Ball's Bluff is a 600-yard-long shale and sandstone cliff that rises in a shallow bell curve from two ravines about 300 yards to the north and south. At this point it stands about 100 feet high, and just to the north it reaches its highest elevation of 110 feet above the Potomac River, which flows due south here, so the view across the river into Maryland is eastward rather than northward. Below lie the river and the floodplain where Union troops landed on the morning of October 21, 1861, with their landing point about 300 yards upriver to the left, after which they moved down the floodplain to the path at the southern end of the bluff that climbs upward near the cemetery. The Virginia channel below is normally about 75 to 80 yards wide, beyond it lies Harrison's Island, which Federal troops picketed before the battle and sought as a refuge after the rout at day's end, and beyond that is the Maryland channel, roughly 350 yards wide, with Maryland proper on the far side. On the horizon to the right stands the site of Poolesville, the small town that served as General Stone's division headquarters from August 1861 until his arrest in February 1862, while his approximately 10,000 troops camped 8 to 10 miles north and south of Poolesville to cover the river and watch for Confederate activity.