28 October 2010

Accretionary Wedge #28

Accretionary Wedge #28 at Research at a snails pace is a about desk crops and since it is October there is supposed to be a scary theme.

The four bivalves in this picture were collected on a beach in the Gulf Coast of Florida in 2005. I am a sedimentologist but had taken time out from the Mesozoic to study some modern systems, particularly modern beach ridges for a project that was coincidently just published in last months Journal of the Geological Society of London.

I have always believed that sedimentology is easy because if you are struggling to understand the rocks, then all you have to do is go and look at the modern and the answer is there for you. So when the seismic data from the North Sea was ambiguous it seemed obvious that we should take a trip to Florida. There are definitely worse ways to spend your field grant than travelling around the beaches of the SE USA.

So I collected these bivales, not for any scientific reason but simply because they looked nice. They now live on a shelf in my bathroom (does that count as a desk crop?). I am not a palaeontologist and famously "don't do dead things" but I think these are "marsh clams". If somebody wants to correct me and tell me the proper species name, I would be very happy to hear.

So what is scary about the picture? At first glance it seems to be 4 bivalves arranged in order of size. But if you look more closely you will see that in addition to getting larger towards the right, they also get more haggered. The small left hand one is pure white and pristine. A perfect body that radiates a combination of innocence and optimism - the world is his oyster (or marsh clam). Moving toward the right the amount of discolouration increases as does the amount of worm borings, until the one on the right looks like it has definitly had a hard life! He is big and tough, stained and scared by his environment, like a middle aged boxer. It is an insight into what the others have to look forward to.

But then we must remember that they are all in fact dead. The left hand one will never get to grow old. It's youthful beauty preserved by an early death.

The more you think about it, the more disturbing it all becomes.

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