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Larvikite

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This, as the header of this post suggests, is Larvikite.  You've probably seen it cladding buildings and sparkling in the sun.  It is an intrusive igneous rock - one that is formed from magma that solidified underground. In this case, this happened near what is now Larvik (hence the name) in Norway. Larvikite is similar to granite in many ways but it has far less quartz than granite has. The feldspar minerals are iridescent because of some rather cool optical interference, rather like a kingfisher's feathers, and the iridescence varies as the angle you're looking at it from changes.  A polished slab is a so-and-so to photograph because the camera just looks through it to your reflection and you wind up with a selfie.* You also see it used in large, unpolished, blocks as coastal defences, and it's still very much worth a close look then. Incidentally, a chap by the name of Sir Montague Maurice Burton (of menswear fame) used Larvikite on the outside of his premises    in

The Whin Sill

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  While I have been 'curating' - she says grandly - photos to put on this blog, I've been reminiscing about when I took some of them.  Take this one, for example:  I was on an Open University geology summer school (SXR260, anyone?), and it was the first time I had been to Teesdale (County Durham, in northern England). One of our field trips was to see the Whin Sill (a lens-shaped igneous rock intrusion that took place in the  late Carboniferous ). There's an amazing exposure of the sill here at High Force Waterfall!  I can just imagine the heat of the magma as it forced its way through the country rock, and the cracking, creaking and groaning as it happened.  The basalt columns, by the way, are the same structures formed by the dolerite cooling that you see at Fingal's Cave and the Giants' Causeway.  Further along the Tees, at Low Force, you can walk across the exposed tops of such columns to see the hexagonal shape of the columns from above. I was using my

Rock bang full of oysters

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You've just got to love Portland Stone, with its distinct facies.  This is grove whitbed, a Jurassic limestone famous for being absolutely full of oysters.  I took this one, I think, at Green Park tube station in London. The station entrance, on Piccadilly, is literally a work of art; called Sea Strata, it was created by John Maine RA with the building clad in different facies of Portland Stone. This is the highly fossiliferous Grove Whitbed, which is full of oyster shells.

A twist(er) in the tale

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We (the local geology and palaeontology group) were in a huge quarry In Rutland one Saturday. We'd been collecting marine invertebrate fossils in the morning - I'd collected enough fossil shellfish to make a decent gumbo.  There were mussels, horse mussels, clams, sea urchins, all from a warm, tropical sea in the Jurassic, all living in their own trophic niches.  Some of my friends found fish teeth – bony fishes and hybodont (peg-toothed) sharks. During the morning, the sky had become more threatening, and we had to run to try (and fail) to avoid the downpour that came with a thunderstorm.  Luckily, this quarry has excellent facilities including a warm, dry room with a coffee machine, chairs and tables. It’s not a pretty room but it’s a very welcome one.  Anyway, this was a good time to have lunch, so we did, then we started to move out to another area with rocks and fossils deposited in a freshwater environment. I was a little behind some of the others, as I’d stopped to c

The sorry-looking Coelacanth

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I grew up reading about the coelacanth and about how it had been rediscovered in 1938 when it was thought to have become extinct millions of years ago.  When I first saw this specimen, in London's Natural History Museum a mere decade ago, my first reaction was an almost child-like wonder.  Here in the actual flesh was this living fossil (well, this example wasn't living, obviously...).  It was a solid, primitive, hefty-looking fish and looking at it felt like looking at a living dinosaur.  Yes, I know...  It is fair to say that as a species it isn't an underwhelming fossil fish this month (if you know, you know) or any other month. My second reaction was that it actually looks rather sorry for itself and this particular one is in fact underwhelming.  Like everything else that has been 'pickled' the way this one has, it has become pale and colourless over time. It really is a shame - and not just because live ones are the most amazing blue that would suit what se

Crinoids in the hall!!

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In general, people don't really expect floors to be interesting but, just sometimes, you come across something like this.  Before I tell you about this stone, and the fossils in it, I'll tell you about the day I took this photo.   It was Sunday just gone, and for me it was a Red Letter Day.  I have a bucket list, and one of the items on it was to hear Mussorgsky's 'Pictures at an Exhibition' live.  If I could hear 'Night on the Bare Mountain' at the same performance, that would be a real bonus.  This Sunday, the Philharmonia Orchestra were performing both at the Royal Festival Hall on the South Bank, London, and Steven Isserlis was the soloist for Kabalevsky's Cello Concerto number 2 in addition.  The whole concert was a real treat and well worth the trip to London. I'd got there early - a couple of hours early.  Deliberately.  That allowed for rail delays and gave me time to buy lunch (this was an afternoon performance).  It also gave me time to loo

A rite of passage

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  Every summer, the Open University used to hold a residential course, SXR260 The geological history of the British Isles , based at Durham University. For a week’s study, you didn’t just need your everyday clothes; you needed your outdoor gear (not forgetting waterproofs!) and boots, camera, books, stationery, sunblock, hairdryer... you get the picture.   You tended to gain the odd hand specimen of rock to take home for your reference collection as well; not many, of course, but choice.   If you’re interested enough to be reading this, you have probably been on the same course or on a good few field trips so you know what I’m talking about in terms of luggage! Durham Station did not have lifts.   At the end of my week (I was there in 2005), there I was, struggling to carry my case down the stairs.   I’m not tiny but the case was hefty.   Bang on cue, this chap and his girlfriend overtake me and said chap takes the chance to impress his girlfriend with his gallantry. “Can I help you