Nature's Tracers Through Time

Witness trees from the Civil War still stand on battlefields at Gettysburg and Antietam: white oaks associated with generals Reynolds and Sickles, a black walnut linked to John Gibbon, and a sycamore beside Burnside’s Bridge. Diabase boulders at Gettysburg, along with bullet holes and artillery shells embedded in buildings, provide other physical traces of the fighting. Military historian William Frassanito used distinctive rocks to match 19th-century photographs of Gettysburg with the landscape today. Unlike the rocks, whose appearance changes little on a historical timescale, witness trees have grown considerably since 1863.