Geysers are natural fountains that throw up jets of hot water and steam at regular intervals through a vent in the surface. In some areas, rainwater seeps through cracks in the rocks and drains into a crevice or a large cave-like chamber so deep that it reaches hot rocks. The heat of these rocks comes from the molten rocks below. Eventually, the intense heat boils the water, which then turns into steam. This increases the pressure inside the crevice as bubbles of steam build up. Finally, the pressure is strong enough to shoot the water and steam upwards and out through a vent, high into the air. When the jet has died down, the crevice fills with new water and the process repeats.
Some geysers gradually lose their power and stop erupting as the volcanic heat dies down. A geyser that experienced this is Iceland's Great Geyser, which gave its name to all other geysers.
Hot springs are gushes of hot water that are found on the land surface. As molten materials deep in the earth cool down, they give off water vapor and carbon dioxide. This hot vapor then find its way upward through the cracks in the rocks, cooling as it goes, until it condenses to become water. Finally, it gushes from the ground as a hot spring. This water may be pure and clear, but it is rich in mineral salts dissolved from the rocks it has passed through on its way to the surface. As water cools around the edges of the spring, the minerals form crystals and grains. These build up into beautiful rock layers shaped like waves, basins and terraces. These hot springs can be found in Japan, New Zealand, Kenya and Iceland.