Snap, crackle and rock

-

A macro photo of Ketton Stone, demonstrating the ooliths it is composed of

A lot of photos don’t really come out like you hope they will.  They are fine, yes, but nothing to write home about – bog-standard landscape shots or whatever...  On the other hand, one occasionally does come out like you were really hoping it would, a landscape that takes your breath away or a detail of something you’ve seen.  This was one such photo, and yes, it does look like a certain well-known breakfast cereal!  I don’t think milk would soften it much, though.

This particular photo is a macro shot of a piece of oolitic Lincolnshire Limestone, so we are looking at a fairly small area of it.  The ooliths, which are each smaller than 1mm in diameter, are formed of layers of limestone – calcium carbonate – which have formed around a tiny piece of sand or shell.  I was lucky in that when I took the photo, the sun was shining – the lighting makes all the difference in photography!  I didn’t take it out on site – I laid the rock horizontally on a picnic table in our back garden when the sun was just at the right angle.  The height of the table also made it comfortable to take the photo.

To set the photo in its context: The Lincolnshire Limestone (but the piece in the photograph came from Ketton Quarry, in Rutland) was formed roughly 155 million years ago, in the Jurassic Period.  The area that is now south-east England (and a lot wider area, actually) was then a warm, sub-tropical sea.  It would have been rather like the seas around the Bahamas are now!  The seabed was subject to some quite strong currents, so the ooliths were being rolled around and coated in calcium carbonate.  Rutland may be England’s smallest county but, with an impressive record of changing climatic and depositional environments, it is certainly not the least interesting from a geological point of view.

Comments

Post a Comment

Popular posts from this blog

A rite of passage

-
Image
  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...
Read more

Rock-hard 'toffee'

-
Image
Portoro marble - looking more like a dessert than a rock The day I took this photo was a feast for the eyes and the soul; whilst a rehearsal for the following week's Trooping of the Colour was underway nearby, my Other Half and I were visiting the [then] Queen's Gallery  at Buckingham Palace, London. It was the first time we saw any of the Royal Collection. We saw a Fabergé egg for the first time, and it was as beautiful and as finely wrought as we had imagined it would be.  We saw the golden Exeter Salt, we saw sculptures carved from the finest marble, we saw paintings by Old Masters and we saw, for the very first time for either of us, sketches by Leonardo da Vinci with notes in his mirror writing! One thing I also drank in, though, was this polished slice of Portoro marble. Stonemasons often refer to any stone that will take a polish as a marble, but Portoro is a true marble, i.e. a limestone that has been altered (metamorphosed) by heat and pressure; it comes from La Spezi...
Read more

St. John's, Smith Square, London

-
Image
If there's a type of stone that characterises London, especially the Government estate and major historic buildings including Buckingham Palace and St Paul's, then that stone is Portland Stone. It's a limestone, dating back to the Jurassic Period; some facies (varieties) are very fossil-rich, with Grove Whitbed being rich in oysters, and Roach Stone being famous for it's 'Osses' heads' (Trigoniid bivalves) and Portland screws, a variety of gastropod mollusc.  Other facies are freestones, very suited to carving by stonemasons. There's a reason for the popularity of  Portland Stone in London, and for its use to rebuild St Paul's after the Great Fire of London in particular - Sir Christopher Wren owned shares in a certain quarry on the Isle of Portland!  His use of the stone set a trend, and now, in addition to the buildings I've already cited, think in terms of Regent Street, the Old Bailey, the Bank of England...  One of my favourite buildings is ...
Read more