The small island El Hierro was formed about 35 Million years ago, by volcanic activities. But this volcanism was going on below sea level, and the rising volcanoe finally reached the sea about three Million years ago. The peak of the volcanic activites was about 50,000 years ago, and the island reched its highest elevation with the 1501 m asl high Malpaso. The last eruption was in 1793. The youngest lava fields are located in the south and the west, called Malpaíses. They are showing typical pahoehoe lava and contain lava tubes.