffold students' spatial skills.Spatial skills are a set of cognitive skills that enable us to manipulate, organize, reason about, and make sense of spatial relationships in real and imagined spaces (e.g.Atit et al., 2020;Newcombe and Shipley, 2015;Uttal et al., 2013).Field geology heavily relies on the use of spatial skills as the goal is to use present day spatial properties to infer the geologic history of a region (e.g.Atit et al., 2020;Shipley and Tikoff, 2016).In particular, identifying the relevant spatial properties in the field requires the geologist to focus their attention on the critical spatial information (e.g. the orientation of a bedding plane).Focusing attention on the important spatial information involves actively ignoring many other aspects of the scene (e.g. the size of the minerals, the fault slightly offsetting the layers, the talus pile at the base of the outcropgeologic features not pertinent to the problem at hand).The spatial skills used to identify relevant information for further cognitive processing is called disembedding in the geosciences (Manduca and Kastens, 2012;Reynolds, 2012) and selective attention in psychology (Moran and Desimone, 1985).Novices find disembedding to be difficult (Coyan et al., 2010;Shipley and Tikoff, 2016).Google Earth allows the user to remove the extraneous irrelevant information from the scene, bolstering geologically-relevant disembedding tasks for novice users.

From General Public VFT to Geologically-Reasoned Decisions
Through our Geology of Yosemite Valley activity, we provide an example of how a VFT can be designed to be approachable to a broad general public audience and at the same time serve as background information for an advanced undergraduate student mapping project.Hyperlinking technical words to external resources is an invaluable way of unobtrusively broadening the target audience.Distilling VFT stops to the most critical learning goals (especially with annotated images and videos) and encouraging interaction with the immersive view at the stop likely increases learning and engagement.Designing exercises that require students to utilize a combination of data they create (e.g.mapping) and real world data (e.g.hazard data, stream gauge data) to justify decisions trains them to develop professional skills and increases their investment in the task.The progression from VFT to mapping to professional-style consultant no student thought it was their least favorite or that they learned the least from it (unfortunately no anonymous feedback was collected from students in 2020).
Despite a global pandemic, United States national parks still hosted 237 million visitors in 2020; the top ten visited parks all prominently feature geology (NPS Press Release, 25 February 2021).One could imagine the value of linking immersive VFTs on park websites to help visitors plan their physical trips and phone-scannable QR codes displayed outside visitor centers that would allow self-guided trips.
report produced the highest quality work of any of the eight activities and exercises covered in UCR's 2020 and 2021 virtual Summer Field Geology course offerings.Student feedback (n=10) collected through an anonymous web-survey in the 2021 offering indicates that the Geology of Yosemite Valley activity garnered the most positive response.50% of the class said the activity was their favorite component of the course and 60% said they learned the most from it;

Figure 1 .
Figure 1.From the field to the virtual.(A) Image of students learning about flooding in Yosemite Valley as part of an in-person field trip in 2017.Just to the left of the view is a ~1.5m tall sign marking the peak flood water level on January 2 nd 1997 (seen in B), a striking location to discuss flood hazards as students look over the meadows, trails, and roads that would have been inundated.(B) A corresponding stop in the Geology of Yosemite Valley virtual field trip (https://bit.ly/2Zbn3R7)that utilizes a precisely chosen © Google Street View view orientation and zoom level to provide the same discussion of 1997 flooding.Students can pan the view to get a similar sense of flood inundation around them.Supporting text and hyperlinks are in the sidebar at right.A historic photo of the flooding event, map of the flooding extent, and a NPS-produced video on Yosemite rain-on-snow flooding fill the full-screen when clicked on.Virtual field trip is an Earth project created with © Google Earth Web viewed in © Google Chrome web browser.

Figure 2 .
Figure 2. Creating a VFT Earth project in © Google Earth Web.(A) A view highlighting the interface for editing a project (i.e.VFT).All changes are instantly saved to the cloud (the creator's Google Drive).(B) A view highlighting the interface for editing a feature (i.e.virtual field trip stop).Many customizable options exist.

Figure 3 .
Figure 3. VFT stops highlighting learning through guided exploration.Left panels show the VFT stop view in © Google Earth Web; right panels show the corresponding annotated image embedded in the stop's description.VFT stops showcase (A) the medial moraine at the junction of Tenaya Creek and Merced River, (B) exfoliation-related rockfall sources of different ages on the slopes of Half Dome, and (C) regional joints exposed in the cliff faces of Sentinel Rock.By simulating the dynamic view in a figure, the viewer can better visualize the key features emphasized.In each instance the dynamic view encourages the viewer to zoom in closer to a feature or search the surrounding area for similar features.

