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Published online by Cambridge University Press: 01 May 2009
Logan, in 1840, noted the occurrence of pebbles of cannel in the roof of a coal-bed in South Wales; also of pebbles of coal in the ‘Pennant’ rock (Proc. Geol. Soc., vol. iii, p. 276). De la Beche refers to coal pebbles in the Monmouth and Glamorganshire Coalfield, and H. K. Jordan to similar forms of coal in the base of the Pennant Series, and to a coal pebble the size of a hen's egg in the roof of the ‘Rock Fawr’ coal-seam near Bridgend (Q.J.G.S., vol. xxxiii, p. 932). In the roof of the ‘Nanaimo’ coal, in Vancouver Island, a coal pebble in a conglomerate was recorded in 1906. Several instances of water-worn lumps of coal have been mentional in the volumes of the second Geological Survey of Pennsylvania as having been found in the semi-bituminous and Pittsburg regions.
page 157 note 2 [Mem. Geol. Survey, 1846, vol. i, pp. 153. 193, etc.Google Scholar; see also Geology of the S. Wales Coal-field, 1907, pt. vii, by A. Strahan and others.—Ed.]
page 158 note 1 [See also remarks by W. Sanders and H. Cossham on pebbles of coal in the Bristol Coalfield. The pebbles found in the Upper Measures were stated to be anthracitic, proving their derivation from the Lower Measures. (Geol. Mag., 1865, p. 134.)—Ed.]
page 158 note 2 There are, approximately, 1,000 feet of Coal-measures above and 1,000 feet beneath this seam.
page 159 note 1 The pebble takes a high polish similar to spirey coal.