Published online by Cambridge University Press: 01 May 2009
The selection of a base for the Devonian System has evoked much controversy, and summaries of the literature are given in several papers. The subject has acquired a new significance recently through the work of Ch. Barrois and his coadjutors in the north of France, and that of W. W. King and L. D. Stamp in England. The matter has been argued at length in the papers referred to, and it is impossible to appreciate all the factors involved without reference to them.
Communicated by permission of the Director of H.M. Geological Survey.
page 385 note 2 Schuchert, C., Bull. Geol. Soc. Amer., vol. xi, 1900, p. 241CrossRefGoogle Scholar.Wiiliams, H. S.Google Scholar ibid., p. 333. de Dorlodot, H., Ann. Soc. Geol. de Belgique, tom. xxxix, 1912, p. M 291.Google Scholar Barrois, Ch., Pruvost, P. and Dubois, G., Mem. Soc. Geol. du Nord, torn. vi, fase. 2, 1922 (for 1920), p. 163.Google Scholar Stamp, L. D., Geol. Mag., 1923, p. 276.CrossRefGoogle Scholar
page 385 note 3 Proc. Geol. Assoc., vol. xxxvi, 1925, pp. 383–9.Google Scholar
page 386 note 1 Quart. Journ. Geol. Soc., vol. xii, 1856, pp. 15–25.Google Scholar
page 386 note 2 See Geikie, A., Quart. Journ. Geol. Soc., vol. xvi, 1860, p. 312CrossRefGoogle Scholar, and “The Geology of Edinburgh” (Mem. Geol. Surv.), 1861, pp. 4–7.Google Scholar
page 387 note 1 “Explanation of Sheet 23” (Mem. Geol. Bury. Scotland), 1873, p. 13.Google Scholar
page 387 note 2 “The Silurian Rocks of Britain, vol. i, Scotland” (Mem. Geol. Surv.), 1899, pp. 64–9 and 564–606.Google Scholar
page 388 note 1 It should be noted that this is not the sense in which the term Downtonian was defined by Lapworth, C., Ann. Mag. Nat. Hist., ser. v, vol. v, 1880, p. 48: “…the sandy strata of the Upper Ludlow, the Bone-beds and the Downton Sandstone. For the sake of distinction these may collectively be termed the Downtonian formation.” This definition has been adhered to subsequently by certain other authors.Google Scholar
page 388 note 2 In the literature of the subject the term Ludlow includes in some eases the grey beds above the Ludlow Bone Bed but in others it does not. In this article Upper Ludlow means the beds between the top of the Dayia Shales and the base of the Ludlow Bone Bed.
page 388 note 3 “Summary of Progress” for 1901 (Mem. Geol. Sure.), 1902, p. 36Google Scholar; and “The Country around Ammanford” (Mem. Geol. Sure.), 1907, pp. 37–52.Google Scholar
page 389 note 1 Quart. Journ. Geol. Soc., vol. lxii, 1906, p. 195.Google Scholar
page 389 note 2 Op. cit.
page 389 note 3 Ibid., p. 386.
page 389 note 4 “The Downtonian Fauna of Norway,” Vid. Selsk. Skrifter, Kristiania 1924, No. 6, fig. 29.Google Scholar
page 390 note 1 Op. cit., pp. 18–20.
page 391 note 1 Mém. Mus. r. Nat. Hist. Belg., vol. vi, 1912, pp. 57–8.Google Scholar
page 391 note 2 Op. cit.
page 391 note 3 op. cit.
page 391 note 4 op. cit.
page 391 note 5 Hede, J. E., Sver. Geol. Unders. Arsbok., 14 (1920), No. 7, 1921.Google Scholar
page 391 note 6 See Geol. Meg., 1895, p. 170.Google Scholar
page 391 note 7 Amer. Journ. Sc., ser. v, vol. iv, 1922, p. 53.Google Scholar
page 392 note 1 Maryland Geol. Surv., “Silurian,” 1923, p. 45, etc.Google Scholar
page 392 note 2 Schuchert, op. cit., pp. 264–5.
page 392 note 3 This unfortunate word has been the cause of much confusion and should be abandoned for everything except the Tilestones of the Llandilo area and beds proved to be identical with them. We have still no convincing demonstration of their relationship to the Shropshire sequence.
page 394 note 1 Cantrill, T. C., in “The Country around Milford” (Mem. Geol. Surv.), 1916, p. 59.Google Scholar
page 394 note 2 Kiaer, J., op. cit., p. 6.
page 395 note 1 King, W. W., op. cit., p. 387.
page 396 note 1 Identified by Mr. J. Pringle.
page 397 note 1 Robertson, T., “Summary of Progress” for 1926 (Mem. Geol. Surv.), 1927, p. 93.Google Scholar
page 397 note 2 Ibid., p. 85.
page 397 note 3 Phillips, J., Mem. Geol. Sun., vol. ii, pt. i, p.98.Google Scholar
page 397 note 4 Pringle, J., in “Summary of Progrss” for 1915 (Mem. Geol. Surv.), 1916, p. 44.Google Scholar
page 398 note 1 “The Country around Ammanford” (Mem. Geol. Bury.), 1907, p. 52. To these may be added Tentaculites, found during a recent visit. There are poorly preserved brachiopods in the Sawdde river section. Additional fossil evidence in this district is very desirable.Google Scholar
page 398 note 2 Perner, J., and O. Kodym, op. cit., pp. 67–72.