A protocol for paleontological resource monitoring at George Washington Birthplace National Monument

Tweet, Justin; Santucci, Vincent

George Washington Birthplace National Monument (GEWA) was established in recognition of its historic and cultural resources, but also contains significant natural resources, including fossils. The paleontological resources of GEWA are found within and along the bluffs that face the Potomac River flowing north and east of the park. They include wood fragments, impressions of mollusk shells and rare original shell material, shark teeth, partial fish skeletons, isolated bones of marine mammals, and invertebrate burrows and bioturbation (disruption of sediment by organisms). These fossils are found in the Miocene-aged Calvert Formation, a coastal marine unit composed of sand, silt, and clay deposits. Paleontological resources at GEWA are impacted by natural and human-caused factors. The bluffs are subject to tides and strong storms, including hurricanes, and recede on the order of 30 cm (1 ft) a year, not including larger local losses due to slumping and tree falls. Recreational use of the beach at GEWA exposes fossils in the bluffs and along the shore to theft and vandalism. There is a culture of unauthorized fossil collection by the public, particularly of shark teeth, from the Calvert Formation and other geologic units along the Potomac River. Over the years, the shore at GEWA has become identified as a productive fossil collecting locality. Together, these factors ensure rapid turnover of paleontological resources. Except for one large piece of fossil wood, no individual fossils have been observed on more than one visit since observation began in 2014. This observation indicates that the time frame for the survival of an exposed fossil is less than a year and probably less than six months, depending on when the fossil is subject to the winter storm season. In addition, the small size of typical fossils (usually less than 15 cm [6 in]) and their presence in small numbers throughout the bluffs make designating individual localities unproductive. Together, these factors render many traditional means of monitoring and protection ineffective, except in special circumstances. To address these issues, the authors have prepared a modified protocol for monitoring fossil resources at GEWA. The basis of the protocol is recording a tally of various categories of fossils via a shoreline walk from one end of the bluffs to the other, with the bluffs divided into three segments. Along the way, the field data collector will photograph objects and take GPS points as necessary, for example at the locations of excavation pits. This protocol is intended to enable park staff to get an idea of the scope of the resource, monitor unauthorized collecting activities, and observe if there are any unusual fossil occurrences that may require additional management or collection. The protocol as it exists now is designed to be performed in conjunction with the semi-annual shoreline monitoring conducted by NPS Northeast Coastal Barrier Network (NCBN) personnel, but if tidal conditions are not appropriate during shoreline monitoring or there are other occasions when paleontological surveying is desired, it can also be performed with Geologic Resources Division or GEWA personnel. Further, this monitoring strategy has been designed so that staff who are not paleontologists can implement it. Once staff have participated in an initial training and a monitoring walk accompanied by a paleontologist and have become familiar with the broad categories of fossils depicted and described in the photo guide included in this protocol, they should be able to implement the protocol for GEWA.

A protocol for paleontological resource monitoring at George Washington Birthplace National Monument

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