Richard Alley, the Evan Pugh professor of geosciences, was awarded the Seligman Crystal presented by the International Glaciological Society. He received this award for his prodigious contribution to our understanding of the stability of the ice sheets and glaciers of Antarctica and Greenland, and of erosion and sedimentation by this moving ice. Through the interpretation of paleoclimatic records from ice cores, Alley has examined their response to past and future climate change. He has provided evidence that large, abrupt global climate changes have occurred repeatedly in the Earth's history and has contributed to our understanding of the driving mechanisms of these changes. The Seligman Crystal is awarded from time to time to one who has made an outstanding scientific contribution to glaciology so that the subject is now enriched. In the 43 years since the award was first presented in 1963, only 28 people have received the award.