Sometimes the crust has folded and buckled, sometimes it breaks into huge blocks. In both cases, great areas of land are lifted upwards to form mountains. Other mountains are formed by the earth's crust rising into a dome, or by volcanic activity when the crust cracks open. Volcanic mountains like Mt. St. Helens in the USA, or Mt Kilimanjaro in Tanzania, may rise from the surrounding land in isolated splendour. Others form part of huge ranges like the European Alps or the Himalayas of Asia.
Mountain ranges have a major impact on the earth's climate.
If you climb from base to peak of a big mountain, you will pass through a number of different types of plant community. As you climb higher it gets colder and colder and the trees eventually thin out and disappear. The highest parts of the mountain support only sparse grasses and low-growing Alpine flowers. If the mountain is high enough even this vegetation disappears and the peak is bare and rocky and perhaps covered in snow and ice. A carpet of flowers Alpine plants in high mountain regions are slow growers.