seems to be a parasitic cone of a stratovolcano, whereas Keilir is located adjacent to presently active volcanic systems and looks as if it were placed on top of the shield volcano Þráinskjöldur, though the last one is younger than the subglacial formation. Interestingly, similar tectonics, rift zones, are behind both expressions of volcanism: the West Antarctic Rift System on the one hand, and in the case of Keilir the Reykjanes Rift as part of the rift zones crossing Iceland. Also similar are their rocks – mafic lapilli tuff (in Icelandic: móberg). Landmark As the mountain is easily recognized from afar, eg. from Reykjavík, but also from sea, it was used as a landmark by fishermen and seamen for many centuries. Hiking There is a hiking trail leading up on the mountain from ENE. At the top, a guestbook can be found within a box. An excellent view over a big part of Reykjanes Peninsula and Faxaflói is to be expected from the top in good weather. See also Geology of Reykjanes Peninsula Krýsuvík (volcanic system) References Reykjanes Subglacial volcanoes of Iceland Mountains of Iceland Pleistocene volcanoes