Hostname: page-component-848d4c4894-p2v8j Total loading time: 0 Render date: 2024-04-30T18:34:07.731Z Has data issue: false hasContentIssue false
  • English
  • Français

Seismically-induced load structures in the basal Coal Measures, South Wales

Published online by Cambridge University Press:  01 May 2009

J. D. Weaver
J. D. Weaver
Affiliation:
Division of Geology, Derby College of Art and Technology, Kedleston Road, Derby DE3 1GB, England
Get access Rights & Permissions [Opens in a new window]

Summary

Within the basal Coal Measures between Ystradgynlais and Abercraf a number of liquefaction layers are seen displaying ball and pillow structures. These layers consist of balled-up, ovoid masses of sandstone some 0.25–0.3 m thick and 0.5–0.7 m across. It is considered that they were formed by loading, resulting from the lique-faction of underlying silts, produced by the passage of earthquake shock waves associated with the main fault zone of the Swansea Valley Disturbance. Elsewhere in South Wales, horizons displaying load and slump structures in rocks of Upper Palaeozoic age may have resulted from seismic shock waves caused by contemporary movements along major Variscan fractures.

Type
Articles
Information
Geological Magazine , Volume 113 , Issue 6 , November 1976 , pp. 535 - 543
Copyright
Copyright © Cambridge University Press 1976

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Allen, J. R. L. 1963. Depositional features of Dittonian Rocks: Pembrokeshire Compared with the Welsh Borderland. Geol. Mag. 100, 385–400.CrossRefGoogle Scholar
Anketell, J. M., Cegla, J. & Dzulynski, S. 1970. On the deformational structures in systems with reversed density gradients. Ann. Soc. Géol. Pol. 40, 3–30.Google Scholar
Anketell, J. M. & Dzulynski, S. 1968. Transverse deformational patterns in unstable sediments. Ann. Soc. Géol. Pol. 38, 411–416.Google Scholar
Blatt, H., Middleton, G. & Murray, R. 1972. Origin of Sedimentary Rocks. Prentice Hall.Google Scholar
Dix, E. 1933. The succession of fossil plants in the Millstone Grit and the lower portion of the Coal Measures of the South Wales Coalfield. Palaeontographica 78B, 158–202.Google Scholar
Ferm, J. C. & Huddle, J. W. 1955. Slumps and mud flows in rocks of Pennsylvanian age in the Appalachian Plateau. Bull geol. Soc. Am. 66, 1557.Google Scholar
Gill, W. D. & Kuenen, P. H. 1957. Sand Volcanoes on slumps in the Carboniferous of County Clare, Ireland. Q. Jl geol. Soc. Lond. 113, 441–60.CrossRefGoogle Scholar
Jenkins, T. B. H. 1962. The sequence and correlation of the Coal Measures of Pembrokeshire. Q. Jl geol. Soc. Lond. 118, 65–101.CrossRefGoogle Scholar
Kelling, G. & Williams, B. P. J. 1966. Deformation structures of sedimentary origin in the Lower Limestone Shales (basal Carboniferous) of South Pembrokeshire, Wales. J. Sedim. Petrol. 36, 927–39.Google Scholar
Kendall, P. F. 1919. On ‘wash-outs’ in coal seams and the effects of contemporary earthquakes. Abs. Proc. Geol. Soc., 1031, 28–31.Google Scholar
Keunen, P. H. 1948. Slumping in the Carboniferous rocks of Pembrokeshire. Q. JI. geol. Soc. Lond. 104, 365–85.CrossRefGoogle Scholar
Keunen, P. H. 1958. Experiments in geology. Trans. Geol. Soc. Glasgow, 23, 1–28.CrossRefGoogle Scholar
Leitch, D., Owen, T. R. & Jones, D. G. 1958. The basal coal measures of the South Wales Coalfield from Llandybie to Brynmawr Q. Jl geol. Soc. Lond. 113, 461–86.CrossRefGoogle Scholar
Lowe, D. R. 1975. Water escape structures in coarse grained sediments. Sedimentology 22, 157–204.CrossRefGoogle Scholar
Robertson, T. 1932. The geology of the South Wales Coalfield. V. The geology of the country around Merthyr Tydfil. 2nd edition. Mein. geol. Surv. U.K.Google Scholar
Selley, R. C., Shearman, D. J., Sutton, J. & Watson, J. 1963. Some underwater disturbances in the Torridonian of Skye and Raasay. Geol. Mag. 100, 224–243.CrossRefGoogle Scholar
Smith, B. 1916. Ball or pillow-form structures in sandstones. Geol. Mag. 3, 146–56.CrossRefGoogle Scholar
Sullivan, R. 1966. The stratigraphical effects of the mid-Dinantian movements in South West Wales. Palaeography. Palaeoclimatol., Palaeoecol. 5, 213–244.CrossRefGoogle Scholar
Weaver, J. D. 1975. The structure of the Swansea Valley Disturbance between Clydach and Hay-on-Wye, South Wales. Geol. J. 10, 75–86.CrossRefGoogle Scholar
Williams, P. F. 1969. Notes on some deformation structures of sedimentary origin in the Little Haven – Amroth Coalfield, Pembrokeshire. Geol. Mag. 106, 395–411.CrossRefGoogle Scholar