Figure 5 from the Hippensteel article, (IMAGE) Geological Society of America Caption Figure 5 from the Hippensteel article, "Carbonate rocks and American Civil War infantry tactics." Union reenactors during a National Battlefield Park demonstration in the limestone outcrops at the center of the Union line at Stones River on the 152nd anniversary of the battle. Karrens (or "cutters," right) provided critical defensive positions for the center of the crumbling Union line during the Battle of Stones River. Credit Credit Scott P.Hippensteel and Geosphere. Usage Restrictions Credit Scott P.Hippensteel and Geosphere. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.