States Geological Survey (USGS). The Cove Mountain wild area is covered by USGS topographic maps Arnold Valley, Buchannan and Montvale. A key to the topographic maps for the northern half of the Jefferson National Forest is in the gallery below. Natural history The habitat of the southern Appalachians is rich in its biological diversity with nearly 10,000 species, some not found anywhere else. The great diversity is related to the many ridges and valleys which form isolated communities in which species evolve separately from one another. The region lies south of the glaciers that covered North America 11,000 years go. To escape the glaciers, northern species retreated south to find refuge in the southern Appalachians. When the glaciers retreated, many of these species remained along with the southern species that were native to the area. The diversity includes trees, mosses, millipedes and salamanders. According to historians, Bearwallow gap, at the intersection of Va 43 and the Blue Ridge Parkway, was an important path for Buffalo crossing the Blue Ridge Mountain. Until the mid-1700s, buffalo were plentiful in Virginia. There has been a road crossing the gap since the late eighteenth century. McFall's Creek special biological area, on the southeast side of the wild area, contains rare plants such as the orchid nodding pogonia. Invasive plants, such as tree of heaven, Paulownia and autumn olive, are a problem in open areas with roads. clearcuts and game openings. There are several tracts of old growth forest, one near the Appalachian Trail on the south end of the area near Little Cove Mountain Trail, and others to the north and south near the Appalachian Trail. A one-mile long tract on the northeast has trees at least 140 years old. Wild natural trout streams in Virginia are classified by the Department of Game and Inland Fisheries by their water quality, with class i the highest and class iv the lowest. Peters Creek, McFalls Creek, Yellowstone Branch and McCoglin Branch are ranked as a class ii trout streams. In 2008, large woody debris enhancement projects in McCoglin Branch and Yellowstone Branch were designed to improve stream habitat for trout and other species by creating small pools that provide habitat for fish. The debris collects organisms for the fish to eat, and protects the streams from erosion during floods. Topography Cove Mountain (elevation 2684 feet) is a spur of the Blue Ridge, stretching from the James