26 2025 New Scholars Floyd, A. 2025. Volume of a potential lake in the Colorado Plateau Basin In J.H. Whitmore (editor), Proceedings of the 2025 New Scholars International Conference on Creationism, pp. 26-27. Cedarville, Ohio: Cedarville University International Conference on Creationism [poster presentation]. VOLUME OF A POTENTIAL LAKE IN THE COLORADO PLATEAU BASIN New Scholars 2025 Andrew Floyd, School of Science and Mathematics, Cedarville University, 251 N. Main St., Cedarville, Ohio 45314. andrewfloyd@cedarville.edu KEYWORDS Lake Bidahochi, Bidahochi Basin, Hopi Lake, Grand Canyon origin, lake overspill, Colorado Plateau ABSTRACT The southernmost area of the Colorado Plateau, known as the “Bidahochi Basin,” is a structural depression over much of the Little Colorado River. The basin is primarily bounded by the Mogollon Rim and the Kaibab Uplift and is filled with Miocene-Pliocene sedimentary strata that reflect a lacustrine environment, most notably preserved in the diatremes and maars of the Hopi Buttes. Initially interpreted as remnants of smaller playa-like lakes (~7000 km³), recent discoveries of tufa deposits and shoreline terraces at 18002000 m elevations suggest a larger lake. Others have estimated this “Hopi Lake” to have volumes up to 30,000 km³ (Dallegge et al. 2003). Due to its size and proximity to the Grand Canyon, others have hypothesized that this large lake contributed to the carving of the Grand Canyon by catastrophically overflowing the Kaibab Uplift (Austin et al. 2023; Douglass and Gootee 2024). Alternative theories have also been suggested, such as karst piracy (Hill and Polyak 2014) or serial lake spillover models. Given these interpretations, creating a comprehensive map to better analyze the basin is essential. The basin was initially outlined in Google Earth Pro using the polygon tool at the 1830 m contour, providing a rough surface area estimate. All subsequent analyses were performed in ArcGIS Pro. Raster data for the Colorado Plateau was acquired from USGS EarthExplorer and merged into a mosaic. A fitted polygon, created in Google Earth Pro and imported into ArcGIS, was used to trim the raster. This trimmed raster generated 20m elevation contours for the basin. Six key elevations—1600, 1800, 1860, 1950, 2000, and 2100 meters—were selected based on prior research and converted into polygons. Volume calculations for each elevation were made using ArcGIS’s “Surface Volume (3D)” tool. Notable features and Mogollon Rim/Kaibab Uplift gaps were recorded, and relevant geologic map units were included to highlight the basin’s volcanic and lake deposits. Hopi Lake extended much further north than previously thought, reaching from the Grand Canyon’s mouth up to Moab, Utah, at each studied elevation. At elevations above the 1800 m contour, it reached the Uinta Mountains. Additional “basins” appeared in Glen Canyon, Monument Valley, and areas west of Canyonlands National Park. A lake “outlet” also opened north of the Vermillion Cliffs across the Cockscomb (Kaibab Uplift, Utah). At the 1860 m contour, a “shoreline” lies along the Hopi Buttes, and above the 2000 m contour, another outlet occurs north of the San Francisco volcanic field. Volumes for each elevation are shown in Table 1. Our analysis suggests Hopi Lake extended farther north, possibly suggesting a serial lake spillover model. With a volume of ~40,000 km³, it could have catastrophically carved the Grand Canyon, similar to how Lake Missoula (~2600 km3) or Lake Bonneville (~10,000 km³) shaped their respective drainages (Smith 2006; O’Connor et al. 2020). Based on its current elevation, the Hopi Buttes volcanic event may also have contributed to Hopi Lake’s overspill, possibly uplifting and displacing enough water to over top the Kaibab Uplift. Field investigations at proposed outlets or shorelines could further clarify the lake’s true extent and geologic history. REFERENCES Austin S.A., E.W. Holroyd III, T.F. Folks, and N. Loper. 2023. Shoreline transgressive terraces: Tufa-encrusted landforms indicate rapid filling and failure of Hopi Lake, western Bidahochi Basin, northeastern Arizona. In J.H. Whitmore (editor), Proceedings of the Ninth International Conference on Creationism, pp. 346-362. Cedarville, Ohio: Cedarville University International Conference on Creationism Dallagge T.A., M.H. Ort, and W.C. McIntosh. 2003. Mio-Pliocene chronostratigraphy, basin morphology and paleodrainage relations derived from the Bidahochi Formation, Hopi and Navajo Nations, Northeastern Arizona. The Mountain Geologist 40(5):55-82. Douglass J., and B.F. Gootee. 2024. Discovery of beach sand, beachrock, and capping tufa on Balakai Mesa: Implications for the Bidahochi Formation and the overflow origin of the Grand Canyon. Open-File Report 24-02, 9 p. University of Arizona: Arizona Geological Survey. Hill C. A., and V. J. Polyak. 2014. Karst piracy: A mechanism for integrating the Colorado River across the Kaibab Uplift, Grand Canyon, Arizona, USA. Geosphere 10(4):627–40. DOI: 10.1130/GES00940.1 O’Connor J.E., V.R. Baker, R.B. Waitt, L.N. Smith, C.M. Cannon, D.L. George, and R.P. Denlinger. 2020. The Missoula and Bonneville floods—A review of ice-age megafloods in the Columbia River basin: Earth-Science Reviews 208, pp. 1-51. DOI: 10.1016/j.earscirev.2020.103181 Smith L.N. 2006. Stratigraphic evidence for multiple drainings of glacial Lake Missoula along the Clark Fork River, Montana, USA. Quaternary Research, 66:311-322. DOI: 10.1016/j.yqres.2006.05.009 Table 1. Comparison of Colorado Plateau lake volumes with other lakes. Colo Plat contour Elev Vol (km3) Lake Vol (km3) 1600 m 10,649 Missoula 2,600 1800 m 33,656 Bonneville 10,420 1860 m 44,178 Superior 12,100 1950 m 62,429 Caspian Sea 78,200 2000 m 74,393 2100 m 101,816
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