Appalachian Trail - Topography

Topography

No sub-alpine regions exist between Mount Rogers in Virginia and Mount Greylock in Massachusetts, mainly because the trail stays below 3,000 feet (910 m) from Shenandoah National Park in Virginia to Mount Greylock. Mount Greylock, however, has a large subalpine region, the only such forest in Massachusetts, extending down to 3,000 feet (910 m), which in the south would be far from the sub-alpine cutoff. This is especially low because Greylock is exposed to prevailing westerly winds, as the summits along its ridgeline rise approximately 200 feet (61 m) to 650 feet (200 m) higher than any other peak in Massachusetts. Further north, several peaks in Vermont reach into the sub-alpine zone, the bottom of which steadily descends as one proceeds northward, so that by the White Mountains in New Hampshire, it often occurs well below 3,000 feet (910 m). At Mount Moosilauke, which summits at 4,802 feet (1,464 m), the first alpine environment on the trail is reached, where only thin, sporadic flora is interspersed with bare rocks. Between the two regions is the krummholz region, where stunted trees grow with their branches oriented away from the winter's prevailing northwest wind, thus giving the appearance of flags (they are often called "flag trees"). This region resembles lowland terrain hundreds of miles north in Canada. It also contains many endangered and threatened species. The trail has been rerouted over New Hampshire's Presidential Range so the Appalachian Mountain Club can protect certain plant life. The alpine cutoff in the Whites is generally between 4,200 feet (1,300 m) and 4,800 feet (1,500 m). Mountains traversed by the AT above treeline include Mount Moosilauke, several miles along the Franconia Range and along the Presidential Range. In the Presidentials, the trail climbs as high as 6,288 feet (1,917 m) on Mount Washington and spends about 13 miles (21 km) continuously above treeline, in the largest alpine environment in the United States east of the Rocky Mountains.

The segments of the trail through Pennsylvania are so rocky that hikers refer to the region as "Rocksylvania". These small rocks—the result of erosion that has worn away the dirt along the trails—can be tough to walk on for extended periods of time without proper hard-soled shoes.

In Maine, the trail extends into even harsher environments, and sub-alpine and alpine growth descends to lower elevations. Alpine growth in the state ranges from around 2,500 feet (760 m) in the Mahoosuc Range to below 1,000 feet (300 m) in parts of the Hundred-Mile Wilderness, where nearly every area higher than 1,000 feet (300 m) is evergreen forest. These forests include more species of evergreen, as well. In addition to the white pine, spruce and hemlock prevalent further south, Maine has many cedar trees along the trail. Near the northern terminus, there are even some tamarack (larch), a coniferous, pine-needled deciduous tree, which provides displays of yellow in the late fall after the birches and maples have gone bare. The hemlocks in Maine are also notable, as the woolly adelgid, which has ravaged populations further south, has not come into the state yet, and may be unable to make it so far north due to the cold climate.

Maine also has several alpine regions. In addition to several areas of the Mahoosuc Range, the Baldpates and Old Blue in southern Maine have alpine characteristics despite elevations below 4,000 feet (1,200 m). Saddleback Mountain and Mount Bigelow, further north, each only extend a bit above 4,000 feet (1,200 m), but have long alpine areas, with no tree growth on the summits and unobstructed views on clear days. From Mount Bigelow, the trail extends for 150 miles (240 km) with only a small area of alpine growth around 3,500 feet (1,100 m) on the summit of White Cap Mountain. Mount Katahdin, the second largest alpine environment in the eastern United States, has several square miles of alpine area on the flat "table land" summit as well as the cliffs and aretes leading up to it. Treeline on Mount Katahdin is only around 3,500 feet (1,100 m). This elevation in Massachusetts would barely be a sub-alpine region, and, south of Virginia, consists of lowland forest. This illustrates the drastic change in climate over 2,000 miles (3,200 km).

Despite the alpine environments well below 5,000 feet (1,500 m) in New Hampshire and Maine, some higher places further south are not alpine. Examples include Wayah Bald in North Carolina 5,342 feet (1,628 m) and Clingmans Dome in Great Smoky Mountains National Park 6,643 feet (2,025 m).