Relative sea level, sediment supply and barrier dynamics as driving mechanisms of Holocene coastal change.

The combined effects of climate change and population pressure lead to regional and local coastal responses that pose major challenges for the future resilience of coastal landscapes, increasing the vulnerability of communities, infrastructure and nature conservation interests. Improving understanding of coastline evolution in the past, using the Holocene record of geomorphological change preserved within coastal stratigraphy, is one way to improving understanding of coastal evolution and coastal response to climate and geomorphic change. This thesis aims to improve understanding of long-term coastal system behaviour by investigating the role of relative sea level, sediment supply and barrier dynamics as driving mechanisms of Holocene coastal change. The Suffolk coast, an understudied and vulnerable section of coastline in southeast England, is used as a case study to improve understanding of the mechanisms driving Holocene coastal change. Stratigraphic investigation demonstrated significant spatial and temporal differences in sedimentation. A multiproxy approach, comprising lithostratigraphic, sedimentological, bio- and chronostratigraphic methods, identified and constrained the timing of major phases of coastal change. New sea-level index points (11 intercalated peat and 6 basal peat samples) constrain the position of relative sea level during the Holocene and support the gradual rise reconstructed by the existing data for southeast England. Changes in sea-level tendency during the mid-Holocene are consistent on the Suffolk coast and wider East Anglia region, with predominantly positive (increase in marine influence) changes recorded, indicating that coastal sedimentation was controlled predominantly by relative sea level. In contrast, changes in sea-level tendency during the late Holocene varied substantially, indicating that local factors, notably sediment supply and barrier dynamics, were the main influences on coastal sedimentation, with relative sea level acting only as a background control. The importance of sedimentological and morphological factors in shaping Holocene coastal changes requires consideration when using the southern North Sea basin database of evidence as an analogue for future change under accelerated sea-level rise