Jessica McCoy, Tabitha Barrass-Barker, Emma Hocking, Jennifer O’Keefe, James Riding, Matthew Pound 

The Middle Miocene was a warmer and wetter interval than present-day (Steinthorsdottir et al., 2021). In the UK, the most extensive Middle Miocene deposit is the Serravallian Kenslow Member of the Brassington Formation as exposed at Bees Nest Pit, near Brassington, Derbyshire, UK. While known to contain a diverse palynological and palaeobotanical record, the stratigraphical distribution of these fossils has not been studied in detail, thus biome variations through a most important proxy period are very poorly understood. This important unit has never been the subject of a detailed, multi-sample study. Here we present a 58-sample record covering 133 cm of clay and lignite. The results comprise the first reconstruction of a bog succession in the Miocene palaeobotanical record of the UK. A predominant warm-temperate and mixed mesophytic forest biome was present. Within this forest, the local wetland developed in response to environmental changes that were not related to any major climatic shift. This wetland development produced a relatively open shrub and reed-dominated mire which produced the lignite-precursor peat. The limited extent of the lignite lentil and its position adjacent to a preserved fallen tree suggests that the peat was deposited in a tree throw, although it is not possible to rule out a slightly deeper stagnant pond within the overall wetland environment.