Salt-marsh evolution at Northwick and Aust warths, Severn Estuary, UK: a case of constrained autocyclicity.

  • Simon K. Haslett University of Wales
  • John R.L. Allen School of Archaeology, Geography and Environmental Sciences, University of Reading, Whiteknights, Reading RG6 6AB, UK
Keywords: Severn Estuary, tidal salt marshes, marsh terraces, marsh cliffs, autocyclicity, weather types, wind-wave climate

Abstract

Historic maps, remote imagery and field surveys reveal that a terraced sequence of four salt marshes has arisen on a decadal-centennial time-scale over a frontage of about 4 km at Northwick and Aust warths exposed to westerly to northerly winds on the east bank of the Severn Estuary, UK. Except for the youngest marsh, at present very immature, each marsh built up through differential sedimentation from a mudflat until the outer zone reached a critical steepness; at that point wave-attack caused erosion that led to the rapid landward retreat of a bold, laterally extensive, marsh-edge cliff. This observed behaviour is consistent with previous models of autocyclic marshes, but evidence suggests that the extrinsic factor of medium-scale changes in wind-wave climate constrained the particular timing of marsh responses.

Author Biography

Simon K. Haslett, University of Wales
Professor of Physical Geography and Associate Pro Vice-Chancellor at the University of Wales.
Published
2014-03-05
How to Cite
Haslett, S. K., & Allen, J. R. (2014). Salt-marsh evolution at Northwick and Aust warths, Severn Estuary, UK: a case of constrained autocyclicity. Atlantic Geology, 50, 1 - 17. https://doi.org/10.4138/atlgeol.2014.001
Section
Articles