BLYTT-SERNANDER SYSTEM

chronology of bog peat deposits in Scandinavia worked out by the 19th-century Swedish geologist Axel Blytt and later modified by the 20th-century Swedish botanist Johan Rutger Sernander; the Blytt-Sernander system divides the Holocene Epoch, roughly the last 10,000 years of Earth history, into smaller units. These units are based upon the sequence of plant fossils, such as remains of twigs and leaves, found preserved in bogs. The fossil sequence represents the climatic changes that have occurred since the prominent continental glaciers retreated about 10,000 years ago. Later studies have modified the Blytt-Sernander system and incorporated the results of studies on fossil pollen. To a large extent, the Blytt-Sernander system has been confirmed by these later studies as valid. Although first worked out for northern Europe, the Blytt-Sernander system has been applied to sequences throughout the world with modifications.