PHOTOGRAMMETRIC DOCUMENTATION OF NATURAL TRAP CAVE, WYOMING

Natural Trap Cave (NTC) is located on the flanks of the northern Bighorn Mountains, in north-central Wyoming overlooking the semi-arid Bighorn Basin. This site is managed by the Bureau of Land Management exclusively for scientific research purposes. Paleontological studies conducted in the 1970s and 1980s, revealed ice age taxa (including extinct megafauna and smaller extant species) indicating that this location during the last glacial was likely at an important juncture between sub-glacial tundra and more temperate eco-zones, which can provide information on major extinction events in the Pleistocene. Recently, renewed excavations at NTC have yielded new fossils and other scientific samples, allowing for analysis of ancient DNA, stable isotopes, radiocarbon dating, as well as geochemical and palynological research. As the last decade of paleontological research has witnessed a marked increase in the use of 3D data capture for the purpose of documentation, evaluation, and preservation of fossil resources; state-of-the-art photogrammetric technology has been used to document the scientific resources of the cave. At Natural Trap Cave, photogrammetric documentation has included a holistic approach, with efforts to document the entirety of the main chamber below the mouth or “trap” of the cave. Excellent results are achieved from photogrammetry when the software solves for a robust camera calibration and when overlapping photographs are taken with proper geometry. These techniques elevate the camera from simply a device for capturing images to a virtual surveying and data collection instrument. We present the results from photogrammetric modeling efforts during the 2014, 2015 and 2016 field seasons at the cave. These data capture the entirety of the main chamber and are useful for monitoring the progress of excavation. More importantly, the use of 3D models allow for mapping of paleontological data and other results into a spatial context not easily compiled with a more traditional plan view cartographic effort drawn as part of an excavation. In turn, 3D data help facilitate the spatial and temporal relationships of the sedimentology, paleo-taxa variation, and paleo-environmental changes preserved within the cave.