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The geology of Silfra
The North Atlantic Ridge is the longest mountain range in the world but for the most part submerged deep beneath the surface of the Atlantic Ocean.
Two tectonic plates, the Eurasian and the American plate meet here. Right between the tectonic plates lava underneath the earths crust flows out into the ice cold water of the Atlantic. The lava coalgates instantly and over millions of years this process has formed the North Atlantic Ridge. Due to a vulcanic hot spot and the massive vulcanic activity underneath Iceland one mountain has risen higher, broken through the surface of the Atlantic Ocean and formed the island of Iceland. |
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The geology of Silfra and the Thingvellir valley are connected to the tectonic drift of the Eurasian and the American tectonic plates.
Every year the tectonic plates drift about 2cm apart, which causes tention between the plates and the earth mass above. Every 10 or so years this tention is released through a major earthquake. The last one in 2008 reached 5.4 on Richter.
In these earthquakes the cracks and fissures that one can see in Thingvellir have formed. The earth has literally been torn apart.
Silfra is one of these and has the Eigenart of being right at the rim of lake Thingvellir. Therefore it's filled with water down to it's deepest know point of 63 meters. These 63 meters are deep down in one of Silfra's caves. The caves have formed also through the earthquakes, when boulders and rocks have fallen into the crack and got stuck at the point the crack got more narrow than the boulder was wide. Over time more smaller rocks have laid on top of the big rock(s) and formed caves underneath. |
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