Note 125 — Chapter XI · THE CAMBRIAN VOLCANOES OF NORTH WALES, THE MALVERN HILLS AND WARWICKSHIRE
Reading edition
Their antiquity was recognized by Yates as far back as 1825 (Trans. Geol. Soc. 2nd series, vol. ii. p. 261). They had been confounded with "Millstone Grit" and "Coal-shale" by Conybeare and Phillips, and this mistake was adopted on the maps and memoirs of the Geological Survey.
[126] Geol. Mag. (1882), p. 563.
[127] Op. cit. (1886), p. 319.