George Williams has made outstanding contributions across a wide range of fields in the earth and planetary sciences through innovative research in sedimentology, palaeoclimatology, palaeomagnetism, meteoritics, and Earth–Moon dynamics, all grounded in critical and extensive observations principally in Australia and also in North America and Britain. His discoveries and pioneering studies of global relevance have illuminated Precambrian glacial environments, the geological and environmental effects of asteroid impact on the Earth, the history of the Earth’s rotation and lunar orbit, and early Palaeozoic Milankovitch orbital cycles. His findings have instigated many new lines of research in geology and geophysics.