17 August 2011

Looking for ashes

If my never sufficiently praised boss can’t find something, can I? (Roland reads this, I know, and one can discuss if it’s wise to boost his ego, but let’s have it.) This week will provide the answer to this question! Over the past two years we have made a splendid state-of-the-art sea level reconstruction for west Iceland, but the age model still can be improved on. And we know that in 1721 the Katla erupted, and that the ashes fell on our marsh. Unfortunately it was very, very high tide just then, and we don’t know how much of that ash has been washed away. If we can find it, and recognise it by its chemical composition, we have a marvellously dated level in our sediments. Roland has looked for it some years ago, but only found ash from who knows how many other eruptions. This is Iceland, after all, and there are all sorts of ash kicking around all the time. But we haven’t given up, and now I’m Scotland, on a mission to find this elusive ash after all.

Going to St Andrews you travel through Edinburgh. Looks like I should have another look on the way back!

 Crossing the Firth of Forth

As Plymouth doesn’t have the necessary lab facilities I get onto the train an early Monday afternoon, and after two rail journeys, a flight, and three bus journeys (not in that order), I arrived in St Andrews. It was a nice welcome by a lovely view from the train over beautiful Scottish landscapes in the low evening sun, and nice locals who told me which bus stop would give me the best starting position for finding a meal.

The first day I would mount my samples. I had brought 15 seemingly empty pots with ash shards in them. I showed the first to Donald, the lab technician who would show me the ropes. He looked in horror, and said “we can’t process that!” He had assumed, without checking, I would bring large chunks of material. And I had assumed, without checking, that if they wouldn’t give me size requirements then Plymouth standard procedure would be fine. But no...

The university of St Andrews is the oldest in Scotland, and it shows! This is the classy geography building.

We decided to give it a try anyway. Donald thought of a way to reduce the unevenness of the surface we would be mounting the shards on. And I spent the rest of the day mounting every shard I had brought. And I even made two improvised bulk samples. You can pick out the shards beforehand, but you can also just mount anything, and only while microprobing pick out what looks like volcanic ash, and analyse that.

The microscope lab had a view over sea!

Mounting in progress.

The samples have been cast in resin and are dry now. Today we have to polish them; that’s the part that will prove the challenge. And when I say "we" I mean "I"; Donald is afraid to ruin my samples, so I'll have to do it myself. If that works not only can we analyse away, and hope fervently we find what we’re looking for, but also have we proven that this lab can actually do it, which is a first timer! I’ll do my bloody best... and stay tuned!

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