The tephrochronology of Iceland and the North Atlantic region is reviewed in order to construct a unified framework for the last 400 kyr BP. Nearly all of the tephra layers described are also characterised geochemically. A number of new tephra layers are analysed for the first time for their geochemical signature and a number of pre-Holocene tephra layers have been given an informal denotation. The tephrostratigraphy of Ash Zone II is highlighted. Where possible the rhyolitic tephra layers found outside Iceland have been correlated to known Icelandic tephra layers or to the volcanic source area. The application of tephra fallout in various depositional environments is described and discussed. Copyright © 2000 John Wiley & Sons, Ltd.