Geologically speaking Iceland is a very young country - just 20 million years since it first emerged from the sea. It lies on the mid-Atlantic rift which runs NE to SW across the island and is visible in many places. It is also at a point where the earth's molten interior is relatively close to the surface. This leads to regular volcanic activity, earthquakes and, from time to time, the emergence of new islands. The appearance of the volcanic rocks is determined by their speed of cooling. In some places whole lava fields have cooled quickly and then been weathered into bizarre shapes. Where rocks have cooled more slowly tall 6-sided basalt pillars have formed, sometimes vertical andsometimes horizontal. Some volcanic craters are full of water. Other craters such as the vast Hverfjall may have been formed by a sudden steam eruption. Power stations tap the supplies of hot water and steam lying close to the surface. As well as the famous hot pools for swimming (see Background) there are numerous mud pools and vents (fumaroles) from which gases escape creating a bizarre coloured landscape rich in both smells and sound. Despite the dangers tourists can follow walkways between the pools of boiling sulphur where they must take care not to leave the path and meet a certain death. To see the photos click here.