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On an Inverted Mass of Upper Cretaceous Strata near Leighton Buzzard, Bedfordshire; and on an Overlap of the Upper Gault in that Neighbourhood

Published online by Cambridge University Press:  01 May 2009

F. L. Kitchin  and
J. Pringle
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Summary of conclusions.

We may summarize our chief conclusions as follows:—

(1) The brachiopod-bed of Shenley Hill, as described by Messrs. Lamplugh & Walker, who referred it to the Lower Greensand, is shown by stratigraphical and palæontological evidence to be of a composite character. Its constituent parts belong respectively to the basement-bed of the Upper Gault and to the basement-bed of the Cenomanian stage, as understood by English geologists (sub-zone of Catopygus columbarius).

(2) The Cenomanian bed is present in the form of isolated lenticles of limestone. Although no comparable stratum can be found at the present outcrop, which has receded from the area where conditions produced this particular type of deposit, the bed has a close lithological counterpart in Northern France (Matringhem), where there is an almost identical bed at the base of the varians zone.

(3) At Harris's Pit the Cenomanian bed, an inconstant layer of Upper Greensand formerly seen above it, and an overlying mass of Gault Clay of rostratus age are in an inverted order of succession. There is a junction of erosion and non-sequence between the Gault and the Cenomanian bed.

Type
Original Articles
Information
Geological Magazine , Volume 57 , Issue 3 , March 1920 , pp. 100 - 113
Copyright
Copyright © Cambridge University Press 1920

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References

page 102 note 1 Lamplugh, G. W. & Walker, J. F., “On a Fossiliferous Band at the top of the Lower Greensand near Leighton Buzzard (Bedfordshire)” Quart. Journ. Geol. Soc., vol. lix, 1903, p. 240.Google Scholar

page 103 note 1 “Excursion to Leighton Buzzard”: Proc. Geol. Assoc., vol. xx, pt. vi, 1908, p. 475.Google Scholar

page 103 note 2 Lamplugh, G. W. & Walker, J. F., op. cit., 1903, p. 240.Google Scholar

page 107 note 1 Compare remarks by Woodward, H. B., “The Chalky Boulder-clay and the Glacial Phenomena of the Western Midland Counties of Englaod”: Geol. Mag., 1897, pp. 495–6.Google Scholar

page 108 note 1 In a discussion on Mr. Home's paper, cited below, p. 381.Google Scholar

page 108 note 2 Fisher, O., “On Roslyn or Roswell Hill Clay-pit near Ely” Geol. Mag., 1868, p. 407.Google Scholar Bonney, T. G., “Notes on the Roslyn Hill Clay-pit”: Geol. Mag., 1872, p. 403Google Scholar. Also Cambridgeshire Geology, 1875, p. 69.Google Scholar

page 108 note 3 Home, H., “On a transported mass of Ampthill Clay in the Boulder.clay at Biggleswade, Bedfordshire”: Quart. Journ. Geol. Soc., vol. lix, 1903, p. 375.CrossRefGoogle Scholar

page 108 note 4 For references to some striking eases see Woodward, H. B., op. cit., 1897, p. 495.Google Scholar

page 108 note 5 Carruthers, R. G., “On the occurrence of a Cretaceous Boulder of unusual size at Leavad, in Caithness” Summary of Progress for 1910 (Mem. Geol. Surv.), 1911, P. 80Google Scholar. Tait, D., “On a large glacially transported mass of Lower Cretaceous Rock at Leavad, in the County of Caithness”: Trans. Edin. Geol. Soc., vol. x, pt. i, 1911.Google Scholar