Glacial relics from ice age glaciers are widely visible, and erosion forces have carved out the land since there is no volcanic activity in the Westfjords, as they are far from any fissure and eruption areas. It is for certain that the last eruption in the Westfjords took place approx. 8 million years ago, and the geothermal heat that can be found there is therefore a remnant of the time when the area was an active volcanic area.  The bedrock around Vatnsfjörður belongs to rock layers that were formed in the mid-Miocene period, or around 13 million years ago. Dykes characterize the area to some extent, and geothermal power is often found near them.