The map is in the scale of 1:100 000 and is based on several maps in scales 1:20 000 – 1:50 000 made by ÍSOR and its forerunner, National Energy Authority, for different customers. The maps have been simplified, revised and filled in with new geological mapping.The oldest units on the map are 4 million years old and the youngest are lavas from an eruption on Reykjanes peninsula in the years 1211-1240 A.D. Alltogether there are about 160 different lava flows on the map.