The Rauðhólar (“red hills”) are remnants of a cluster of rootless cones in Elliðaárhraun lava fields on the south-eastern outskirts of Reykjavík, Iceland next to the South Iceland part of Hringvegur, the Suðurlandsvegur. The name Rauðhólar means “Red Mounds”. It refers to the reddish color of their rocks due to iron oxidations. Some other volcanic cone groups in Iceland also bear the name of Rauðhólar (see eg. Rauðhólar (Vesturdalur)).
The cone group is situated not far from Reykjavík’s district of Norðlingaholt and between the Hringvegur and the lake Elliðavatn. Sometimes the rootless cone group is also called Rauðhólar við/near Elliðavatn. The cones are placed directly over the connected lava flow, in this case the Elliðaárhraun, which has a width of about 2 km and a length of about 27 km. Scientists to the beginning of the 20th century counted 150 cones.
These rootless cones, also called pseudocraters, are part of the Leitahraun lava, lava flows from a shield volcano up on Hellisheiði. This shield volcano, Leitin, is part of the Brennisteinsfjöll volcanic system. The resp. lava flow, a branch of the Leitahraun, is called Elliðaárhraun and was emitted by the shield volcano about 5000 years ago.
The Rauðhólar built up on a location where lava flows entered and covered a small lake just north of today’s Elliðavatn. The stratigraphy shows a mudstone bed (the lake bottom before-eruption), a 7 m high lava flow and a 5 m high scoria platform.