I am sad to hear about John. However we can celebrate a wonderful and creative life in science and education. I was a first year student at Imperial College in 1969 when I attended a lecture by John which was without doubt the most influential and inspiring of my career. I had enjoyed maths at school and John gave a lecture essentially on the subject that maths helps you understand rocks. As usual he drew beathtaking 3-d images of folds and strain ellipses with chalk on the black board. It was something to do with strain involving matrices and calculus, but amply illustrated with rocks. It was an epiphany for me and from then on I realised that maths was important in geology and the message stayed with me ever after.  I recollect an incredibly exciting field trip to Scotland led by John in my third year. I never did any research with John but corresponded with him a few times after he retired concerning folds on lava surfaces and columnar joints. I still have his classic book on my shelf.