A division of Holocene chronology which began about 10,000 years ago and ended about 9,500 years ago. The Pre-Boreal Climatic Interval preceded the Boreal Climatic Interval and was a time of increasing climatic moderation. Birch-pine forests and tundra were dominant. It is a subdivision of the Flandrian Interglacial and represents the start of the Flandrian.