Jefferson Rock is a rock formation in the Appalachian Trail in Harpers Ferry National Historical Park. It consists of several large masses of shale rock, piled one on the other, that overlook the Shenandoah River just prior to its confluence with the Potomac River. The name of this landmark derives from Thomas Jefferson, who stood there on unknown date while writing his 1785 book on Virginia. He found the view from the rock impressive and wrote in Notes on the State of Virginia:
"The passage of the Potomac through the Blue Ridge is perhaps one of the most stupendous scenes in Nature. You stand on a very high point of land. On your right comes up the Shenandoah, having ranged along the foot of the mountain a hundred miles to seek a vent. On your left approaches the Potomac in quest of a passage also. In the moment of their junction they rush together against the mountain, rend it asunder and pass off to the sea.