Dr Summons is one of the leading organic geochemists in the world. He applied innovative instrumental techniques to biological marker identification and explained the significance of the biomarker data in terms of their relevance to biological evolution, the behaviour of microbial ecosystems and the co-evolution of the biogeochemical cycles and the surface environment of the Earth. He was able to demonstrate that a reliable and interpretable record of Proterozoic molecular fossils could be deciphered. His work has revealed substantial new clues about the proterozoic oceanic environment and he has made numerous significant contributions to fundamental work on changes in the distribution of chemical fossils with time.