Designing Monitoring Strategies for National Park Service Fossils

By Vincent L. Santucci, National Park Service (retired); Justin S. Tweet, National Park Service, Geologic Resources Division; Aubrey Bonde, National Park Service, Shared Paleontologist for Southern Network Parks; and John-Paul Hodnett, Maryland-National Capital Park and Planning Commission, NHRD Paleontology Unit

Monitoring non-renewable paleontological resources on federal lands is specifically mandated in Section 6302 of the Paleontological Resources Preservation Act of 2009 (16 U.S. Code 470aaa-1). The National Park Service (NPS) Paleontology Program defines monitoring as the assessment of the stability and condition of in situ fossils and fossil localities.

In 2003, the NPS presented an initial blueprint for defining a conceptual framework for paleontological resource monitoring as a basic resource management activity involving fossils (Santucci and Koch 2003). A more comprehensive strategy for paleontological resource monitoring was presented by the National Park Service in 2009 (Santucci et al. 2009). Several case studies involving paleontological resource monitoring are presented here to demonstrate the variety of resource-specific strategies that have been developed for each situation, which utilize the framework of the 2003 and 2009 strategies.

During 2009, the NPS, in partnership with the Utah Geological Survey, piloted a fossil monitoring project at Glen Canyon National Recreation Area, Arizona and Utah, to evaluate factors potentially impacting vertebrate ichnofossils along the shoreline of Lake Powell. This research documented both natural processes (rise and fall of lake levels) and anthropogenic activities (theft and vandalism) impacting in situ fossils and paleontological localities. This applied and pioneering work identified practical paleontological resource management strategies that can be utilized in other shoreline parks.

At George Washington Birthplace National Monument, Virginia, storm activity and rising sea level on the Potomac River Estuary have resulted in rapid erosion of fossiliferous strata exposed along the park’s shoreline. Fossils are also routinely impacted by unauthorized visitor collection at the park.

In dry caves at Grand Canyon National Park, Arizona, temperature and humidity monitoring have been undertaken in cave passages where the fragile remains of desiccated (“mummified”) bats from the Pleistocene were discovered. These techniques can be applied in monitoring fossils in other caves and in different cave environments.

Fossils impacted by a series of widespread fires in Santa Monica Mountains National Recreation Area, California, have been documented through post-fire resource assessments. This monitoring serves as a pilot for understanding wildland fire impacts on fossils and informs planning and assessments for fossils subjected to fire in other parks.

Experience gained through paleontological resource monitoring in NPS areas and the development of park-specific field monitoring protocols have helped inform staff regarding threats to the fossils and the best practices for mitigating resource impacts through proactive management actions (Nyborg and Santucci 2000; Santucci et al. 2001; Clites and Santucci 2009, 2012a, 2012b; Wood and Santucci 2014; Santucci and Wood 2015; Pearson et al. 2016; Wood et al. 2021; Bonde et al. 2024; Salcido et al. 2024; Santucci et al. 2024).

Glen Canyon National Recreation Area, Utah and Arizona

NPS work to help define the concept of paleontological resource monitoring was initially field tested at Glen Canyon National Recreation in 2009 through a partnership between the NPS Paleontology Program and the Utah Geological Survey (Santucci et al. 2009; Kirkland et al. 2010, 2011). This park was selected based on several factors, including the abundance and diversity of its in situ paleontological resources. Both natural processes and unauthorized fossil collecting were recognized as influencing the stability and condition of the park’s in situ fossils.

Several fossil localities along the shoreline of Lake Powell that are periodically submerged below or exposed above the fluctuating lake water levels were selected as test sites for this pilot project. These fossil localities were also readily accessible to visitors by boat. At each fossil locality, a rebar post was installed to designate a photo point for repeat photography.

A map of the fossil locality was drafted and accompanied by geospatial data and photography. The fossil monitoring localities were revisited annually to assess and measure any observable changes in the stability and condition of the fossil dinosaur tracks. Both natural processes and unauthorized fossil collecting were documented at the Slick George Dinosaur Tracksite (Figure 1).

Within a decade after the first documentation, the Slick George Dinosaur Tracksite was heavily damaged, with approximately 60 percent of the original fossil tracks no longer observable at the location. There were no newly exposed fossils observed at the site after the initial assessment.

Figure 1. Slick George Dinosaur Tracksite at Glen Canyon National Recreation Area. Red circle shows dinosaur tracks. Blue arrow marks current water level of Lake Powell. Red arrow shows high-water mark,  indicating the area is periodically below water. Green arrow shows undercutting of strata due to erosion. Yellow arrow shows sandstone block that fell and damaged the fossil track layers. Yellow circle shows where individuals removed fossil tracks through unauthorized collecting.

