studies showed that the Glades were formed by easily eroding rocks in the basin and more resistant rock at its lower end. This effectively prevented down-cutting and maintained a low gradient in the valley. This resulted in an elevation of at the upper end and at the back, eliminating the possibility of origin by water impoundment. The water from the Glades drains to form the headwaters of the Cranberry River, a popular trout stream joined by the Yew and Charles Creeks. It starts at about above the sea, and then it meanders through the glades and recedes through a narrow gap between Kennison and Black Mountains. It then joins the Gauley River down the mountains at about above sea level. Ecology Flora Many of the plants found in the Glades resemble those in the northern region of North America. They are descendants of seeds that took root over ten thousand years ago before the last glacial retreat. Among these are two unusual species of carnivorous plants that thrive in the area — the purple pitcher plant and native sundew. They evolved carnivorous habits because of the scarce root food in the spongy soil. Two very rare boreal plants — bog rosemary and buckbean — also live in the Big Glade. Much of the area provides a home for many species of mosses. These include a cover of sphagnum moss, bird-wheat moss, bog moss and reindeer lichen. Hummocks of these plants reach a height of . Over top of these grow prostrate cranberry vines that bloom nice pink flowers in the summer and a bunch of fruits in late September. Trees Within the Glades floodplain, most tree species occur in the "bog forest" habitat, which is composed primarily of a mixture of red spruce, eastern (or Canada) hemlock, yellow birch and red maple. The upland forests immediately surrounding the wetlands are dominated by these same species, but also include American beech, sugar maple, black cherry, American basswood, white ash, yellow buckeye, black birch, cucumber tree, Fraser magnolia, and northern red oak. Shrubs The Glades' shrub layer, unlike the tree layer, is relatively species-rich. This is a consequence of the widespread presence of low- to medium-height woody plants throughout shrub swamps, forest habitats, and open glades. In the fringes of open glades and along streams, the dominant species is usually speckled alder. Also common are willow, pipestem, glade St. Johns-wort, great rhododendron,