The Upper Carboniferous rocks of the Ingleton Coal-field in North-West Yorkshire present a difficult study, and at the present time they are very imperfectly known. As mapped by the Geological Survey, there is apparently a perfect succession, passing up from the Yoredales, through the Millstone Grits, to the Lower and Middle Coal-measures. The coal-measures are in part overlain hy a series of red rocks, which have been assigned to the Permian, as in the case of other of the Midland Coal-fields. In the index of the Survey map of the north-eastern portion of the coal-field, the Deep Coal is taken as the top of the Lower, and the bottom of the Middle Coal-measures.