by Mary Caperton Morton Tuesday, February 27, 2018
Since the late 19th century, Civil War battlefield landscapes have changed. Some have been plowed under and developed, while elsewhere, woods have been cut down or become overgrown. But the rocks that dotted those battlefields from Gettysburg to Mississippi largely still stand. Historians are now using the steadfast boulders and ridges seen in the backgrounds of 154-year-old battlefield photographs to learn more about the skirmishes that took place at certain sites.
The biggest and bloodiest battle of the Civil War took place over three days in the fields around Gettysburg, Pa., where ridges, hills and outcrops of diabase sometimes offered strong defensive positions, and at other times forced troops into the open, where they were easily targeted. “It’s no surprise that geologists who are interested in military history go to Gettysburg to study how the landscape influenced the war,” says Robert Whisonant, a military geologist at Radford University in Virginia. “When you’re standing in the Devil’s Den, it’s easy to imagine how the underlying geology influenced the fighting.”
The Devil’s Den is a boulder-strewn ridge in Gettysburg where a natural fortress of lichen-encrusted rocks set the stage for one of the most famous Civil War photographs taken by battlefield photographer Alexander Gardner. Captioned “Rocks could not save him at the Battle of Gettysburg,” the photo shows a dead Confederate soldier lying next to a rifle. But in 1975, historian William Frassanito spotted the same dead soldier in a different series of battlefield photographs also taken by Gardner. In one of those photos, a distinctive boulder seen in the background allowed Frassanito to pinpoint the shot’s location and determine that Gardner’s crew must have carried the soldier’s body half the length of a football field to stage the photo by the boulders of Devil’s Den.
Rocks and boulders make for more reliable markers than other features of the landscape, but even the rocks have changed some in the past 150 years, says Scott Hippensteel, a geoarchaeologist at the University of North Carolina at Charlotte who has been studying erosion patterns on the diabase boulders of Gettysburg. Last October, Hippensteel presented his work at the annual meeting of the Geological Society of America in Seattle. “In the geologic instant that is 1863 to 2017, the rocks themselves have not changed very much from natural weathering, but anthropogenic change has defaced quite a few of them,” he says about the area’s durable boulders, which are chunks of igneous rock that initially solidified as an underground sill about 180 million years ago.
“Soldiers and tourists carved their initials and graffiti into rocks all over the Devil’s Den. When the National Park Service took over Gettysburg, [the agency] chiseled off all the graffiti, obliterating some of the surfaces,” he says. But even with the anthropogenic alterations, the relative positions and overall appearance of the rocks have not drastically changed, he says.
Last summer, Hippensteel sought out Gettysburg boulders that appeared in the background of Civil War-era images and photographed them from the same vantage points to create a series of then-and-now photographs. In most cases, the vegetation and overall setting of the rocks have changed dramatically, but the boulders are still readily recognizable from the 1863 images. Next, Hippensteel says he plans to study the Devil’s Den rocks for scarring patterns in hopes of reconstructing where artillery may have been positioned during the skirmish.
“It’s so gratifying to see people using geology to help historians and the public better understand these battles,” says Whisonant, who was not involved in Hippensteel’s work. “Military geologists love Gettysburg because it’s such a great example of how geology and history fit together. In the big picture of the Civil War, geology didn’t favor one side or the other, but when you look at particular battles, sometimes the terrain was crucial to the outcome.”
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