A shutterbug of stone

  Roach stone with many 'Portland screws' England’s ‘Jurassic Coast’ is rightly famous.  Stretching along the English Channel coastlines of Devon and Dorset, it’s rocks bear witness to the entire Mesozoic – the Triassic, Jurassic and Cretaceous Periods (together known as the ‘Age of the Dinosaurs’) from East to West.  That’s a span of 185 million years, in the space between Exmouth in the west to Old Harry Rocks at Studland Bay, Dorset. Even if geology isn’t your thing, you’ve seen quite a few bits of it on film or television – West Bay, Bridport, is the setting for Broadchurch, Lyme Regis was home to Mary Anning (and of course to Trey), Kimmeridge Bay is famous for its fossils, Weymouth hosted the maritime events in the 2012 Olympics, and Lulworth Cove and Durdle Door are rightly famous. Chesil Beach and the Fleet are very important for their geomorphology and the lagoonal fauna of the brackish water in the Fleet. The Isle of Portland, tied to the mainland at the eas...

Following on  from the 'mintcake' Carrara marble I blogged about previously:  This column, in London's Royal Academy of Arts, is cipollino (little onion) marble - the green colouration comes from bands of chlorite and epidote.  Looking at it, it is easy to see how it got its name!  Both the ancient Greeks and the Romans used to quarry it, mainly for use as columns.  That still seems to be the case now; Westminster Cathedral (The Catholic one at Victoria) used it for the same purpose and, if memory serves, for a number of panels as well.   We happened to be at the RA for an exhibition and I was pleased to see this column there; I greeted it like an old friend.

  I was once sitting in a cathedral built from local limestones (from more than one source), and commented to my friend David that it would take some worthwhile heat and pressure to turn it into marble. He asked me, in total shock, whether one kind of rock can change into another.  The look on his face as he was asking was priceless!  I gave him the elevator pitch about metamorphic rocks, which have been transformed from one type of rock to another by the actions of heat and pressure.  Marble is one such metamorphic rock.  The purer the limestone was to start with, the purer (and more valuable!) the resulting marble.   Carrara Marble, one of the most famous stones in the world, was originally laid down as a pure marine limestone some 190 million years ago during the Jurassic, and then subjected to the aforementioned heat and pressure between 27 and 12 million years ago as the Apuan Alps formed.  The quarries, in Northern Italy, are enormous. ...

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  ...

  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...

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.

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 s...

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 sui...

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 tim...

  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 hi...

Or is it, though?  Is it not lemon mousse?  Well, I for one would not want to try to serve this into a bowl with a spoon... And neither are the orangey lines toasted sugar.  This is harder than your average chalk - which in turn is far from bring the boring white featureless mass that you might think. When you look at it you see details, structures, layers and beds.  It tells tales of a greenhouse Earth, of the movement of continents and the growth of mountains.  It tells tales of the life that lived in the seas where it settled. This is West Runton in Norfolk on the east coast of the UK.  You're standing on the top of the Chalk (with a capital 'C') and looking up at huge blocks and rafts of chalk which have been driven uphill by glaciers. Yes, glaciers can do that - they can do whatever they want. The chalk now finds itself surrounded by much younger sediments that tell the tale of temperatures falling into an Ice Age.  West Runton was home to a Stepp...