Ann Wintle: why is loess interesting?

Ann Wintle explains how deposits of loess (deposits of silt or fine-grained material that have been transported and deposited by the wind) record features of past climates.

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Can you give us a sense of why the geologists involved here were interested in doing anything at all with these deposits? What was the reason?

Well, they saw them as the equivalent of the deep sea records. At that time Nick Shackleton and his colleagues round the world were constructing climate records based on what was going on in the oceans. They were looking at the oxygen isotopes of these foraminifera and they’re recording the temperatures and ice volume records through the ocean water and the isotopes going into the shells. But, you know, man is living on the land, so we actually would like to know rather more directly, and here we have these deposits where you can see the climate change rather more directly. Was there no deposit there because at that time it was under ice? How did the climate change? In the sense that you could look at – different grain sizes would tell you how close you were to the ice front. So you could get all sorts of subtle changes in the loess in terms of grain size, depending on wind strength and the – of source – availability of source material, like a retreating ice sheet will be churning out lots of glacial flour, which can then be picked up and blown. So you’re able to construct what the environment was like. And also within it, when there were the warmer interglacial periods like we’re in now, then you have soils forming in them and you want to know when those soils formed, how long did they last, how long is our present interglacial going to be? It’s been around for about 10,000 years, you know, how rapidly will it end? How rapidly did the last interglacial end? And so when you’re going into a cold period, what happens? So all of those things are recorded there on the land and you can go and look at it. It’s inexpensive. It’s not like you have to get a deep sea drilling ship to go and drill. Anybody can just walk up to the deposit, look at it and say, ‘Ooh, I can see that it isn’t completely uniform. I wonder why it’s not. What was going on?’

  • Interviewee Ann Wintle
  • Duration 00:02:30
  • Copyright British Library Board
  • Interviewer Paul Merchant
  • Date of interview 9/23/2011
  • Shelfmark C1379/57

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