Published online by Cambridge University Press: 01 May 2009
Mine sections beneath the Firth of Forth at Wellesley Colliery fill gaps in the Knowledge of the strata adjacent to the junction between Middle and Upper Coal Measures. A hitherto unrecorded marine band which may formerly have been confused with Skipsey's Marine Band is now placed about 70 feet lower in the succession. A coal seam near the base of the Upper Coal Measures contains a rib of kaolin mudstone comparable with tonstein. Local reddening and alteration of coal to limestone in the Upper Coal Measures and more particularly in the upper part of the Middle Coal Measures is typical of a zone of partial oxidation beneath some major unconformity which may lie within the Upper Coal Measures or at some unlocated sub-Permian horizon above. Structureless highly-coloured clayrocks in the Upper Coal Measures, however, are regarded as primary red beds comparable with, and perhaps the equivalents of, the Etruria Marl of the English Midlands.