Links between magnetic measurement and the record of climatic change in Pleistocene and Late Tertiary sediments are examined. The possible reason for variations in mineral magnetism in lake sediments and deep sea cores are discussed. The supply of magnetic minerals to most sediments is dominated by continental sources, and the processes of weathering and erosion which influence the supply are obviously under direct climatic control. Apparent geomagnetic-palaeoclimatic linkages may therefore be generated by climatically modulated changes in the supply of magnetic mineral assemblages.