Monte Rosa, a mountain group at the eastern extremity of the Pennine Alps, on the frontier line between the Swiss canton of Valais and the kingdom of Italy, in lat. 45° 55' N., lon. 7° 52' E. It is, after Mont Blanc, the loftiest mountain of the Alps, the highest peak being 15,150 ft. above the sea. The main ridge stretches S. from the peak known as Nordende to the Parrot-Spitze, where it connects with the Lyskamm range. Between these points two principal branches radiate, one westward, with the highest summit or Höchste Spitze at its junction with the main ridge, and the other eastward from the Signal-Kuppe, somewhat to the south of the middlemost point. Four angles are thus formed; those on the west contain the Monte Rosa and Lys glaciers, and give rise to the great Gorner ice stream, and those on the east enclose the Macugnaga and Sesia glaciers. Monte Rosa thus forms a part of the watershed between the basins of the Rhône and the Po. The mountain walls are most precipitous in the N. E. angle above the Macugnaga glacier. Along the crest, especially in the neighborhood of the Höchste Spitze, the edge is sometimes so sharp as to allow the climber to bestride it.

All the summits of Monte Rosa are composed of gneiss and white mica slate, and all have of late years been ascended.