The Himalayas are the world's highest mountain chain. They stretch from Iran to Burma, right across the north of India. They are not a single range of mountains, but many ranges, each parallel to one another. They have been formed by two parts of the Earth's crust pushing against one another, crumpling up the edges into fold mountains. As these mountains rise, so frost, glaciers and rivers cut deep valleys and leave tall peaks with jagged summits and ridges. The highest of the mountain peaks is Mount Everest.