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I have run across many pictures of rocks that look like almost perfectly carved columns. For example: the Twyfelfontein Organ Pipes, the Basaltic Prisms of Santa Maria Regla, and the waterfall Svartifoss (pictures included on this link: http://www.touropia.com/natural-rock-formations/). All of the rocks I have seen that look like this have been basaltic. Is this shape caused more by how the rock originally formed, its mineralogy, or how the rock was eroded?

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  • $\begingroup$ You are asking too much with one question - each formation has it own story & one simple answer doesn't fit all of them. The columnar structure of basaltic organ pipes is due to there mineralogy & how they cooled. Wave Rock is an exposed granite dome that has eroded by water running of the top of the dome & largely down one side of the dome to form its current shape - it's much smaller that pictures of it suggest. The sedimentary formations & pillars have their appearances due to erosion. $\endgroup$ – Fred Jan 29 '17 at 6:43
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    $\begingroup$ For the columnar basalt, see Giant's Causeway geology and Basalt vs. columnar basalt. As this is basically the same rock formation (just elsewhere in the world) I am voting to close this as duplicate. $\endgroup$ – Gimelist Jan 29 '17 at 6:46
  • $\begingroup$ youtube.com/watch?v=c3TpGtUZEjc $\endgroup$ – MaxW Jan 29 '17 at 18:36
  • $\begingroup$ sciencedaily.com/releases/2008/12/081216104325.htm $\endgroup$ – MaxW Jan 29 '17 at 18:45