The rockart boulder known as Silsby’s Rock was published in Hranicky (2010) and is a large boulder with cupules and a design (Figure 9). It was moved from its original location to the Great Falls Park’s Visitors Center and is maintained by the National Park Service.

Silsby's Ethnographic Rock

Class: Ethnographic

Time: Unknown

​Location: Loudoun County, Virginia

Wm Jack Hranicky RPA

​ rockart glyphs pictographs petroglyphs