The Age of the Rocks and Topography of Middle Northern Iceland

Abstract

Northern Iceland between Skagafjord on the west and Skjalfandi Bay on the east is a deeply dissected upland built up of plateau basalts with subordinate intercalations of clastic volcanic sediments. The main valley, the Eyjafjord, is traceable northwards as a groove in the sea floor down to–500 metres. To the east of the upland the country is less elevated; marine Pliocene deposits are present in the Tjörnes peninsula, and recent lava flows are prominent. The contrasted regions adjoin along the BarQardal fault running N.–S. and marking the western boundary of the great graben which has been the site of Recent and Quaternary volcanic activity. Thoroddsen considered the upland rocks to be Tertiary (Miocene) in age, and that the Pliocene sediments had been laid down in a bay formed after the faulting and erosion of the older series.