The Melange ecoregion is characterized by dissected mid-elevation mountains with the complex geology typical of mélange formations. Elevation varies from 3,500 to 7,500 feet (1,067 to 2,286 m). The mountains are mostly blanketed in Tertiary basalt but have a core of mixed metamorphic, metavolcanic, metasedimentary, and sedimentary rocks. Soils are droughty and high in magnesium, creating a poor medium for plant growth; reforestation problems limit logging. Placer mining for gold altered the structure of many stream channels and left extensive tailings piles in riparian areas. Lithology affects soil, vegetation, and the quantity and quality of surface water, which vary across the region. Forests are dominated by Douglas-fir, ponderosa pine, and lodgepole pine, with subalpine fir, western larch, and grand fir; elsewhere, juniper steppe woodlands, shrublands, and grasslands are found. Understory plants include mountain-mahogany, snowberry, serviceberry, grouse huckleberry, snowberry, prince's pine, sidebells pyrola, twinflower, pinegrass, elk sedge, heartleaf arnica, Idaho fescue, and bluebunch wheatgrass. Riparian areas support mountain alder, red-twig dogwood, prickly currant, black currant, Columbia monk's hood, and bluebells. The region covers in Oregon and in Idaho, including parts of the Malheur, Umatilla, and Payette national forests and lower elevations in the Strawberry Mountain, Monument Rock, and North Fork John Day Wildernesses.