Volcanic rock is porus; water flows through it. Here are two different examples. In both cases, the Langjokull is the source of the water.
Notice that there is no river upstream of the waterfall. The water flows through
the rocks.
Water emerges at 97 °C (almost boiling). It is the highest-flow hot spring in Europe. Some of the water is used for heating, being piped 34 kilometers to Borgarnes and 64 kilometers to Akranes. Most homes in Iceland have two water pipes entering: one for cold water and one for hot, from geothermal springs like this. There is so much hot water available that, in Reykjavik, the water is run through pipes just below the sidwalks and roads, and so the capitol city does not have to shovel its walks or streets in the winter!
pipe carring hot water for heating
