Holocene Relative Sea-Level Changes along the Northwest Cumbrian Coastline

Holocene relative sea-level (RSL) changes from four sites along the Cumbrian coastline have been reconstructed. A multiproxy approach including lithostratigraphical, biostratigraphical combined with radiocarbon dating, enabled the production of ten sea-level index points (SLIPs). The SLIPs constrained Holocene RSL changes in the region between 8324 cal BP and 6018 cal BP. All four sites appear to have recorded the Main Postglacial Transgression, with Allonby, Cowgate Farm and Pelutho potentially also recording the earlier glacial Lake Agassiz-Ojibway flood event. All SLIPs were corrected for post-depositional lowering using a geotechnical model. The ten SLIPs produced in this study have refined the trend of Holocene RSL changes for the coastal region situated between the southern Solway Firth and central Cumbria, a region where only four SLIPs were available prior to this study. Changes in the palaeo-tidal range in the Solway Firth were also modelled for the last 10000 year and corrections were applied to the SLIPs produced in this study, as well as for the 88 existing SLIPs from the Solway Firth allowing a comparison of these data to glacio-isostatic adjustment model predictions. Examination of the data from the northern and southern shores of the Solway Firth indicated that differential isostatic uplift had occurred in this region.
Pollen analysis was undertaken at Cowgate Farm and Herd Hill, to provide a record on vegetation and coastal changes and act as a chronostratigraphic marker when compared to the published pollen records of the region. In addition, a local, foraminifera-based transfer function was developed from three contemporary saltmarshes located on the southern Solway Firth to aid in the reconstruction of sea-level changes. However, the lack of preservation of calcareous foraminiferal species at the four study sites led to a bias in the species assemblage of the fossil data and therefore, the transfer function was deemed unreliable.