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Gravity Anomalies in the Channel Islands

Published online by Cambridge University Press:  01 May 2009

A. A. Day
Affiliation:
Department of Geology and Geophysics, University of Sydney.

Abstract

Bouguer gravity anomalies have been determined at seventy-nine stations on Alderney, Guernsey, and Jersey. On Alderney the anomalies are clearly dependent on the nature of the outcropping rock-types, and permit approximate values for the thickness of two outcropping rock masses to be obtained. On Guernsey the anomalies are not closely related to the surface geology, and suggest that the north-eastern coastal area is underlain by a body of dense rock, possibly of ultrabasic composition. The anomalies on Jersey indicate that the sedimentary rocks of western Jersey are underlain at no great depth by rock of density comparable to that of granite. In eastern Jersey the dominating feature of the anomalies is a pronounced “high” centred near Grande Charriére. It is shown that this feature is most reasonably considered to be the effect of a large buried gabbro intrusion.

Type
Articles
Copyright
Copyright © Cambridge University Press 1959

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References

Cook, A. H., and Murphy, T., 1952. Measurements of Gravity in Ireland. Dublin Inst. Adv. Stud., Geophys. Mem., ii (4), 7.Google Scholar
Day, A. A., 1955. On the values of Gravity at St. Anne (Alderney), St. Peter Port (Guernsey), and St. Helier (Jersey). Mon. Not. Roy. Astron. Soc., Geophys. Suppl., vii, 76–9.Google Scholar
Day, M. N. Hill, Laughton, A. S., and Swallow, J. C., 1956, Seismic Prospecting in the Western Approaches of the English Channel. Quart. Journ. Geol. Soc., cxii, 1544.CrossRefGoogle Scholar
Groves, A. W., 1927. The Heavy Minerals of the Plutonic Rocks of the Channel Islands: 1, Jersey. Geol. Mag., lxiv, 457.CrossRefGoogle Scholar
Henson, F. A., 1956. The Geology of South-West Jersey, Channel Islands. Proc. Geol. Assoc., lxvii, 266293.CrossRefGoogle Scholar
Mourant, A. E., 1933. The Geology of Eastern Jersey. Quart. Journ. Geol. Soc., lxxxix, 273307.Google Scholar
Noury, C., 1886. Geologie de Jersey. Paris and Jersey.Google Scholar
Plymen, G. H., 1921. The Geology of Jersey. Proc. Geol. Assoc., xxxii, 151172.Google Scholar
Plymen, G. H., 1922. The Geology of Alderney. Trans. Soc. guernesiaise, ix, 128.Google Scholar
Plymen, G. H., 1932. The Geology of Guernsey. Trans. Soc. guernesiaise xi, 301.Google Scholar
Plymen, G. H., 1951. Trans. Soc. guernesiaise xiv, 104.Google Scholar
Plymen, G. H., 1953. Trans. Soc. guernesiaise xiv, 266.Google Scholar
Wells, A. K., and Wooldridge, S. W., 1931. The Rock Groups of Jersey, with special reference to Intrusive Phenomena at Ronez. Proc. Geol. Assoc., xlii, 178215.CrossRefGoogle Scholar