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The Late Triassic Blue Anchor Formation and the initial Rhaetian marine transgression in south-west Britain

Published online by Cambridge University Press:  01 May 2009

M. J. Mayall
M. J. Mayall
Affiliation:
The British Petroleum Company Limited, Britannic House, Moor Lane, London EC27 9BU.
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Summary

The Blue Anchor Formation of the Upper Trias in south-west Britain is divided into two members. The lower (Rydon Member) was deposited in an evaporitic lacustrine environment whilst the upper (Williton Member) was deposited in a shallow marine environment and represents the initial marine transgression into south-west Britain late in the Triassic Period. Sedimentological and clay mineralogical evidence indicates that the Williton Member is bounded by erosional disconformities and, at present, can only be positively recognised in North Somerset.

Type
Articles
Information
Geological Magazine , Volume 118 , Issue 4 , July 1981 , pp. 377 - 384
Copyright
Copyright © Cambridge University Press 1981

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References

Bhattacharya, N. 1962. Weathering of glacial tills in Indiana Bull. geol. Soc. Am. 73, 1007–20.CrossRefGoogle Scholar
Birkland, P. W. 1974. Pedology, Weathering and Geomorphological Research. New York: Oxford University Press.Google Scholar
Boyd-Dawkins, W. B. 1864. Outline of the Rhaetic Formation of West and Central Somerset Geol. Mag. 1, 257–60.CrossRefGoogle Scholar
Bradshaw, M. J. 1975. The origin of montmorillonite bands in the middle Jurassic of eastern England Earth Planet. Sci. Lett. 26, 245–52.CrossRefGoogle Scholar
Droste, J. B. 1956. Alteration of clay minerals by weathering in a Wisconsin till Bull. geol. Soc. Am. 67, 911–18.CrossRefGoogle Scholar
Hamilton, D. & Whittaker, A. 1977. Coastal exposures near Blue Anchor, Watchet and St Audrie's Bay, Somerset. In Geological Excursions in the Bristol District (ed. Savage, R. J. G.), pp. 101–10. University of Bristol.Google Scholar
Ivimey-Cook, H. C. 1974. The Permian and Triassic deposits of Wales. In The Upper Palaeozoic and Post-Palaeozoic Rocks of Wales (ed. Owen, T. R.), pp. 295–321. Cardiff: University of Wales Press.Google Scholar
Jeans, C. V. 1978. The origin of the Triassic clay assemblages of Europe with special reference to the Keuper Marl and Rhaetic of parts of England Phil. Trans. R. Soc. Lond. A. 289, 549–639.Google Scholar
Mayall, M. J. 1979. The clay mineralogy of the Rhaetic transgression in Devon and Somerset – environmental and stratigraphic implications Proc. Ussher Soc. 4 (3), 303–11.Google Scholar
Orbell, G. 1973. The palynology of the British Rhaeto-Liassic Bull geol. Surv. Gt. Br. 44, 1–44.Google Scholar
Picard, M. D. 1966. Orientated, linear shrinkage cracks in Green River Formation (Eocene), Raven Ridge area, Uinta Basin, Utah J. sediment. Petrol. 36 (4), 1050–7.Google Scholar
Richardson, L. 1905. The Rhaetic and contiguous deposits of Glamorganshire. Q. Ji Geol. Soc. Lond. 61, 385–424.CrossRefGoogle Scholar
Richardson, L. 1911. The Rhaetic and contiguous deposits of West, Mid and parts of East Somerset Q. Jl Geol. Soc. Lond. 67, 1–74.CrossRefGoogle Scholar
Sellwood, B. W., Durkin, M. K. & Kennedy, W. J. 1970. Field meeting on the Jurassic and Cretaceous rocks of Wessex Proc. Geol. Assoc. 81 (4), 715–32.CrossRefGoogle Scholar
Stevenson, C. R. 1970. Discussion to Geological Society Trias Symposium, November 1967. Q. Ji Geol. Soc. Lond. 126, 16, 81, 88.Google Scholar
Stevenson, C. R. & Warrington, G. 1971. Jurassic and Cretaceous rocks of Wessex: highest Keuper deposits. Proc. Geol. Ass. 82, 297–99.CrossRefGoogle Scholar
Tucker, M. E. 1977. The marginal Triassic deposits of South Wales: continental facies and palaeogeography J. Geol. 12, 169–88.CrossRefGoogle Scholar
Tucker, M. E. 1978. Triassic lacustrine sediments from South Wales: shore-zone clastics, evaporites and carbonates. In Modern and Ancient Lake Sediments (ed. Matter, A. and Tucker, M. E.), pp. 205–24. Int. Assoc. Sedimentologists Spec. Publ. 2.CrossRefGoogle Scholar
Warrington, G., 1974. Studies in the palynological biostratigraphy of the British Trias. I. Reference sections in West Lancashire and North Somerset Rev. Palaebot. Palynol. 17, 133–47.CrossRefGoogle Scholar
Warrington, G., Audley-Charles, M. G., Elliott, R. E., Evans, W. B., Ivimey-Cook, H. C., Kent, P. E., Robinson, P. L., Shotton, F. W. & Taylor, F. M. 1980. The Triassic – correlation of Triassic rocks in the British Isles. Geol. Soc. Special Report No. 13.Google Scholar