Iceland – geology 2

The geology was initially supposed to be covered by one post only, but as you can see, there were too many exciting geo-sites to fit in in one post 😉

So, let's continue the photo-journey through the magnificent, raw Icelandic landscapes with some geology in mind.

Driving along the southern coast may be a bit monotonous, but if you are a curious observer, you will notice that there are kilometers and kilometers of moss-covered fields of pillow lava dominating the landscape of area close to Kirkjubaerjarklaustur. These are attributed to the extrusion of the lava under water in the ocean ridges as well as subglacial eruptions, which is likely the case for these fields.

On the way, there are many signs of volcanic activity including Álftaver cone group (first picture above) and Eldborg (second picture above). The Álftaver cones are actually pseudocraters, while Eldborg is a real volcanic crater rising 60m above the surrounding lava.

The group of pseudocraters was formed during a volcano eruption, which resulted in lava flow over the wetland. The insulating crust shields the hot lava in the lobe interiors from the water, which inflate and expand laterally in response to the injection of lava. As the lava thickens, it sinks into the water-logged sediments below until the basalt crust cracks and enables the glowing hot lava to flow straight into the water-logged substrate and initiates the steam explosions. It these explosions are powerful enough, they burst through the overlying lava to emerge as rootless eruptions that build cones around the vents. *

Eldborg is a beautiful real crater close to the road 54 North from Reykjavik. It was formed during volcanic eruptions 5000-8000 years ago. It's a symmetrically-shaped crater, about 60m tall and 200m wide.

* From the information plate at Álftaver.


Geysir area of geothermal activity is named after the biggest of the geysers. The eruptions of Geysir can reach as high as 70 metres in the air. However, eruptions are rather infrequent and hard to observe. The biggest attraction in the park is Strokkur, which explodes every few minutes.

The formation of geysers requires particular hydrogeological conditions, which exist in only a few places on Earth, so they are a fairly rare phenomenon. Generally, all geyser field sites are associated with volcanic areas with magma activity. When the surface water reaches deep down and gets in contact with hot rocks, it starts to boil and results in ejecting of hot water and steam out of the geyser's surface vent (a hydrothermal explosion). 

There are very few places on Earth which provide the conditions for existing of the phenomena: Yellowstone National Park, U.S., Valley of Geysers, Russia, El Tatio, Chile, Taupo Volcanic Zone, New Zealand and Iceland.

One of the coolest geological sites, however very under advertised: lava caves. We visited Raufarholshellir Cave on our way back to Reykjavik and were quite impressed with it's size, even though it is only the 3rd lardest lava tube on the island. The cave is located on top of the hill, which is one big lava deposit. It's quite amazing to imagine that the volcanic eruption and lava flow reached so high above the sea level.


The last but not least, the Þingvellir park. While most people are following the marked paths with historic notes and admiring the oldest Icelandic Parliament, we have been amused by the idea of standing on the connection of two separate continental plates: Eurasian and American. The rift zone crossing Iceland makes it grow, increasing the Atlantic Ocean and pushing Europe and Americas away. But we will hold it 😉