The Portsdown Anticline is a north-facing geological fold of Tertiary age affecting rocks in Hampshire, southern England.Toghill, P. 2000 The Geology of Britain: an introduction Crowood Press, Marlborough Wilts p166 This upfold of the local sedimentary rock sequence is paralleled by the Bere Forest/Chichester Syncline (downfold) about 2km to its north and a postulated deep fault to the north again. Further west, this major east-west structure adopts more of a NW - SE alignment.Melville, R.V. and Freshney, E.C. 1982 British Regional Geology: The Hampshire Basin and adjoining areas IGS/NERC, London p116 & 121 At the surface the Portsdown Anticline is seen to affect the Chalk rocks of Late Cretaceous age at Ports Down though it is known to also affect the underlying Jurassic strata.British Geological Survey 1998 Fareham England and Wales sheet 316 Solid and drift geology. 1:50,000 (Keyworth, Nottingham: BGS)
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