A geological tour of Iceland



Here is another guest blog from my husband, Larry.  When we got back from Iceland he said he wanted to write about the geology of the country.  His post is below:

Marla and I have been asked about our recent trip to Iceland.   In an earlier post, my wonderful wife described some of the dining and lodging we enjoyed.  I am going to talk about Iceland’s incredible geology.   When visiting Iceland, it is impossible to ignore the country’s dramatic vistas and unusual geologic formations.    Even the non-geological-minded cannot help to be impressed.

The secret to Iceland’s very existence can be described by two words: “plate tectonics.”   Iceland sits on the line between the Eurasian and North American tectonic plates. The boundary runs like a stitched-up scar down the middle of the Atlantic Ocean in a formation called the Mid-Atlantic Ridge.   Volcanic activity in Iceland is the result of magma from the earth’s mantle pushing up into the gap between the plates.  The two continents are being forced apart from each other at the rate of about one centimeter a year.  For most of its length, the Mid-Atlantic Ridge is deep under the ocean.  The ridge emerges on land in the southwest corner of Iceland on the Reykjanes Peninsula and runs in various faults and canyons northeast through the entire country.


The “bridge” crosses between the Eurasian and North American continental shelves.  The near side is a part of Europe.  The far side is North America! 

Thanks to the Mid-Atlantic Ridge, Iceland has many active and inactive volcanoes.  The most recent major volcanic event occurred in 2010.  That year in the southern part of the country,  Eyjafjnallajokull erupted and sent a huge ash cloud over Europe.  While it caused the cancellation of thousands of flights throughout Europe, in Iceland there were no fatalities and very little damage.  We visited a family-run museum below the volcano  and watched  a video that graphically described the 2010 eruption.   Unfortunately we were not able to see the volcano through the rain clouds.

Because Iceland was formed volcanically, the island is primarily basalt, a dark colored igneous rock formed from cooled lava.  Iceland is covered in lava.  We saw it everywhere.  Some of the lava is just a few years or centuries old.  Although we did not visit any volcanoes, guided tours were available.

Throughout Iceland the hot magma from the earth’s mantle is relatively close to the surface.   Because of this, Iceland is blessed with incredible geothermal resources.  The most well known and visited site is the Blue Lagoon, located near Keflavik International Airport on the Reykjanes Peninsula.  The thermal waters at the Blue Lagoon are a popular tourist destination.  Because of this, a visit to the Blue Lagoon requires a reservation.  We learned this to our chagrin when we dropped by and found out all the tickets were sold out for the day.  We booked tickets for the next day at 8 a.m., the only timeslot available.


Visitors enjoy the thermal waters of Blue Lagoon, Iceland’s foremost tourist destination.


Natural geothermal springs are common in Iceland.  We visited a number of them.  Many are easily accessible from the road.   In the not too distant future, the country hopes to derive 100% of its energy needs from this spectacular natural resource.


The hot springs at Krysuvik.   Look but don’t touch!

Iceland is also famous for its geysers.  The word “geyser” comes from another of Iceland’s major tourist attractions, a hot water spout that rivals its equally famous counterparts in Yellowstone National Park.  In Icelandic, “geysir” literally means “gusher.”   These geothermal hotspots form where groundwater under incredible pressure gets close to the magma.  The water becomes superheated to hundreds of degrees above the boiling temperature at sea level.   The water seeps towards the surface.  When it emerges, it is boiling hot.  Occasionally, when the water gushes out in spectacular fashion  under pressure, a geyser is formed.


The “Great Geyser” which erupts every ten to fifteen minutes in spectacular fashion.

Since Iceland is located in the middle of the North Atlantic Ocean, it rains a lot there.  The runoff from the country’s mountainous terrain, including from Europe’s largest glaciers, combined with high basalt ridges, creates amazing waterfalls.  Many can be seen from Iceland’s main highway, Highway 1.  From parking lots, visitors need hike only a few hundred meters to the various waterfalls.  We visited some of Iceland’s most famous, including the country’s most visited, Gullfoss.   My photos hardly do Gullfoss adequate justice.  To fully feel its power a visitor must be close to hear the roar of the water and feel the spray of the mist.


The power of Gullfoss, a double cascade with over 100 feet of drop.


In western Iceland, Barnafoss falls run off the lava plateau into a spectacular canyon.

As the lava fields erode with time, the volcanic soil can be very rich.  We observed green pastures that rivaled Ireland in color.   What we did not see was forests.  When the first Norsemen arrived in Iceland in the late ninth century the island was covered with trees.  Within a couple of centuries the trees had been cut down for firewood, ship building, and other uses.  Because of this the Icelandic environment of today is very different from its original virgin state.

As a spelunker, no trip to Iceland would be complete without a visit to a lava tube cave.  On the Snaefellsnes Peninsula in western Iceland, we toured Vatnshellir Cave.  Most caves are formed in sedimentary rock such as limestone by the activity of water– and may take many dozens or hundreds of millennia to form.  Lava tube caves form rapidly with the flow of hot lava finding cracks in older pre-existing lava.  This “tunneling” can be hundreds of meters long and form very large chambers.



Visitors to Vatnshellir Lava Tube Cave.


Stairs to the lower chamber of Vatnshellir Lava Tube Cave.  Lava tubes were formed by flowing lava, not flowing water. 

Not sure when we will get to Iceland again.  There are many other places on our “bucket list” that we hope to visit.  But if we do return, we will plan to get up into the parts of the country we missed this time, especially the central region where the largest glaciers are, and the Westman Islands, famous as a nesting spot for puffins.


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