Wednesday, 3 May 2017

Mull April 2017: A visit to Staffa

Our trip to Mull presented the perfect opportunity to visit the geological gem that is Fingal’s Cave on Staffa. This we accomplished by taking a combined boat excursion from Ulva Ferry that also allowed us the chance to spend some time on the largest of the Treshinish Islands, Lungha, to see the puffins and whatever other birdlife was there at the time. The weather was as good as it could be, with blue skies and a calm sea. Could a day out be any better than this?
A seven hour excursion on a custom-built sea cruiser we were promised. This isn't what we had in mind.
Phew! Luckily Captain Hamish came to our rescue with the Salty Haggis, a fine sea-going vessel with plenty of room for the 15 of us.
Staffa is a dramatic looking island, with huge columns of hexagonal columnar basalt topped with the compressed ash of volcanic explosions. According to our resident geologist, basalt is an igneous rock, meaning it was formed from lava (or magma). Specifically, it is an extrusive igneous rock, meaning it formed as a lava flow at the surface. As you approach by boat you see this green-topped shape looming out of the sea, and as you come closer its unique structure becomes apparent
Rounding the island, you come upon Fingal’s Cave. Personally I much prefer the Gaelic name An Uamh Bhin, which means ‘the melodious cave’. That would, in fact, have lent itself better to Mendelssohn for his Hebrides Overture. However, it is universally known after the Irish hero Fionn MacCool, hence Fingal’s Cave. It was a bit naff but entirely predictable in a pleasant way that, as we moved closer to the cave, the boat crew fired up the PA system and piped out Mendelssohn's Overture. Hearing it in-situ makes you realise how well the music reflects its origins.
The on-foot approach to the cave is reasonably safe these days, with non-slip surfaces and a handrail to guide you. The tops of the basalt columns make pretty good stepping stones. Walking gives you a much better look at the columns and one of things you’ll notice is that, although they are described as ‘hexagonal’, they don’t all have six sides. This is, apparently, just one of those things. Geologists defaulted to calling them hexagonal long before they were properly studied, but they can have any number of sides (usually between 3 and 7). Once you get your eye in, you find yourself counting the number of sides to find the non-hexagonal ones!
When inside the cave, the sound of the waves breaking and echoing makes the visitor understand why it was originally called the 'melodious cave' and why it inspired Mendelssohn. I was inspired myself, in fact, but I could only manage a tuneless whistle. Look up and you see that the ceiling is studded with a mosaic of the moss-covered remains of broken/eroded columns.
Inside looking out. Blue sky, calm sea.
The columns don’t just go straight up and as the land has been squished (that's a geological term) and stretched and moved about over millions of years, the columns have ended up bent in places and seem like waves of rocks.
It really is an amazing sight and is in the 'see if you can' category. The alignments reminded me of the patterns produced by iron filings and a magnet.
A solitary Shag drying its wings in the sun. The silhouette clearly shows the distinctive tuft of feathers above the forehead which is present in its breeding plumage.
Looking back to Mull, with Ben More in the distance and the island of Ulva to the right.
Sitting near the highest point on Staffa, and just above Fingal's Cave, is a trig point. But not any old trig point. It's a circular trig point and one of the relatively few of the Vanessa design. Only seen north of the border, these are the gold medallists of the trig point spotting world - and this is the first Vanessa I've seen. Imagine my joy - it was a very quiet joy because I thought that jumping up and down in glee was not appropriate under the circumstances. So, you ask, what's so special about Vanessas? A little context will help you appreciate my joy.
When the OS triangulation had progressed to the Highlands of Scotland, it was necessary to design a new and lighter pillar, cylindrical in shape, in order to avoid excessive transport costs. These round pillars, usually called 'Vanessas', or sometimes 'Branders' or 'Kelsey Columns', were considered "less aesthetically satisfying" than the standard pillar, so they were only placed in inaccessible locations to "reduce the risk of criticism from the more sensitive element of the population to an acceptable level." Vanessa pillars weigh around 6½ cwt (330kg), less than half of a typical and more common Hotine pillar (14 cwt, or 711kg), and did not require such a large foundation, making them ideal for the rocky outcrops of the Scottish Highlands.
'Vanessas' are so-called because the name is derived from 'Venesta', the name of the company which produced the cardboard tubes that the concrete was poured into. And this is the bit of the story I really love, Venesta was chosen because of their expertise in making other cardboard tubes - the centres of toilet rolls. I can imagine the lateral thinking in operation here. "You know what we need is something like a giant toilet roll tube to mould these things. Now who makes 'em?".
When I get engrossed in something like this, I start to think that I'm losing the plot. I need help!
Ah, there's someone who can do just that. But she seems otherwise engaged..
And then it was back down the ladders to the boat and the rest of our trip. Next stop Lungha to see the puffins. But were they there? Stay tuned for the next exciting episode to find out.

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