OR/18/016 Further work and applications

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Palamakumbura, R. 2018. A new palaeogeographic model for the post-glacial marine and estuarine sediments of the Firth of the Forth, Scotland. Nottingham, UK, British geological Survey. (OR/18/016).

The new data from borehole records provides a constraint on the nature of the superficial sediment infilling the Firth of the Forth. Previous work in the area focused on scattered outcrop and boreholes across the Firth of the Forth. In contrast, this new work provides the first overview of the entire system, particularly the deepest superficial sediments. However, the geotechnical dataset used for this work is relatively low resolution and provides little detail on the sedimentology and thus hampers interpretations as to depositional environments. To develop the interpretations of the post-glacial marine and intertidal infill depositional environments further, more detailed core descriptions in terms of sedimentary structures would be needed, particularly from the deepest sediments, such as at Grangemouth.

A major aspect of this work is the understanding of wider controls such as eustatic sea-level change, isostatic rebound and climate variability of the post-glacial sediments. More detailed dating work would be needed to understand the allocyclic controls of the post-glacial environment of the Firth of the Forth. Dating of the various depositional environments, such as the Late Devensian raised marine deposits and the first sub-tidal estuarine infilling would provide dates for key markers in the sedimentary record of major environmental change. This information can be used to compare and contrast to other systems across Scotland to understand how they are responding to LGM deglaciation and associated sea level changes, such the Tay and Clyde estuaries. This could contribute to understanding regional variations in deglaciation.

The complex nature of the sediments across the Firth of the Forth and other glaciated estuarine systems in both Scotland and globally needs to be distinguished from non-glaciated estuaries. For example, the Quaternary provinces and domains model, which qualifies and quantifies the UK landscape into domains based on surface processes and geology defines 10 distinct domains (Booth, Merritt, & Rose, 2015[1]). This work is aimed at being used for academic and applied sciences, including hydrology, mineral resources, industry risk assessment and water resources. However, the study groups all the estuarine systems in the UK as part of the ‘coastal, estuarine and fluvial domain’ and does not distinguish between glaciated and non-glaciated estuaries. This work shows that there is a significant difference between a glaciated and non-glaciated estuarine systems, in terms of sediment type and thickness. This is a significant distinction when using the Quaternary domains to understand glaciated estuarine system for hydrology or water resources. We suggest that glaciated estuaries should represent its own domain in this scheme.

References

  1. BOOTH, S, MERRITT, J, and ROSE, J. 2015. Quaternary Provinces and Domains–a quantitative and qualitative description of British landscape types. Proceedings of the Geologists' Association, Vol. 126, 163–187.