Mountains are landforms that rise steeply above the surrounding terrain and are generally over 600 meters high. They have sloping sides, sharp ridges, and sometimes snow-capped peaks. Key features include the summit, slopes, and gorges between younger mountains. Mountains exist on every continent and under oceans, and all have rapidly changing altitude, climate, soil, and vegetation over short distances. The highest mountains are found in the Himalayas, and some areas have permanently frozen rivers called glaciers.