segment of the central Alps along the Italian-Swiss border, bounded by the Great St. Bernard Pass and the Mont Blanc group (southwest), by the Upper Rhône Valley (north), by Simplon Pass and the Lepontine Alps (qq.v.; northeast), and by the Dora Baltea River valley (south). The highest point is Dufour Peak ( Dufourspitze, q.v.; 15,203 feet 【4,634 m】) in the Monte Rosa group; other important peaks include the Matterhorn and the Weisshorn. Most of the glaciers lie on the north slopes, including the well-known Gorner Glacier near Zermatt, Switz. Mountain climbing has long been the main activity of the region. The Swiss portion of the range is sometimes called the Walliser Alpen (German) or Alpes du Valais (French).