A survey was made of all existing radiocarbon dates relating to the Corylus rise in Europe in order to find the possible areas of refugia of Corylus during the Weichselian glaciation. Using the radiocarbon dates an isochron map was drawn which indicated areas of refugia off the west coast of the British Isles, south-west Scandinavia and in south-western Europe. The possible routes of migration of Corylus are indicated on this. On the basis of the radiocarbon dates the rates of migration of Corylus along the possible routes have been calculated and show that migration from northern refugia was faster than that from southern refugia.
The climatic and edaphic conditions in the suggested refugia during the Weichselian glaciation and their importance in relation to the survival of Corylus are discussed. The number of radiocarbon dates is inadequate for definite conclusions to be drawn on the location of refugia and so the need for an extensive programme of radiocarbon dating of important pollen strati-graphic events in Europe is stressed.