George Patrick Leonard Walker, an outstanding and multi-faceted geologist and one of the most influential volcanologists in the world, died on 17 January 2005, at the age of 78. He was born in London on 2 March 1926 and grew up mainly in Northern Ireland. He read geology for B.Sc. honors and M.Sc. degrees at Queens University in Belfast, Northern Ireland, and completed his training with a Ph.D. in mineralogy from Leeds University in England, which he received in 1956. By then, he had already been appointed, in 1954, to a lectureship at Imperial College London.