^{page 244 note 1} The piece of core showing this surface is in the Geological Museum of the University of Birmingham.

^{page 248 note 1} “A Critical Examination of Stricklandia (= Stricklandinia) lirata (J. de C. Sowerby), 1839, forma typica,” GEOL. MAG., 1935, LXXII, 401–424.Google Scholar

^{page 248 note 2} An account of geo-electrical measurements in the boring is given by Shaw, S. H., Mining Mag., 1937, lvi, pp. 205–206, who suggests that an increase in resistivities observed at and below 920 ft. may mark the Wenlock- Llandovery junction.Google Scholar

^{page 248 note 3} See, for example, the Lichfield Memoir (Explanation of Sheet 154) of the Geological Survey, 9.Google Scholar

^{page 249 note 1} Wills, L. J. and others, “New Exposures in the Rubery-Longbridge-Rednal District, South of Birmingham. B: The Upper Liandovery Series of Rubery,” Proc. B'ham. Nat. Hist, and Phil. Soc., xv, part iii, 1925, 67–83.Google Scholar

^{page 249 note 2} Wills, L. J., “An Outline of the Palaeogeography of the Birmingham Country,” Proc. Geol. Assoc., xlvi, 1935, pt. ii, 217.Google Scholar

^{page 249 note 3} “The Stratigraphy of the Valentian Rocks of Shropshire. The Longmynd-Shelve and Breidden Outcrops,” Quart. Journ. Geol. Soc., 1932, lxxxviii, 869.Google Scholar

^{page 252 note 1} “The Minerals of Bentonite and Related Clays and their Physical Properties,” Amer. Ceramic Soc. Journ., 1926, 9, No. 2, 79. See also C. S. Ross, “Altered Volcanic Materials and their Recognition,” Bull. Amer. Assoc. Petroleum. Geol., 1928, 12, 143–164.Google Scholar

^{page 252 note 2} See Spence, S., “Bentonite” Mines Branch, Dept. of Mines, Canada, 1924, pp. 1–36, 13 plates; and C. W. Davies, “Bentonite, Its Properties, Mining, and Utilization,” Technical Paper 438, Bureau of Mines, U.S. Dept. of Commerce, 1928, pp. 1–51.Google Scholar

^{page 253 note 1} The Silurian System, 1839, pt. i, 304, 434–5.Google Scholar

^{page 253 note 2} Explanation of Sheet 154, 1919, 214.Google Scholar

^{page 253 note 3} Bonine, C. A. and Honess, A. P., “Bentonite in Pennsylvania,” Bull. 5 Mineral Industries Experiment Station, Pennsylvania State College, Proc. Pennsylvania Acad. of Science, iii, 1929, 1–8. L. Whitcombe, “Correlation by Ordovician Bentonite,” Journ. Geol., 1932,522–534. R. R. Rosenkrans, “Correlation Studies of the Central and South Central Pennsylvania Bentonite Occurrences,” Technical Paper ii, Min. Ind. Experiment Station, Amer. Journ. Science, 5th Series, 1934, xxvii, 113–134.Google Scholar

^{page 256 note 1} Ross and Shannon, loc. cit., 96.Google Scholar

^{page 256 note 2} See Bonine and Honess, loc. cit., p. 4; Rosenkrans, loc. cit., 128.Google Scholar

^{page 257 note 1} Turner, J. Selwyn, “Gotlandian Vuleanicity in Western Europe,” GEOL. MAG., 1935, LXXII, 145–151.CrossRefGoogle Scholar