2006 Philadelphia Annual Meeting (22–25 October 2006)

Paper No. 10
Presentation Time: 4:00 PM


BOLAND, Irene B., Deptartment of Chemistry, Physics, and Geology, Winthrop Univ, Rock Hill, SC 29733, bolandi@winthrop.edu

The topography of Cowpens National Battlefield, little changed from the time of the Battle of Cowpens, is controlled by geology. The battlefield resides in the Six Mile thrust sheet of the Southern Appalachian Inner Piedmont Terrane. The Six Mile thrust sheet is a stack of shallowly-dipping thrust sheets composed predominantly of Late Proterozoic to Early Paleozoic biotite gneiss, amphibolite gneiss, mica schist, and metagranite. The gneiss and schist, remnants of the Late Proterozoic to Early Paleozoic Laurentian continental margin, were metamorphosed, deformed, intruded by granitic magmas, and thrust westward during Paleozoic collisions leading to formation of Pangaea. Recent detailed mapping data show that the battlefield is on a topographic high with a radial drainage pattern and approximately 18 m of gently- to moderately-gently-sloping relief. The eminence, capped by weathered quartz muscovite schist and quartz muscovite biotite schist, is part of an E-W-trending ridge that forms the hinge of a series of tightly folded NE-SW-double-plunging folds that includes Thickety Mountain, a prominent Revolutionary era landmark. The valleys are underlain by moderately to strongly foliated biotite gneiss that crops out as hard rock only within stream beds. At the time of the Revolutionary War the Cowpens were used to hold cattle prior to taking them to market. The road used on 17 January 1781 by British troops under command of Banastre Tarleton as they approached the battlefield from the east rises up a gentle slope. It is bounded on both sides by swales that harbor wet-weather springs. Wet weather prior to the battle had activated the springs and made the floors of the swales boggy, unable to support easy movement of men, horses, or cannon. Continental troops and militia under command of Daniel Morgan strategically used that topography to lay a tactical trap and defeat Tarleton. Today, due to recent droughts and use of water wells, the wet-weather springs are non-flowing and the floors of the swales are dry. A shallow (~1 m deep) ditch of uncertain age that parallels the old road to the SW is underlain by orange-colored, oxidized, well-drained soil. The absence of black, reduced, poorly drained soil in the ditch suggests it is a man-made feature, not a dry stream bed or irrigation channel as has been interpreted by some historians.