Caves in Iceland
Icelandic caves are not just any old holes in the ground
Given the extremely volcanic nature of Iceland, a feature for which Iceland has in recent years gained a certain amount of notoriety, it is not surprising that the vast majority of our caves are of the lava tube variety.
A lava tube is, as the name suggests, quite a unique type of cave that is found in relatively few locations around the world compared with, for instance, lime stone or sedimentary rock caves, which are found all over the world. Lave tubes are found only in highly volcanic locations such as – apart from Iceland – Hawaii, the Canary Islands, the Azores, New Zealand, certain parts of Australia and the USA, and the Moon!
Not all lava caves, however, are lava tubes.
Other types include ´lava mold´, ´rift´, ´inflationary´, and ´vertical conduits´. A particularly stunning example of a vertical conduit is the magnificent Þríhnjúkagígur (http://cave.is/caves-in-iceland/thrihnjukagigur/), which is essentially a spent magma chamber that just happens to have been left with an opening on top.
Apart, perhaps, from Þríhnjúkagígur, lava tubes tend to offer by far the most exciting and awe-inspiring caving experience due to the fact that they were created by the flow of highly fluid lava rivers during an eruption and are therefore known as ´primary´ caves. This in reference to the fact that they are formed at the same time as the rock of which they are composed.
They have not come about through earthquakes shifting the earth´s crust, or been carved out by man, micro-organisms, air or water erosion (´erosional caves´), or other forces of nature.
The fact that lava tubes are primary caves provides a unique window into what happens during an actual lava flow, when super-hot lava is rushing forth, splashing its way through a tube shaped tunnel to then become petrified, as if frozen in time, for us to marvel at for eternity.
This is why, apart from the fact that being able to go underground and trek an actual lava tube is a thrilling and unique experience not to be missed by anyone fascinated by the forces of nature, lava tubes exhibit some of the most unusual and entrancing natural features found anywhere on Earth.
This refers to the wonderfully weird and wacky rock formations, or speleothems, often found inside lava tubes – especially in Iceland where many of them remain largely unexplored by the masses.
These speleothems take the form of various types of stalacmites and stalactites, or ´lavacicles´. Among the more interesting ones are ´shark tooth´, ´splash´ and ´tubular´ stalactites, to name a few.
Frankly speaking, these are rock formations that defy even the most vivid imagination. No description or photo can begin to do them justice – although we do try :-)