I have for some years had serious doubts as to the correctness of the Map of the Geological Survey so for as it relatesto the supposed presence of Millstone-grit in the northern portion of the Bristol Coal-field in the neighbourhood of Kingswood Hill; and in a foot-note to a most valuable lecture delivered by my friend Mr. Robert Etheridge, F.G.S. (of the RoyalSchool of Mines) at the Bristol Mining School in 1857, and published in a volume of Lectures issued by that Institution, Ihad, so long ago as that year, expressed doubts as to the existence of Millstone-grit at the surface near kingswood. Sincethen I have had much greater opportunities of investigating the matter, having taken, with my partners, a large tract of mineral property in that district; and the results of those investigations thoroughly confirm the doubts I had previously entertained, and in fact fully satisfy my mind that what is shown as Millstone-grit on the Government Geological Map, as also on the valuable map lately published by Mr. William Sanders, F.R.S., of Bristol, is really nothing more than one of thesandstones (the ‘Holmes Rock’) so common in the Coal-measures proper, and developed on a grand scale in the Pennant-grit dividing the Upper and Lower Coal-series of all the South-western Coal-fields.