When the geological mapping of England and Wales moved onto the 'New Series' base maps and the consequent change of sheetlines and sheet numbers, the sheet memoirs followed suit. This series covers those memoirs issued with New Series numbers whether 1:63,360 or 1:50,000 scale. This series is still current. While differing in style over their long history, the stated aim of the later memoirs was to provide an objective and comprehensive account of the geology of the published 1:50,000 map area. They were designed to be read in conjunction with the map, though they also contained enough geographical information to allow them to be read alone. See also the earlier sheet memoir series based on the Old Series numbering and the recent 'Sheet descriptions' and 'Sheet explanations' series.