91热爆

The mountains of the Andes - including Mount Cotopaxi at 19,000 feet high - are part of a range of volcanoes. Some are active and some dormant, but they run the length of South America, and are surrounded by the high cold plains of the altiplano. The flanks of the mountains support a wide range of life, all adapted to living at high altitudes and low temperatures. One of these animals is a wild South American camel called a vicuna. Its wool is so warm and soft that man has hunted it almost to extinction. The people of the Andes have domesticated another wild camel called a guanaco which has excellent wool and is a very good beast of burden. In Ecuador and Peru, close to the Equator, these wild camels live at around 14,000 feet. But the further south one goes, the lower the snowline becomes. Two thousand miles south of Cotopaxi the line of permanent snow drops from 16,000 feet to 13,000 feet. Another thousand miles further south and the mountains are smaller but almost completely covered in snow, even though they come down to a few hundred feet from the sea. Here the guanaco lives almost at sea level. But it is still very cold even in summer as the sun's rays only hit these latitudes at an angle, so are weaker.