National Park Service geologic type section inventory: Northern Great Plains Inventory & Monitoring Network

Henderson, Tim; Santucci, Vincent; Connors, Tim; Tweet, Justin

doi:10.36967/2294167

Type sections are one of several kinds of stratotype. A stratotype is the standard (original or subsequently designated), accessible, and specific sequence of rock for a named geologic unit that forms the basis for the definition, recognition, and comparison of that unit elsewhere. Geologists designate stratotypes for rock exposures that are illustrative and representative of the map unit being defined. Stratotypes ideally should remain accessible for examination and study by others. In this sense, geologic stratotypes are similar in concept to biological type specimens, however, they remain in situ as rock exposures rather than curated in a repository. Therefore, managing stratotypes requires inventory and monitoring like other geologic heritage resources in parks. In addition to type sections, stratotypes also include type localities, type areas, reference sections, and lithodemes, all of which are defined in this report. The goal of this project is to consolidate information pertaining to stratotypes that occur within NPS-administered areas, in order that this information is available throughout the NPS to inform park managers and to promote the preservation and protection of these important geologic heritage resources. This effort identified 13 stratotypes designated within five park units of the Northern Great Plains Inventory & Monitoring Network (NGPN): Agate Fossil Beds National Monument (AGFO) contains one type locality; Badlands National Park (BADL) contains five type sections and one type area; Missouri National Recreational River (MNRR) contains one type area; Niobrara National Scenic River (NIOB) contains one type section, one type locality, and two reference sections; and Scotts Bluff National Monument (SCBL) contains one reference section. Table 1 provides information regarding the 13 stratotypes currently identified within the NGPN. There are currently no designated stratotypes within Devils Tower National Monument (DETO), Fort Laramie National Historic Site (FOLA), Fort Union Trading Post National Historic Site (FOUS), Jewel Cave National Monument (JECA), Knife River Indian Villages National Historic Site (KNRI), Mount Rushmore National Memorial (MORU), Theodore Roosevelt National Park (THRO), and Wind Cave National Park (WICA). However, DETO, FOUS, JECA, and WICA contain important rock exposures that could be considered for formal stratotype designation, as discussed in “Recommendations”. The inventory of geologic stratotypes across the NPS is an important effort in documenting these locations in order that NPS staff recognize and protect these areas for future studies. The focus adopted for completing the baseline inventories throughout the NPS has centered on the 32 inventory and monitoring (I&M) networks established during the late 1990s. Adopting a network-based approach to inventories worked well when the NPS undertook paleontological resource inventories for the 32 I&M networks and was therefore adopted for the stratotype inventory. The Greater Yellowstone I&M Network (GRYN) was the pilot network for initiating this project (Henderson et al. 2020). Methodologies and reporting strategies adopted for the GRYN have been used in the development of this report for the NGPN. This report includes a recommendation section that addresses outstanding issues and future steps regarding park unit stratotypes. These recommendations will hopefully guide decision-making and help ensure that these geoheritage resources are properly protected and that proposed park activities or development will not adversely impact the stability and condition of these geologic exposures.

National Park Service geologic type section inventory: Northern Great Plains Inventory & Monitoring Network

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