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Journal of the Geological Society

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Discussion on lithospheric flexure, uplift, and landscape evolution in south-central England

¹ Department of Geology, Ulster Museum, Botanic Gardens, Belfast BT9 5AB, Northern Ireland. (e-mail: michael.simms@nics.gov.uk)
² Department of Geological Sciences, University College London, Gower StreetLondon WC1E 6BT (e-mail: d.donovan@ucl.ac.uk)
³ Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX2 3PR, UK (e-mail: tony@earth.ox.ac.uk)

The first 20% of the full text of this article appears below.

Michael J. Simms writes: Watts, McKerrow and Fielding (2000) have made an interesting suggestion, that much of the present topography of the Cotswolds and the clay vales to the west has arisen through Late Pleistocene (post-450 ka) uplift in the Midlands, but the evidence on which it is based is extremely weak. The basic premise on which their hypothesis is founded is that the Northern Drift Group in Oxfordshire originated from outcrops of Triassic conglomerates in the Midlands, with these two regions once being linked by a continuous river along which the clasts were transported. They also contend that such a river could not develop across strike unless close to sea level, an assumption they fail to justify, from which they conclude that Pleistocene uplift must account for the presence of the Northern Drift Group at altitudes today of >100 metres OD.

However, although the ultimate source of the exotic (pre-Jurassic) clasts is not in doubt, Watts et al. (2000), and others before them (e.g. Whiteman & Rose 1992; Bridgland 1994), fail to provide convincing evidence for the putative ‘Northern Drift River’. It seems that the only evidence for this supposed river is clast lithology and rather speculative interpretation of terrace gradients in the Evenlode valley (Whiteman & Rose 1992). A more parsimonious transport mechanism for these exotic clasts, that of ice movement from the NW, has not been accorded due consideration in any of these recent papers.

Although much of the Northern Drift Group clearly is fluvial in character, observations cited by Hey (1986) are far more reminiscent of till. They include striated boulders at several sites and sediments consisting ‘for the most part of unstratified reddish sandy clay with pebbles, the latter often matrix-supported’ (Hey 1986, p. 293). Even the sandy, . . . [Full Text of this Article]

This article has been cited by other articles:

				A.B. Watts, W.S. McKerrow, and K. Richards Localized Quaternary uplift of south-central England Journal of the Geological Society, January 1, 2005; 162(1): 13 - 24. [Abstract] [Full Text] [PDF]