Plowing the Ancient Seas: Iceberg scours found off South Carolina Sid Perkins Recent sonar surveys off the southeastern coast of the United States have detected dozens of broad furrows on the seafloor—trenches that were carved by icebergs during the last ice age, researchers suggest. FLOW REVERSAL. Currents driving the icebergs that scoured channels in the seafloor off South Carolina at the height of the last ice age ran almost exactly opposite to today's prevailing currents. Channel shown in inset is about 100 meters wide. Hill, et al. The channels, roughly parallel to the coast, are between 10 and 100 meters...