Chapter 7 Western outliers of Dorset and Devon

B. Daley

Introduction

To the west of the main outcrop of Palaeogene strata in the Hampshire Basin, there are a number of localities that represent a variety of continental facies which, with the possible exception of the Creechbarrow Limestone, lay beyond the influence of the Palaeogene sea to the east. Six have GCR status as a result of their stratigraphical importance (see (Figure 7.1) for their location).

In Dorset, the outliers of gravel at Blackdown and Bincombe Down are thought to reflect alluvial fan developments associated with contemporaneous fault movement, whilst at Creechbarrow, the succession includes a unique remnant of a non-marine limestone of early late-Eocene age. In Devon, Tower Wood Quarry and Buller's Hill Quarry comprise gravels that predominantly originated as the weathering residue of the Chalk and its reworking by fluvial processes in early Palaeogene times. The Aller Sand Pit further west represents a braided stream deposit associated with the development of the economically important Bovey Tracey Basin.

The latter, together with the Petrockstowe Basin further north, reflect downwarping associated with movement on the Sticklepath–Lustleigh fault. Both contain thick sequences of Palaeogene strata of which a large proportion comprises kaolin-rich ball-clay'. The latter may be examined together with associated sediments in numerous working pits in both the Bovey Tracey and Petrockstowe basins, and to the east in Dorset.

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