GEO. Icelandic geology for
complete beginners
Introduction
This small display of text, an interactive map and pictures is not
intended as a complete summary of Iceland´s geology, but is
meant to explain the main features and make you interested.
Iceland owes its dynamic geology to several natural features:
- It is situated on an active spreading ridge where two plates
diverge at a rate of 1 cm per year to the east and west. (If you
need some help on such things, you can see an excellent and easy
to understand "Internet" summary of plate tectonics at Plate
Tectonics, the Cause of Earthquakes ).
- In addition it is generally
believed to be situated over a rising mantle plume whose approximate mid
point is at Kverkfjöll in the north of Vatnajökull. The mantle plume explains
the great amount of volcanic activity and thickening of the ridge at this
point and also chemical trends in the magma produced, which differ from
typical ocean ridges.
- As a result it is an active volcanic area with frequent eruptions from
well known volcanoes such as Hekla, Katla and Krafla as well as recent eruptions in the
Westmann Islands (Vestmannaeyjar) and Surtsey which first emerged
from the sea in 1963.
- It is an earthquake zone, with frequent small earthquakes
where spreading takes place, but also with large earthquakes at
intervals of around 100 years at transform fault zones, in areas
where the spreading ridge has moved laterally. These areas are in
the south and along the nothern coastline.
- It is a country with several glaciers, including the largest
in Europe (Vatnajökull). Some of the most active volcanic
areas lie underneath these glaciers so that when eruption takes
place, it leads to huge meltwater floods (icel.
jökulhlaup) and explosive activity. The latest of
these was in November 1996, when the subglacial volcano
Bárðarbunga/Grímsvötn erupted leading to
floods on the Skeiðarársandur. These floods have long
been a feature of Iceland´s geologic history as the landscape
clearly shows.
- Because of its northern latitude and situation in the
Atlantic, Iceland has a very vigorous climate and high winds and
precipitation are common. There are two important results of this.
Firstly it has a very high - energy coastline and rapid erosion
and movement of material takes place. Secondly, because of the
sparse vegetation and other aggrevating factors, there is an
extremely serious wind erosion problem, with large areas reverting
to desert yearly.
These pages maintained by Dr Georg Douglas, Hamrahlíð
College, 105 Reykjavík, Iceland. Last updated March 2005.