The rise of varves

• Varves are exceptional in many aspects: they are rare, can be used to constrain and build chronologies, and contain highresolution records of past environment and climate. Moreover, their occurrence and reproducibility in different settings allows for an internal validation of their continuity and integrity. Gerard De Geer of Sweden understood the value of varved sediments over a century ago. Although other geologists during his time had described rhythmic, glacial lake sediments that they interpreted as annual layers (e.g. Smith 1832; Hitchcock 1841; Upham 1884), it was De Geer who saw the potential of varves (from the Swedish word varv, meaning cycle), for dating the retreat of the Scandinavian ice sheet, and by extension, the late Quaternary. And it was De Geer and his students who built the socalled Swedish Time Scale, which extends from the present to over 13,000 years before present. Much of De Geer’s early work was in fact published in GFF (e.g. De Geer 1908, 1921, 1935). However, De Geer’s considerations of teleconnections (today, a hot topic in climate research), along with strong reservations from North American geologists about the implications of the varve chronology in the Connecticut River valley by Ernst Antevs (one of De Geer’s ler-jungar; Antevs 1922, 1928), led many to doubt the annual nature of varves. Ages for the New England varves, based on the, at that time, new 14C technique, as well as varves’ similarities to the turbidites that Philip Kuenen was describing, convinced many that varves were not annual (for details, see Ridge and Larsen 1990; Ridge et al. 2012). Today, the varves that De Geer (as well as Antevs) looke

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Geologi (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geology (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Klimatforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Climate Research (hsv//eng)

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varves

GFF

recent varves

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