Thursday, September 1, 2011

What I found out this week: If you ask a certain kind of question when you work in a museum you can find yourself on an interesting journey.

Liz, our Keeper of Archaeology, has been preparing a blog post on mammoths in Bedfordshire coming next week!), and while chatting about it, it raised the question in my mind about the way the climate in Bedford has changed over the centuries and millennia, and the things that have caused this. In the museum's galleries (now all packed away for the redevelopment) were geological specimens from Bedfordshire’s pre-historical past and information about the various different eras in the Earth's history. Words like Jurassic and Pre-Cambrian were clearly explained and illustrated. But with the text panels in store and the objects packed carefully in boxes where do I start?

All our collections are carefully packed away in many, many boxes.

Books, books, books...
When I first posed my question I presumed that we may have objects that might help answer it – stones that revealed that Bedford had been under the sea, or a tropical forest, or whatever the truth turns out to be. But I also needed context and I was first handed a book that could provide that. Museums are stores for all kinds of things and we have books that are some of the first written on geology and archaeology, which in themselves could offer a fascinating insight into how our understanding has changed over the past 150 years or so. Thankfully, this book, ‘Digging up the Ice Age’ was published in 2009 by the University of Birmingham and gave me an very readable and up-to-date introduction to the subject. Technology and industry have made the last 30 years a period of great advancement in what we know about the earth and that that advancement continues at pace: scientific understanding is based on what we know today and can often be changed by what we find out tomorrow. One fascinating aspect of this advancement was that it wasn't only technology that was the cause but it had also come from the way geologists and companies who extract gravel have learnt to work together.

There is so much to absorb about the different causes of climate change: from continental drift, with England crashing into Scotland millennia ago while moving from somewhere low in the Southern Hemisphere on its way past the equator up to its present position relatively high up in the Northern Hemisphere; the variations in the earths orbit around the sun, or the tilt of its axis; the balance of life and death producing different gases into the atmosphere; and ‘positive acceleration’ where a frozen landscape, being white and icy reflects the sun’s rays and makes it colder still (or vice versa). Distilling all this into a simple answer can make your head spin. We think of the Ice age as one period of time but in fact the have been many ice ages "The" ice age is really just the last one (on which there'll be more next week).

A Bedfordian standing on Bedford soil.
So the ground beneath a Bedfordian's feet has covered most latitudes between the south pole and its present spot and survived numerous ice ages and warmer periods. But what was happening above this moving landscape? A clearer picture of the local environment's changes over the millenia came from the Bedfordshire Geology Group who will be helping us with our new displays. They have a very helpful map here that shows the different layers of rock across the length of the county. During the Jurassic period (150-200 million years ago) tropical seas covered Bedfordshire and were variously shallow and warm or deep and cold containing the smallest of life forms to huge reptiles. The clay that formed at the bed of that sea is at the surface in north Bedfordshire but deep beneath the chalk escarpments and other layers of rock by the time you get to Dunstable, which in itself revels something else - the erosion of the landscape due to glaciation and the melting of the glaciers.

And then Liz says “Have you looked at pollen?” and a whole other possible direction of how the climate of our town has changed has opened up before I have even got to any objects! It's certainly going to be fascinating to see how the experts put all this together and pull out the story of Bedford's Geological past for our new displays.

Kristian Purcell,
Curatorial Assistant

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