Fingal’s Cave, Staffa
Viewed from the approach with Staffa Trips last week.
Okay, I’m still getting used to using Lightroom and the tobacco filter on the sky might be a little heavy, but I’m pleased with the seawater.
Fingal’s Cave
Patrick Mackie
humanism and secularism, environmental health, random thoughts and (mostly) photography from Argyll
For what it’s worth, my own photos of columnar basalt (Giants Causeway) are at Time turned to stone, Part 2: The Giants’ Causeway; time as process https://paulbraterman.wordpress.com/2014/12/14/time-turned-to-stone-part-2-the-giants-causeway-time-as-process/ http://wp.me/p21T1L-oc
Do you know why there is this sharp cut off between the columnar basalt and the rock above, which also looks (as far as I can tell from the photo) very similar? Any chance of getting a higher resolution image? No quarrel with the aesthetics, but scientifically the more detail the better
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Wikipedia she say: “It consists of a basement of tuff, underneath colonnades of a black fine-grained Tertiary basalt, overlying which is a third layer of basaltic lava without a crystalline structure. By contrast, slow cooling of the second layer of basalt resulted in an extraordinary pattern of predominantly hexagonal columns which form the faces and walls of the principal caves.” It would appear to be down to the rate of cooling of the basalt.
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Which like all good scientific answers leads to the next question: why did one flow cool more slowly than another?
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Here’s a seemingly-different explanation from http://www.geolsoc.org.uk: “As the newly-formed basalt lava cooled, it contracted and broke into sections which, in the lower part of the flow, produced regular 6-sided columns. The rubbly upper part of the flow contains many gas bubbles trapped as the lava solidified, and so did not break as evenly.”
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That figures. As lava solidifies, dissolved gas becomes more concentrated in residue, until that becomes saturated and subsequent coling gives lava with air pockets. And since these pockets can expand, the tension that leads to columnar fracture never has a chance to build up
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