Chapter 4

To Iceland

“I then tried to use the existing geochemistry, petrology and isotope geochemistry to throw some light on what went on in the mantle,” remembers McKenzie. “And I got completely frustrated. The isotope geochemists absolutely won’t work with each other; they won’t share samples. I got totally frustrated with this sort of dog-in-the-manger attitude with which I was entirely unfamiliar. It was at the absolute opposite extreme from the seismologists.”

To find out more about the mantle, McKenzie needed well-located samples from a spreading ridge, away from continental influences; he started work in Iceland. “I thought right, I am going to work on a spreading ridge, if I can, and I’m going to collect the samples and I’m going to map it properly, and then I’m going to ask individuals who do particular isotopic systems whether they are interested in working on these samples …I took on a postgraduate student called Lucy Slater, from Durham. I annoyed the Cambridge people by saying we didn’t really teach proper field mapping compared with Durham; that put me in disgrace for a bit. … She stayed there the whole summer and collected three hundred samples. … The only snag about Iceland then was everything was so expensive. A pint of beer cost you £10. I had to remind myself all the time that this was really cheap compared with working at sea, where the ship costs were about $25,000 a day.”

What caused you to then study the mantle and develop the notion of it being “mixed but not stirred” ?