The change from a warm, ice-free greenhouse world to the glacial Antarctic icehouse occurred during the latest Eocene-earliest Oligocene. Prior to this, during the Early-Middle Eocene, Antarctica experienced warm climates, at least on the margins of the continent where geological evidence is present. Climates appear to have been warm and wet, the seas were warm and plants flourished in a frost-free environment, although there is some suggestion of valley glaciers on King George Island. Climate signals in the geological record show that the climate then cooled but not enough to allow the existence of significant ice until the latest Eocene.Glacial.