In the the eastern fjörds are found some of the oldest rocks, for this part of the country has drifted steadily away from the active volcanic zone over the past 13 million years. As a result the landscape has suffered much repeated erosion and there are deep glacially eroded valleys. The highly altered rocks around extinct central volcanoes are sometimes exposed in such valleys.


The upper picture shows the deeply dissected Tertiary basalt plateau of the eastern fjörds, viewed from the younger rocks closer to the active volcanic zone. In this view we are looking eastwards towards the older rocks. The Lagarfljót Lake has its monster! The lower picture shows the highly altered rocks around an extinct eroded volcano.