Álftanes is a low-lying peninsula linked to land by a narrow isthmus. Bedrock of Álftanes is dolerite, dolerite is old lava and in this area they have run forth around the closing of last ice-age. In Álftanes it is possible see ancient moraines from the cold season for about 12,000 years. Gallows-lava (Gálgahraun) that is opposite Bessastaðanes (peninsula) is younger or about 7,000 years old and it flowed from the volcano Búrfellsgjá which is about 15 km away. In the Gallows-lava on Álftanesi is preserved unique monuments of hiking and riding trails from the first settlers. Kjarvalwhich is by many considered one of the most important artists of Iceland was very fund of Gálgahraun and it is still possible to see some of his motives in the lava.