THE WELL-KNOWN SAN YSIDRO/WHITE MESA MAPPING AREA TURNED DIGITAL; IT WORKS!

For decades the Ojito White Ridge Bike Trail area on BLM and State land, located about 5 km southwest of San Ysidro, north-central New Mexico, has been a popular field geologic mapping site for courses from numerous institutions. In a typical May, it is not uncommon for some hundred students a day to be roaming in the area. The first author has visited the site continuously since the mid-1980’s. The Ojito area exposes a sequence of upper Triassic through mid-Cretaceous strata, which preserve the transition from a broad, low relief dominantly fluvial setting to the Interior Seaway of North America as North America migrated from low equatorial latitudes to high mid-north latitude. Students become very familiar with the following map units, from oldest to youngest: Chinle, Entrada, Todilto, Summerville, Salt Wash Member (Morrison), Brush Basin Member, Jack Pile Member, Encinal, Oak Canyon, Cubero, Clay Mesa, Paguate, Mancos, and Two Wells. Over the past ten years, UTD students in introductory field geology (GEOS3300), many of whom have just had Physical Geology and general field methods, spend three days mapping a 1.5 km² area, as their first project. The first day includes an introduction to the stratigraphic section and time for the students to work on their own; the morning of the second day has all students working in a relatively small area of the map, at very high spatial resolution. Each student turns in their map for this small area, which is returned before that evening, with abundant comments. The following items are submitted, after a full day spent compiling data; field map, notebook, final map, interpretive cross section, legend for map and cross section, stereographic projection of structural data, and a field report. We transformed all aspects of this project into a digital field experience. Although dealing with statistics of small numbers, based on what most students submitted, we assert that the exercise was a very positive one for our students. We employed both Google Earth Pro and QGIS in the project. The Google Earth file for the mapping area includes over 175 stations, with a bedding plane measurement, a specific map unit contact identified, or a field image with direction taken. A distinct attribute of this field area is that, once the students recognize the general characteristics of map units (e.g., color and resistance), tracing very accurate contacts using either Google Earth or QGIS is straightforward. Several of the final maps and cross-sections compiled by our class of 2020 rival the best products that the first author has seen.