This story reports on the results of a UNC-Charlotte geologist’s study of how geology impacted battles in the war. Professor Scott Hippensteel tells us, “It is not an overstatement to say that rocks helped determine the outcome of the Civil War. Geology determines terrain, and terrain can be exploited by a skilled commander on both offense and defense.” His study is titled, “Carbonate Rocks and American Civil War Infantry Tactics” and give examples of how geology affected the war.
“Carbonate rocks, named for the minerals involved in their composition, are sedimentary rocks consisting of two major types: limestone and dolostone. Limestone is a soft rock that’s easily scratched. Dolostone – also called dolomite to reference its mineral composition – is similar to limestone but harder and heavier.”
Hard rocks, he tells us, erode much less than other types of rocks, and they make good defensive lines. “Part of Hippensteel’s analysis examined a mix of the harder diabase (dark-colored igneous rock) and softer sedimentary rocks, which produced famous Civil War landscape features such as Cemetery Hill and Little Round Top. Those features proved to be key defensive strongholds for the Union at the pivotal Battle of Gettysburg. Cemetery Hill, Little Round Top and Seminary Hill, which was used by the Confederates at Gettysburg as a staging area for assaults on Union positions, were all underlain by diabase, Hippensteel notes. ‘This harder rock formed hills, and the outcropping boulders could be used for breastworks – temporarily constructed fortifications, usually about breast-high,’ Hippensteel said. Between these two hills, Hippensteel notes, is softer sedimentary rocks that formed the broad, gently sloping plain over which Confederate Gen. Robert E. Lee launched the ill-fated ‘Pickett’s Charge.’ Lee’s attack left one high ridge of hard igneous rock, traveled across softer sedimentary rock, and attacked another high ridge of igneous rock. This jumble of terrain contributed to the Confederates’ struggles at Cemetery Ridge.”
I think interdisciplinary approaches like this are fascinating, and points up another element that we students of the war should be considering, especially since terrain determined how the battles would be fought.