Figure 4 .
Figure 4. Introducing a complex relative dating exercise.(A) Stop on the Geology of Yosemite Valley VFT (© Google Earth Web) highlighting the vertical geologic map of El Capitan created by Putnam et al. (2014) and providing an overview of the knowledge (cross-cutting relationships, law of included fragments, gradational contacts) necessary to relatively date intrusive units.(B) An excerpt from the modified Putnam et al. (2014) El Capitan geologic map that students use to determine the relative timing of eight intrusive units.Black boxes highlight three areas that provide unambiguous relationships between two or more units.

Figure 5 .
Figure 5. From geomorphic mapping to hazard planning.(A) An excerpt from a virtual summer field student geomorphic map scored "highly competent" (still room for improvement) submitted as a © Google Earth KMZ file (final product of Part III of the activity).Basemap shown in both panels is a hillshade of bare-earth airborne lidar data collected by NCALM (2006), web-served by OpenTopography (https://doi.org/10.5069/G9GQ6VP3).Students use a combination of the lidar visualizations and satellite imagery provided to map deposits based on texture, slope, and valley position.(B) A visualization of two hazard extents utilized by Yosemite National Park and provided to students.Blue line indicates the maximum extent of January 1997 flooding (approximating a 100-year flood).Orange line indicates the expected extent of rockfall hazard within the valley (i.e.beneath the valley walls) from Stock et al. (2014).In Part IV of the activity, students use their geomorphic mapping and these hazard extents to examine the hazards posed to existing infrastructure and identify areas of lower hazard suitable for further development.Geologically-based justifications are expected for all of their recommendations.Location, scale, and orientation are deliberately excluded from this figure.Width of valley floor here is ~1 km.
Google Earth Pro desktop, and a trackpad or mouse.The four parts are described in the suggested order of completion, as each part builds on the previous one.Particular detail is given to the virtual field trip (Part I) created through the Projects feature of Google Earth Web, a user-friendly and highly-adaptable format with advantages over many other VFT platforms.An overview of Parts II, III, and IV are provided to illustrate how a VFT can be used as background material for more advanced-level mapping and writing exercises.Introduction to Google Earth Web ProjectsThe Geology of Yosemite Valley VFT (https://bit.ly/2Zbn3R7)was created as an Earth project using the Creation Tools available in Google Earth Web accessible via web browser.Google introduced Tour Builder as a beta tool in 2013 as a way to create shareable place-based narratives with images, text, videos and links hosted within their Google Earth engine; Tour Builder was discontinued in July 2021, but most of the functionality has been made permanent in Google Earth Web's Creation Tools, which launched in 2019.Creating with Creation Tools requires signing into the web version of Google Earth (preferred browser: Google Chrome) with a Google account (free); all projects are stored in the creator's Google Drive storage system.Much of the functionality will be familiar to users of other Google products (Docs, Sheets, Slides, etc.): a creator can make a project shareable or completely private, collaborate with other creators if they choose, and project changes are immediately saved and updated with an internet connection (i.e. Geology of Yosemite Valley is a four-part educational activity that we intentionally designed to be flexible in duration and student knowledge-level (https://serc.carleton.edu/NAGTWorkshops/online_field/activities/237092.html; last accessed: 11 October 2021).Full functionality requires a computing device with internet connection, Google Chrome browser,2.1 Geology of Yosemite Valley Virtual Field Trip2.1.1 Senger et al., 2021)lowsthe students to readily rejoin the tour.The mixture of medias and vantages allows for a particularly dynamic and engaging format.Peer reviewers, students, and general public viewers all praised the VFT format.Creating a VFT using Google Earth Web Creation Tools is intuitive and easily taught; students could create their own VFT as an alternative to an oral slide-based presentation (e.g.Senger et al., 2021).
). Students create their geomorphic map by interpreting web-served high-resolution hillshades (greyscale NW-illuminated representation of surface) derived from unfiltered (i.e.includes trees and buildings) and last return (i.e.bare-earth) airborne lidar data collected in 2006 (e.g.https://doi.org/10.5069/G9GQ6VP3)and the internal web-served Google Earth satellite imagery built into the Google Earth engine.The different Quaternary features (debris fans, rock avalanches, etc.) have very distinct textural and slope styles readily distinguishable in the bare-earth lidar hillshade; once students gain an eye for it they can efficiently map the 75 km 2 Yosemite Valley region.
This mapping exercise is most appropriate for an advanced undergraduate course (e.g.geomorphology, applied geology, capstone field geology).The maps are scored based on correctness, completeness, and neatness; the quality of the work is expected to be comparable to that produced by an entry-level professional geoscientist.An instructorproduced map is available through the SERC website with verified instructor credentials.An entire class' KMZ maps can be added to the instructor's Google Earth, allowing them to efficiently and objectively sort maps based on quality, check for cheating, and identify obvious gaps in quality signifying score boundaries.From our experience in 2020 and 2021, these maps are among the best products students have produced in UCR's remote summer field alternative