Holocene sea-level variation and spit development: data from Skagen Odde, Denmark

Extensive exposures of peat located in inter-ridge swales, at the contact b etween beach and overlying coastal dune deposits at Skagen Odde, northern D enmark, provide a record of spit development in relation to glacioisostatic rebound and sea-level variation. The elevation of the base of the swale pe ats was measured over a distance of 15 km and represents spit growth betwee n 5600 and 1400 cal. years BP. The swale peats fall from 13-14 m a.s.l. in the south (proximal part) to 3-4 m a.s.l. in the north (distal part) reflec ting the influence of isostatic rebound during spit growth. The new data su ggest that isostatic rebound progressively declined with time from c. 3 mm yr(-1) to c. 1.5 mm yr(-1). Superimposed on the isostatic controlled change s are smaller-scale fluctuations in peat elevation related to eustatic sea- level changes. Sea-level highstands are identified at 5450 (+2.7 m), 4700 ( +1.7 m) and 2450 cal. years BP (+0.4 m), and lowstands at 5200 (+1.5 m), 41 00 (-1.9 m) and 1650 cal. years BP (-0.6 m). A final component that contrib utes to variations in pear elevation is local topography, and at a few plac es peat drapes across small aeolian dunes. The age model indicates that the spit-growth rate varied between 2 and more than 10 m y(-1). These variatio ns in growth rate may partly record sea-level controlled fluctuations in th e supply of sand from eroding cliffs on the west coast of northern Jutland.