Open AccessMorphology and sedimentary architecture of a beach‐ridge system ( A nholt, the K attegat sea): a record of punctuated coastal progradation and sea‐level change over the past ∼1000 years
Author(s) -
Clemmensen Lars B.,
Nielsen Lars,
Bendixen Mette,
Murray Andrew
Publication year - 2012
Publication title -
boreas
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 74
eISSN - 1502-3885
pISSN - 0300-9483
DOI - 10.1111/j.1502-3885.2012.00250.x
Subject(s) - geology , progradation , swale , sea level , beach ridge , foreland basin , sedimentary rock , oceanography , ridge , geomorphology , paleontology , surface runoff , holocene , sedimentary depositional environment , structural basin , ecology , stormwater , biology
F lakket on the island of A nholt in D enmark is a cuspate foreland facing the microtidal K attegat sea. It is composed of a number of beach ridges typically covered by dune sand and separated by swales and wetlands. OSL dating indicates that the evolution of F lakket began c. AD 1000. Foreland growth was punctuated by a major episode of coastal reorganization leading to coastal retreat c. AD 1800. Coastal retreat led to the formation of an erosion surface that separates older and higher‐lying beach‐ridge and swale deposits from younger and lower‐lying deposits. The palaeo‐sea level is deduced from the architecture of the deposits, and interpretation of ground‐penetrating radar data and geomophological observations indicates that relative sea level was about 1.90±0.25 m above present sea level c. AD 1000, but about 0.00±0.25 m relative to present sea level c. AD 1830 and c. AD 1870. A nholt is situated at the margin of the uplifted F ennoscandian area; assuming uplift to be about 1.2 mm a −1 it follows that absolute sea level was about +0.70±0.25 m at AD 1000, but around −0.22±0.25 m at AD 1830 and around −0.17±0.25 m at AD 1870. Within the uncertainties of the age control, the sea‐level indicators mapped by ground‐penetrating radar reflections and the variability of estimates of uplift found in the literature, the result obtained for AD 1000 is consistent with findings from the S tockholm area in S weden and with a recently published global sea‐level curve.