Talk by Professor Ed D. Waddington – Niels Bohr Institute - University of Copenhagen

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Talk by Professor Ed D. Waddington

Perils in science when ideas go bad -
The life, death, and after-life of glacier extrusion flow

Abstract: Brick masons understand ‘extrusion flow’  - the weight of a heavy brick squeezes out, or 'extrudes' the wet mortar below. Does this process operate in glaciers?  By 1914, ice was known to flow like a viscous fluid, and to slide when its bed was at the melting temperature, but between the world wars, geologists studying ice sheets did not communicate well with physicists studying fundamental flow processes. Max Demorest brought concepts from fluid mechanics into glacial geology to develop the extrusion-flow idea, which 'explained' how ice could flow out of central Greenland. Meanwhile, Rudolf Streiff-Becker found an apparent imbalance between snow accumulation on Claridenfirn, Switzerland, and ice discharged by flow. He proposed that a strong undercurrent (extrusion flow) evacuated the excess mass. Although both studies were flawed, confluence of two lines of evidence gave stature to the extrusion-flow concept.  In 1952, John Nye showed that free extrusion flow was impossible. Although glaciologists were then reluctant to use the term 'extrusion flow' for many years, two forms of extrusion flow survive, capped extrusion flow and rotational flow. 

The lesson? Even respected scientists can go astray when they believe what they think.