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George Washington Birthplace National Monument, Virginia

The cliffs along the Potomac River estuary at George Washington Birthplace National Monument are extremely fossiliferous, preserving Miocene plant, marine invertebrate and vertebrate fossils. Storm activity and rising sea level have resulted in rapid erosion of fossiliferous strata exposed along the park’s shoreline. Additionally, unauthorized fossil collecting by visitors occurs at the park despite the prohibition of this activity (Figure 2).

Figure 2 (left). “No Fossil Collecting” sign along the beach at George Washington Birthplace National Monument.

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Figure 2 (right). Yellow circle showing a fossil shark tooth on the beach at the park.

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Figure 3. The cover of the George Washington Birthplace National Monument Paleontological Resource Monitoring Protocol (Tweet and Santucci 2017).

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In order to help inform park staff about the natural and anthropogenic impacts to the park’s fossils, a paleontological resource monitoring strategy was established and implemented (Tweet and Santucci 2017, 2020, 2024). Park-specific protocols and a field assessment form were developed for the park’s monitoring strategy and were designed for park staff to easily implement. Nearly a decade of paleontological resource monitoring at the park has resulted in the discovery and preservation of important new fossils (Figure 3).

Because of the rapid pace of erosion, repeat site visits are not feasible. Periodic assessments of the entire shoreline are preferred instead, looking for unusual newly exposed material and evidence of collecting. The park partners with local institutions if a significant specimen is determined to be at risk.

Grand Canyon National Park, Arizona

Hundreds, perhaps thousands, of well-preserved, desiccated (“mummified”) bats have been discovered in two remote caves in Grand Canyon National Park (Figure 4). Radiocarbon dating of the bat carcasses has yielded ages ranging from approximately 3,500 to over 50,000 years ago, spanning the Last Glacial Maximum (Chambers et al. 2024). These results indicate that the bats did not die at approximately the same time, as might occur with an epidemic or exposure to toxic gases, resulting in contemporaneous mass mortality. Instead, the bats lived and died at different times over 50,000 years during the Late Pleistocene and Holocene.

In order to better understand and monitor the climatic and environmental conditions currently in the cave preserving the fossil bats, data loggers have been placed to record air temperature and relative humidity in the cave passages. The digital data loggers captured the data in 30-minute intervals for four years and showed relatively constant temperatures and low humidity ranges. These somewhat stable conditions likely contributed to the long-term preservation of the fossil bat carcasses.

Figure 4. Late Pleistocene desiccated (mummified) bat attached to a surface in a remote cave in Grand Canyon National Park.

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Santa Monica Mountains National Recreation Area, California

Wildland fires, often fueled by high winds, frequently occur in Santa Monica Mountains National Recreation Area. During November 2018, the Woolsey Fire burned extensive acreage of the steep, chaparral-covered canyons of the recreation area and destroyed several historic buildings and other park infrastructure.

In 2023, the NPS Paleontology Program deployed paleontologist J.P. Hodnett to the Santa Monica Mountains to assess and document how the fire impacted in situ paleontological resources. During field work, 155 new fossil localities were documented in the park, some of which showed direct evidence of fire impacts, including surface charring, baking, cracking and other damages to in situ fossils (Figure 5) (Hodnett et al. 2024).

Additional fires in the Santa Monica Mountains, including the devastating Palisades Fire in January 2025, resulted in additional post-fire paleontological resource assessments at the park. NPS paleontologist Aubrey Bonde coordinated additional post-fire paleontological resource monitoring and actively trained other NPS staff in the principles and practices associated with paleontological resources monitoring.

Figure 5. Fossil scallop shell exposed in the fire zone at Santa Monica Mountains National Recreation Area showing evidence of fire effects, including charring, discoloration, and cracking.

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Conclusion

Strategies developed by the NPS under such a diverse set of paleontological resource monitoring conditions fill an important void in the paleontological literature, where there is a general lack of this kind of research. A “Best Practices” document on the evaluation, monitoring, mitigation and preservation of paleontological resources by the NPS Paleontology Program (Jazi et al., in press) is forthcoming. It will enhance the preservation and protection of NPS fossils and paleontological localities and further the management and science of in situ fossils on NPS and other lands.

References

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Tags: george washington birthplace national monument, glen canyon national recreation area, grand canyon national park, santa monica mountains national recreation area, fossils, paleontology, parkpaleonewsseries