Groups and Networks

In England, Palaeogene rocks are preserved in two E–W trending tectonic basins, the London Basin and the Hampshire Basin, and in small outliers further west as far as Devon. These two basins probably developed during the Miocene, replacing what had previously been a single depositonal basin, which extended well beyond the present-day limits. Tertiary, and particularly Palaeogene, strata were formerly more extensive. The ‘clay-with-flints’ that blankets much of the Upper Cretaceous Chalk in SE and Eastern England, comprises the altered remains of a former cover of Tertiary sediments, as do are the ‘sarsens’ (predominantly comprising siliceous sandstones, but also silicified conglomerates, probably remnants of silcrete duricrusts), which occur widely on the higher parts of the Chalk downlands of southern England. For a long period, Shortly after the end of Cretaceous times (65 Ma), much of the British landmass was uplifted (roughly coincident with establishment of the British Tertiary Igneous Province) and was being actively eroded. As a result, the ~7 million years of the early-mid Palaeogene is unrepresented by onshore sediments in southern Britain, but in the Late latest Palaeocene there began a long period of sedimentation in south-eastern England that lasted at least until the beginning of Oligocene times. This was accompanied by continued erosion of the area to the north and west, as indicated by the presence of pebbles derived from pre-Cretaceous strata in sediments of latest palaeocene age.

With the exception of a few outliers of early Palaeogene sediments that provide information about the contemporaneous palaeogeography of the south-western areas, there is little tangible onshore evidence to help with determination of the Palaeogene palaeogeography of British area, away from SE England. In the western part of this Palaeogene ‘Proto-Britain’, sediments were accumulating in localized tectonically controlled basins such as that recognized in the Mochras borehole in North Wales, where some 525 m of sediment were deposited in the late Oligocene and perhaps early Miocene. It is clear, however, from pebble composition in the Paleocene strata of southern England that that For Palaeocene strata, the provenance of pebbles from central southern England suggests that, in places, erosion had breached the Chalk cover to erode older Mesozoic strata.

The Neogene is most widespread in East Anglia, mostly below a Pleistocene cover, whilst elsewhere, a few outliers are present in the North Downs, and of Brassington in Derbyshire. The few onshore remnants of Neogene strata elsewhere are difficult to date and provide but fleeting glimpses of palaeoenvironmental conditions in Britain. The Miocene– Pliocene Lenham Beds, preserved only in solution pipes in Kent), are a good example. In the absence of age-diagnostic faunas, they can be dated only as Miocene to Pliocene in age.  Whilst their molluscan faunas suggest that they were deposited during marine incursions, the former presence of marine phases, the thickness and extent of these phases incursions will probably? presumably remain, unknown (extracted from Daley and Balson, 1999).

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Further Information

Daley, B. & Balson, P., (1999). British Tertiary Stratigraphy, Geological Conservation Review Series, No. 15, Joint Nature Conservation Committee, Peterborough.

King, C. (2006). Palaeogene and Neogene: uplift and a cooling climate. In: Brenchley, P.J. & Rawson, P.F. (eds.) The geology of England and Wales , 2nd edn, p. 395-428. The Geological Society, London.