added by archaeologs A period occurring following a glacial episode, especially that from the end of the Pleistocene Ice Age c 8300 BC to the present. The substages in northern Europe are: Pre-Boreal (c 8300-7700 BC), Boreal (7700-5550 BC), Atlantic (5550-3800 BC), Sub-Boreal (3800-1200 BC), and Sub-Atlantic (1200 BC to present).