Jowsey, N.L., Parkin, D.L., Slipper, Ian J., Smith, A.P.C. and Walsh, P.T. (1992) The geology and geomorphology of the Beacon Cottage Farm Outlier, St Agnes, Cornwall. Geological Magazine, 129 (1). pp. 101-121. ISSN 0016-7568 (Print), 1469-5081 (Online) (doi:https://doi.org/10.1017/S0016756800008153)

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Abstract

The mid-Oligocene sediments forming the Beacon Cottage Farm Outlier at St Agnes, Cornwall, have a stratigraphical and geomorphological importance which is out of all proportion to their modest residual bulk (some 300000 m3). During 1986-8 61 holes were sunk into the area surrounding Beacon Cottage Farm; many penetrated the Palaeozoic floor beneath the outlier. Collectively, these show that the outlier mostly covers rotten granite and Killas. The sub-Oligocene unconformity is uneven and varies in altitude by at least 20 m. The local Bovey Formation succession comprises two members: Basal Sand, which is often pebbly, and sandy silts, known commercially as Candle Clay, the whole totalling a maximum of 8.9 m. There is indirect evidence either that slopes on the rotted Palaeozoic floor locally exceed 45° or that several post-mid-Oligocene faults affect the outlier. We conclude that the Beacon Cottage Farm sediments probably represent aeolian, colluvially and fluvially redistributed rotten rock residues, formed locally during a break in the long period of late-Palaeogene subtropical weathering and pediplanation. The outlier is considered in relation to the geomorphological evolution of the Cornubian Massif.

Item Type:	Article
Uncontrolled Keywords:	Oligocene, Geomorphology, Stratigraphy
Pre-2014 Departments:	School of Science
Last Modified:	15 Oct 2016 11:47
URI:	http://gala.gre.ac.uk/id/eprint/12577

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