Tuesday, January 29, 2013

Litlanesfoss, Iceland


The stunning image below is of a waterfall crossing an ancient lava flow at Litlanesfoss. The columnar jointing seen in the lava flow is a result of cooling. As the lava cools it contracts and forms cracks. The cracks, once developed continue to grow perpendicular to the surface of the lava.
Straight, regular columnar jointing is known as “colonnade” and is believed to have formed from slow cooling from the base of the flow upwards, and irregular columnar jointing, known as “entablature” is believed to be the result of rapid cooling from the top of the flow downwards.
Most of the columns have 6 sides and are a what we deem a “classic” hexagonal shape, such as Giants Causeway in Ireland, but the columns can have up to 7 sides, or as little as 3.
Classic examples of columnar jointing include; Giants Causeway (Ireland), Fingals Cave(Staffa Island, Scotland), and Devils Tower (Wyoming USA).
For more information head to the links below.

Links:
http://maps.unomaha.edu/maher/geo330/julia1.html
http://ngm.nationalgeographic.com/2012/05/iceland/kunzig-text?source=podrelated
http://www.icelandvirtualtour.com/hengifoss-litlanesfoss.html
Image: Wild Wonders of Europe



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