Onshore Miocene rocks in the UK are extremely rare. The Brassington Formation of Derbyshire is the most extensive deposit of Neogene sediments within the onshore UK. The Brassington Formation is a relatively thick sequence of sands and clays preserved in around 60 karstic hollows. Originally studied in the 1970's a palynoflora was recovered from the lignite and clay beds of the Kenslow Member - the uppermost member of the Brassington Formation (Boulter, 1971). Based on the state of the art at the time, the formation was assigned to the Late Miocene or Early Pliocene. The erosional surface that these sediments rest upon has been used to date the uplift of the Pennines mountain chain of central England. The uncertainties in the dating of the palynoflora has led to uncertainties in the rate of uplift. To better resolve the age of the palynoflora and the evolution of the Pennine landscape, a new study of the Brassington Formation has been undertaken.

A new field campaign at Kenslow Top Pit, Derbyshire has produced a new palynoflora from the coloured clays of the Kenslow Member. This new palynoflora contains many taxa recorded in the original work but also some previously not reported. The palynoflora represents two ecosystems. A dominant warm - temperate mixed forest, and a more herbaceous upland flora. By comparison of the new palynoflora, and the original palynoflora, with floras from continental Europe, the age of the Kenslow Member can confidently be placed in the Tortonian Stage (11.61 - 7.25 Ma) of the Miocene. This means that the uplift rate of the Pennines has been more modest than previously reported.

Boulter, M.C. 1971. A palynological study of two of the Neogene plant beds in Derbyshire. Bulletin of the British Museum (Natural History) Geology, 19, 359-410.