Microfaunas, microfloras and the environmental stratigraphy of the Late Glacial and Holocene in Cardigan Bay

Abstract

The distribution of foraminifers, ostracods, diatoms and pollen is studied in cores from submarine boreholes. This reveals that the history of the Flandrian transgression is largely the record of the infilling of meltwater channels cut during the early Late Glacial with transgressive estuarine and finally marine deposits. It also supports the idea of the 'climatic earliness' of the Welsh seaboard at all stages. Estuarine deposits in excess of -51 m O.D. suggest that Late Glacial sea levels were initially as low as -60 m O.D. and support the idea that the Welsh ice withdrew before 14,000 years B.P. The sea-level rise plots as a smooth curve but was probably episodic in its early phases.

The ‘lost’ islands of Cardigan Bay, Wales, UK: insights into the post-glacial evolution of some Celtic coasts of northwest Europe

“…The infill of the submarine channel marked by the Trawling Grounds depression is characterised by the Mud Facies of the Western Irish Sea Formation of Tappin et al (1994), which spans the end of the Pleistocene extending into the Holocene. Garrard (1977) and Haynes et al (1977) report a radiocarbon date (Birm. 400) from a peat sample collected in the Trawling Grounds northeast of Newquay.…”

“…The sample came from c. 2.5 m downcore in a water depth of c. 16 m near the base of the Mud Facies, approximately 0.5 m above the junction with underlying glacial till. The sample yielded a date of 8740 ± 110 BP (9539-10, 154 cal BP; calibrated using OxCal with IntCal20 (Reimer et al 2020) at 95.4% probability) and a palaeoenvironmental study of the core indicates that the Trawling Grounds channel was under estuarine conditions at this time due to postglacial sea-level rise (Haynes et al 1977). Garrard (1977) interprets the Trawling Grounds channel as being initially formed by early post-glacial rivers in the southern part of Cardigan Bay being diverted to the south as the route to the west was blocked by retreating Irish Sea ice.…”