Wind Cave National Park: Paleontological resource inventory (public version)
Authors: Herring Theodore , Tweet Justin , Santucci Vincent 
Published: June 2023

Wind Cave National Park (WICA), the first cave in the world to become a national park, is famous for the park’s namesake feature. Wind Cave, named for the noticeable wind-flow patterns observed as air moves in and out of the natural cave entrance, is currently the third longest cave system in the United States and seventh longest in the world. Wind Cave formed when groundwater dissolved buried layers of the fossiliferous Madison Limestone, which were deposited during the Mississippian subperiod approximately 359 to 347 million years ago. In addition to the Madison Limestone, several other formations are exposed within the park, dating from the early Proterozoic to the Holocene. The presence of fossils within the park has been known since at least the late 19th century when early settlers explored the cave to turn the geologic feature into a tourist attraction. However, most of the geologic work conducted during the park’s history has focused on the exploration and development of the cave itself, rather than its fossils. Paleontology became a bigger focus in the late 20th century when the park partnered with the South Dakota School of Mines and Technology to recover and research fossils found within the cave and on the park’s surface. Other partnerships include those with the Mammoth Site of Hot Springs and Northern Arizona University, through which researchers have studied Quaternary cave deposits found across the park. In ascending order (oldest to youngest), the geologic formations at WICA include undifferentiated lower Proterozoic rocks (Precambrian), Harney Peak Granite (Precambrian), Deadwood Formation (Cambrian–Ordovician), Englewood Limestone (Devonian–Mississippian), Madison Limestone (Mississippian), Minnelusa Formation (Pennsylvanian–Permian), Opeche Shale (Permian), Minnekahta Limestone (Permian), Spearfish Formation (Permian–Triassic), Sundance Formation (Middle–Upper Jurassic), Unkpapa Sandstone (Upper Jurassic), Lakota Formation (Lower Cretaceous), Fall River Formation (Lower Cretaceous), White River Group (Eocene–Oligocene), and Quaternary alluvium, conglomerate, and gravel deposits. The units that are confirmed to be fossiliferous within the park are the Deadwood Formation, Englewood Limestone, Madison Limestone, and Minnelusa Formation, which contain a variety of marine fossils from a shallow sea deposition environment; the Sundance Formation, which has much younger marine fossils; the Lakota Formation, which has yielded petrified wood; and the White River Group and Quaternary deposits, which contain vertebrate and invertebrate fossils deposited in and near freshwater streams, lakes, and ponds. Many of the fossils of WICA are visible from or near public trails and roads, which puts them at risk of poaching or damage, and there is evidence that fossil poaching occurred at several of the Klukas sites soon after they were discovered. Furthermore, there are several fossil sites on the tour routes within Wind Cave, which are of value to interpretation and the park experience. WICA has implemented cyclic fossil surveys in the past to monitor site conditions, and it is recommended that this paleontological resource monitoring be continued in the future.